Text

Sequoyah, Units 1 and 2, Enclosure 1, Evaluation of Proposed Changes Attachment 1 Proposed Sqn Units 1 and 2 UFSAR Text Changes (Markups), Page 2.4-42 Through Enclosure 2
	ML12226A563
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Site:	Sequoyah
Issue date:	08/10/2012
From:	; Tennessee Valley Authority
To:	; Office of Nuclear Reactor Regulation
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SQN-2.4.8 Cooling Water Canals and Reservoirs (HISTORICAL INFORMATION)2.4.8.1 CanalsThe intake channel, as shown in Figure 2.1.2-1, referenced in paragraph 2.4.1.1, is designed for a flowof 2,250 cfs. At minimum pool (elevation 675.0 ft), as shown in Figure 2.4.8-1, this flow is maintainedat a velocity of 2.7 fps.The protection of the intake channel slopes from wind-wave activity is afforded by the placement ofriprap, shown in Figure 2.4.8-1, in accordance with TVA Design Standards, from elevation 665.0 ft toelevation 690.0 ft. The riprap is designed for a wind velocity of 45 mph.2.4.8.2 Reservoirs (HISTORICAL INFORMATION)Chickamauga Reservoir provides the cooling water for SQN. This reservoir and the extensive TVAsystem of upstream reservoirs, which regulate inflows, are described in Table 2.4.1-42. The locationin an area of ample runoff and the extensive reservoir system assures sufficient cooling waterflow forthe plant.2.4.9 Channel Diversions (H,'ISTORDICAL., .N FORMATION)Channel diversion is not a potential problem for the plant. There are now no channel diversionsupstream of SQN that would cause diverting or rerouting of the source of plant cooling water, andnone are anticipated in the future. The floodplain is such that large floods do not produce majorchannel meanders or cutoffs. Carbon 14 dating of material at the high terrace levels shows that theTennessee River has essentially maintained its present alignment for over 35,000 years. Thetopography is such that only an unimaginable catastrophic event could result in flow diversion abovethe plant.2.4.10 Flooding Protection RequirementsAssurance that safety-related facilities are capable of surviving all possible flood conditions is providedby the discussions given in Paragraph 21.2.2Section 2.4.14, SeetieO-3.4, SeetiGR-3.8.1, 3.8.2, andAppendix2.4 3.8.4.The plant is designed to be shutdown and remain in a safe shutdown condition for any rainfall floodexceeding plant grade, up to the "design basis flood" discussed in Su*bsection 2.4.37 and for lower,seismic-caused floods discussed in Subsection 2.4.4. Any rainfall flood exceeding plant grade will bepredicted at least 27 hours3.125e-4 days 0.0075 hours 4.464286e-5 weeks 1.02735e-5 months in advance by TVA's Reservoir Operations.-Warning of seismic failure of key upstream dams will be available at the plant at4 eastapproximately27 hours before a resulting flood surge would reach plant grade. Hence, there is adequate time toprepare the plant for any flood.See Appendix-2AASection 2.4.14 for a detailed presentation of the flood protection plan.2.4.11 Low Water ConsiderationsBecause of its location on Chickamauga Reservoir, maintaining minimum water levels at SQN is not aproblem. The high rainfall and runoff of the watershed and the regulation afforded by upstream damsassure minimum flows for plant cooling.2.4.11.1 Low Flow in Rivers and StreamsThe targeted minimum water level at SQN is elevation 675.0 ft, which cOrresponds to the lower boundof the ..iFnte operating zone fr Chickamrauga Re.....ir and would occur in the winter flood season asa result of Chickamauga Reservoir operation. On rare occasions, the water level may be slightly lower(.1 or .2 tenths of a foot) for a brief period of time (hours) due to hydropower peaking operations at2.4-42 SQN-Chickamauga and Watts Bar Dams during the winter season. A minimum elevation of 675.0 ft mustbe maintained in order to provide the prescribed commercial navigation depth in ChickamaugaReservoir.The "Preferred Alternative" Reservoir Operating Policy was designed to provide increased recreationopportunities while avoiding or reducing adverse impacts on other operating objectives and resourceareas. Under the Preferred Alternative, TVA will no longer target specific summer pool elevations at10 tributary storage reservoirs. Instead, TVA tends to manage the flow of water through the system tomeet operating objectives. TVA will use weekly average system flow requirements to limit thedrawdown of 10 tributary reservoirs (Blue Ridge, Chatuge, Cherokee, Douglas, Fontana, Nottely,Hiawassee, Norris, South Holston, and Watauga) June 1 through Labor Day to increase recreationopportunities. For four main stem reservoirs (Chickamauga, Guntersville, Wheeler, and Pickwick),summer operating zones will be maintained through Labor Day. For Watts Bar Reservoir, the summeroperating zone will be maintained through November 1.Weekly average system minimum flow requirements from June 1 through Labor Day, measured atChickamauga Dam, are determined by the total volume of water in storage at the 10 tributaryreservoirs compared to the seasonal total tributary system minimum operating guide (SMOG). If thevolume of water in storage is above the SMOG, the weekly average system minimum flow requirementwill be increased each week from 14,000 cfs (cubic feet per second) the first week of June to 25,000cfs the last week of July.Beginning August 1 and continuing through Labor Day, the weekly average flow requirement will be29,000 cfs. If the volume of water in storage is below the SMOG curve, 13,000 cfs weekly averageminimum flows will be released from Chickamauga Dam between June 1 and July 31, and 25,000 cfsweekly average minimum flows will be released from August 1 through Labor Day.Within these weekly averages, TVA has the flexibility to schedule daily and hourly flows to best meetall operating objectives, including water supply for TVA's thermal power generating plants. Flows maybe higher than these stated minimums if additional releases are required at tributary or main riverreservoirs to maintain allocated flood storage space or during critical power situations to maintain theintegrity and reliability of the TVA power supply system.In the assumed event of complete dam failure of the north embankment of Chickamauga Damresulting in a breach width of 400 feet, with the Chickamauga pool at elevation 681 .0 ft, the watersurface at SQN will begin to drop within one hour and will fall to elevation 641.0 ft about 6051 hour0.07 days 1.681 hours 0.01 weeks 0.0023 months safter failure. TVA will begin providing steady releases of at least 14,000 cfs at Watts Bar within 12hours of Chickamauga Dam failure to assure that the water level recession at SQN does not dropbelow elevation 641.0 ft. The estimated minimum river flow requirement for the ERCW system is only45 cfs.Reference: Programmatic Environmental Impact Statement, TVA Reservoir Operations Study, Recordof Decision, May 2004.2.4.11.2 Low Water Resulting From Surges, Seiches, or TsunamisBecause of its inland location on a relatively small, narrow lake, low water levels resulting from surges,seiches, or tsunamis are not a potential problem.2.4.11.3 Historical Low WaterFrom the beginning of stream gauge records at Chattanooga in 1874 until the closure of ChickamaugaDam in January 1940, the lowest daily flow in the Tennessee River at SQN was 3,200 cfs onSeptember 7 and 13, 1925. The next lowest daily flow of 4,600 cfs occurred in 1881 and also in 1883.Since January 1942, low flows at the site have been regulated by TVA reservoirs, particularly by WattsBar and Chickamauga Dams. Under normal operating conditions, there may be periods of severalhours daily when there are no releases from either or both dams, but average daily flows at the site2.4-43 SQN-have been less than 5,000 cfs only 0.65 p- rnabout 2.2% of the time and have been less than10,000 cfs,45-peF~eet about 10.4% of the time.On March 30 and 31, 1968, during special operations for the control of water milfoil, there were noreleases from either Watts Bar or Chickamauga Dams during the two-day period. The prey4eusminimumn daily flow was 700 cfs On Novcmnber 1, 1953. TVA no longer conducts special operations forthe control of water midfoil on Chickamnuga Reser-oirOver the last 25 years (1986 -2010) the numberof zero flow days at Watts Bar and Chickamaugqa Dams have been 0 and 2, respectively.Since January 1940, water levels at the plant have been controlled by Chickamauga R*sscvoir. Sincethen, Dam. For the period (1940 -2010), the minimum level at the dam was elevation 673.3 ft onJanuary 21, 1942. TVA no longer routinely conducts pre-flood drawdowns below elevation 675.0 ft atChickamauga Reservoir and the minimum elevation in the past 20 years (1987 -2006) was elevation674.97 ft at Chickamauga head water.2.4.11.4 Future ControlFuture added controls which could alter low flow conditions at the plant are not anticipated because nosites that would have a significant influence remain to be developed. However, any control that mightbe considered would be evaluated before implementation.2.4.11.5 Plant Requirements2.4.11.5.1 Two-Unit OperationThe safety related water supply systems requiring river water are: the essential raw cooling water(ERCW) (Subsection 9.2.2), and that portion of the high-pressure fire-protection system (HPFP)(Subsection 24A.42.4.14.4.1) supplying emergency feedwater to the steam generators. Thefire/flood mode pumps are submersible pumps located in the CCW intake pumping station. The CCWintake pumping station sump is at elevation 648.0 ft. The entrances to the suction pipes for thefire/flood mode pumps are at elevation 651.0 ft-feet-I 4knhes which is 32 feet and 24 feet, respectively,below the maximum normal water elevation of 683.0 ft and the normal minimum elevation of 675.0 ftfor the reservoir. Abnormal reservoir level is elevation 670 feet with a technical specification limit ofelevation 674 ft. For flow requirements of the HPFP during engineering safety feature operation(Reference 22). The ERCW pump sump in this independent station is at elevation 625.0 ft, which is58.0' ft below maximum normal water elevation, 50.0! ft below minimum normal water elevation, and16'ft below the 641 'ft minimum possible elevation of the river.Since the ERCW pumping station has direct communication with the river for all water levels and isabove probable maximum flood, the ERCW system for two-unit plant operation always operates in anopen cooling cycle.2.4.11.6 Heat Sink Dependability RequirementsThe ultimate heat sink, its design bases and its operation, under all normal and credible accidentconditions is described in detail in Subsection 9.2.5. As discussed in Subsection 9.2.5, the sink wasmodified by a new essential raw cooling water (ERCW) pumping station before unit 2 began operation.The design basis and operation of the ERCW system, both with the original ERCW intake station andwith the new ERCW intake station, is presented in Subsection 9.2.2. As described in these sections,the new ERCW station is designed to guarantee a continued adequate supply of essential coolingwater for all plant design basis conditions. This position is further assured since additional river watermay be provided from TVA's upstream multiple-purpose reservoirs, as previously discussed duringLow Flow in Rivers and Streams.2.4.11.6.1 Loss of Downstream DamThe loss of downstream dam will not result in any adverse effects on the availability of water to theERCW system or these portions of the original HPFP supplying emergency feedwater to the steam2.4-44 SQN-generator. Loss of downstream dam reduces ERCW flow about 7% to the component cooling andcontainment spray heat exchangers. ERCW flow does not decrease below that assumed in theanalysis (analyzed as 670' to 639') until more than two hours after the peak containment temperatureand pressure occurs. (See Section 6.2.1.3.4.)2.4.11.6.2 Adequacy of Minimum FlowThe cooling requirements for plant safety-related features are provided by the ERCW system. Therequired ERCW flow rates under the most demanding modes of operation (including loss ofdownstream dam) as given in Subsection 9.2.2 are contained in TVA calculations and flow diagrams.Two other safety-related functions may require water from the ultimate heat sink; these are fireprotection water (refer to Subparagraph 2.4.11.6.3) and emergency steam generator feedwater (referto Subsection 10.4.7). These two functions have smaller flow requirements than the ERCW systems.Consequently, the relative abundance of the river flow, even under the worst conditions, assures theavailability of an adequate water supply for all safety-related plant cooling water requirements.River operations methodology for maintaining UHS temperatures are discussed in "Monitoring andModerating Sequoyah Ultimate Heat Sink," Reference 21.2.4.11.6.3 Fire-Protection WaterRefer to the Fire Protection Report discussed in Section 9.5.1.2.4.12 Environmental Acceptance of EffluentsThe ability of surface waters near SQN, located on the right bank near Tennessee River Mile (TRM)484.5, to dilute and disperse radioactive liquid effluents accidentally released from the plant isdiscussed herein. Routine radioactive liquid releases are discussed in Section 11.2.The Tennessee River is the sole surface water pathway between SQN and surface water users alongthe river. Liquid effluent from SQN flows into the river from a diffuser pond through a system ofdiffuser pipes located at TRM 483.65. An accidental, radioactive liquid effluent release from SQNwould enter the Tennessee River after it reached the diffuser pond and entered the diffuser pipes.The contents of the diffuser pond enter the diffuser pipes and mix with the river flow upon discharge.The diffusers are designed to provide rapid mixing of the discharged effluent with the river flow. Theflow through the diffusers is driven by the elevation head difference between the diffuser pond and theriver [1] (McCold 1979). Descriptions of the diffusers and SQN operating modes are given inParagraph 10.4.5.2. Flow is discharged into the diffuser pond via the blowdown line, ERCW System(Subsection 9.2.2) and CCW System (Subsection 10.4.5). A layout of SQN is given in Figures 2.1.2-1and 2.1.2-2. Two pipes comprise the diffuser system and are set alongside each other on the riverbottom. They extend from the right bank of the river into the main channel. The main channel beginsnear the right bank of the river and is approximately 900 feet wide at SQN [1] (McCold, 1979). Eachdiffuser pipe has a 350-foot section through which flow is discharged into the river. The downstreamdiffuser leg discharges across a section 0 to 350 feet from the right bank of the main channel. Theupstream diffuser leg starts at the end of the downstream diffuser leg and discharges across a section350 to 700 feet from the right bank of the main channel. The two diffusers therefore provide mixingacross nearly the entire main channel width.The river flow near SQN is governed by hydro power operations of Watts Bar Dam upstream (TRM529.9) and Chickamauga Dam downstream (TRM 471.0). The backwater of Chickamauga Damextends to Watts Bar Dam. Peaking hydro power operations of the dams cause short periods of zero(i.e., stagnant) and reverse (i.e., upstream) flow near the plant. Effluent released from the diffusersduring these zero and reverse flow periods will not concentrate near the plant or affect any waterintake upstream. The maximum flow-reversal during 1978-1981 were not long enough to causedischarge from the diffusers to extend upstream to the SQN intake [2] (EI-Ashry, 1983), which is thenearest intake and located at the right bank near TRM 484.7. Moreover, the warm buoyant dischargefrom the diffusers will tend toward the water surface as it mixes the river flow and away from the2.4-45 SQN-cooler, denser water found near the intake opening below the skimmer wall. The intake openingextends the first 10 feet above the riverbed elevation of about 631 feet mean sea level (MSL). Theminimum flow depth at the intake is approximately 45 feet [3] (Ungate and Howerton, 1979). Thereare no other surface water users between the diffusers and this intake.Subsection 2.4.13 discusses groundwater movement at SQN. Effluent released through the diffuserswill have no impact on SQN groundwater sources along the banks of the river. Paragraph 2.2.3.8discusses the effect on plant safety features from flammable or toxic materials released in the rivernear SQN.The predominant transport and effect of a diffuser release is along the main channel and in thedownstream direction. The nearest downstream surface water intake is located along the left bank atTRM 473.0 (Table 2.4.1-41).A mathematical analysis is used to estimate the downstream transport and dilution of a contaminantreleased in the Tennessee River during an accidental spill at SQN. Only the main channel flow areawithout the adjacent overbank regions is considered in the analysis. The mathematical analysis of apotential spill scenario can involve: (1) a slug release, which can be modeled as an instantaneousrelease; (2) a continuous release, which can be modeled as a steady-state release; (3) a bankrelease, which can be modeled as a vertical line source; and (4) a diffuser release, which can bemodeled either as a vertical line or plane source, depending on the width of the diffuser with respect tothe channel width.The following assumptions are used in the mathematical analyses to compute the minimum dilutionexpected downstream from SQN and, in particular, at the nearest water intake.1. Mixing calculations are based on unstratified steady flow in the reservoir. River flow, Q, isassumed to be 27,474 cubic feet per second (cfs), which is equalled or exceeded in the reservoirapproximately 50 percent of the time (Paragraph 2.4.1.2). Because various combinations of theupstream and downstream hydro power dam operations can create upstream flows past SQN, aminimum flow is not well defined. Larger (smaller) flows will decrease (increase) the travel time tothe nearest intake but cause less than an order of magnitude change in the calculated dilution.2. Because the SQN diffusers and the nearest downstream water intake are on opposite banks ofthe river, and the diffusers extend across most of the main channel width, an analysis using adiffuser release (rather than a bank release) is selected to yield a lesser (i.e., more conservative)dilution at the intake. Thus, the accidental spill is modeled as a vertical plane source across thewidth of the main channel.3. The contaminant concentration profile from a slug release is assumed to be Gaussian (i.e.,normal) in the longitudinal direction.4. The contaminant is conservative, i.e., it does not degrade through radioactive decay, chemical orbiological processes, nor is it removed from the reservoir by adsorption to sediments or byvolatilization.5. The transport of the contaminant is described using the motion of the river flow, i.e., thecontaminant is neutrally buoyant and does not rise or sink due to gravity.The main channel and dynamic, flow-dependent processes of the reservoir reach between SQN andthe first downstream water intake are modeled as a channel of constant rectangular cross section withthe following constant geometric, hydraulic and dispersion characteristics.Longitudinal distance, x = 10.6 milesAverage water surface elevation = 678.5 feet MSL (Figure 2.4.1-34 (1))Average width, W = 1175 feet2.4-46 SQN-Average depth, H = 50 feetAverage velocity, U (= Q/(W H)) = 0.468 feet per second (fps)Average travel time (for approximate peak contaminant), t (= x/U) = 1.4daysManning coefficient n (surface roughness) = 0.03Longitudinal dispersion parameter, alpha = 200where: alpha = Ex / (H u)Ex = constant longitudinal dispersion coefficient(square feet per second)u = shear velocity (fps) = -gRSg = acceleration due to gravity = 32.174 ft/s2R = hydraulic radius (ft)S = slope of the energy line (ft/ft)The average width and depth were estimated from measurements of 9 cross sections in the reach [4](TVA) [5] (TVA). For wide channels (i.e., large width-to-depth ratio), the hydraulic radius can beapproximated as the average depth. The value of alpha = 200 is on the conservative (i.e., low) side[6] (Fischer, et al., 1979). The value of the Manning coefficient n is representative for natural rivers [7](Chow, 1959).The equation used to describe the maximum downstream activity (or concentration), C, at a point ofinterest due to an instantaneous plane source release of volume V is [8] (Guide 1.113):C VCG WH -4 -EX t (2.4.12-1)where:C, = initial activity (or concentration) in the plant of the releasedcontaminant= 3.14156Any consistent set of units can be used on each side of Equation 2.4.12-1 (e.g., C and Co in mCi/mI; Vin cf; W and H in ft; E, in ft2/s; t in s).The term, C/Co, is the relative (i.e., dimensionless) activity (or concentration) and its reciprocal is thedimensionsless dilution factor. Equation 2.4.12-1 simplifies to C/Co = 8.3E-10

V (V expressed incubic feet (cf)) when the parameters are substituted and the Manning equation [7] (Chow, 1959) isused in the definition of the shear velocity, u. In the substitution, u = 0.028 ft/s and Ex = 282.1 ft2/s.The equation used to describe the maximum downstream concentration at a point of interest due to acontinuous plane source release rate, Qs, where Q, << Q, is [8] (Guide 1.113):2.4-47 SQN-(2.4.12-2)C Q_Co QAny consistent set of units can be used on each side of Equation 2.4.12-2 (e.g., C and Co in mCi/ml;Q. and Q in cfs).Equation 2.4.12-2 simplifies to C/Co = 3.64E-05

Qs (Qs expressed in cfs) for Q = 27,474 cfs.Examples of quantities and concentrations of potential contaminant releases and the use of Equations2.4.12-1 and 2.4.12-2 follow. Because C, is defined as the in-plant activity (or concentration) and notthat of the diffuser release, an estimate of the dilution of liquid waste occurring in the diffuser pond anddiffuser pipes is not needed. This is because the flow available for dilution in the plant (e.g., CCW andERCW) is taken from and returned to the river. Only effluent extraneous to the river flow requiresconsideration in the analyses to calculate the dilution. More information on the possible means whichliquid waste from the plant enters the diffuser pond is contained in Subsection 10.4.5.The largest outdoor tanks whose contents flow into the diffuser pond are the two condensate storagetanks (Paragraph 11.2.3.1), which each have an overflow capacity of 398,000 gallons. Liquid wastethat reaches the diffuser pond enters the Tennessee River through the diffuser system. The diffuserpond is approximately 2000 feet long and 500 feet wide with a depth that, although it depends on theChickamauga Reservoir elevation, averages about 10 feet [9] (McIntosh, et al., 1982). The designflow residence time of the pond is approximately one hour (i.e., diffuser design flow is 2,480 cfs atmaximum plant capacity [3] [Ungate and Howerton, 1979]).For example, assume an instantaneous plane source release into the Tennessee River of the contentsof one condensate storage drain tank. Assume the full 398,000 gallon (53,210 cf) volume containsIodine-131 (1-131) at an activity of 1.5E-06 mCi/gm (Table 10.4.1-1). From Equation 2.4.12-1, theactivity, C, at the first downstream water intake would be 6.6E-1 1 mCi/gm, which is within theacceptable limit [10] (CFR) for soluble 1-131.For a continuous plane source release, assume the contents of the 398,000 gallon (53,210 cf) floordrain tank leak out steadily over a 24-hour period. The effective release rate is 0.6 cfs at an activity of1.5E-06 mCi/gm. The expected activity at the first downstream water intake would be 3.4E-1 1 mCi/gmusing Equation 2.4.12-2 and is within the acceptable limit [10] (CFR) for soluble 1-131.REFERENCES (for Section 2.4.12 only)[1] McCold, L. N. (March 1979), "Model Study and Analysis of Sequoyah Nuclear Plant SubmergedMultiport Diffuser," TVA, Division of Water Resources, Water System Development Branch,Norris, TN, Report No. WR28-1-45-103.[2] EI-Ashry, Mohammed T., Director of Environmental Quality, TVA, February 1983 letter to PaulDavis, Manager, Permit Section, Tennessee Division of Water Quality Control, SEQUOYAHNUCLEAR PLANT---NPDES PERMIT NO. T0026450.[3] Ungate, C. D., and Howerton, K. A. (April 1978; revised March 1979), "Effect of SequoyahNuclear Plant Discharges on Chickamauga Lake Water Temperatures," TVA, Division of WaterManagement, Water Systems Development Branch, Norris, TN, Report No. WR28-1-45-101.[4] TVA, Chickamauga Reservoir Sediment Investigations, Cross Sections, 1940-1961, Division ofWater Control Planning, Hydraulic Data Branch.[5] TVA, Measured Cross Sections of Chickamauga Reservoir, 1972, Flood Protection Branch.[6] Fischer, H. B., List, E. J., Koh, R.C.Y., Imberger, J., Brooks, N. H. (1979), Mixing in Inland and2.4-48 SQN-Costal Waters, Academic Press, New York.[7] Chow, V. T. (1959) Open-Channel Hydraulics, McGraw-Hill, New York.[8] United States Nuclear Regulatory Commission, Office of Standards Development, RegulatoryGuide 1.113 (April 1977), "Estimating Aquatic Dispersion of Effluents from Accidental andRoutine Reactor Releases for the Purpose of Implementing Appendix I," Revision 1.[9] McIntosh, D. A., Johnson, B. E. and Speaks, E. B. (October 1982), "A Field Verification ofSequoyah Nuclear Plant Diffuser Performance Model: One-Unit Operation," TVA, Office ofNatural Resources, Division of Air and Water Resources, Water Systems Development Branch,Norris, TN, Report No. WR28-1-45-110.[10] 10 CFR Part 20, Appendix B, Table II, Column 2.[11] TVA SQN Calculation SQN-SQS2-0242, SQN Site Iodine-131 Release Concentration inTennessee River.2.4.13 Groundwater (HISTORICAL INFORMATTON)2.4.13.1 Description and Onsite UseThe peninsula on which SQN is located is underlain by the Conasauga Shale, a poor water-bearingformation. About 2,000 feet northwest of the plant site, the trace of the Kingston Fault separates thisoutcrop area of the Conasauga Shale from a wide belt of Knox Dolomite. The Knox is the major waterbearing formation of eastern Tennessee.Groundwater in the Conasauga Shale occurs in small openings along fractures and bedding planes;these rapidly decrease in size with depth, and few openings exist below a depth of 300 feet.Groundwater in the Knox Dolomite occurs in solutionally enlarged openings formed along fracturesand bedding planes and also in locally thick cherty clay overburden.There is no groundwater use at SQN.2.4.13.2 SourcesThe source of groundwater at SQN is recharged by local, onsite precipitation. Discharge occurs bymovement mainly along strike of bedrock, to the northeast and southwest, into Chickamauga Lake.Rises in the level of Chickamauga Lake result in corresponding rises in the water table and rechargealong the periphery of the lake, extending inland for short distances. Lateral extent of this effect varieswith local slope of the water table, but probably nowhere exceeds 500 feet. Lowering levels ofChickamauga Lake results in corresponding declines in the water table along the lake periphery, andshort-term increase in groundwater discharge.When SQN was initially evaluated in the early 1970s, it was in a rural area, and only a few houseswithin a two-mile radius of the plant site were supplied by individual wells in the Knox Dolomite (seeTable 2.4.13-1, Figure 2.4.13-1). Because the average domestic use probably does not exceed 500gallons per day per house, groundwater withdrawal within a two-mile radius of the plant site was lessthan 50,000 gallons per day. Such a small volume withdrawal over the area would have essentially noeffect on areal groundwater levels and gradients. Although development of the area has increased,public supplies are available and overall groundwater use is not expected to increase.Public and industrial groundwater supplies within a 20 mile radius of the site in 1985 are listed in Table2.4.13-2. The area groundwater gradient is towards Chickamauga Lake, under water table conditions,and at a gradient of less than 120 feet per mile. The water table system is shallow, the surface ofwhich conforms in general to the topography of the land surface. Depth to water ranges from lessthan 10 feet in topographically low areas to more than 75 feet in higher areas underlain by KnoxDolomite. Figure 2.4.13-2 is a generalized water-table map of SQN, based on water level data from2.4-49 SQN-five onsite observation wells, and in private wells adjacent to the site in April 1973, and also based onsurface resistivity measurements of depth to water table made in 1972.Because permeability across strike in the Conasauga Shale is extremely low, and nearly all watermovement is in a southwest-northeast direction, along strike, the Conasauga-Knox DolomiteContact is a hydraulic barrier, across which only a very small volume of water could migrate in theevent large groundwater withdrawals were made from the adjacent Knox.Although some water can cross this boundary, the permeability normal to strike of the Conasauga istoo low to allow development of an areally extensive cone of depression.Groundwater recharge occurs to the Conasauga Shale at the plant site. Recharge water moves nomore than 3,000 feet before being discharged to Chickamauga Lake.2.4.13.3 Accident EffectsDesign features in SQN further protect groundwater from contamination.Category I structures in the SQN facility are designed to assure that all system components performtheir designed function, including maintenance of integrity during earthquake.Buildings in which radioactive liquids could be released due to the equipment failure, overflow, orspillage are designed to retain such liquids even if subject to an earthquake equivalent to the safeshutdown earthquake. Outdoor tanks that contain radioactive liquids are designed so that if theyoverflow, the overflow liquid is redirected to the building where the liquid is collected in the radwastesystem. Two outdoor tanks that contain low concentrations of radioactivity at times overflow to yarddrains which discharge into the diffuser pond. Overflow liquid is discharged near the dischargediffuser.The capacity for dispersion and dilution of contaminants by the groundwater system of the ConasaugaShale is low. Dispersion would occur slowly because water movement is limited to small openingsalong fractures and bedding planes in the shale. Clay minerals of the Conasauga Shale do, however,have a relatively high exchange capacity, and some of the radioactive ions would be absorbed bythese minerals. Any ions moving through the groundwater system eventually would be discharged toChickamauga Lake.The Conasauga Shale is heterogeneous and anisotropic vertically and horizontally. Water-bearingcharacteristics change abruptly within short distances. Standard aquifer analyses cannot be applied,and meaningful values for permeability, time of travel, or dilution factors cannot be obtained.Bedrock porosity is estimated to be less than 3 percent based on examination of results of exploratorycore drilling. It is known from experience elsewhere in this region that water movement in theConasauga Shale occurs almost entirely parallel to strike. Subsurface movement of a liquid radwasterelease at the plant site would be about 1,000 feet to the northeast or about 2,000 feet to thesouthwest before discharge to Chickamauga Lake.Time of travel can only be estimated as being a few weeks for first arrival, a few months for peakconcentration arrival, and perhaps two or more years for total discharge. The computed mean time oftravel of groundwater from SQN to Chickamauga Lake is 303 days.No radwaste discharge would reach a groundwater user. At the nearest point, the reservationboundary lies 2,200 feet northwest of the plant site, across strike. Groundwater movement will notoccur from the plant site in this direction across this distance.During initial licensing, the radionuclide concentrations were determined for both groundwater andsurface water movement to the nearest potable water intake (Savannah Valley Utility District, which isno longer in service) and found to be of no concern (see Safety Evaluation Report, March 1979,2.4-50 SQN-Section 2.4.4 Groundwater).2.4.13.4 Monitoring or Safeguard RequirementsSQN is on a peninsula of low-permeability rock; the groundwater system of the site is essentiallyhydraulically isolated and potential hazard to groundwater users of the area is minimal. Theenvironmental radiological monitoring program is addressed in Section 11.6.Monitor wells 1, 2, 3, and 4 were sampled and analyzed for radioactivity during the period from 1976through 1978. Well 5 was not monitored because of insufficient flow. An additional well (Well 6) wasdrilled in late 1978 downgradient from the plant and a pump sampler installed.Wells 1, 2, 4, and 5 are each 150 feet deep, Well 6 is 250 feet deep, and Wells L6 and L7 are 75-80feet deep. All of the wells are cased in the residuum and open bore in the Conasauga Shale.2.4.13.5 ConclusionsSQN was designed to provide protection of groundwater resources by preventing the escape of theleaks of radionuclides. Site soils and underlying geology provide further protection in that they retardthe movement of water and attenuate any contaminants that would be released. All groundwatermovement is toward Chickamauga Lake. The Knox Dolomite is essentially hydraulically separatedfrom the Conasauga Shale; therefore, offsite pumping, including future development, should have littleeffect upon the groundwater table in the Conasauga Shale at the plant.Even though the potential for accidental contamination of the groundwater system is extremely low,the radiological monitoring program will provide ample lead times to mitigate any offsite contamination.As a consequence of the geohydrologic conditions that remain unchanged from evaluations conductedin the 1970s, the information in Chapter 2.4.13 Groundwater is historical and should not be subject toupdating revisions.2.4.14 Reguircments aRnd Em-ergenY OperationFlooding Protection Requirementsflood protecti. plans, designed to minimize impact of floodS above plant grade onsafety ilated facilities, a le deslribld in Appendix 2A.IA. Proeenlidurei for predicting rainfall floods,arrangements to Warn Of upStream d-am failure floods, and lead times available and typcs of action tobhe taken to mect related safety requirements for both SOUrcos of flooding aro described therein. TheTechnical RcqUircments Manual specify the action to be takcn to mini~mize the consequences etfleeds.The plant grade elevation at SQN can be exceeded by large rainfall and seismically-induceddam failure floods. Assurance that SQN can be safely shut down and maintained in these extremeflood conditions (Section 2.4.2.2 and this Section 2.4.14) is provided by the discussions given inSections 3.4, 3.8.1, and 3.8.4.2.4A.-2.4.14.1 IntroductionThis appeR subsection describes the methods by which the Sequeyah Nuc'ear PRantSQN will bemade capable of tolerating floods above plant grade without jeopardizing public safety. Since floodingof this magnitude, as explained in seetien-24,Sections 2.4.2 and 2.4.4, is most unlikely, extreme stepsare considered acceptable including actions that create or allow extensive economic damage to theplant. The actions described herein will be implemented for floods ranging from slightly below plantgrade, to allow for wave runupT to the Design Basis Flood (DBF).2.4A.42.4.14.1.1 Design Basis FloodThe DBF is the calculated upper limit flood that includes the probable maximum flood (PMF) plus thewave runup caused by a 45-mile-per-hour overwater wind; this is discussed in subsection 2.4.3.6. Thetable below gives representative levels of the DBF at different plant locations.2.4-51 SQN-Design Bases Flood (DBF) LevelsProbable maximum flood (still reservoir) 74-9.722.0 ftDBF runup on Diesel Generator Building 723.2 ftDBF runup on vertical external, unprotected walls 7-2=3.726.2 ftDBF surge level within flooded structures 720.4722.5 ftThe lower flood elevations listed above are actual DBF elevations and are not normally used for thepurpose of design but are typically used in plant procedures including procedures which direct plantactions in response to postulated DBF. For purposes of designing the flood protection for systems,structures, and components, the following higher elevations should be used thus ensuring additionalmargin has been included in the development of design analysis.Design Analysis Flood LevelsMaximum still reservoir 723.5 ftRunup on vertical external, unprotected walls 729.5 ftSurge level within flooded structures 724.0 ftSee FSAR-References 2AA-40--11[271 and 2AA [0 2r281.In addition to level considerations, plant flood preparations will cope with the "fastest rising" floodwhich is the calculated flood that can exceed plant grade with the shortest prediction notice. Reservoirlevels for large floods in the Tennessee Valley can be predicted well in advance.A minimum of 27 hours3.125e-4 days 0.0075 hours 4.464286e-5 weeks 1.02735e-5 months , divided into two stages, is provided for safe plant shutdown by use of thisprediction capability. Stage I, a minimum of 10 hours1.157407e-4 days 0.00278 hours 1.653439e-5 weeks 3.805e-6 months long, will commence upon a prediction thatflood-producing conditions might develop. Stage II, a minimum of 17 hours1.967593e-4 days 0.00472 hours 2.810847e-5 weeks 6.4685e-6 months long, will commence on aconfirmed estimate that conditions will provide a flood above plant grade. This two-stage scheme isdesigned to prevent excessive economic loss in case a potential flood does not fully develop. Refer toSection 2.4.14.4.24A-4_.22.4.14.1.2 Combinations of EventsBecause floods above plant grade, earthquakes, tornadoes, or design basis accidents, including aloss-of-coolant accident (LOCA), are individually very unlikely, a combination of a flood plus any ofthese events or the occurrence of one of these during the flood recovery time or of the flood during therecovery time after one of these events is considered incredible.Surges from seismic, failur of upstream. dams, however, can oxe .d plant grade, but to I.wer.. DBFlevels, when imposed coincident With Wind and cortain floods. A MRn~imwn 27 hours3.125e-4 days 0.0075 hours 4.464286e-5 weeks 1.02735e-5 months of warning isas.ur.d so that ample 6 available to pr..paro the plant foflooding. However, as an exception,certain reduced levels of floods are considered together with seismic events. Refer to Section2.4.14.10 and 2..4.Post Flood PeriodBecause of the improbability of a flood above plant grade, no detailed procedures will be establishedfor return of the plant to normal operation unless and until a flood actually occurs. If flood modeoperation (subsec'tin .2. Section 2.4.14.2) should ever become necessary, it will be possible tomaintain this mode of operation for a sufficient period of time (100 days) so that appropriate recoverysteps can be formulated and taken. The actual flood waters are expected to recede below plant gradewithin 1 to 6 days.2.4-52 SQN-2AA 42.4.14.1.4 Localized FloodsLocalized plant site flooding due to the probable maximum storm (subsection 2..3Section 2.4.2.3) willnot enter vital structures or endanger the plant. Plant shutdown will be forced by water ponding on theswitchyard and around buildings, but this shutdown will not differ from a loss of offsite power situationas described in Chapter 15. The other steps described in this appeRdsubsection are not applicableto this case. Refer to Section 2.4.2.3.2.4A.22.4.14.2 Plant Operation During Floods Above Grade"Flood mode" operation is defined as the set of conditions described below by means of which theplant will be safely maintained during the time when flood waters exceed plant grade (elevation705.0 ft) and during the subsequent period until recovery (subsection 2.I Section 2.4.14.7) isaccomplished.2.4A242.4.14.2.1 Flooding of StructuresQoly-4heThe Reactor Building, the Diesel Generator Building (DGB), and the Essential Raw CoolingWater Intake Station will be maintained dry during the flood mode. Walls and penetrations aredesigned to withstand all static and dynamic forces imposed by the DBF.The lowest floor of the DGB is at elevation 722.0 ft with its doors on the uphill side facing away fromthe main body of flood water. This celvation is lower th1n thc prcv'ius DBF e!cvation of 722.6. The1998 reanalysis determined the still wate. With the PMF elevation te 71-.6 f 722.0 ft, wi4h-windwave runup at the DGB teis elevation 721-1.8723.2 ft. Therefore, flood levels de- et-exceed floorelevation of 722.0 ft. The entrances into safety-related areas and all mechanical and electricalpenetrations into safety-related areas are sealed either prior to or during flood mode to prevent majorleakage into the building for water up to the PMF, including wave runup. Du-o to thc 998 reanalysisthis only applies to below grade features. Redundant sump pumps are provided within the building toremove minor leakage.The Essential Raw Cooling Water (ERCW) intake station is designed to remain fully functional forfloods up to the PMF, including wind-wave runup. The deck elevation (elevation 720.0 ft) is below thePMF plus wind wave runup, but it is protected from flooding by the outside walls. The traveling screenwells extend above the deck elevation up to the design basis surge level. The wall penetration forwater drainage from the deck in nonflood conditions is below the DBF elevation, but it is designed forsealing in event of a flood. All other exterior penetrations of the station below the PMF arepermanently sealed. Redundant sump pumps are provided on the deck and in the interior rooms toremove rainfall on the deck and water seepage.All other structures, including the service, turbine, auxiliary, and control buildings, will be allowed toflood as the water exceeds their grade level entrances. All equipment, including power cables, that islocated in these structures and required for operation in the flood mode is either above the DBF ordesigned for submerged operation.2.4A.2.22.4.14.2.2 Fuel CoolingSpent Fuel PitFuel in the spent fuel pit will be cooled by the normal Spent Fuel Pit Cooling (SFPC) System. Thepumps are located on a platform at elevation 721.0 ft which is abey'ebelow the surge level of72.1elevation 722.5 ft. However, the pumps are located in an enclosure that provides floodingprotection up to elevation 724.5 ft. During the flood mode of operation, heat will be removed from theheat exchangers by ERCW instead of component cooling water.As a backup to spent fuel cooling, water from the Fire Protection (FP) System can be dumped into thespent fuel pool, and steam removed by the area ventilation system.2.4-53 SQN-ReactorsResidual core heat will be removed from the fuel in the reactors by natural circulation in the ReactorCoolant (RC) system. Heat removal from the steam generators will be accomplished by adding riverwater from the FP System (subsection 9.5.1) and relieving steam to the atmosphere through thepower relief valves. Primary system pressure will be maintained at less than 500 lb/in 2g by operationof the pressurizer relief valves and heaters. This low pressure will lessen leakage from the system.Secondary side pressure will be maintained at or below 90 psig by operation of the steam line reliefvalves.An analysis has been performed to ensure that the limiting atmospheric relief capacity would besufficient to remove steam generated by decay heat. At times beyond approximately 10 hour1.157407e-4 days 0.00278 hours 1.653439e-5 weeks 3.805e-6 months sfollowing shutdown of the plant two relief valves have sufficient capacity to remove the steamgenerated by decay heat. Since a minimum of 27 hours3.125e-4 days 0.0075 hours 4.464286e-5 weeks 1.02735e-5 months flood warning is available it is concluded thatthe plant could be safely shutdown and decay heat removed by operation of only two relief valves.Reference FSAR 2.A.1&A4[271.The main steam power operated relief valves will be adjusted to maintain the steam pressure at orbelow 90 psig. If this control system malfunctions, then the controls in the main control room can beutilized to operate the valves in an open-closed manner. Also, a manual loading station and the reliefvalve handwheel provide additional backup control for each relief valve. The secondary side steampressure can be maintained for an indefinite time by the means outlined above.The cooling water flow paths conform to the single failure criteria as defined in FSAR Section 3.1.1. Inparticular, all active components of the secondary side feedwater supply and ERCW supply areredundant and can therefore tolerate a single failure in the short or long term. A passive failure,consistent with the 50 gpm loss rate specified in FSAR Section 3.1.1, can be tolerated for an indefiniteperiod without interrupting the required performance in either supply.If one or both reactors are open to the containment atmosphere as during the refueling operations,then the decay heat of any fuel in the open unit(s) and spent fuel pit will be removed in the followingmanner. The refueling cavity will be filled with borated water (approximately 2000 ppm boronconcentration) from the refueling water storage tank. The SFPC System pump will take suction fromthe spent fuel pit and will discharge to the SFPC System heat exchangers. The SFPC System heatexchanger output flow will be directed by a piping connection to the Residual Heat Removal (RHR)System heat exchanger bypass line. The tie-in locations in the SFPC System and the RHR Systemare shown in Figures 9.1.3-1 and 5.5.7-1, respectively. This connection will be made usingprefabricated, in- position piping which is normally disconnected. During flood mode preparations, thepiping will be connected using prefabricated spool pieces.Prior to flooding, valve number 78-513 (refer to Figure 9.1.3-1) and valves FCV 74-33, and 74-35(refer to Figure 5.5.7-1) will be closed; valves HCV 74-36, 74-37, FCV 74-16, 74-28, 63-93, and 63-94(refer to Figure 5.5.7-1 and 6.3.1-1)will be opened or verified open. This arrangement will permit flowthrough the RHR heat exchangers and the four normal cold leg injection paths to the reactor vessel.The water will then flow downward through the annulus, upward through the core (thus cooling thefuel), then exit the vessel directly into the refueling cavity. This results in a water level differentialbetween the spent fuel pit and the refueling cavity with sufficient water head to assure the requiredreturn flow through the 20-inch diameter fuel transfer tube thereby completing the path to the spentfuel pit.Except for a portion of the RHR System piping, the only RHR System components utilized below floodelevation are the RHR System heat exchangers. Inundation of these passive components will notdegrade their performance for flood mode operation. After alignment, all valves in this cooling circuitlocated below the maximum flood elevation will be disconnected from their power source to assurethat they remain in a safe position.The modified cooling circuit for open reactor cooling will be assured of two operable SFPC System2.4-54 SQN-pumps (a third pump is available as a backup) as well as two SFPC System heat exchangers. Also,the large RHR System heat exchangers are supplied with essential raw cooling water during the openreactor mode of fuel cooling; these heat exchangers provide an additional heat sink not available fornormal spent fuel cooling.Fuel coolant temperature calculations, assuming conservative heat loads and the most limiting, singleactive failure in the SFPC System, indicate that the coolant temperatures are acceptable.The temperatures can be maintained at a value appreciably less than the fuel pit temperaturecalculated for the nonflood spent fuel cooling case when assuming the loss of one equipment train.As further assurance, the open reactor cooling circuit was aligned and tested, during pre-operationaltesting, to confirm flow adequacy. Normal operation of the RHR System and SFPC System heatexchangers will confirm the heat removal capabilities of the heat exchangers.High spent fuel pit temperature will cause an annunciation in the MCR, thus indicating equipmentmalfunction. Additionally, that portion of the cooling system above flood water will be frequentlyinspected to confirm continued proper operation.For either mode of reactor cooling, leakage from the Reactor Coolant System will be collected, to theextent possible, in the reactor coolant drain tank; nonrecoverable leakage will be made up fromsupplies of clean water stored in the four cold leg accumulators, the pressurizer relief tank, the caskdecontamination tank, and the demineralized water tank. If these sources prove insufficient, the FPSystem can be connected to the Auxiliary Charging System (subsection 9.3.5) as a backup. Whateverthe source, makeup water will be filtered, demineralized, tested, and borated, as necessary, to thenormal refueling concentration, and pumped by the Auxiliary Charging System into the reactor (seeFigures 2-A-.22.4.14-1 and 2AA 32.4.14-2).9(wefElFcIticepeor Will be supplied by the OnSite diesel gonorators 6taFting at the beginRing of Stage I! Or'hcn offsite power is lost, whicheve, r o.ur.s (subsectin 2.4A.5.3).2.4.14.2.3 Cooling of Plant LoadsPlant cooling requirements, with the exception of the FP System which must supply feedwater to thesteam generators, will be met by the ERCW System (refer to subsectienSection 9.2.2).2.4.14.2.4 PowerElectric power will be supplied by the onsite diesel generators starting at the beginning of Stage II orwhen offsite power is lost, whichever occurs first (Section 2.4.14.5.3).2.4.14.2.5 Plant Water SupplyThe plant water supply is thoroughly discussed in suseeGtieiSection 9.2.2. The following is asummary description of the water supply provided for use during flooded plant conditions. The ERCWstation is designed to remain fully functional for all floods up to and including the DBF. The CCWintake forebay will provide a water supply for the fire/flood mode pumps. If the flood approaches DBFproportions, there is a remote possibility that Chickamauga Dam will fail. Such an event would leavethe Sequoyah Plant CCW intake forebay isolated from the river as flood water recedes below EL 665.Should this event occur, the CCW forebay has the capacity of retained water to supply two steamgenerators in each unit and provide spent fuel pit with evaporation makeup flow until CCW forebayinventory makeup is established. The ERCW station is designed to be operable for all plant conditionsand includes provisions for makeup to the forebay. Reference FSAR 2-4A.1- 1[27].24A.32.4.14.3 Warning PlaRScheme2.4-55 SQN-See Section 2.4.14.8 (Warning Plan).grade elevation. 705 can be eXceeded by both rainfall floods and seismic caused dam. failu, rfloods. A warning plan is nceded to assure plant safety fromn these floods2.4A.3.1 Rainfall Floodsof the Sequ'yah Plant from the lW pFrobability rainfall floods that might eXeed plant gfradedepends on a flood warning issued by TVA's RiVer OpeFations as desc-ribedh in Secnfion 224A8. W 1ithTVA's extensive climate monitoringand flood systems and flood control facilitie., flo+d. inthe Se.u.yah area can be reliably predicted well in advance. The Sequoyah Nuclear Plant flotda,-ing plan will pro.vide a minimum preparation time of 27 ho urS including a 3 hour3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months foroperation in the flood mode. Four additional, preceding hours will provide time to gather data andpro4dUce the waring. The wa.ring plan w-llhbe divided intO MG stages the first a mini;mum o.. f 10hours long and the second of 17 hours1.967593e-4 days 0.00472 hours 2.810847e-5 weeks 6.4685e-6 months so that unnecessary economic penalty can be avoided whileadequate time is ensured. for preparing for operation in the lood, m.-,,4.The first stage, Stage 1, of shutdown will begin when there is suffic~ient rainfall onA the ground in theupstream watershed t yi4eld a projected plant site wate+r level of 6,97 in. the w.inter months (October 1through April 1) aRnd 703 in the (April 16 through September 30). This assuF6e that thead-ditionAal. time rouirFed is aV-ail-able whe .htow...ntitd The wa;ter level of 703 (two feet beoplant grade) will allow imargin so that waves due to high Winds disrupt the 9fod mndepreparation;. Stage 1 will allow preparation steps causing some damage to be sustained but willw:ithhold major damage until the Stage II warning assures a f,,fh-ominRg flood above grade.The plant preparation status will be held at Stage I until either Stage II begins or TVA's RiveOperations determines that floo waters.will not eXceed eleevation 703 at the plant. The Stage II.:anig will be issued only when eno)ugh rain has fallen to predict that elevationR 703 is likely to beeXoeeded-2.4A.3.2 Seismoic Dam Fai!ure FloodsProtection of the S ,quyah plaRt from flood waves generated by Glly caused dam- failures;.hih exceed plant grade depends on WA's River Operation eoganization to identify when a criticalcombination of dam failures -and- flooedis exi~st. The-re are nine upstreamn dams, whose failure, incombination coincident With ce~taiR storm conditions, would cause a flood to exceed plant gradeThese dams are Norris, Cherokee, Douglas, PFot Loudoun, Fon)tana, Hiwassee, Apalachia, BlueRidge, and Tellico.2-4A42.4.14.4 Preparation for Flood ModeAn abnormal operating instruction is available to support operation of the plant.At the time the initial flood warning is issued, the plant may be operating in any normal mode. Thismeans that either or both units may be at power or either unit may be in any stage of refueling.24A-4-.-2.4.14.4.1 Reactors Initially Operating at PowerIf both reactors are operating at power, Stage I and then, if necessary, Stage II procedures will beinitiated. Stage I procedures will consist of a controlled reactor shutdown and other easilyrounkablerevocable steps such as moving supplies necessary to the flood protection plan above theDBF level and making temporary connections and load adjustments on the onsite power supply.Stage II procedures will be the less easily Fevokablerevocable and more damaging steps necessary tohave the plant in the flood mode when the flood exceeds plant grade. The fire/flood mode pumps maysupply auxiliary feedwater for reactor cooling (Refere-i.[)291. Other essential plant cooling loadswill be transferred from the component cooling water to the ERCW System (subsection 9.2.2). TheRadioactive Waste (Chapter 11) System will be secured by filling tanks below DBF level with enoughwater to prevent flotation; one exception is the waste gas decay tanks, which are sealed and anchored2.4-56 SQN-against flotation. The CVCS hold up tank will also be filled and sealed to prevent flotation. Somepower and communication lines running beneath the DBF and not designed for submerged operationwill require disconnection. Batteries beneath the DBF will be disconnected.2 4A422.4.14.4.2 Reactor Initially RefuelinqIf time permits, fuel will beis removed from the unit(s) undergoing refueling and placed in the spent fuelpit; otherwise fuel cooling will be accomplished as described in subsection 2.4A.2.2Section 2.4.14.2.2.If the refueling canal is not already flooded, the mode of cooling described in sub~eGtion:24AA2 2Section 2.4.14.2.2 requires that the canal be flooded with borated water from the refuelingwater storage tank. If the flood warning occurs after the reactor vessel head has been removed or at atime when it could be removed before the flood exceeds plant grade, the flood mode reactor coolingwater will flow directly from the vessel into the refueling cavity. If the warning time available does notpermit this, then the upper head injection piping will be disconnected above the vessel head to allowthe discharge of water through the four upper head injection standpipes. Additionally, it is requiredthat the prefabricated piping be installed to connect the RHR and SFPC Systems, and that ERCW bedirected to the secondary side of the RHR System and SFPC System heat exchangers.2.4A-.132.4.14.4.3 Plant Preparation TimeAll steps needed to prepare the plant for flood mode operation can be accomplished within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months ofreceipt of the initial warning that a flood above plant grade is possible. An additional 3 hours3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months areavailable for contingency margin before wave runup from the rising flood might enter the buildings.Site grading and building design prcvcnt any flooding bcforce the end of thc 27 hour: preflood pcriod-.2.4A.52.4.14.5 EquipmentBoth normal plant components and specialized flood-oriented supplements will be utilized in copingwith floods. All such equipment required in the flood mode is either located above the DBF or is withina nonflooded structure or is designed for submerged operation. Systems and components neededonly in the preflood period are protected only during that period.2.4A.542.4.14.5.1 Equipment QualificationTo ensure capable performance in this highly unlikely but rigorous, limiting design case, only highquality components will be utilized. Active components are redundant or their functions diverselysupplied. Since no rapidly changing events are associated with the flood, repairability offersreinforcement for both active and passive components during the long period of flood mode operation.Equipment potentially requiring maintenance will be accessible throughout its use, includingcomponents in the Diesel Generator Building.2.4A.5.22.4.14.5.2 Temporary Modification and SetupNormal plant components used in flood mode operation and in preparation for flood mode operationmay require modification from their normal plant operating configuration. Such modification, since it isfor a limiting design condition and since extensive economic damage is acceptable, will be permittedto damage existing facilities for their normal plant functions. However, most alterations will be onlytemporary and nondestructive in nature. For example, the switchover of plant cooling loads from thecomponent cooling water to the ERCW System will be done through valves and a prefabricated spoolpiece, causing little system disturbance or damage.Equipment especially provided for the flood design case includes both permanently installedcomponents and more portable apparatus that will be emplaced and connected into other systemsduring the preflood period.Detailed procedures to be used under flood mode operation have been developed and areincorporated in the plant's Abnormal Operating Instructions.2.4-57 SQN-2AA5.32.4.14.5.3 Electric PowerBecause there is a possibility that high winds may destroy powerlines and disconnect the plant fromoffsite power at any time during the preflood transition period, only onsite power will be used onceStage II of the preparation period begins. While most equipment requiring alternating current electricpower is a part of the permanent emergency onsite power system, other components will betemporarily connected, when the time comes, by prefabricated jumper cables.All loads that are normally supplied by onsite power but are not required for the flood will be switchedout of the system during the preflood period. Those loads used during the preflood period but notduring flood mode operation will be disconnected when they are no longer needed. During thepreparation period, all power cables running beneath the DBF level, except those especially designedfor submerged operation, will be disconnected from the onsite power system. Similarly, direct currentelectric power will be disconnected from unused loads and potentially flooded lines. Charging will bemaintained for each battery by the onsite alternating current power system as long as it is required.Batteries that are beneath the DBF will be disconnected during the preflood period when they are nolonger needed.2.4A..42.4.14.5.4 Instrument Control, Communication and Ventilation SystemsAll instrument, control, and communication lines that will be required for operation in the flood modeare either above the DBF or within a nonflooded structure or are designed for submerged operation.Unneeded cables that run below the DBF will be disconnected to prevent short circuits.Redundant means of communications are provided between the central control area (the main andauxiliary control rooms) and all other vital areas that might require operator attention, such as theDiesel Generator Building.Instrumentation is provided to monitor all vital plant parameters such as the reactor coolanttemperature and pressure and steam generator pressure and level. Control of the pressurizer heatersand relief valves and steam generator feedwater flow and atmospheric relief valves will ensurecontinued natural circulation core cooling during the flood mode. All other important plant functionswill be either monitored and controlled from the main control area or, in some cases where timemargins permit, from other points in the plant that are in close communication with the main controlarea. Ventilation, when necessary, and limited heating or air-conditioning will be maintained for allpoints throughout the plant where operators might be required to go or where required by equipmentheat loads.2-.4A.62.4.14.6 SupliesAll equipment and most supplies required for the flood are on hand in the plant at all times. Somesupplies will require replenishment before the end of the period in which the plant is in the flood mode.In such cases supplies on hand will be sufficient to last through the short time 2 3Section 2.4.14.1.3) that flood waters will be above plant grade and until replenishment can besupplied. For instance, there is sufficient diesel generator fuel available at the plant to last for 3 or 4weeks; this will allow sufficient margin for the flood to recede and for transportation routes to bereestablished.2 4A-72.4.14.7 Plant RecoveryThe plant is designed to continue safely in the flood mode for 100 days even though the water is notexpected to remain above plant grade for more than 1 to 6 days. After recession of the flood, damagewill be assessed and detailed recovery plans developed. Arrangements will then be made forreestablishment of offsite power and removal of spent fuel.The 100-day period provides more than adequate time for the development of procedures for anymaintenance, inspection, or installation of replacements for the recovery of the plant or for acontinuation of flood mode operations in excess of 100 days. A decision based on economics will be2.4-58 SQN-made on whether or not to regain the plant for power production. In either case, detailed plans will beformulated after the flood, when damage can be accurately assessed.2.4A.92.4.14.8 Basis For Flood Plan In Rainfall FlooWarninq PlanPlant grade elevation 705.0 ft can be exceeded by both rainfall floods and seismic-caused dam failurefloods. A warning plan is needed to assure plant safety from these floods.The warning plan is divided into two stages: Stage I, a minimum of 10 hours1.157407e-4 days 0.00278 hours 1.653439e-5 weeks 3.805e-6 months long and Stage II, aminimum of 17 hours1.967593e-4 days 0.00472 hours 2.810847e-5 weeks 6.4685e-6 months so that unnecessary economic consequences can be avoided, while adequatetime is allowed for preparing for operation in the flood mode. Stage I allows preparation steps causingminimal economic consequences to be sustained but will postpone manor economic damage until theStage II warning forecasts a likely forthcoming flood above elevation 703.0 ft.2.4.14.8.1 Rainfall FloodsProtection of the Sequoyah Plant from the low probability rainfall floods that might exceed plant gradedepends on a flood warning issued by TVA's River Operations (RO). With TVA's extensive climatemonitoring and flood forecasting systems and flood control facilities, floods in the Sequoyah area canbe reliably predicted well in advance. The SQN flood warning plan will provide a minimum preparationtime of 27 hours3.125e-4 days 0.0075 hours 4.464286e-5 weeks 1.02735e-5 months including a 3 hour3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months margin to prepare for operation in the flood mode. Four additional,preceding hours will provide time to gather data and produce the warning.The first stage, Stage I, of shutdown will begin when there is sufficient rainfall on the ground in theupstream watershed to yield a forecasted plant site water level of 694.5 ft in the winter months and699.0 ft in the summer. This assures that the additional time required is available when shutdown isinitiated. The water level of 703.0 ft (two feet below plant grade) will allow margin so that waves dueto high winds cannot disrupt the flood mode preparation. Stage I will allow preparation steps causingsome damage to be sustained but will withhold maior economic damage until the Stage I1 warningassures a forthcoming flood above grade.The plant preparation status will be held at Stage I until either Stage I1 begins or TVA's RO determinesthat flood waters will not exceed elevation 703.0 ft at the plant. The Stage II warning will be issuedonly when enough rain has fallen to predict that elevation 703.0 ft (winter or summer) is likely to beexceeded.2.4.14.8.2 Seismically-Induced Dam Failure FloodsFour postulated combinations of seismically induced dam failures and coincident storm conditionswere shown to result in floods which could exceed elevation 703.0 ft at the plant. SQN's notification ofthese floods utilizes TVA's RO forecast system to identify when a critical combination exists. Stage Ishutdown is initiated upon notification that a critical dam failure combination has occurred or loss ofcommunication prevents determining a critical case has not occurred. Stage I shutdown continuesuntil it has been determined positively that critical combinations do not exist. If communications do notdocument this certainty, shutdown procedures continue into Stage II activity. Stage I1 shutdowncontinues to completion or until lack of critical combinations is verified.....mar.2.4.14.9 Basis For Flood Protection Plan In Rainfall Floods2.4.14.9.1 OverviewLarge Tennessee River floods can exceed plant grade elevation 705.0 ft at S..uoyah Nucl,'rPaRatSQN. Plant safety in such an event requires shutdown procedures which may take 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months toimplement. TVA flood forecast procedures will provide at least 27 hours3.125e-4 days 0.0075 hours 4.464286e-5 weeks 1.02735e-5 months of warning before river levelsreach elevation 703.0 ft. Use of elevation 703.0 ft, 2 feet below plant grade, provides enoughfreeboard to prevent waves from 45-mile-per-hour, overwater winds from endangering plant safetyduring the final hours of shutdown activity. For conservatism the fetches calculated for the PMF(Figures 2.4.3-14-24 and 2.4.3-4-625) were used to calculate maximum wind wave additive to the2.4-59 SQN-reservoir surface at elevation 703.0 ft feet--msl. The maximum wind additive to the reservoir surfacewould be 2-.S4.2 feet and would not endanger plant safety during the final hours of shutdown. This isdue to the long shallow approach and the waves breaking at the perimeter road (elevation 705.0 ft4eetmsl). After the waves break there is not sufficient depth or distance between the perimeter road andthe safety-related facilities for new waves to be generated. Forecast will be based upon rainfallalready reported to be on the ground.Different target river level criteria are needed for winter use and for summer use to allow for seasonallyvaried reservoir levels and rainfall potential.To be certain of 27 hours3.125e-4 days 0.0075 hours 4.464286e-5 weeks 1.02735e-5 months for preflood preparation, warnings of floods with the prospect of reachingelevation 703.0 ft must be issued early; consequently, some of the warnings may later prove to havebeen unnecessary. For this reason preflood preparations are divided into two stages. Stage I steps,requiring 10 hours1.157407e-4 days 0.00278 hours 1.653439e-5 weeks 3.805e-6 months , would be easily revokablerevocable and cause minimum damage. The estimatedprobability is less than 0.0026small that a Stage I warning will be issued during the 40-year-life of theplant.Additional rain and stream-flow information obtained during Stage I activity will determine if the moredamaging steps of Stage II need to be taken with the assurance that at least 17 hours1.967593e-4 days 0.00472 hours 2.810847e-5 weeks 6.4685e-6 months will be availablebefore elevation 703.0 ft is reached. The estimated probability of a Stage II warning during the life ofthe plant is less tha .Q0010 thnat shutdown will need to continue inRt Stage 11 during plant lifeverysmall.Flood forecasting and warnings, to assure adequate warning time for safe plant shutdown duringfloods, will be conducted by Ric. Operatiens f River System ,OpeationsTVA's RO.2.4.14.9.2 TVA Forecast System (H ISTORCAL INFORMATION)TVA has in constant use an extensive, effective system to forecast flow and elevation as needed in theTennessee River Basin. This permits efficient operation of the reservoir system and provides warningof when water levels will exceed critical elevations at selected, sensitive locations which includesSQN.Elements of the present (20042012) forecast system above Sequoyah Nuc!ear PlantSQN include thefollowing:1. One hundred sixty (160)More than 100 rain gages measure rainfall, with an average density of465about 200 square miles per rain gage. Of these gages 112 are Ownd by TVA, 35 areowned by the National Weather Scr.'icc (ISMS), 7 aro ownod by the United Stater, GeologicalSeprdice (USGS), 2 are owned by the United States Corps of Engineers (USACE), and 4 areowned by Aircea. Most of these gages are tipping buckets collector type and the transmission-of the- dAta isb either by satellite or telephone. At some of the gages located at hydrOplants, thedata is manually read.All are Geostationary Operational Environmental Satellites (GOES)Data Collection Platform (DCP) satellite telemetered gages.Information Rnormally is roeived daily from the gages. at 6 a.mh. and at least eVerY 6 hqursduring flood periods. Close interval rainfall reports can be obtained fromA a majority Of theg r IAll of the rainfall -gages transmit hourly rainfall data.Streamflow data are received for 3523 gages from 16 TVA gages amd 19 USGS gages.Those gages trasmit their dat eihrb atellite Or telephone or both-., Discharge data are2.2_ nynronnl.nte iSTno. Oh plnan, 25 a1o6 tranRmfI nuauwonater elelvation alta, andi13 transmnit tailWateF elevation data. Therefore, steamnflio da;ta ;;areavalable from6during flood .P..at.....in the system. All are GOES Data Collection Platform satellitetelemetered gages. The satellite gages transmit 15-minute stage data every hour duringnormal operations.2.4-60 SQN-3. Real-time headwater elevation, tailwater elevation, and discharge data are received from 21TVA hydro proiects (Watts Bar, Melton Hill, Fort Loudoun, Tellico, Norris, Douglas, Cherokee,Fort Patrick Henry, Boone, Watauga, Wilbur, South Holston, Chickamauga, Ocoee No. 1,Ocoee No. 2, Ocoee No. 3, Blue Ridge, Apalachia, Hiwassee, Chatuge and Nottely) andhourly data are received from non-TVA hydro plants (Chilhowee, Cheoah, Calderwood andSanteetlah).34. Weather forecasts including quantitative precipitation forecasts are received few imesat leasttwice daily and at other times when changes are expected.45. Computer programs which translate rainfall into streamflow based on current runoff conditionsand which permit a forecast of flows and elevations based upon both observed and predictedrainfall. Two sepatateA network of UNIX servers and personal computers are utilized and aredesigned to provide backup for each other. One computer is used primarily for data collection,with the other used for executing forecasting programs for reservoir operations. The timeinterval between receiving input data and producing a forecast is less than 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months . Forecastsnormally cover at least a 8three-day period.As effective as the forecast system already is, it is constantly being improved as new technologyprovides better methods to interrogate the watershed during floods and as the watershedmathematical model and computer system are improved. Also, in the future, improved quantitativeprecipitation forecasts may provide a more reliable early alert of impending major storm conditions andthus provide greater flood warning time.The TVA ccnt-o is manned 24 h.ous a day. No"rmal oprFation w ho forccasts daily,one by 12 noon based on data collected at 6 a.mR. Ccntral time, and the second by 4 A. m. based odata collected at mnidnight Centfral Time. When serious flood situations demand, forecaStS areproduced eVery 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months .2.4.14.9.3 Basic AnalysisToevelop aThe forecast procedure to assure safe shutdown of scqu.yah Nuclear PlantSQN forflooding-4-7 is based upon an analysis of nine hypothetical PMP storms, incudi;g storms, were analyzed. They up to PMP magnitude. The storms enveloped potentially critical arealand seasonal variations and time distributions of rainfall. To be certain that fastest rising floodconditions were included, the effects of varied time distribution of rainfall were tested by alternativelyplacing the maximum daily PMP efin the fiFsPthe middle7 and the last day of the 3three-day mainstorm. In day the m;aXi mum 6- hour depth was placed during the secend inte,'al except when themaximum daily rain was placed on the last day. Then the maximum 6 hour6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months amount was placed in thelast 6 hew*s.Earlier analysis of 17 hypothetical storms demonstrated that the shortest warning timesresulted from storms in which the heavy rainfall occurred on the last day and that warning times weresignificantly longer when heavy rainfall occurred on the first day. Therefore, heavy rainfall on the firstday was not reevaluated. The warning system is based on those storm situations which resulted inthe shortest time interval between watershed rainfall and elevation 703.0 ft at SQN, thus assuring thatthis elevation could be predicted at least 27 hours3.125e-4 days 0.0075 hours 4.464286e-5 weeks 1.02735e-5 months in advance.The procedures used to compute flood flows and elevations are described in subsections 2.4.3.1,2.4.3.2, and 2.4.3.3 Section 2.4.3. Some flood events, were analyzed using earlier versions of theWateshed, moAdel described in sub..ectioen 22.4.3.3. Those events which eotablished impertantelements of the warning system or tho-s-e whe-re the present model might produce significantd-iffe~renes, in w.arning times have been reevaluated. EvYent6 reevaluated have been noted either iRt~ablesF- or figures where appropriate.The warniRg system is based en these sterm situations which resulted inthe shortest time ,n-er...betw.e. waterhed rainfall and- elevatin 703, thus assuring that this could be predicted atlest27 hours in advance.2.4.14.9.4 Hydrologic Basis for Warning System2.4-61 SQN-A minimum of 27 hours3.125e-4 days 0.0075 hours 4.464286e-5 weeks 1.02735e-5 months has been allowed for preparation of the plant for operation in the flood mode,three hours more than the 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months needed. An additional 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months for communication and forecastingcomputations are provided to allow TVA's RO to translate rain on the ground to river elevations at theplant. Hence, the warning plan must provide 31 hours3.587963e-4 days 0.00861 hours 5.125661e-5 weeks 1.17955e-5 months from arrival of rain on the ground until GlitiGaIelevation 703.0 ft could be reached. The 27 hours3.125e-4 days 0.0075 hours 4.464286e-5 weeks 1.02735e-5 months allowed for shutdown at the plant are utilized for aminimum of 10 hours1.157407e-4 days 0.00278 hours 1.653439e-5 weeks 3.805e-6 months of Stage I preparation and an additional 17 hours1.967593e-4 days 0.00472 hours 2.810847e-5 weeks 6.4685e-6 months for Stage II preparation that isnot concurrent with the Stage I activity. This 27 hour3.125e-4 days 0.0075 hours 4.464286e-5 weeks 1.02735e-5 months allocation includes a 3-hour margin.Although river elevation 703.0 ft, 2 feet below plant grade to allow for wind waves, is critical duringfinal stages of plant shutdown for flooding, lower forecast target levels are used in most situations toassure that the 27 hours3.125e-4 days 0.0075 hours 4.464286e-5 weeks 1.02735e-5 months preflood transition interval will always be available. The target river levelsdiffer with season.During the October 1 through April 15 "winter" season, Stage I shutdown procedures will be started assoon as target river elevation 6W7694.5 ft has been forecast. ShutdownStage I1 shutdown will beinitiated and carried to completion if and when target river elevation 703.0 ft at SQN has been forecast.Corresponding target river elevations for the April 16 through September 30 "summer" season at SQNis 703 are elevation 699.0 ft and elevation 703.0 ft. The one target river elevation in the summerseason peFrmit waiting to initiate shutdown procc3dUres until enough rain is On the ground to forecasreaching critical elcvatiOn 703-- shutdoWn would then be initiated and carried to comnpletion.Inasmuch as the hydrologic procedures and target river elevations have been designed to provideadequate shutdown time in the fastest rising flood, longer times will be available in other floods. Insuch cases there w4I#may be a waiting period after the Stage 1, 10-hour shutdown activity during whichactivities shall be in abeyance until it iG predicted f.ro recorded rainfall that Stage I Shutdown shouldbe implemented Or it is f.ro.m wther .onditios that plant operation can be resumedweather conditions determine if plant operation can be resumed, or if Stage II shutdown should beimplemented.Resumption of plant operation following Stage I shutdown activities will be allowable only after floodlevels and weather conditions, as determined by TVA's RO, have returned to a condition in which 27hours of warning will again be available.River Scheduling of River Operations prepares at least aR 9 day .wate level forecast seven days per.Aoeek fo-r Te~nnesseep River locations. DurWing prospective flooding conditions forecasts can beprepared 4 times a day so that warnings for Soqueyah will assure that 27 hours3.125e-4 days 0.0075 hours 4.464286e-5 weeks 1.02735e-5 months always will beavailable to shut down the plant and prepare it for flooding.2.4.14.9.5 Hydrologic Basis for Target StagesFigure 2.A. 4, in fo.ur parts, shows hoW target floo,,d elevations at the Sequoyah plant ha.ebeen determined to assure adequate warning times. The flo-ods shown are the fastest rising floods athe site which are producod by the 21,100 square mile PMVP with downstream contoring deScribed ia 3 day having 40 percent of the main storm rainfall This has caused so.I moisture to be highand reser.'oirs to be 'well above seasonal cyvels w;hen the main storm benins.Fiaure 2.4.14-3 (Sheet 11and Figure 2.4.14-3 (Sheet 2) for winter and summer respectively, show target forecast flood warningtime and elevation at SQN which assure adequate warning times. The fastest rising probablemaximum flood for the winter at the site is shown in Figure 2.4.14-3 (Sheet 1A). Figure 2.4.14-3(Sheets 1 B and 1 C) show the adopted rainfall distribution for the 21,400 square mile storm and the7,980 square mile storm, respectively. An intermediate flood with average basin rainfall of 10 inches(rainfall heavy at the end) is shown in Figure 2.4.14-3 (Sheet ID). Figure 2.4.14-3 (Sheet 2A) showsthe 7,980 square mile fastest rising probable maximum flood for the summer with heavy rainfall at theend. The 7,980 square mile adopted rainfall distribution is shown in Figure 2.4.14-3 (Sheet 2B). Anintermediate flood with average basin rainfall of 10 inches heavy at the end is shown in Figure2.4.14-3 (Sheet 2C). All of these storms have been preceded three days earlier by a three-day stormhaving 40% of PMP storm rainfall.2.4-62 SQN-Figuro 2.4A. 4 (A, B, G) shows the Wint.. PMP .Whic cou.1ld produce the fatest risng 6 ,flood which... coss plant and- variations. causod by changed timoi distribution. -The fastest rising floodoccurs during a PMP when the 6six-hour increments increase throughout the storm with the maximum6-heurssix-hour increment increase occurring in the last period. Figure-2.4A-4 2.4.14-3 (BSheet 1A)shows the essential elements of this storm which provides the basis for the warning s4hemeplan. Inthis flood 9,27.35 inches of rain would have fallen 31 hours3.587963e-4 days 0.00861 hours 5.125661e-5 weeks 1.17955e-5 months (27 + 4) prior to the flood crossingelevation 703.0 ft and would produce elevation 697694.5 ft at the plant. Hence, any time rain on theground results in a predicted plant stage of 6W7694.5 ft a Stage I shutdown warning will be issued.Examination of Figure 2.4A. 4 (A and-C)_2.4.14-3 (Sheets 1 B and 1 C) shows that following thisprocedure in these nencr44ical-floods would result in a lapsedtime-.f longer times to reach elevation703.0 ft after Stage I warning was issued. These times would be 4233.6 and 4443.6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months between.:hPn A.2 inches had fallon and the flooed woul- id cross critical oleyation 703(icue4horfr., ..._ .4 ....l.. z , includes 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months forforecasting and communication) for Figure 2.4.14-3 (Sheet 1 B) and (Sheet 1C), respectively. Thiscompares to the 31 hours3.587963e-4 days 0.00861 hours 5.125661e-5 weeks 1.17955e-5 months for the fastest rising flood as shown in Figure 2.4.14-3 (Sheet 1A). Stage Iwarning would be issued for the storm shown in Figure 2.4.14-3 (Sheet 1 D) and 63 hours7.291667e-4 days 0.0175 hours 1.041667e-4 weeks 2.39715e-5 months would passbefore elevation 703.0 ft would be reached.ARA Stage II warning would be issued if an additional 2--2-2.44 inches of rain must-fal4fel_ promptly for atotal of 4-4149.79 inches of rain to cause the flood to cross critical elcv-tion 703. In the fastest risingflood, Figure-2.4A,.-44B)2.4.14-3 (Sheet 1A), this rain would have fallen in the next 56.9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months . Thus,6.9 hours1.041667e-4 days 0.0025 hours 1.488095e-5 weeks 3.4245e-6 months after issuance of a Stage I warning, enough rain would have fallen to reguire a Stage IIwarning. A Stage II warning would be issued within the next 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months and the flood wood exceedelevation 703.0 ft in 24.1 hours1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months . Thus, the Stage 11 warning would be issued 5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months after issuanc ofa Stage I warning and 22 hourcs befo-re the flooed wou-ld- cro4s~s c-ritica,-l flooed elevatio-n 7032 In the slowerrising floods, Figure 2.4A.. 4 (A -a-GC 2.4.14-3 (Sheets 1 B and 10), the time between issuance of aStage I warning and when the 4-1-49.79 inches of rain required to put the flood to elevation 703.0 ftwould have occurred is 63.6 and 1-03.3 hours3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months , respectively. This would result in issuance of a Stage IIwarning not loss than 4 ho-urs later or 32 and 3030 or 40.3 hours3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months , respectively, before the flood wouldreach elevation 703.0 ft.The summer flood shown by Figure-24A.-4-(D) 2.4.14-3 (Sheet 2A), with the maximum 1-one-day rainon the last day provides controlling conditions when reservoirs are at summer levels. At a time 31hours (27 + 4) before the flood reaches elevation 703.0 ft, 448.18 inches of rain would have fallen.This 448.18 inches of rain, under these runoff conditions, would produce 7-93699.1 ft,so this lpeoel brcomes both the Stage I and-Stage4l-target. An additional 1.3 inches of rain must fallpromptly for a total of 9.48 inches of rain to cause the flood to exceed elevation 703.0 ft.The above criteria all relate to forecasts which use rain on the ground. In actual practice quantitativerain forecasts, which are already a part of daily operations, would be used to provide advance alertsthat need for shutdown may be imminent. Only rain on the ground, however, is included in theprocedure for firm warning use.Because the above analyses have used fastest possible rising floods at the plant, all other floods willallow longer warning times than required for all physical plant shutdown activity.In summary, the predicted target levoLsforecast elevations which will assure adequate shutdown timesare:Forecast Flood Elevations at SequoyahFor ForSeason Stage I Shutdown Stage II ShutdownWinter- 1 April 15 697694.5 ft 703.0 ftSummer (Apr!i 16 September 30) ft 703.0 ft2.4.14.9.6 Communications Reliability (HISTORICAL INFORMATION)2.4-63 SQN-Communication between projects in the TVA power system is via (a) TVA owned microwave network,(b) Fiber-Optic System, and (c) by commercial telephone. In emergencies, additional communicationlinks are provided by Transmission Power Supply radio network. The four networks provide a highlevel of dependability against emergencies. Additionally, RO have available satellite telephonecommunications with the TVA hvdro proiects upstream of Chattanooga (listed in Section 2.4.14.9.2).The hydrologic neptwPork fo-r the iWAte;rsqhe~d_ above Seguoyah that would be available in floodemegeniesif commecial telcphone communications is lost include 138 rainfall gages (21 at powerinst-allations -and 1114 satellite and Aile transfer gages) and 47 streamfiow gages (26 at hydroplants,sate ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~s. I~ III gaea ~~tFgg) R~FShdl 0is inU LO the I V1A power systemIby all fetwfive communication networks. The data from the satellite gages are received via a datacollection platform-satellite computer system located in the River ScRh, eduling'sRO office. These are soditstnbuted over the watershed that reaSonabic fleed trecasting can be done #Gro this data whole thebalance of data is bcing secured from the remaining hydrologic nctwork stationS.-The preferred, complete coereage of the watershed, employ 160 rainfall and- 61 streamfiow locatinabovo the Sequoyah plant. Involved in the commR~unicationsR link to these locations are routine radio-,radio) satellite, and commR~ercial telephone systemR nctwerks. In an emergcncY, available radiocommunications would be called upon to assist.The va;rious networks proved to be capablc in the large fioods of 1957, 1963, 197-3, 1981, 1994, ad1998 of provYiding the rain and- streamrfoiow d-ataa necded- for reliable forecasts.2AA-92.4.14.10 Basis for Flood Protection Plan in Seismic-Caused Dam FailuresFloods resulting fromR combined seismicG and flood events can exceed plant grade, thureiinemnergencGy measures. The 1 998 reanalysis showed that only two combinatfions, of seismice dafailures coincident with a flood would result in floods above plant grade: (1) failure Of Fontana,Hiwassee, Apalachia, and Blue Ridge Dams in the on.e ha-lf = ...cn.urrent with a 1/2 PMF, (2) SSEfailuhre o-f NorFris, Cherokee, and Douglas concurrent with a 25 year flood. A s shon in ; Table 2.1414all other potentially critical c0and-idates wsould- create flooad levels below plant grade elevation 705- Plantgrade would be exceeded by four of the five candidate seismic failure combinations evaluated, thusrequiring emergencv measures. Table 2.4.4-1. shows the maximum elevations at SQN for thecandidate combinations. The combination producinq the shortest time interval between seismic eventand plant qrade crossinq is a OBE located so as to fail Fontana, Tellico, Hiwassee, Apalachia, andBlue Ridge Dams during the one-half PMF. The time between the seismic event and the resultingflood wave crossing plant grade elevation 705.0 ft is 40 hours4.62963e-4 days 0.0111 hours 6.613757e-5 weeks 1.522e-5 months . The time to elevation 703.0 ft, whichallows a marain for wind wave considerations. is 32 hours3.703704e-4 days 0.00889 hours 5.291005e-5 weeks 1.2176e-5 months . The event Droducina the next shortest timeinterval to elevation 703.0 ft involves the OBE failure of Tellico and Norris durino the one-half PMFresultinq in a time interval of 34 hours3.935185e-4 days 0.00944 hours 5.621693e-5 weeks 1.2937e-5 months . These times are adeguate to permit safe plant shutdown inreadiness for flooding.Dam failure during non-flood periods -would netnFeSeRt a nFONeM at Me 1312M 1 no Feanal -sneweaQ- A'A i i ' 'i i AS-----------. ,.---........ .........k; f; Qcc f ;I f K! ; r1k 6 .47M CZ f fin ,.I f., 1 A fnl t fI,. K I~n 1 f All ,hfin- k; ..4nIt;+1 A ; 14 !14produce elevations mF. uh lower,. was not evaluated, but would be bounded by the four critical failurecombinations.The time from seismcocurrene to arrival of failre surge at the plant is adequate to permit safeplant shutdown in readiness forF flooding. Tabhle 2 4A-:2lit the timeq betwmeen the postulated seismic,event and when. the fooed- wlave wolexcoeed plant grad~e elevatfion 70-5 -anAd eeain73 1_s6 ofelevation 703 provides a margin for possible wind wave effec-ts.vThe warning plan for safe plant shutdown is based on the fact that a combination of critically centeredlarge earthquake and 4Rai produced flood conditions must coincide before the flood wave fromseismically caused dam failures will eess~approach plant grade. In flood situations, an extremeearthquake must be precisely located to fail threetwo or more major dams before a flood threat to the2.4-64 SQN-site would exist.The comFbinationR produc~ing the 8ho9486t time inteR'al between seism~ic event and plant grade crossinSmgis a one half SS-" located s as to fail Fontana, Hiwassee, Apalachia, and Blue Ridge DamS during theone half RMF. The time bebween the sciSMic event and the resulting flood wave crossing"plant gradeelevation 705 is 40 hours4.62963e-4 days 0.0111 hours 6.613757e-5 weeks 1.522e-5 months . The time to elevation 703, which allows a mnargin forind wavecGrsiderations, i6 35 hours4.050926e-4 days 0.00972 hours 5.787037e-5 weeks 1.33175e-5 months . The event the next shotest time intep'al to elevation 703... ....s the SSE failure of Norris, ChcrOk.., and Douglas during the 25 year flood resulting in a timeintePval of 63 hours7.291667e-4 days 0.0175 hours 1.041667e-4 weeks 2.39715e-5 months .The warning system utilizes TVA's flood forecast system to identify when flood conditions will be suchthat seismic failure of critical dams could cause a flood wave to exceed elevation 703.0 ft at the plantsite. In addition to the critical combinations, failure of a single major upstream dam will lead to anearly warning. A Stage I warning is declared once failure of (1) Norris, Cherokee, Douglas, and TellicoDams or (2) Norris and Tellico Dams, or (3) Fontana, Tellico, Hiwassee, Appalachia, and Blue RidgeDams, or (4) Cherokee, Douglas and Tellico Dams has been confirmed.Two levels of warning will be provided: (1) an earlywarning will be issued to SQN whenever a damfailure has occuFred OF is inmminent for any s.ngle critia-l dam; or it appeasF fonm and flodforecasts that a critical situation may develop and (2) a flood wa.rnig or ale+t to begin preparation forplant shutdown when a critical situation exists that will result in the flood level to exceeding plantgrade. A Stage 1 flood warning is declared Once failure Of critical dam~s has been ~onfirmed andl floodcOnditions; are such that the flood surge will eXceed plant It shall he issued at least 27 hour3.125e-4 days 0.0075 hours 4.464286e-5 weeks 1.02735e-5 months sbefore the flood- level exceeds elevation 703 at the site. A Stage 11 fleed- warning will be issued at least17 hours before the flood lo'vel exceeds elevation 703 at the site. Communication will1 be establishedand mnaintained during these two levels of warning to assure the 27 hour3.125e-4 days 0.0075 hours 4.464286e-5 weeks 1.02735e-5 months flood preparation period. Anyprolonged interruptionR Of commFunication Or failure to confirmn that a critical case has not occurred willresult in theitiato of flood preparation at the plant site. The flood preparation shall continue unticOmpletion, unless communication is Fe established and the site is notified that a critical case has notGuF-ed-.4lf loss of or damage to an upstream dam is suspected based on monitoring by TVA's RO,efforts will be made by TVA to determine whether dam failure has occurred. If the critical case hasoccurred or it cannot be determined that it has not occurred, Stage I shutdown will be initiated. Onceinitiated, the flood preparation procedures will be carried to completion unless it is determined that thecritical case has not occurred.Communications between the-platSQN, dams, power system control center, and River Operations atKnoxville, Te,.esseeTVA RO, are iaccomplished by TVA-owned microwave networks, fiber-optics network, radio networks, and commercial and satellite telephone service.9A 1A 1IQ -rini (crn-fiti-~ Ali I n~x~n-...H -The flood orotection nlan is based uDon the minimum time available for the worst case. This worstcase provides adequate preparation time including contingency margin for normal and anticipatedplant conditions including anticipated maintenance operations. It is conceivable, however, that a plantcondition might develop for which maintenance operations would make a longer warning timedesirable. In such a situation the Plant Manager determines the desirable warning time. He contactsTVA's RO to determine if the desired warning time is available. If weather and reservoir conditions aresuch that the desired time can be provided, special warning procedures will be developed, ifnecessary, to ensure the time is available. This special case continues until the Plant Managernotifies TVA's RO that maintenance has been completed. If threateninq storm conditions are forecastwhich might shorten the available time for special maintenance, the Plant Managqer is notified by ROand steps taken to assure that the plant is placed in a safe shutdown mode.2.4A.10 References1. -SQN DG V 1 .1, Design of Reinforced ConcreFte StructreAis; Design Criteria2. DG. V 12.1, Flood rotectio-,n rovisions Doign Criteria2.4-65 SQN-3. SQN DG V 43.0, High Pr.....e Fire Protection Water Supply System2.4.15 References1. U.S. Weather Bureau, "Probable Maximum and TVA Precipitation Over The Tennessee RiverBasin Above Chattanooga," Hydrometeorological Report No. 41, 1965.2. U.S. Weather Bureau, "Probable Maximum and TVA Precipitation for Tennessee River BasinsUp To 3,000 Square Miles in Area and Duration to 72 Hours," Hydrometeorological Report No.45, 1969.3. Garrison, J. M., Granju, J. P., and Price, J. T., "Unsteady Flow Simulation in Rivers andReservoirs," Journal of the Hydraulics Division, ASCE, Vol. 95, No. HY5, Proceedings Paper6771, September 1969, pp. 15559-1576.4. PSAR, Phipps Bend Nuclear Plant, Docket Nos. 50-553, 50-554.5. Tennessee Valley Authority, "Flood Insurance Study, Hamilton County, Tennessee,(Unincorporated Areas)," Division of Water Resources, February 1979.6. U.S. Army Engineering, Corps of Engineers, Omaha, Nebraska, "Severe Windstorms of Record,"Technical Bulletin No. 2, Civil Works Investigations Project CW-178 Freeboard Criteria for Damsand Levees, January 1960.7. U.S. Army Corps of Engineers, "Computation of Freeboard Allowances for Waves in Reservoirs,"Engineering Engineer Technical Letter No. 1110-2-8, August 1966.8. U.S. Army Coastal Engineering Research Center, "Shore Protection, Planning, and Design," 3rdEdition, 1966.9. Reference removed per Amendment 6.10. Hinds, Julian, Creager, William P., and Justin, Joel D., "Engineering For Dams," Vol. II, ConcreteDams, John Wiley and Sons, Inc., 1944.11. Bustamante, Jurge I., Flores, Arando, "Water Pressure in Dams Subject to Earthquakes," Journalof the Engineering Mechanics Division, ASCE Proceedings, October 1966.12. Chopra, Anil K., "Hydrodynamic Pressures on Dams During Earthquakes," Journal of theEngineering Mechanics Division, ASCE Proceedings, December 1967.13. Zienkiewicz, 0. C., "Hydrodynamic Pressures Due to Earthquakes," Water Power, Vol. 16,September 1964, pp. 382-388.14. Tennessee Valley Authority, "Sedimentation in TVA Reservoirs," TVA Report No. 0-6693,Division of Water Control Planning, February 1968.15. Reference removed per Amendment 6.16. Cristofano, E. A., "Method of Computing Erosion Rate for Failure of Earthfill Dams," Engineeringand Research Center, Bureau of Reclamation, Denver 1966.17. "The Breaching of the Oros Earth Dam in the State of Ceara, North-East Brazil," Water andWater Engineering, August 1960.18. NRC letter to TVA dated December 8, 1989, "Chickamauga Reservoir Sediment Deposition andErosion -Sequoyah Nuclear Plant, Units 1 and 2."2.4-66 SQN-19. Programmatic Environmental Impact Statement, TVA Reservoir Operations Study, Record ofDecision, May 2004.20. Updated Predictions of Chickamauga Reservoir Recession Resulting from Postulated Failure ofthe South Embankment at Chickamauga Dam; TVA River System Operations and Environment,Revised June 2004 (B85 070509 001).21. Monitoring and Moderating Sequoyah Ultimate Heat Sink, June 2004, River System Operationsand Environment, River Operations, River Scheduling (B85 070509 001).22. SQN Calculation MDQ0026970001A, "High Pressure Fire Protection Supply to the SteamGenerators for Flood Mode Operation."23. Newton, Donald W., and Vineyard, J. W., "Computer-Determined Unit Hydrographs FromFloods," Journal of the Hydraulics Division, ASCE, Volume 93, No. HY5, September 1967.24. U.S. Army Corps of Engineers, Hydrologic Engineering Center, River Analysis System,HEC-RAS computer software, version 3.1.3.25. Federal Emergency Management Agency (FEMA), "Federal Guidelines for Dam Safety:Earthquake Analysis and Design of Dams," FEMA 65, May 2005.26. Price, J. T. and Garrison, J. M., Flood Waves From Hydrologic and Seismic Dam Failures," paperpresented at the 1973 ASCE National Water Resources Engineering Meeting, Washington, D. C.27. SQN-DC-V-I.1, Design of Reinforced Concrete Structures Design Criteria.28. SQN-DC-V-12.1, Flood Protection Provisions Design Criteria.29. SQN-DC-V-43.0. Hiah Pressure Fire Protection Water SuDDlV System.2.4-67 ENCLOSURE1EVALUATION OF PROPOSED CHANGESATTACHMENT 2Proposed SQN Units I and 2 UFSAR Tables SQN-Table 2.4.1-1Public and Industrial Surface Water Supplies Withdrawn from the 98.6 Mile Reach of theTennessee River between Dayton Tennessee and Meade Corp. Stevenson Ala.ApproximateDistanceFrom Site(River Miles)Plant NameCity of DaytonCleveland Utilities BoardBowaters Southern PaperHiwassee UtilitiesOlin CorporationSoddy-Daisy Falling Water U.D.Sequoyah Nuclear PlantEast Side Utility*Chickamauga DamDuPont CompanyTennessee-American WaterRock-Tennessee MillDixie Sand and GravelChattanooga Missouri Portland CementSignal Mountain CementRacoon Mount. Pump Stor.Signal Mountain CementNickajack DamSouth PittsburgPenn Dixie CementBridgeportWidows Creek Stream PlantMead CorporationUse (MGD)1.7805.03080.0003.0005.0000.9271615.6805.0007.20040.9300.5100.0350.1002.8000.5610.2000.9000.000010.600397.4404.400LocationTRM 503.8 RTRM 499.4 LHiwassee RM 22.9TRM 499.4 LHiwassee RM 22.7TRM 499.4 LHiwassee RM 22.5TRM 499.4 LHiwassee RM 22.3TRM 487.2 RSoddy Cr. 4.6Plus 2 WellsTRM 484.7 RTRM 473.0 LTRM 471.0TRM 469.9 RTRM 465.3 LTRM 463.5 RTRM 463.2 RTRM 456.1 RTRM 454.2 RTRM 444.7 LTRM 433.3 RTRM 424.7TRM 418.0 RTRM 417.1 RTRM 413.6 RTRM 407.7 RTRM 405.2 RType Supply19.1 (Upstream)37.6 (Upstream)37.4 (Upstream)37.2 (Upstream)37.0 (Upstream)7.1 (Upstream)0.011.7 (Downstream)13.7 (Downstream)14.8 (Downstream)19.4 (Downstream)21.2 (Downstream)21.5 (Downstream)28.6 (Downstream)30.5 (Downstream)40.0 (Downstream)51.4 (Downstream)60.0 (Downstream)66.7 (Downstream)67.6 (Downstream)71.1 (Downstream)77.0 (Downstream)79.5 (Downstream)MunicipalMunicipalIndustrial& PotableMunicipalIndustrial& PotableMunicipalIndustrialMunicipalIndustrialIndustrialMunicipalIndustrialIndustrialIndustrialIndustrialIndustrialIndustrialIndustrialMunicipalIndustrialMunicipalIndustrialIndustrial# Water usage is not metered Flow Rate fluctuates as needed and is directed by power control center in Chattanooga.2.4-68 SQN-Table 2.4.1-2 Facts About TVA Dams and Reservoirs(Page 1 of 2)0a10L216ns, a 6100290 LAAJo, a1 1 habrA/ao (FeA Ab ~oeMenSea Leoo) R60 orAVoume(Ao e Fo ) anAboAe FirstUniti LOOI7 UA. Wflt- Ne Ab0ve S -0, Widt, 6,Roi OrNl2l Jan 1 Jn 1 ConttolledDam,1 Seolc SOIAN Depend4ble Number of M.t do Height L SLengh 107n170 Surface R2 PIAlo Flood AIJan1 A. June I1- RtAge Nu-,eMainRivt (qua Cot~b) Contrutio Da (A-1 or) (A-tul or Cpciy -Gnrting (i-r .1- 1a -fa Type .fM1 iu LAf Re kr= ile If Area.) ef Gid Toe-uie lo G..,!e A, Top o Fl-od GuIde. ceelDPrAojets -rive 810. M09 .s) (M-ons) B-aI AAA)u0 Shedule) --hed9 d MgA) (M A UAits (MoNes) I-) ( F.1) OF-) (Mles) NhlA --1 (- (A-) E AI EAAesIEleati1on OeaA aOe, leIonA F0 t) Pto, t PAoc=KentuAckyc) 700nes 74AKY 40,200 126.OAI 1193A 8191344 91411414 110 .1946 lA4 7 22A4 2. .422 AGA 110,6A047NF1 1-0. 0 20- IN 21,- ANA A A -5A 2,121,OO 6,129,A0O 2.6739AO@ 4,4860AA AN Av- ApiTkwick Tenoooo AN 32,62A 12A IAOAI194 211-1901 6Oll1-338 12/3111952 229 6 206,7 113 7,715 CGE 1-0,1-00x63(1 52.7 4W06 42,74 9AO0 408. 41800 414A1 O1.,OO 1.A02,000 1.1190.0A 492.700 TN R.-eo ALaOdoig 110x6I O63W0o0l-1) Ten0s0e AL E0.7-A 133.5 411411918 411411924 .1211- 4A12)1192 N-A 21 2474 117 4,A.l C A 1Ax60xo7(' 155 166I2 17646 9,1A 50I7 7 A7-6 .07.7 ..A,7W0 -4A,200 637.2N0 NA,SAO TN 0Iet AWtAl- I.-- AL 2H..0 6940 1112101933 10-1936 10 11021530 17181143 361 11 274- 12 S.3A2 CAG A x4A 12 7-1 10212 6711A 1,600 5505 550.28 O5N.A 742,000 1,06O,000 10500 320.500 T7 R-,110.600.521100untei"O Tennes4 AL 24,450 74.2 -A11935 111611939 811/1040 .3A.1196 124 4 14A 0 -AA9 A cAE NA,60,S4 757 6961 66.046 12406 5-0 A 595.44 A95.0 886,60 1,048,700 1.A18,000 162.100 R- Rie, I110.600.451,kiN.j4 T e T7 21.67A 50.1 411116- 12-141107 2-201344 4/3-1966 lOS 4 4247 86 2,167 A-E 110x04 l4JA 463 106.1 10.,200 4,00 6325- 635.00 632.5- NIA 251,600 NTA 1-,A 79 RioeI1106041 635 634 5ACh~lek ug Tenne, 7TN 20.740 744 111911630 1115/1140 3/4)1840 31711-52 11. 4 4A1 12. 54 000 1... .SE 6 03 5 SBA 760-7 36,OA 9500 6750 685.44 662.5 32,.000 737.300 -22.500 027.00 TN 50 1W Itts,64a 74T6n0ess 7TN 77.,10 66T 71171939 11111-2 071/1942 4124-4 12 15I') 2,460 000 601041.70 9-33r) 2217 -7,500 10,34 7350 7456 741.0 74.,000 1,175,000 1.0107001 379,000 TN Riet IFe21L4do4n Ten46s4e 7N 0.574 45.3 7 -81700 6011023 1111023 1127-9 162 4 600.3 129(-) 4,190 CGE N-80 60-( 32 14046 4,420 4070 615-4 61610 02A00I 303,000 303.000 110,0 TN R-,ve IRaul~l n ..TN 1 207.6 11111971 171111177 1 1100111176 1811.420A.7 ]..26 f 153 ] _- 11111 N61 1 1 11 011 I N-A II 1t5o I-T-.,tar P.-, -rje-t71- Ford E6k TN 7 529 43.8 3081967 12111170 1711972 -11972 36 1 13- 175 1".0 E3R 7A 02 30067 10.50, 365 6730 605.00 860,0 3M6.446 602,000 530000 219.600 Elk 06,1 1H-.-0.0 0iw04000 N. 1,018 294 011171-1 21411023 --221103 111171143 862 2 660 146 1.706 0G N.A 91N AI. 1100 807 1270 0- 126000 12212.0. 6 67,600 700 N0A 001-00 4HiwasB Hiwass. NC 96 46 2 7411-1936 081100 -21)1040 5l24l19M0 141 21"1 705 307 1.378 00 N.A 202 1646 ..670 1,000 1466,0 102650 1521.0 226,400 402,000 399.000 205,600 H6,4S4 4Chatug5 Hiw..4 NC 1189 .5 7E1711-41 211-1122 1 -611962 100)1462 10 1 1210 130 2.800 E 600 lAO 1260 6.700 107 191810 132800 102.0 177,900 2421,00 205,500 62,600 Has0 4coo,, l)'B1) 6046 75 593 11.6 4,001010 1211611 1-281912 0011414 0 5 7 11 9 735 0 0 G N.A 7 5 470 1,620 170 6200 07.16 623.0 02,00 63,000 70.900 13000 O. 3ooe2(h) O046 TN 512 26- -146/912 10001913 10-01913 100040913 23 2 242 30 4.0 O N.) 600 N)0 610 600 700 111520 600 60A 8I) 610 610 00 3-cee3 O-oe TN 092 49ý 711711.41 -1./92 4-31.93 4-01.43 29 1 2.2 110 612.1 C G TO 7 24. 600 26D 14428.0=- 1435.00 1442.- 1,1A 4.2.0 WNA O. 34350 .43IEl-e To GA 232 204 1190limu92) 12196300 7-01931 7-01931 13 1 530 175 1000 0E N. 110 661 3,220 162 16-o.0 1691.00 1687.0 127,400 105,000 162,646 66,SOO looo/ IR73,,(h6' O-eN1o3ly Noelly GA 214 1772 711711941 11241022 1/lI01950 1110119.0 1 1 210 197 2,346 R6E 60 22 102.1 3,.70 170 1762.0 178000 17770 112700 174,300 162,000 61,600 H...s0 4Me.1- Hil) Chneh TN 3,023 21.5 -61196B94 115111964 7- 0 21.1 109 1700 2 0 75-46,60 44 1034 5090 1,'23 7920- 796.00 7920 kA 126,000 )A NA C30nch 21 1 795.0 7950-00s Q-inh TN 2.-12 461 10l1)B33 -30)796 7-081976 9-001936 110 2 796 263 1660 00GE 5) 12.0.&1) 002 2 N 4ON 2,930 1-0 1703400 71,020,0 1,439M.0 2,552,00O 2043,460 1,1137946 016 2Tello ittle T14 TN 2027 11770 3)N1967 711A9l1971 (1) B) (4) (0) 0.3 133)) 3,236 006 (0) 3342 3570 17660 2.133 807.0 81500 8130 304,0 424,000 392,000 120.460 L1100N 2FotOno LittleTN TN 1,71 64- 1 11111622 1117117 4 102023 2)4)1460 3 610 460 2,365 0G N1A 209 297. 10,290 1,03 1653.0 171 00 17030 929O04 1,443,400 1,370,000 514,000 Ltte TN 2001u9l0 F 707nch1463 TN 461 890 022/-.2 -19)1643 -2-1 3 6)017354 I1I 4 021 0155 1,705 00 )0 431 61251 20,070 3.170 9300 100246 9020 373046 1.461,000 7.223.300 7.062046 Frenco 1Ch05704 A14.1,- TN 3,428 293 -111940 12 941 4B161-42 7007962 148 0 52.3 178(') 6,760 CGER N-0 040 902. 29,560 2,426 10-50 107534 10710 797,600 7l427, 900 7,400,40 749,46 H0I0)0) 4F46 P.I1o- S4u1h -or 7N 1,903 109 5/141)1977 17027)1902 12-51953 2001694 41 2 62 95 737 C0G 3) 104 390 600 333 72760- 126030 7 1236 N.0 0604 N2ANW0 lo- 421,03 0 126370Boo Soh Fo TN 17740 15.7 8-201950 12/1611952 903-1953 89 3 810 178 1.532 ECG 6)0 32,7) 120.6 4300 716 1762.0 138564 13820 117,600 193,400 180,500 15,800 H207 360th HolIto SOh Fo1k TN 703 217 --04l197(P) 110950 2101357 2-111951 44 1 497 285 1.6w6 E5 N1A 237 -17.9 7,060 710 17760 174246 17290 51,.300 76 65480 36,000 252,800 H0A.- 4-040,96 00001g9 TN 468 22.1 7022S14( l12/111006 w001700 -00)1749 66 2 -7 002 9NO E7R N. 10.3 10.0 60,440 313 1.520 1975 N 19590 52I.200 6770 0 61646 102,300 WN040g11W4lbN11r) W-.ug. TN 471 7.6 11 00-1909 00N0,-/1912 0-9012 7/19)1950 -7 0 020 761033 3755 0 G N)A ,8 40. 70 014641 1650300 7671- N)A 714 N)A N)A0 w90o3g AG0a, Cosoy -or TN 1,670 21.4 101)1615 1081916 00)1116 0/0)125 36 2 910 00 846 00 61 220 10.0 1,800 1.4N0 7850 60330 6000 19.7.0 3004 4.,1004 3,00. COny Fo. 1N.i)00110 N-l4-0u1k, T7 1.173 01 00-1913 (q) () 0610 482 0G 20-0 1 0 124610 Noh-tlueky 12.4-69 SQN-Table 2.4.1-2 Facts About TVA Dams and Reservoirs(Page 2 of 2)a) All i. -ae T -n -,asm ,except for G- Fas w -bb u ieeamaada aeyb) Csit e1 pa t iudd d te botan .f hel plant -a.dall dd b -Id1an d 1-ts e MheM plan Tn ssyeaaayaaai .a- nicdedada) winter dat daysydabs aaaof Octberdd mad iner nes depey~adile caaaay isale aidnleeidposraa plant onie aseegsewinter day. tesmis se elCsamty ased by m eaei~t am')lfI) E: E-ay; R -htl; G: G itya C: Conlea. Om OM, (C-dss lb, h-,.a 1-ea .1 pesieii -)deroimaat )e) At Juie Isao guidec a6 a.F) V -fute.w-n eeeJanac3 I dsicaiianead td p If gates.g) C- -td ta laiticy yIsy r by 1-lid eisa -1, -hi op-teed July 14.1966,) A uii: WilAan by t- e f.. -U S u-a y C-. .Egy 1933; Xy:O 1, Ames 2, due didge. ard re.t rails D.y pamnas tm GTtFen1ess, biacaic POb. Tompaniy iP -1939; Wilbreaedd (.b-ed) by yiemyas frm E-siTayy.asse Pace, ayd Liget Campanyminaa4. Seb uaot to ameiisibaon Tu sAisaled alddbai anc ai Wilsa Did Wilur, aeReens1,ead flame at Itas deaa pmacd in se11a.e an Naemcer 1.d3,) A-i -ck plac- in ---a~o ,in 59 It .1 Whi l., -195a G- -11.,~e ..d1 4 -.iwc Land.,.j) Caeaneatn If baman -c ait Ndkajaaa I-mitea t. u -ae -aieren t -ai.k) G--eeaig unitsat R-.a.o Mount-ai arrea Francistype up-turbinee-it. each th 428y400 kW g -eerao ygana 612,000 hp puy p i tormratiga) -at 2 et Hwi Ie -ble F ci y- e p ptb iee ait with 95,1 kW- g-seaera i n-.g -d 121,530 hp p p oair Iatein t 2Wa ft Ie adm)O-a 1 creates Pearksci Re-.sae, Natichcky ( ) tes,)t aa ayecr attaRese ir andssaRd-,. sd -.u Rdge a a T.a. Reairn) Ca-syaa- af Ble RidgeaioM-e0- -a,,yiy 1926, -esudaiM1med 19-o) p,,Iect haI no Ib~k or ---flO Str 11. -qogh navigable -.1a t, Fort Loub0 t R-111i pIer1 Iaalo .-ira saeag nuleegy output .t F-r Loudoupi Iarol aanstaaa at daam msionad .ay a ua.ga st-artd Facbae 161.942; t-m; am ly d-any-eD a aanee t, al 1ae-a1 da- yg -1dII.a) Aeaeatngaaiia atsciaaaky werea av.d from sys-emgse.-.-g--Anerg ayieusi h 1972 Te-dh ,,am -a -s sreaair fia .a asfacwiidfbs paer) WIlu 72,4 -Ie p 0, Ten -Rier IFot -L.-d~ D. -23.1 -1 up Oln- R-v lb ael- H,1 Dama) i 6cl.u 5 -l. up -F.-en Ba d -d1.and 4 dmda ump .ieH.- Rive.I) ieud 17.4 -des up th -oh F- H.lso Feer a d 15 3 -P -s a Watua R-iae.a) leatades -m Ites -C- -,n c I andaei 56 -aItI1 u o e.a) TheUS. Armyc aorp b! E- i- ie -e-.ng thsie aoIf -IsacJsaaiet nJky a-d Catb aa uga.c) Thysta1actiu deeg at dam jam , isath -i d -iaca 1m- at. p- -t A me saaatsd icndaom tame my- aims .am. T96 at dam ee ts bacb ct ter Iamce mean cbane nyt (b, t aeaet wali) ayd deak -1ct-1, imtad af -adapt c1l) Ice ace ta daecs5) As ay interm m.-Ie A1 ieant aaera. them -oat dams ace e'usad by HESCO Cona-aine flOdintyuayS.Fad Lad -3 fft ct am aabnt at e ataab e 767 a a y.1-tda t 770F-r L~d , -3.75 f~t: Im~ e t .1 e -l 3 was r-se I -~ I, alla= 837 (3,75 %we .bov opo n-et. Iatltelao83T.-li -4 1-t -ba1-n It .l1--~o 830 rise. Ito .-e v Bý,t~t ma ~ la l~l 09rie oee hn12.4-70 SQN-Table 2.4.1-3 TVA Dams -River Mile Distances to SQN(Page 1 of 2)Distance fromRiver Structure/River Mouth River Mile(a) SQN (mi.)Tennessee RiverChickamauga Dam 471 13.7SQN 484.7Hiwassee River 499.5 14.8Watts Bar Dam 530 45.3Clinch River 568 83.3Little Tennessee River 601 116.3Fort Loudoun Dam 602 117.3Holston River 652 167.3French Broad River 652 167.3Hiwassee River 0 14.8Ocoee River 34.5 49.3Apalachia Dam 66 80.8Hiwassee Dam 76 90.8Nottely River 92 106.8Chatuge Dam 121 135.8Ocoee River 0 49.3Ocoee #1 Dam 12 61.3Ocoee #2 Dam 24 73.3Ocoee #3 Dam 29 78.3Toccoa River 38(b) 87.3Toccoa River 0 87.3Blue Ridge Dam 15(b) 102.3Nottely River 0 106.8Nottely Dam 21 127.8Clinch River 0 83.3Melton Hill Dam 23 106.3Norris Dam 80 163.3Little Tennessee River 0 116.3Tellico Dam 0.5 116.82.4-71 SQN-Table 2.4.1-3 TVA Dams -River Mile Distances to SQN(Page 2 of 2)Distance fromRiver Structure/River Mouth River Mile(a) SQN (mi.)Chilhowee Dam 33.5 149.8Calderwood Dam 43.5 159.8Cheoah Dam 51.5 167.8Fontana Dam 61 177.3Holston River 0 167.3Cherokee Dam 52 219.3French Broad River 0 167.3Douglas Dam 32 199.3a) Approximated to the one-half river mile based on U.S. Geological Survey Quadrangles rivermile designations.b) Estimated river mile. River miles not provided for Toccoa River on U.S. Geological SurveyQuadrangles.2.4-72 SQN-Table 2.4.1-4 Facts about TVA Dams Above ChickamaugaProjectSpillway TypeOutlet WorksSpillway CrestElevationTop of Gate Capacity, cfs at GateElevation TopApalachiaBlue RidgeBooneChatugeCherokeeChickamaugaDouglasFontanaFort LoudounFort Patrick HenryHiwasseeMelton HillNorrisNottelySouth HolstonTellicoWataugaWatts Bara) At elevation 1752.b) At elevation 1985.Ogee, radial gatesOgee, tainter gatesOgee, radial gatesConcrete chute, curved weir, vertical-lift gatesOgee, radial gatesConcrete gravity, vertical-lift fixed roller gatesOgee, radial gatesOgee, radial gatesOgee, radial gatesOgee, radial gatesOgee, radial gatesOgee, radial gatesOgee, drum gatesConcrete chute, curved weir vertical-lift gatesUncontrolled morning-glory with concrete-linedshaft and discharge tunnelOgee, radial gatesUncontrolled morning-glory with concrete-linedshaft and discharge tunnelOgee, radial gates12571675135019231043645970167578312281503.5754102017751742773197571312801691138519281075685.441002171081512631526.579610341780N/A815N/A745135,90039,000141,70011,700255,900436,300312,700107,300392,200141,70088,300115,60055,00011,50041,200(a)117,90041,200(b)560,3002.4-73 SQN-.-Jkl,. '2 A 4_ C 6KIL-MIlA n-r% ,.-n, DA 0 V ..-T-kI ' 4 ~ k.~.4L0%,-raL %~'JUL %J" a 0I~ a"a~i woolu~ VLDII RDrainageArea(so. mi.)Distancefrom Mouth(mi.uMaximumHeight,(ft-AreaofLakeLength(ft.) (ac.iLengthofLakeLmi.LProiectsMajor DamsCalderwoodCheoahChilhoweeNantahalaSanteetlahThorpe(Glenville)RiverTotal1Storage,(ac.-ft.)41,16035,030.49,250138,730158,250ConstructionStartedLittle TennesseeLittle TennesseeLittle TennesseeNantahalaCheoahWest ForkTuckasegee1,8561,6081,97610817636.743.751.433.622.89.39.723222591250212150Minor DamsBear Creek East ForkTuckasegeeCedar Cliff East ForkTuckasegeeMission(Andrews)Queens CreekWolf CreekEast ForkTuckasegeeHiwasseeQueens CreekWolf CreekEast ForkTuckasegeeWest ForkTuckasegee75.380.72923.5815.224.954.74554.8 2159167501,3731,0421,0549007406003903828103852545365951,6901,6052,8631,4624764.5 70,8104.6 34,7112.4106.11.51.710.93.138.0165507818014061200121 2.4 6,3158108.94.67.561371763993401.460.52.228381710,056192819161955193019261940195219501924194719521952194919271.4 1,7970.5 1835.5 25,390Walters(CarolinaP&L)Pigeon870(1) Volume at top of gates.2.4-74 SQN-Table 2.4.1-6 Flood Detention Capacity -TVA Projects Above Sequoyah Nuclear PlantFlood StorageJanuary 1(ac-ft)ProjectTributaryBooneChatugeCherokeeDouglasFontanaHiwasseeNorrisNottelySouth HolstonTellicoWataugaBlue RidgeMain RiverFort LoudounWatts Bar75,80062,600749,4001,082,000514,000205,6001,113,00061,600252,800120,000152,80068,500111,000379,0004,948,100Flood StorageMarch 15(ac-ftI60,00062,600749,4001,020,000514,000205,6001,113,00061,600220,000120,000152,80049,500111,000379,0004,818,500Flood StorageSummer(ac-ft112,90013,900118,100237,50073,00035,000512,00012,300106,00032,000108,50013,10030,000165,0001,469,300Total2.4-75 SQN-Table 2.4.2-1Water Year(a)1867187418751876187718781879188018811882188318841885188618871888188918901891189218931894189518961897189818991900190119021903Peak Streamflow of the Tennessee River at Chattanooga, TN(USGS Station 03568000) 1867- 2007(Page 1 of 5)Date Discharge (cfs)3/11/1867 459,0005/01/1874 195,0003/01/1875 410,00012/31/1875 227,0004/11/1877 190,0002/25/1878 125,0001/15/1879 252,0003/18/1880 254,00012/03/1880 174,0001/19/1882 275,0001/23/1883 261,0003/10/1884 285,0001/18/1885 174,0004/03/1886 391,0002/28/1887 181,0003/31/1888 178,0002/18/1889 198,0003/02/1890 283,0003/11/1891 259,0001/17/1892 252,0002/20/1893 221,0002/06/1894 167,0001/12/1895 212,0004/05/1896 269,0003/14/1897 257,0009/05/1898 167,0003/22/1899 273,0002/15/1900 159,0005/25/1901 221,0001/02/1902 271,0004/11/1903 210,0002.4-76 SQN-Table 2.4.2-1Water Year(a)1904190519061907190819091910191119121913191419151916191719181919192019211922192319241925192619271928192919301931193219331934Peak Streamflow of the Tennessee River at Chattanooga, TN(USGS Station 03568000) 1867 -2007(Page 2 of 5)Date Discharge (cfs)3/25/1904 144,0002/11/1905 146,0001/26/1906 140,00011/22/1906 222,0002/17/1908 163,0006/06/1909 163,0002/19/1910 86,6004/08/1911 198,0003/31/1912 190,0003/30/1913 222,0004/03/1914 105,00012/28/1914 185,00012/20/1915 197,0003/07/1917 341,0002/02/1918 270,0001/05/1919 189,0004/05/1920 275,0002/13/1921 213,0001/23/1922 229,0002/07/1923 188,0001/05/1924 143,00012/11/1924 138,0004/16/1926 92,90012/29/1926 249,0007/02/1928 184,0003/26/1929 248,00011/19/1929 180,0004/08/1931 125,0002/01/1932 192,0001/01/1933 241,0003/06/1934 215,0002.4-77 SQN-Table 2.4.2-1 Peak Streamflow of the Tennessee River at Chattanooga, TN(USGS Station 03568000) 1867 -2007(Page 3 of 5)Water Year(a) Date Discharge (cfs)1935 3/15/1935 175,0001936 3/29/1936 234,0001937 1/04/1937 204,0001938 4/10/1938 136,0001939 2/17/1939 193,0001940 9/02/1940 89,4001941 7/18/1941 58,2001942 3/22/1942 72,3001943 12/30/1942 235,0001944 3/30/1944 201,0001945 2/18/1945 115,0001946 1/09/1946 225,0001947 1/20/1947 186,0001948 2/14/1948 225,0001949 1/06/1949 179,0001950 2/02/1950 192,0001951 3/30/1951 140,0001952 (b) (b)1953 2/22/1953 107,0001954 1/22/1954 185,0001955 3/23/1955 118,0001956 2/04/1956 187,0001957 2/02/1957 208,0001958 11/19/1957 189,0001959 1/23/1959 110,0001960 12/20/1959 108,0001961 3/09/1961 178,0001962 12/18/1961 190,0001963 3/13/1963 219,0001964 3/16/1964 122,0001965 3/26/1965 180,0002.4-78 SQN-Table 2.4.2-1Water Year(a)1966196719681969197019711972197319741975197619771978197919801981198219831984198519861987198819891990199119921993199419951996Peak Streamflow of the Tennessee River at Chattanooga, TN(USGS Station 03568000) 1867 -2007(Page 4 of 5)Date Discharge (cfs)2/16/1966 104,0007/08/1967 120,00012/23/1967 148,0002/03/1969 121,00012/31/1969 186,0002/07/1971 90,7001/11/1972 116,0003/18/1973 267,0001/11/1974 181,0003/14/1975 148,0001/28/1976 67,2004/05/1977 191,0001/28/1978 115,0003/05/1979 145,0003/21/1980 168,0002/12/1981 50,8001/04/1982 133,0005/21/1983 116,0005/9/1984 239,0002/02/1985 81,0002/18/1986 66,2002/27/1987 109,0001/21/1988 74,1006/21/1989 173,0002/19/1990 169,00012/23/1990 185,00012/04/1991 146,0003/24/1993 113,0003/28/1994 202,0002/18/1995 99,9001/28/1996 145,0002.4-79 SQN-Table 2.4.2-1Water Year(a)19971998199920002001200220032004200520062007Peak Streamflow of the Tennessee River at Chattanooga, TN(USGS Station 03568000) 1867 -2007(Page 5 of 5)Date Discharge (cfs)3/04/1997 138,0004/19/1998 207,0001/24/19994/05/20002/18/20011/24/20025/8/20039/18/200412/13/20041/23/20061/09/200791,400137,00086,100184,100241,000160,000153,00063,80066,300(a) Water Year runs from October 1 of prior year to September 30 of year identified.(b) Not reported.[36]2.4-80 SQN-Table 2.4.3-1 Seasonal Variations of Rainfall (PMP)Antecedent(in.)3-Day PMP(in.)MonthMarchAprilMayJuneJulyAugustSeptemberRatio to Main Storm(Percent)404040403030307,980 Sq.-Mi. Basin8.148.087.967.815.725.726.0921,400Sq.-Mi.Basin6.716.446.105.633.873.874.47Dry IntervalBefore PMP(Days)333321/22/21/27,980 Sq.-Mi.Basin20.3620.2019.9219.5319.0719.0720.3021,400 Sq.-Mi.Basin16.7816.1115.2714.0912.9213.0914.92Source: HMR Report 412.4-81 SQN-Table 2.4.3-2 Probable Maximum Storm Precioitation and Precipitation ExcessIndexNo.1234567891011121314 & 15Unit AreaaNameAshevilleNewport, French BroadNewport, PigeonEmbreevilleNolichucky LocalDouglas LocalLittle Pigeon RiverFrench Broad LocalSouth HolstonWataugaBoone LocalFort Patrick HenryGate CityTotal Cherokee LocalHolston River LocalLittle RiverFort Loudoun LocalNeedmoreNantahala(Page 1 of 2)Antecedent StormRain, Excessb(inches) linches)6.18 2.916.18 3.676.18 2.916.18 3.676.18 3.676.18 4.436.18 3.816.18 3.816.18 4.606.18 3.676.18 3.816.18 4.606.18 4.606.18 4.60Main StormRain, Excessc(inches) (inches)18.12 15.4418.42 16.4319.26 16.5815.30 13.3115.42 13.4317.16 15.9421.12 19.1319.38 17.3912.12 10.9012.96 10.9713.86 11.8714.34 13.1212.30 11.0815.42 14.20161718192021 Bryson City22 Fontana Local23 Little Tennessee Local -Fontana to Chilhowee Dam24 Little Tennessee Local -Chilhowee to Tellico Dam25 Watts Bar Local aboveClinch River26 Norris Dam27 Melton Hill Local33 Local above mile 1634 Poplar Creek35 Emory River36 Local Area at Mouth6.186.186.186.186.186.186.186.186.186.186.186.186.186.186.186.184.603.813.812.732.732.912.912.912.913.814.604.274.434.434.434.4316.7420.8217.2820.2220.9420.0419.5622.5019.2615.8413.5615.4215.4214.8812.7814.9415.5218.8315.2917.5418.2617.3616.8819.8216.5813.8512.3414.0114.0113.4711.3713.532.4-82 SQN-Table 2.4.3-2 Probable Maximum Storm Precioitation and Precioitation Excess (Continued)(Page 2 of 2)Index Unit AreaaNo. Name37 Watts Bar Local belowClinch River38 Chatuge39 Nottely40 Hiwassee Local41 Apalachia42 Blue Ridge43 Ocoee No. 1, Blue Ridgeto Ocoee No. 144A Hiwassee River Local atCharleston44B Hiwassee River Local mouth toCharleston45 Chickamauga LocalAverage aboveChickamauga DamAntecedent StormRain, Excessb(Inches) (inches)6.18 4.43Main StormRain, Excessc(Inches) (inches)14.28 12.876.186.186.186.186.186.186.186.186.186.182.912.912.733.812.912.913.814.274.273.8521.1218.6618.1818.1822.1418.4215.4814.5213.5616.2518.4415.9815.5016.1919.4615.7413.4913.1112.1514.39a. Unit area corresponds to Figure 2.4.3-5 numbered areas.b. Adopted antecedent precipitation index prior to antecedent storm varies by unit area, rangingfrom 0.78-1.29 inches.c. Computed antecedent precipitation index prior to main storm, 3.65 inches.2.4-83 SQN-Table 2.4.3-3 Historical Flood EventsUnit Area1BasinFrench Broad at Asheville2 French Broad Newport Local3 Pigeon at Newport7 Little Pigeon at Sevierville9 South Holston Dam10 Watauga Dam17 Little River at Mouth18 Fort Loudoun Local23 Chilhowee Local24 Tellico Local26 Norris Dam27 Melton Hill Local42 Blue Ridge Dam44A Hiwassee at Charleston (RM 18.9)Flood4/05/19575/03/20033/13/19633/17/19733/28/19943/28/19945/06/20033/17120025/06/20033/12/19633/16/19733/18/20023/12/19633/17/19731/14/19953/17/19733/17/19733/16/19735/06/20033/17/19735/06/20033/17/20023/16/19733/29/19513/27/19653/16/1973Rain(in.)5.535.665.314.685.606.197.184.616.193.123.334.413.643.616.976.266.816.976.197.347.845.006.665.706.047.36Runoff(in.)2.301.442.472.202.332.922.683.463.851.551.291.552.161.843.753.823.143.243.133.563.722.904.851.613.525.842.4-84 SQN-Table 2.4.3-4 Unit Hvdroaraoh Data(Page 1 of 2)Unit AreaGISDrainageArea Duration(sq. mi.) (hrs.) Qp Cp Tp W50W75TBNumberName1234567891011121314&15AshevilleNewport,French BroadNewport, PigeonEmbreevilleNolichucky LocalDouglas LocalLittle Pigeon RiverFrench Broad LocalSouth HolstonWataugaBoone LocalFort Patrick HenryGate CityTotal Cherokee Local944.4913.1667.1804.8378.7835352.1206.5703.2468.2667.762.8668.9854.6289.6378.6323.4436.590.9653.8389.8404.7650.2295.32912.8431.914,000 0.21 1243,114 0.66 1230,910 0.65 1233,275 0.65 1211,740 0.44 1247,207 0.27 617,000 0.75 128,600 0.20 615,958 0.53 1837,002 0.74 822,812 0.16 62,550 0.19 611,363 0.56 2425,387 0.42 128,400 0.27 911,726 0.68 1620,000 0.29 69,130 0.49 183,130 0.38 826,000 0.43 1017,931 0.14 416,613 0.58 1239 1510 48 410 714 68 510 613 625 176 313 712 734 2620 1018 1215 710 522 1216 1113 714 710 41684890809060666096329066108549696361265460288416 Holston River Local17 Little River18 Fort Loudoun Local19 Needmore20 Nantahala21 Bryson City22 Fontana Local23 Little Tennessee Local-Fontana to Chilhowee Dam24 Little Tennessee Local-Chilhowee to TellicoDam25 Watts Bar Local aboveClinch River646626466 22,600 0.49 126 11,063 0.18 615 8 5410 4 9018 6 10219 10 902627Norris DamMelton Hill Local6643,773 0.07 612,530 0.14 62.4-85 SQN-Table 2.4.3-4 Unit Hvdroaraph Data (Continued)(Page 2 of 2)Unit AreaGISDrainageArea Duration(sq. mi.) (hrs.)NumberNameQp Cp Tp W50W75TB33 Local above mile 16 37.2 2 4,490 0.94 6 3 2 4834 Poplar Creek 135.2 2 2,800 0.61 20 26 13 9035 Emory River 868.8 4 36,090 0.39 8 11 6 8436 Local area at Mouth 29.3 2 3,703 0.99 6 3 2 4837 Watts Bar Local below 408.4 6 16,125 0.19 6 10 4 90Clinch River38 Chatuge 189.1 1 19,062 0.24 2 3 2 3739 Nottely 214.3 1 44,477 0.16 1 1 1 1240 Hiwassee Local 565.1 6 23,349 0.58 12 11 6 9641 Applachia 49.8 1 5,563 0.26 2 4 1 2342 Blue Ridge 231.6 2 11,902 0.40 6 10 7 6043 Ocoee No. 1 Local 362.6 6 17,517 0.23 6 12 8 3644A Hiwassee at Charletson 686.6 6 9,600 0.59 30 39 23 10844B Hiwassee at Mouth 396.0 6 16,870 1.00 18 11 6 7845 Chickamauga Local 792.1 6 32,000 0.38 9 14 7 36Definition of SymbolsQp = Peak discharge in cfsCp =Snyder coefficientTp = Time in hours from beginning of precipitation excess to peak of unit hydrographW50 = Width in hours at 50% of peak dischargeW75 = Width in hours at 75% of peak dischargeTB = Base length in hours of unit hydrograph2.4-86 SQN-Table 2.4.4-1Floods from Postulated Seismic Failures of Upstream DamsPlant Grade is Elevation 705.0 ftOBE Failures With Sequoyah Nuclear PlantOne-Half Probable Maximum Flood Elevation (ft)1. Tellico -Norris 706.72. Partial Fontana -Tellicoa 702.23. Partial Fontana. -Tellico -Hiwassee -Apalachia -Blue Ridgea 706.34. Cherokee -Douglas -Tellico 708.6SSE Failures With 25-Year Flood5. Norris -Cherokee -Douglas -Tellicob 706.0a. Includes failure of four ALCOA dams and one Duke Energy dam -Nantahala (Duke Energy, formerlyALCOA), upstream; Santeetlah, on a downstream tributary; and Cheoah, Calderwood, and Chilhowee,downstream. Fort Loudoun gates are inoperable in open position.b. Gate opening at Fort Loudoun prevented by bridge failure.2.4-87 SQN-Table 2.4.13-1 (Sheet 1)Well and Spring InventoryWithin 2-Mile Radius of Sequoyah Nuclear Plant Site(1972 Survey Only)MapIdent.No.LocationLatitudeEstimatedWell Elevation, FeetDepth, WaterLongitude Feet Ground SurfaceWellDia.,FeetRemarks1 3513-34"2 35°13'23"3 35 13'30"4 35 13'58"5 35 14'15"6 35 14'34"7 35 14'35"8 35 14'36"9 35 15'06"10 35 14'46"11 35 14'55"12 35 14'53"13 35 14'52"14 35 14'50"15 35 14'45"16 35 14'44"17 3514'45"18 35 14'21"19 35 14'26"20 35 14'34"21 3 514'31122 35 14'29"23 35 14'23"24 35 14'22"25 35 14'24"26 35 14'28"27 35 14'26"28 35 14'32"29 35 14-34"30 35 14'38"31 35 14'41"32 35 14'45"33 35 14-43"34 35 14'41"35 35 14'39"36 35 14'39"37 35 14'40"38 35 14'41"39 35 14'35"40 35 14'36"41 35 14'37"42 35 14'33"8506'09"8506,12"8506'47"85 05'45"8506'25"8506-46"8506'52"8506'57"8506'32"850616"850615"85 06'13"85 06'13"850612"85 06,14"8506'18"8506,22"8505,30"8505'27"85 05'29"8505'29"8505-29"850532"8505'40"85 05'46"85 05'45"85 05'41"85 05'44"85 05'44"85 05'41"85 05'41"85 05'46"85 05'47"85 05'48"85 05'50"85 05'53"85 05'58"85 05'56"85 05'54"85 05'57"85 06'01"85 05'02"-- 72575 720116 74542 700-- 68085 72065 72073 73527 780110 720-- 72577 800-- 800-- 80050 720275 795-- 740-- 695200 695150 695-- 695110 69085 700-- 69552 710130 74090 740141 740-- 73558 700-- 720-- 715-- 720-- 69548 69560 700-- 69550 695-- 700-- 700-- 715223 720.5685696670687761680525.5.53.0.5152.5.55.0.5.5.5.5.5.5.5.5.5.75.5Serves 2 families;submersibleSubmersible pumpSubmersible pump1/4-hp pumpSubmersible pump3/4-hp pump1/3-hp pumpBucketSubmersibleSummer homeSummer home1-hp submersiblepump1-hp pump1-hp pump1/2-hp pumpI-hp pumpI-hp jet pumpServes 2 familes;I-hp pump3/4-hp pumpSummer home1/3-hp pumpSummer home1-hp pumpSubmersible pump1 -hp pump3/4-hp pumpSummer homeSummer home680620710650670650653655530.5.5.5.5.5.5.5.5.5.5.5NOTE: The information in this table is historic and not subject to updating revisions.2.4-88 SQN-Table 2.4.13-1 (Sheet 2)Well and Sprinq InventoryWithin 2-Mile Radius of Sequoyah Nuclear Plant Site(1972 Survey Only)EstimatedMap Well Elevation, Feet WellIdent. Location Depth, Water Dia.,No. Latitude Longitude Feet Ground Surface Feet Remarks43 35'14'46" 85'05'54" 65 695 655 .5 3/4-hp pump44 35°14'47" 85°05'54" 95 705 655 .545 35'14'48" 85'05'53" -- 700 -- -Summer home46 35'14'50" 85'05'53" 257 695 665 .5 I-hp submersiblepump47 35'14'52" 85'05'48" -- 710 -- -Summer home48 35'15'04" 8505'56" -- 725 -- Summer home49 35'15'06" 85'06'02" -- 720 -- -Summer home50 3515'06" 8506'05" 90 705 625 .5 Submersible pump51 35'14'58" 85'06'06" -- 695 -- -Summer home52 35'15'01" 85'06'02" 65 720 680 .5 3/4-hp pump53 3514'47" 85'05'57" 46 700 670 .5 2 familes; 1-hppump54 3514'42" 85'06'01" 48 695 675 .5 1/2-hp pump55 35'14'41" 85'06'02' -- 695 -- -Summer home56 3514-40" 8506'03" -- 695 -- -Summer home57 35'14'37" 85'06'08" 155 690 670 .5 1-hp pump58 35 14'34" 85 06'09" -- 695 -- -59 35 14'23" 85 05'53" -- 760 -- .5 Submersible pump60 35 14'49" 85 05'58" -- 705 --61 35'13'01" 85'04'41" -- 720 -- Summer home62 35 13'18" 85 04'24" -- 845 -- .5 1-hp pump63 35'13'19" 85'04'23" 206 845 645 .5 1/2-hp pump64 35'13'33" 85'04'19" 50 720 680 .5 1-hp pump65 35'13'49" 85'04'14" 100 720 640 .5 Servies clubhouse,15 houses66 35'13'57" 85'03'55" 175 741 -- .6 l-hp pump67 35'13'53" 85'03'49" 100 738 690 .5 I-hp submersiblepump68 35'13'50" 85'03'52" 133 720 675 .5 1/2-hp pump69 35 13'48" 85 03'43" 85 736 -- .5 l-hp pump70 35 1343" 85°03'38" 80 780 -- .5 1-hp pump71 35'13'37" 85'03'36" 130 800 715 .5 1-hp pump72 35'13'38" 8503'43" -- 800 -- -Well not used73 35'13'16" 85'03'30" 227 880 680 .5 Submersible pump74 35'13'09" 850341" 397 900 820 .5 2-hp pump75 35'12'47" 85'03'58" 190 860 800 .5 Serves 2 families;submersible76 35'13'03" 85'04'17" -- 720 -- -Summer home77 35'13'05" 85'04'10" 90 740 670 .5 1/2-hp pump78 3512'50" 8504'13" 85 760 -- .5 1-hp pump79 3512'45" 85 03'59" 190 880 -- .5 Serves 2 families;1-hp pump80 35 12'26" 85°04'07" 290 860 .5 Serves 5 families;submersibleNOTE: The information in this table is historic and not subject to updating revisions.2.4-89 SQN-Table 2.4.13-1 (Sheet 3)Well and Sprinq InventoryWithin 2-Mile Radius of Sequoyah Nuclear Plant Site(1972 Survey Only)MapIdent.No.EstimatedWell Elevation. FeetDepth, WaterLongitude Feet Ground SurfaceLocationLatitudeWellDia.,FeetRemarks818283848535 12'20"35 12'15"35 12'24"35 12,22"35°12'21"85 04'33" 265 94085 04'34" 250 96573566569085-04'35"85°05'05"85°05'08"305 965135 740120 74086 35°12'17"85 05'06" 190 8008788899091929394959635 12'2335 12'16"35°12'07"35011,54"35 12'19"35 12,22"35' 12'22"35 12,22"35 12'20"35 12,04"85'05'09"85'05'12"85'05'09"85 04'56"85'05'20"85'05'33"85 05'35"85'05'36"85 05'44"85'05'56"85 05'59-- 74055 740251 775170 980125 740-- 725-- 700-- 705-- 700160 70065 700720700705.5.5.5.5.5.5.52.5.5.5.5.5.5Submersible pump1-hp submersiblepumpSubmersible pump1-hp pumpServes 2 families;3/4-hp jet pump3/4-hp submersiblepump1-hp pumpBucketServes 2 families;3/4-hp pump1/2-hp pumpSubmersible pumpSummer home1-hp pumpSummer homeSummer homeServes 5 families;1-hp pumpHouse and cottage;I-hp pump97 35°12'04"NOTE: The information in this table is historic and not subject to updating revisions.2.4-90 SQN-Table 2.4.13-2 (Sheet 1)Ground Water Supplies Within 20-MileRadius of the Plant Site(1972 Survey Only)AverageDaily UsemcidApproximateDistanceFrom SiteatMilesLocationOwnerSource1.2.3.4.5.ChattanoogaChattanoogaChattanoogaChattanoogaChattanooga6. Chattanooga7. Chattanooga8. Chattanooga9. Chattanooga10. ChattanoogaKay's Ice Cream CompanySelox, Inc.Stainless Metal ProductsAmerican CyanamidDixie Yarns, Inc.Scholze TannerySouthern CelluloseProducts, Inc.Alco Chemical CorporationChattem Drug and ChemicalCumberland CorporationBacon Trailer ParkBethel Church of ChristBlue Water Trail andCampgroundCohulla Baptist ChurchCrystal Springs RecreationAreaEastview SchoolFort Bluff Youth CampFrazier Elementary SchoolGrasshopper Church of God0.04000.02500.01000.07270.53500.15604.00000.10000.23000.85000.23800.23800.0150WellWellWellWellWells (2) and Tennessee-AmericanWater CompanyWells (2) and Tennessee-AmericanWater CompanyWell (1) and Tennessee-AmericanWater CompanyWell (1) and Tennessee-AmericanWater CompanyWells (3) and Tennessee-AmericanWater CompanyWell (1) and Tennessee-AmericanWater CompanyWellWellWell20.421.016.421.013.324.024.224.017.420.019.09.519.09.519.019.011.311.12.13.14.15.16.17.18.19.ChattanoogaDunlapDaytonClevelandDaytonGeorgetownDaytonDaytonBirchwoodWellSpringWellWellWellWellNOTE: The information in this table is historic and not subject to updating revisions.2.4-91 SQN-Table 2.4.13-2 (Sheet 2)Ground Water Supplies Within 20-MileRadius of the Plant Site(1972 Survey Only)ApproximateAverage DistanceDaily Use From SiteaLocation Owner mqd Source (Miles)20. Dayton Hastings Mobile Home Park Spring 19.021. Ooltewah High Point Baptist Church Well 10.022. Dayton Lake Richland Apartments Well 19.023. Dayton Laurelbrook Sanitarium School .017 Wells (7) 19.024. Cleveland Labanon Baptist Church Well 13.525. Cleveland Mt. Carmel Baptist Church Well 13.526. Sale Creek Mt. Vernon Baptist Church Well 11.027. Dayton Mt. Vista Mobile Home Park Wells (2) 19.028. Dayton New Bethel Methodist Church Well 19.029. Cleveland New Friendship Baptist Church Well 13.530. Dayton Ogden Baptist Church Well 19.031. Dunlap Old Union Water System Spring 20.032. Dunlap P.A.W., Inc. #2 Well 20.033. Cleveland Red Clay State Historic Area Well 13.534. Chattanooga Riverside Catfish House Well 25.035. Cleveland Robert Allen Well 13.536. Dayton Salem Baptist Church Well 19.037. Dunlap Sequatchie-Bledsoe VO- Well 20.0Training38. Dayton Seventh Day Adventist Church Well 19.039. Chattanooga Shamrock Motel Well 20.140. Dayton Sinclair Packing House Well 19.041. Dunlap Stonecave Institute Water 0.0064 Spring 20.0System42. Dunlap Old Union Water System Spring 20.043. Sale Creek Sale Creek Marina Well 11.0MultiboatingNOTE: The information in this table is historic and not subject to updating revisions.2.4-92 SQN-Table 2.4.13-2 (Sheet 3)Ground Water Supplies Within 20-MileRadius of the Plant Site(1972 Survey Only)AverageDaily UsemodApproximateDistanceFrom Sitea(Miles)LocationOwnerSource44.45.46.47.48.49.50.51.52.53.54.Sale CreekSale CreekGraysvilleGraysvilleDaytonBirchwoodClevelandClevelandClevelandClevelandCleveland55. Cleveland56. Cleveland57. Cleveland58. HamiltonCounty59. HamiltonCounty60. HamiltonCounty61. Soddy62. HamiltonCounty63. HamiltonCounty64. HamiltonCountySale Creek P.U.A. -TVASale Creek Utility DistrictGraysville Water SupplyGraysville Nursing HomeDayton Golf & CC % MokasBirchwood SchoolCassons Grocery Water SystemBlack Fox SchoolBlue Springs Baptist ChurchBlue Springs SchoolBradley Limestone, Div. ofDalton Rock Product Co.Hardwick Stone CompanyCleveland-Tenn. EnamelMagic Chef, Inc.Savannah Valley U.D.Eastside Utility DistrictHixson Utility DistrictUnion Fork Bakewell, U.D.Walden's Ridge, U.D.Container Corporation ofAmericaDave L. Brown Company0.2040.2200.01700.24000.11300.22400.42000.7203.01300.09204.00000.33300.1920.00100.4711.92000.0200WellWells (2)Wells (2)WellWellWellWellWellWellWellWellWellWellSpringWells (2)Wells (3) and Tennessee AmericanWater CompanyCave Springs (3) and TennesseeAmerican Water CompanyWells (3) and Sale CreekUtility DistrictWells (2)WellWell11.010.815.015.019.011.319.713.513.513.513.513.513.513.55.07.912.99.817.422.0NOTE: The information in this table is historic and not subject to updating revisions.2.4-93 SQN-Table 2.4.13-2 (Sheet 4)Ground Water Supplies Within 20-MileRadius of the Plant Site(1972 Survey Only)ApproximateAverage DistanceDaily Use From SiteaLocation Owner mqd Source (Miles)65. Hamilton De Sota, Inc. 0.0750 WellCounty66. Hamilton Hamilton Concrete Products 0.0050 Spring 24County67. Cleveland Thompson Spring Baptist Well 13.5Church68. Dayton Vaughn Trailer Park Well 19.069. Dayton Walden's Ridge Baptist Well 19.0Church70. Dayton Walden's Ridge Elementary Well 19.0School71. Cleveland White Oak Baptist Church Well 13.572. Bradley Bockman Childrens Home Well 10.2County73. Catoosa Catoosa County U.D. Well 19.0Countya River mile distance from differences (TRM 483.6) for supplies taken from the Tennessee River channel;radial distance to other supplies.NOTE: The information in this table is historic and not subject to updating revisions.2.4-94 SQN-Table 2.4.14-1Time between Floods from Postulated Seismic Failures of Upstream Damsand Sequoyah Nuclear Plant Elevation 703.0 ftOBE Failures WithOne-Half Probable Maximum Flood1. Tellico -Norris2. Partial Fontana -Tellicoa3. Partial Fontana. -Tellico -Hiwassee -Apalachia -Blue Ridgea4. Cherokee -Douglas -TellicoSSE Failures With 25-Year Flood5. Norris -Cherokee -Douglas -TellicobFlood WaveTravel Time (hr)c34N/A324653a. Includes failure of four ALCOA dams and one Duke Energy dam -Nantahala (Duke Energy,formerly ALCOA), upstream; Santeetlah, on a downstream tributary; and Cheoah, Calderwood,and Chilhowee, downstream. Fort Loudoun gates are inoperable in open position.b. Gate opening at Fort Loudoun prevented by bridge failure.c. Time from seismic dam failure to arrival of failure wave at SQN elevation 703.0 ft (two ft belowplant grade).(1) Elevation 705.0 ft not reached(2) Elevation 703.0 ft not reached2.4-95 ENCLOSUREIEVALUATION OF PROPOSED CHANGESATTACHMENT 3Proposed SQN Units I and 2 UFSAR Figures (Public)

SQN-VLSeq uocyahi,NPucanr.t--Plantr -I $L AI " ..-F. I -ITopographic MapPlant Vicinity1,000 2,0000Figure 2.4.1-1 Topographic Map, Plant Vicinity2.4-96 SQN-NwM Fork Holston0DD1010106010206UpperfClinch06010206 SoutEl Fork Hohton060101020610103Nolchucky06010106LOWS" T-.newsee0040006MoistonOW01104Emory06010208Kenrucky L.keS040006Lower clinch06010207Mile BwLako06002D1L-w Little TennO5I 0204H6wasse.06020002Low. French Broad Upper French Broad0010107 05010106Pigeon06010106TlUcka..g..ssee 05010203UpperLittle Tennessee06010202Lower Duck0640003UpperDuck0402Buffdo06040004Lower Tennelses-Beech06040001Upper Bk06030)030ce..56020003Lower Elk06030004Pickwick Loe06030005WMetler Lake0030002B.aW023006SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTUSGS Hydrogogic Units within theTennessee River WatershedFigure 2 .4. 1-20 25 50Mies*Sequoyah Nuclear PlantHydrologic Cataloiging Unit Number and NameSM~iddle Tennessee-Chickamrauga Watershed BoundaryFigure 2.4.1-2 USGS Hydrologic Units within the Tennessee River Watershed2.4-97 SQN-Security-Related Information -Withheld Under IOCFR2.390Figure 2.4.1-3 TVA Water Control System2.4-98 SQN-686685684C 683z 682-J0)E 6810680I--" 679wU-z 6780< 677w-JW 676675674JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DECSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTSeasonal Operating Curve, ChickamaugaFigure 2.4.1-4 (Sheet 1 of 16)Figure 2.4.1-4 Seasonal Operating Curve, Chickamauga (Sheet 1 of 16)2.4-99 SQN-(00I-746745744743742741740739738737736735734JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DECSeasonal Operating Curve, Watts BarFigure 2.4.1-4 (Sheet 2 of 16)Figure 2.4.1-4 Seasonal Operating Curve, Watts Bar (Sheet 2 of 16)2.4-100 SQN-8178166; 815C%1O814C,-z:i 813.8120m811wwU-, 810z0809uJ, w 808807806-TELLICO EMERGENCY SPILLWAY CREST: EL. 817.0--TOP OF GATES: EL. 815.0(FORT LOUDOUN AND TELLICO)=NORMAL OPERATING ZONETOP OF NORMALOPERATING ZONEMEINELIEVATI01INBOTTOM OF NORMAL OPERATING ZONE-FT. LOUDOUN SPILLWAY CREST: EL. 783.0 -TELLICO SPILLWAY CREST: EL. 773.0JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DECSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTSeasonal Operating Curve,Fort Loudoun -TellicoFigure 2.4.1-4 (Sheet 3 of 16)Figure 2.4.1-4 Seasonal Operating Curve, Fort Loudoun -Tellico (Sheet 3 of 16)2.4-101 SON-13901385 ---TOP OF GATES: EL. 1385.0a01380z-jw'Uz01370_j'U13651360.. --- -- -- -- ----- -------- -_--CC0C0C0CCCC0F o LOOD GUIDEMEDIAN *oCOCo* ..** ..---SPILLWAY CREST: EL. 1350.0JAN FEB MAR APR MAY JUN JULAUG SEP OCT NOV DECSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTSeasonal Operating Curve, BooneFigure 2.4.1-4 (Sheet 4 of 16)Figure 2.4.1-4 Seasonal Operating Curve, Boone (Sheet 4 of 16)2.4-102 SQN-10801070o 1060-J= 1050'U04Lu 1040'ut.z04 1030w-j'U10201010JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DECSEQUOYAFIrANALSeasonal OpFigure 2Figure 2.4.1-4 Seasonal Operating Curve, Cherokee (Sheet 5 of 16)kH NUCLEAR PLANTNAL SAFETYLYSIS REPORTerating Curve, Cherokee.4.1-4 (Sheet 5 of 16)2.4-103 SQN-1010100004990z980w0> 970I-ww960z> 950940930JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DECSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTSeasonal Operating Curve, DouglasFigure 2.4.1-4 (Sheet 6 of 16)Figure 2.4.1-4 Seasonal Operating Curve, Douglas (Sheet 6 of 16)2.4-104 SQN-17201710" 17001690W 16801670wzo 1660w- 165016401630JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DECSEQUOY)FlANASeasonal CFigureFigure 2.4.1-4 Seasonal Operating Curve, Fontana (Sheet 7 of 16)\H NUCLEAR PLANTNAL SAFETYLYSIS REPORT)perating Curve, Fontana2.4.1-4 (Sheet 7 of 16)2.4-105 SQN-0LUw0wI-uJ12641263126212611260125912581257125613 -0I-SPILLWAY CREST: EL. 1228.0;.--SPILLWAY CREST: EL. 1228.0JAN FEB MAR APRMAYJUNJULSEPAUGOCTNOVDECSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTSeasonal Operating Curve,Fort Patrick HenryFigure 2.4.1-4 (Sheet 8 of 16)Figure 2.4.1-4 Seasonal Operating Curve, Fort Patrick Henry (Sheet 8 of 16)2.4-106 SQN-7974) 796C~40)> 7950z.Ju, 794w0S793LLIwW 792I-z0791w" 7907897----:--TOP OF GATES: EL. 796.07--:--- SPILLWAY CREST: EL. 754.0 IJAN FEB MAR APRMAY JUN JUL AUG SEP OCT NOVDECSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTSeasonal Operating Curve, Melton HillFigure 2.4.1-4 (Sheet 9 of 16)Figure 2.4.1-4 Seasonal Operating Curve, Melton Hill (Sheet 9 of 16)2.4-107 SQN-10401030---TOP OF GATES: EL. 1034.0a;O 1020z-JO 1010w_jU-wzo 1000'U-J990980--SPILLWAY CREST:EL. 1020.0 FiaFLOOD GUIDEMEDIAN *JAN FEB MARAPR MAY JUNJUL AUG SEP OCT NOV DECSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTSeasonal Operating Curve, NorrisFigure 2.4.1-4 (Sheet 10 of 16)Figure 2.4.1-4 Seasonal Operating Curve, Norris (Sheet 10 of 16)2.4-108 SQN-'.j00z0wujU.'17451740173517301725172017151710170517001695---CREST OF MORNING GLORY SPILLWAY: EL. 1742.0eooeooo0.0eS* S0000MEDIAN *FLOOD GUIDE000000e00e00JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DECSEQUOYAH IFINAlANALY5Seasonal OperatinFigure 2.4.1-Figure 2.4.1-4 Seasonal Operating Curve, South Holston (Sheet 11 of 16)N1LUCLEAR PLANT-SAFETYSIS REPORTg Curve, South Holston-4 (Sheet 11 of 16)2.4-109 SQN-19801975a)S1970Cz1965wo 19604, 1955z0L 1950-j19451940---CREST OF MORNING GLORY SPILLWAY: EL. 1975.0m0 0*0 MEDIAN *eo0FLOOD GUIDEJAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DECSEQUOYAIFir'ANALSeasonal OpFigure 2.ýFigure 2.4.1-4 Seasonal Operating Curve, Watauga (Sheet 12 of 16)H NUCLEAR PLANTIAL SAFETY.YSIS REPORTerating Curve, Watauga4.1-4 (Sheet 12 of 16)2.4-110 SQN-1695-TOP OF GATES: EL 1691.016900 _CD 1685UJ> 16800FLOOD GUIDEwu --SPILLWAY CREST: EL 1675.0U,.. 1675zolo00MEDIANa, 16700Li,16651660165516501645JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DECSEQUOYAHFINASeasonal OpernFigure 2.4.1Figure 2.4.1-4 Seasonal Operating Curve, Blue Ridge (Sheet 13 of 16)NUCLEAR PLANTL SAFETYSIS REPORTating Curve, Blue Ridge-4 (Sheet 13 of 16)2.4-111 SQN-1930C)z0I-wwz0w-Jw1925192019151910JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DECSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTSeasonal Operating Curve, ChatugeFigure 2.4.1-4 (Sheet 14 of 16)Figure 2.4.1-4 Seasonal Operating Curve, Chatuge (Sheet 14 of 16)2.4-112 SQN-0CDz0LU15301525152015151510150515001495149014851480147514701465JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DECSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTSeasonal Operating Curve, HiwasseeFigure 2.4.1-4 (Sheet 15 of 16)Figure 2.4.1-4 Seasonal Operating Curve, Hiwassee (Sheet 15 of 16)2.4-113 SQN-w0C,,U,u.wLtz0I-LU17851780177517701765176017551750JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DECSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTSeasonal Operating Curve, NottelyFigure 2.4.1-4 (Sheet 16 of 16)Figure 2.4.1-4 Seasonal Operating Curve, Nottely (Sheet 16 of 16)2.4-114 SQN-N_j0,w'U14U720700--TOP OF GATES: EL. 685.44680-660---SPILLWAY CREST: EL. 645.0640620600050010001500 2000VOLUME IN THOUSANDS OF ACRE-FEET250030003500SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTReservoir Elevation -StorageRelationship, ChickamaugaFigure 2.4.1-5 (Sheet 1 of 17)Figure 2.4.1-5 Reservoir Elevation -Storage Relationship, Chickamauga (Sheet 1 of 17)2.4-115 SON-790770a 750-.4az 730-s,Inw0 71014.wz 6900w--TOP OF GATES: EL. 745.0-SPILLWAY CREST: EL. 713.0(w6501win0500100015002000250030003500VOLUME IN THOUSANDS OF ACRE-FEETSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTReservoir Elevation -StorageRelationship, Watts BarFigure 2.4.1-5 (Sheet 2 of 17)Figure 2.4.1-5 Reservoir Elevation -Storage Relationship, Watts Bar (Sheet 2 of 17)2.4-116 SQN-860a,z_jw0wzw820820- --TOP OF GATES: EL. 815.0800-7/SPILLWAY CREST: EL. 783.07807607400200400 600 800VOLUME IN THOUSANDS OF ACRE-FEET10001200SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTReservoir Elevation -StorageRelationship, Fort LoudounFigure 2.4.1-5 (Sheet 3 of 17)Figure 2.4.1-5 Reservoir Elevation -Storage Relationship, Fort Loudoun (Sheet 3 of 17)2.4-117 SQN-860o 2 8 2 012 -- TOP OF GATES: EL. 815.0U,a 800Uj700P780U." *.SILVY CREST: EL. 773.02740720 *0 200 400 600 800 1000 1200VOLUME IN THOUSANDS OF ACRE-FEETSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTReservoir Elevation -StorageRelationship, TellicoFigure 2.4.1-5 (Sheet 4 of 17)Figure 2.4.1-5 Reservoir Elevation -Storage Relationship, Tellico (Sheet 4 of 17)2.4-118 SON-('.0z04Unw0m14w04wJ41420140013801360134013201300128012601240TOP OF GATES: EL. 1385.0-*.ý-SPILLWAY CREST: EL. 1350.0050100150 200VOLUME IN THOUSANDS OF ACRE-FEET250300350SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTReservoir Elevation -StorageRelationship, BooneFigure 2.4.1-5 (Sheet 5 of 17)Figure 2.4.1-5 Reservoir Elevation -Storage Relationship, Boone (Sheet 5 of 17)2.4-119 SQN-11101090TOP OF GATES: EL. 1075.0---1070Z 1050>C) --SPILLWAY CREST: EL. 1043.0z1030cn0 1010I-w990z0I..-> 970w-JLU 9509309100 500 1000 1500 2000 2500VOLUME IN THOUSANDS OF ACRE-FEETSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTReservoir Elevation -StorageRelationship, CherokeeFigure 2.4.1-5 (Sheet 6 of 17)Figure 2.4.1-5 Reservoir Elevation -Storage Relationship, Cherokee (Sheet 6 of 17)2.4-120 SQN-O 980z.ILWYCET EL. 970.0U,2 9600wWj 9400, 9209008808600 500 1000 1500 2000 2500VOLUME IN THOUSANDS OF ACRE-FEETSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTReservoir Elevation -StorageRelationship, DouglasFigure 2.4.1-5 (Sheet 7 of 17)Figure 2.4.1-5 Reservoir Elevation -Storage Relationship, Douglas (Sheet 7 of 17)2.4-121 SQN-z0z0w1 7 4 0 -T O P IO F G A T E S : E L .1 7 1 0 .0 -1690 ______ _____________1640 _______1590-______ ______1540- ________ ______1490 ______1390 ______1340 ______ ____________12900 200 490 600 800 1000 1200VOLUME IN THOUSANDS OF ACRE-FEET1400 16001800 2000SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTReservoir Elevation -StorageRelationship, FontanaFigure 2.4.1-5 (Sheet 8 of 17)Figure 2.4.1-5 Reservoir Elevation -Storage Relationship, Fontana (Sheet 8 of 17)2.4-122 SQN-C.,40z0I 3UU1280.12 -TOP OF GATES: EL. 1263.0126012401220 SPILLWAY CR IEST: EL.1228.012201200 _______1Th04 4 i0102030 40VOLUME IN THOUSANDS OF ACRE-FEET506070SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTReservoir Elevation -StorageRelationship, Fort Patrick HenryFigure 2.4.1-5 (Sheet 9 of 17)Figure 2.4.1-5 Reservoir Elevation -Storage Relationship, Fort Patrick Henry (Sheet 9 of 17)2.4-123 SQN-840820N>600800 --TOP OF GATES: EL. 796.0780z760>--SPILLWAY CREST: EL. 754.07407200 50 100 150 200 250 300 350 400VOLUME IN THOUSANDS OF ACRE-FEETSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTReservoir Elevation -StorageRelationship, Melton HillFigure 2.4.1-5 (Sheet 10 of 17)Figure 2.4.1-5 Reservoir Elevation -Storage Relationship, Melton Hill (Sheet 10 of 17)2.4-124 SQN-11001050a> 100002900ww 95040F900'UTOP OF GATES: EL. 1034.0---CREST: EL. 1020.08508000500 10001500 2000 2500VOLUME IN THOUSANDS OF ACRE-FEET300035004000SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTReservoir Elevation -StorageRelationship, NorrisFigure 2.4.1-5 (Sheet 11 of 17)Figure 2.4.1-5 Reservoir Elevation -Storage Relationship, Norris (Sheet 11 of 17)2.4-125 SQN-18001750 -1700z-JS 1650w0w 1600z0w 1550-Jw1500-1450-__II _ I _ _ _ I _ _--SPILLWAY CREST: EL. 1742.0100100 200 300 400 500 600 700VOLUME IN THOUSANDS OF ACRE-FEET800 900 1000 1100SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTReservoir Elevation -StorageRelationship, South HolstonFigure 2.4.1-5 (Sheet 12 of 17)Figure 2.4.1-5 Reservoir Elevation -Storage Relationship, South Holston (Sheet 12 of 17)2.4-126 SQN-00'U2050200019501900185018001750170016500 100 200 300 400 500 600VOLUME IN THOUSANDS OF ACRE-FEET700 800 900 1000SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTReservoir Elevation -StorageRelationship, WataugaFigure 2.4.1-5 (Sheet 13 of 17)Figure 2.4.1-5 Reservoir Elevation -Storage Relationship, Watauga (Sheet 13 of 17)2.4-127 SQN-04zLU0I-LULLz0LU-jLU1740172017001680166016401620160015801560--- TOP OF GATES: EL. 1691.01--- SPILLWýAY CREST: EL. 1675'.0-40050100150 200VOLUME IN THOUSANDS OF ACRE-FEET250300350SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTReservoir Elevation -StorageRelationship, Blue RidgeFigure 2.4.1-5 (Sheet 14 of 17)Figure 2.4.1-5 Reservoir Elevation -Storage Relationship, Blue Ridge (Sheet 14 of 17)2.4-128 SQN-F04m,z:yco~LU.0LU.LU.z0LU.-jU.196019401920190018801860184018201800SPILLWAY CRES I: L. 1923.0--- I --TOP OF GATES: EL. 1928.0SP W YC ET .12.--_ _ _ __ _ _____ ______ _ _ _ _.50050100150200 250VOLUME IN THOUSANDS OF ACRE-FEET3003504004SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTReservoir Elevation -StorageRelationship, ChatugeFigure 2.4.1-5 (Sheet 15 of 17)Figure 2.4.1-5 Reservoir Elevation -Storage Relationship, Chatuge (Sheet 15 of 17)2.4-129 SQN-1550150000z.-ILULJI-u~lw--U.w1450140013501300TOP OF GATES: EL. 1526.5---.qPll I \AIAVY irI:? ;T" P1 IfnA C_._ _12500100200300400500600700VOLUME IN THOUSANDS OF ACRE-FEETSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTReservoir Elevation -StorageRelationship, HiwasseeFigure 2.4.1-5 (Sheet 16 of 17)Figure 2.4.1-5 Reservoir Elevation -Storage Relationship, Hiwassee (Sheet 16 of 17)2.4-130 SQN-0CDw0LU_jU-185018001750170016501600TOP OF GATES: EL. 1780.0--- ---SPILLWAY CREST: EL. 1775.0050100150200250300350VOLUME IN THOUSANDS OF ACRE-FEETSEQUOYAH NUCFINAL SAANALYSIS FReservoir ElevatiRelationship,Figure 2.4.1-5 (:Figure 2.4.1-5 Reservoir Elevation -Storage Relationship, Nottely (Sheet 17 of 17)LEAR PLANTkFETYREPORTon -StorageNottelySheet 17 of 17)2.4-131 SQN-60so5245~44403629omIo B p g Im s400loANawdw .. w1900 1905 1010 11!5 9 ISM 1930 1935 1040 1'U45 1'90 1M I 19 0O 0170 1 1000 6 1M 0 1966 2000 2010_Obmu*Obswwd wft 960O14 WA-cAuaW abswwoA i- AMWW WsuwdCOW.ETB Fat, 2010TENNESSEE RIVER MW 464.2SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTTennessee River Mile 464.2 -Distribution of Floods atChattanooga, TennesseeFigure 2.4.2-1Figure 2.4.2-1 Tennessee River Mile 464.2 -Distribution of Floods at Chattanooga, Tennessee2.4-132 SQN-SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTProbable Maximum PrecipitationIsohyets for 21,400 Sq. Mi. Event,Downstream PlacementFigure 2.4.3-1Figure 2.4.3-1 Probable Maximum Precipitation Isohyets for 21,400 Sq. Mi. Event, Downstream Placement2.4-133 SQN-SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTProbable Maximum PrecipitationIsohyets for 7980 Sq. Mi. Event,Centered at Bulls Gap, TNFigure 2.4.3-2Figure 2.4.3-2 Probable Maximum Precipitation Isohyets for 7980 Sq. Mi. Event, Centered at Bulls Gap, TN2.4-134 SQN-100-6-J40I- o40 12--- ---- _ 24 -36 48 60 7200 12 24 .36 48 60 7:TIME -HOURSSECFigure 2.4.3-3 Rainfall Time Distribution -Typical Mass Curve21UOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTRainfall Time Distribution -Typical Mass CurveFigure 2.4.3-32.4-135 SQN-Figure 2.4.3-4 Not Used2.4-136 SQN-KYNCSCGA"j Mawft"NOa DoSo0I 6SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTDrainage Areas above Chickamauga DamFigure 2.4.3-5ALFigure 2.4.3-5 Drainage Areas above Chickamauga Dam2.4-137 SQN-U)TL050,00045,00040,00035,00030,00025,00020,00015,00010,0005,0000"-I ---- ------ ----- -- -- I------ -p ----- --- -----f I----------- -- --------- ---- ----- -------d0122436486o72TIME -HOURS-AREA 1 -FRENCH BROAD RIVER AT ASHEVILLE. 944.4 SQ. Mi.; 6-HOUR DURATION--. AREA 2 -FRENCH BROAD RIVER, NEWPORT TO ASHEVILLE;-913.1 SQ. MI.; 6-HOUR DURATION--- AREA 3 -PIGEON RIVER AT NEWPORT: 667.1 SQ. Mi.; 6-,HOUR DURATION,.AREA 4- NOLICHUCKY RIVER AT EMBREEVILLE; 804.8 SQ. MIL; 4-HOUR DURATION... -- AREA5 -NOLICHUCKY LOCAL; 378;7 SQ. MI.: 6&HOUR DURATIONSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTUnit Hydrographs, Areas 1-5Figure 2.4.3-6 (Sheet 1 of 11)Figure 2.4.3-6 Unit Hydrographs, Areas 1-5 (Sheet 1 of 11)2.4-138 SQN-0)LLCD60,00046,00040,00035,00030,00025,00020,000165;00010,000.6,.0000ooo--------- -------- -----.. -- ---- ----------------------, ------ ----------.- ---------- -I ---------, --S --------------------------------- ------- --- --------- --- -I --- -- -- --------------- -------4/ -"00122436486TIME- HOURSAREA 6- DOUGLAS DAM LOCAL; 835.0 SO. Ml!; '6-HOUR DURATION---AREA,7-.LITTLE PIGEON RIVER AT SEVIERVILLE; 352.1 SO. MI.; 4-HOUR DURATIONAR- -AEA 8 -FRENCH BROAD LOCAL;.206.5 SQ. MI;.;6-HOUR DURATION-AREA9 -SOUTH HOLSTON DAM; 703.2 SQ. Mi.; 6-HOUR DURATIONSEQIUFicFigure 2.4.3-6 Unit Hydrographs, Areas 6-9 (Sheet 2 of 11)UOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTnit Hydrographs, Areas 6-9lure 2.4.3-6 (Sheet 2 of 11)2.4-139 SQN-4s,ooo.3 o , 0 0 b ......... .........------. .......................... ........------------------. .......40,000 ---35,000 ----------------' --.IiI~pl --.------- ---62,0O0,0---------/ ' -------0 12 24 36 46TIME ..HOURSW -WATAUGA DA- 468-2,S(i. MI.;,4HO RDURATION--.AREA 11 -BOONE LOCAL; 667:7 SQ. Mii: 6-HOURDU)RATION....... AREA 12 -FORT PATRICK,I HENRY DMVI'62.8. SQ..M 'I.: 6-HOUR DURATION50-- --AREA 13-- NORTH FO K HOLSTON RIVER'NEAR GATE-IrY -8-:9:. -UR DU TIONSEQUCAIUnit FFigurFigure 2.4.3-6 Unit Hydrographs, Areas 10-13 (Sheet 3 of 11))YAH NUCLEAR PLANTFINAL SAFETYNALYSIS REPORT-ydrographs, Areas10-13e 2.4.3-6 (Sheet 3 of 11)2.4-140 SQN-30,0004-20,000- 40 2 48 sTIME .--OUR(;) 4)I,5 I ' ;1 0-..R0 1 4',$ -.12 24 3 j86-TIME --OUR--AREA+S 14 &-15- CHEROKESE ILOCAL; 854.6 SQ. MI,;6-HIiOUR DURATION--- EA 16- HOLSTON RIVER LO.AL, CHEROKEE DAM TO KNOXILLE GAUGE;319.6 SQ..ML; 6HOUR DURATION--.AREA 17- LITTLE RIVER; 376.SQ. Mi.; 4ýHOUR DURATION----AREA 18- FORT LQUDOUN LOCAL; 323A SQO. MI. 6-HOUR DURATIONSEQUUnitFiguFigure 2.4.3-6 Unit Hydrographs, Areas 14-18 (Sheet 4 of 11)OYAH NUCLEAR PLANTFINAL SAFETY,NALYSIS REPORTHydrographs, Areas 14-18re 2.4.3-6 (Sheet 4 of 11)2.4-141 SQN-C')U-C,.,wU)a0 12 24 36 48TiME-HOURS60-AREA 19- LITTLE TENNESSEE RIVER AT NEEDMORE; 436:5 SQ MI.; 6.-HOUR DURATION---AREA 20 -NANTAH .ALA DAM; 90.9 SQ. MI.: 2-HOUR DURAT!ON...... AREA 21 -tUCKASEGEE RIVER AT BRYSON CITY, 653.8 SQ. ML; 6-HOUR DURATION.... AREA 22 -FONTANA LOCAL; 389.8 SQ. MI.; 4-HOUR DURATIONSEQUUnitFigLFigure 2.4.3-6 Unit Hydrographs, Areas 19-22 (Sheet 5 of 11)OYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTHydrographs, Areas 19-22ire 2.4.3-6 (Sheet 5 of 11)2.4-142 SQN-50,000I 0 0 I ..450000 ------ ---------- ----------.,O'J I" ' II .I I 1.IS30,000,.1 ------------- ------------23 ,0"00- -4---- ------- -----1? 0,000 ---------------- --------- -- ----,, ------------* 2,00 1 /1IS5I,+/ : x .._I.. .... .......15,000 --, -------------, ./jTIMIE- HOURS----- RA2 AT A OA AOECIC IE, 9. SQ. MI. -MDRT,,E/ 2 '.- "O L ; .M M5 I*+/-* .l * ..............~~~~~~ni Hy rgrps Ara .. :.. ....... ."* +Fu0 12 24 36 48 60 72 84 96TIMEt HOURS-AREA 23:- UITThE TENNESSEE RIVER LOC;AL, FONTANA TO CHILNOWEE DAM: 404.7-SQ. MI.: 6-HOUR DURATION.--.- 24,- "LITPTLE~ TENN E:SSEE: RIVER LOCAL, TEL2LICO DAM: 650.2 SQ. MI. 6-HFOUR .....25 -WATTIS BAR LOCAL ABOVE CLINCH RIVE=R; 295.3 SQ. MI.; 6-HOUR+DURATloNS-* AREA+26 -CLINCHRIVER AT NORRIS DAM; MI.; 6-HOUR DURATION... --AEA 27[- MELTON HILL LOCAL: 431.9 SQ. MI.; 6, HOUR DURATIONSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTUnit Hydrographs, Areas 23-27Figure 2.4.3-6 (Sheet 6 of 11 )Figure 2.4.3-6 Unit Hydrographs, Areas 23-27 (Sheet 6 of 11)2.4-143 SQN-10,0000EL(3w04z(3055,000 ]------------------------------ -------------------------- --------------------0I01224364860TIME- HOURS-- AREA33 -CLINCH RIVER LOCAL ABOVE MILE 16: 37.2SQ. MI.; 2-HOUR DURATION--- AREA 34- POPLAR CREEKAT MOUTH; 135.2 SQ.MI.; 2-HOUR DURATION.... AREA 36 -CLINCH RIVERLOCAL, MOUTH TO MILE 16; 293 SQ. MI.; 2-HOUR DURATIONSEQUO'ANUnit HydFigureFigure 2.4.3-6 Unit Hydrographs, Areas 33, 34, 36 (Sheet 7 of 11)YAH NUCLEAR PLANTFINAL SAFETYIALYSIS REPORTrographs, Areas 33, 34, 362.4.3-6 (Sheet 7 of 11)2.4-144 SQN-U-Uj40,UUU40,000-35,000.30,00025.000-20.00015,000.10,0005,00060-~~~~~ ~ ~ ~ ~ ------------- ---- ------------------ ------------- ----- ---~T01224364860TIME -HOURS-AREA 35 -EMORY RIVER At MOUTH; 868.8 SQO MI.; 4-HOUR DURATION---AREA37 -WATTS BAR LOCAL BELOW CLINCH AIVER,,408.4 SQ. MI.; 6-HOUR DURATIONSEQUAUnitFiguFigure 2.4.3-6 Unit Hydrographs, Areas 35, 37 (Sheet 8 of 11)OYAH NUCLEAR PLANTFINAL SAFETYkNALYSIS REPORTHydrographs, Areas 35, 37ire 2.4.3-6 (Sheet 8 of 11)2.4-145 SQN-60,000-46,000-40,000 --- --- ------. .--.--- --. -.......35,000 -c- -....-- .. ..... ............0 .0 12 24 36TIME -HOURS:AREA 38 -,CHATUGE DAM; 189.1 SQ..Mi; 1-HOUR DURATION---AREA 39- NOTTELY DAM. 214.3 SQ. MI; 1-HOUR .DURATION*---AREA 41 -APALACHIALOiCAL: 49.8 SQ. Mi.; 1-HOUR DURATION.... AREA 42- BLUE RIDGE DAM; 231.6 SQ. MI.; 2LHOUR DURATIONSEQUOYIFlANAUnit HydrogrFigure 2Figure 2.4.3-6 Unit Hydrographs, Areas 38, 39, 41, 42 (Sheet 9 of 11),H NUCLEAR PLANTNAL SAFETYLYSIS REPORTaphs, Areas 38, 39, 41,42.4.3-6 (Sheet 9 of 11)2.4-146 SQN-30,000,2 5 ,0 00. ..... ....---- ...------- ....-- ---- ------ ------- ... --- ----.. .. .... ... ... ....-- ... .... ..... ... --.... ....aJ' S ., I20 ,00 0 .-- --- .......... ----- ----12 ,0000------ ------:.------- --- --- -20.000 , , .*'0 12 24 36 48 60 n ..4 96TIME -HOURS--AREA 40 -HIWASSEE RIVER 565.1i S.Q. M.; DURATION-- -- -- AREA 43- -OCOEEý'ýO_ I LOCAL; 3616 SO. MI.; DURATION....--- -AREA 44A -HIWASSEE RIVER FROM CHARLEETOIWTIO APALACHIA ,AND OCOEE NO, 1:686,6 SQ, MI 6-HOUR DURATlONA- .,RE.A 44B -HIWAssEE RIVER FROM MOUTH To CHARLES'TON; 396.0 SO, Mi.; ($HOR DUtRATION " " + *SEQUOYAHFIN/ANALYUnit Hydrograph,Figure 2.4.3Figure 2.4.3-6 Unit Hydrographs, Areas 40, 43, 44A, 44B (Sheet 10 of 11)NUCLEAR PLANT,L SAFETY'SIS REPORTs, Areas 40; 43, 44A, 44B1-6 (Sheet 10 of 11)2.4-147 SQN-U.U)a'40,00035,00030,00025,00020,000-10,000-5,000A---------------------- ------ --- ---------------- --------------- -------- ----------------------------- ---------------- --------------------------------- -------------------------- ----------------- ------------- ------------------------------1-1, ----------------- ----------------- -------012 24.TIME -HOURS-'AREA 45 -CHICKAIMIAUGA LOCAL; 792.1 SQ. MIL; 8-HOUR DURATIONSEQFi)Figure 2.4.3-6 Unit Hydrographs, Area 45 (Sheet 11 of 11)36}UOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTUnit Hydrographs, Area 45jure 2.4.3-6 (Sheet 11 of 11)2.4-148 SQN-740zNJ0al720----TOP OF NORTH EMB: EL. 706.0 ---TOP OF SOUTH EMB: EL. 707.0700 -690 -_680- j , ---TOP OF GATES: EL. 685.44670 _______-SPILLWAY CREST. 645.0640- HEADWATER RATING, CURRENT CONFIGURATIONI2j630 __________ _ _ _ _ _ _ _ _ _ I _ _ _62 ________ ________ ________0200 400600800DISCHARGE -1000 CFS1000 120014001600SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTDischarge Rating Curve,Chickamauga DamFigure 2.4.3-7(Sheet 1 of 17)Figure 2.4.3-7 Discharge Rating Curve, Chickamauga Dam (Sheet I of 17)2.4-149 SQN-N0C_zwU.0alt.Fw770 ---TOP OF EMBANKMENT EL 770 0760 -750----TOP OF GATES. EL 745 0740 -730 -,- _ _ _720 --_--SPILLWAY CREST. EL 7130 0710- __ _-- HEADWATER RATING700 _ -" ----TAILWATER RATING690 -I680O0 100 200 300 400 500 600 700DISCHARGE -1000 CFS800 900 1000 1100 1200 1300SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTDischarge Rating Curve,Watts Bar DamFigure 2.4.3-7 (Sheet 2 of 17)Figure 2.4.3-7 Discharge Rating Curve, Watts Bar Dam (Sheet 2 of 17)2.4-150 SQN-840 = I ITOP OF EMBANKMENT EL 837 0830 "_ _C)820---TOP OF GATES EL 815 0z 810 .,___ " _ , _ _,, 800 --_0790 F- 1_ ,t ---AY CREST- EL 783 0780 _r-w-HEADWATER RATING760 ---TAILWATER RATING750 -__7400 50 100 150200 250 300 350 400 450 500550 600DISCHARGE -1000 CFSSEQU(/DFigFigure 2.4.3-7 Discharge Rating Curve, Fort Loudoun Dam (Sheet 3 of 17))YAH NUCLEAR PLANTFINAL SAFETY,NALYSIS REPORTischarge Rating Curve,Fort Loudoun Damure 2.4.3-7 (Sheet 3 of 17)2.4-151 SQN-a)aC,z0J84O----TOP OF EMBANKMENT EL. 8330830820 J--EMERGENCY SPILLWAY CREST EL810TOPO GATES E 8150800-- T790-780 -0 o ---SP LLWAY CREST EL 7730760- -HEADWATER RATING'---TAILWATER RATING"* Includes emergency spillway dischargeTailwater shown at Tellico Dam740-7300 100 200 300 400 500 600 700DISCHARGE -1000 CFS800900 1000 1100 1200SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTDischarge Rating Curve, Tellico DamFigure 2.4.3-7 (Sheet 4 of 17)Figure 2.4.3-7 Discharge Rating Curve, Tellico Dam (Sheet 4 of 17)2.4-152 SQN-14101400-TOP OF EMBANKMENT EL 1408 5---TOP OF CONCRETE DAM ELxllý0z0Co-Aw1392 01390---TOP OF GAT :S EL 1385 01380 -1370-1360-1350 --SPILLWAY CREST. EL 13500Note Tailwater rating not shown, no effec on outflowt34n I I III050100150 200DISCHARGE -1000 CFS250300350SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTDischarge Rating Curve, Boone DamFigure 2.4.3-7 (Sheet 5 of 17)Figure 2.4.3-7 Discharge Rating Curve, Boone Dam (Sheet 5 of 17)2.4-153 SQN-110010801060N> 1040C,z1020Waw, 1000wILz0r 980-JuJ960940920---TOP OFI EARTH SADD ILE DAMS EL 11092 75--TOP OF GATES EL 1075 0---SPILLWAY CREST EL 1043 0H___ EADWATER RATING---TAILWATER RATING0 50 100 150 200 250DISCHARGE -1000 CFS300 350 400450SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTDischarge Rating Curve, Cherokee DamFigure 2.4.3-7 (Sheet 6 of 17)Figure 2.4.3-7 Discharge Rating Curve, Cherokee Dam (Sheet 6 of 17)2.4-154 SQN-IN0z0lu1040 O---TOP CONCRETE DAM EL 1022 5 ---TOP OF SADDLE DAMS EL 1023 51020 ---TOP OF GATES EL 1002 01000980960 ---SPILLWAY CREST EL 970 0960940920 _ -_ _,*900,-HEADWATER RATING---TAILWATER RATING680 -.8600100200300 400DISCHARGE -1000 CFS500600700SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTDischarge Rating Curve, Douglas DamFigure 2.4.3-7(Sheet 7 of 17)Figure 2.4.3-7 Discharge Rating Curve, Douglas Dam (Sheet 7 of 17)2.4-155 SQN-a0(0W17601740--TOP OF MAIN DAM EL 1727 01720-17200 --TOP OF GATES. EL 171001700 1660- I ---SPILLWAY CREST EL 1675 0168016401620oNote Tailwater rating not shown no effect on outflow18600 10100200 300DISCHARGE -1000 CFS400500SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTDischarge Rating Curve, Fontana DamFigure 2.4.3-7 (Sheet 8 of 17)Figure 2.4.3-7 Discharge Rating Curve, Fontana Dam (Sheet 8 of 17)2.4-156 SQN-0t-Jw4I--U..z0-.JLu1300-1290-1280-1270 --TOP OF DAM: EL. 1270.0--TOP OF GATES: EL. 1263.01260125012401230 ________ _______--SPILLWAY CREST: EL. 122860Note: Tailwater rating not shown, no effect on outflow.1220 I I050100150 200DISCHARGE -1000 CFS250300350SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTDischarge Rating Curve,Fort Patrick Henry DamFigure 2.4.3-7 (Sheet 9 of 17)Figure 2.4.3-7 Discharge Rating Curve, Fort Patrick Henry Dam (Sheet 9 of 17)2.4-157 SQN-820810m 800z2M 790Lu014.t-m 7800770,-JLU760750--TOP OF NORTH NONOVERFLOW DAM: EL. 805.48-TOP OF SOUTH NONOVERFLOW DAM: EL. 802.0--TOP OF GATES: EL. 796.0-SPILLWAY CREST: EL. 754,0 Note: Tailwater rating not shown, no effect on outflow._ _ _ _ _I__ _II050100150 200DISCHARGE -1000 CFS250300350'SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTDischarge Rating Curve, Melton Hill DamFigure 2.4.3-7 (Sheet 10 of 17)Figure 2.4.3-7 Discharge Rating Curve, Melton Hill Dam (Sheet 10 of 17)2.4-158 SQN-10701060105000w1030t-w1020z 1020iu 10101000990---TOPOF DAM EL 10610--TOP OF GATES EL 1034 0/--SPILLWAY CREST EL 1020 0Note -Tajiwater rating not shown, no effect on spillway outflow050100150200DISCHARGE -1000 CFS250300350400SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTDischarge Rating Curve, Norris DamFigure 2.4.3-7 (Sheet 11 of 17)Figure 2.4.3-7 Discharge Rating Curve, Norris Dam (Sheet 11 of 17)2.4-159 SQN-177011765 ...--TOP OF DAM: EL. 1765.0a)> 1760C,z-jInLUwo 1755- -01750-j175 ..M ::1 Note: Tailwater rating not shown, no effect on outflow.1740050 100 150 200 250DISCHARGE -1000 CFSSEQUOYJFlDisch;LSoFigure 2Figure 2.4.3-7 Discharge Rating Curve, South Holston Dam (Sheet 12 of 17)AH NUCLEAR PLANTINAL SAFETYLYSIS REPORTarge Rating Curve,uth Holston Dam.4.3-7 (Sheet 12 of 17)2.4-160 SQN-m0C,0-TOP OF DAM EL 20120201020052000-19951990 START OF 'THROAT CONTROL" EL 19890 TO 1990 01980-1975 ---MORNING GLORY SPILLWAY CREST EL 19750Note Tailwater rating not shown no effect on outflow1970 10 10 20 3040 50 60 70 80 90 100DISCHARGE -1000 CFSSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTDischarge Rating Curve, Watauga DamFigure 2.4.3-7 (Sheet 13 of 17)Figure 2.4.3-7 Discharge Rating Curve, Watauga Dam (Sheet 13 of 17)2.4-161 SQN-1 7 1 5 --------.... ...... .. .-.... ..... .... ....... rT _T..... .. ... .-1710a> 1705 -TOP OF DAM: EL 17050LiiLU 16950=_jI-4 41 6 8 5 ---... ......... ..-168501675 -SPLL WAY CRESTL O75ANote; Tailwater rating not shown, no effect on outflow1670 I0 20 40 60 80 1 00 120 140 160 180 200DISCHARGE -1000 CFSSEQUOYAHIFINALANALYSDischarge RatingFigure 2.4.3-7Figure 2.4.3-7 Discharge Rating Curve, Blue Ridge Dam (Sheet 14 of 17)4JUCLEAR PLANTSAFETYIS REPORTCurve, Blue Ridge Dam(Sheet 14 of 17)2.4-162 SQN-19501945z-LJ0u.1z0-1Lu194019351930--TOP OF DAM: EL 1940 _ _-TOP OF GATES: EL 1928I _______________1925-SPILLWAY CFEST: EL 1923Note: Tailwater rating not shown, no effect on outflowI I1920 4-0.0020.0040.0060.00 80.00DISCHARGE -1000 CFS100.00120.00140.00SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTDischarge Rating Curve, Chatuge DamFigure 2.4.3-7 (Sheet 15 of 17)Figure 2.4.3-7 Discharge Rating Curve, Chatuge Dam (Sheet 15 of 17)2.4-163 SQN-1550 _ _ -_1545 .--TOP OF DAM: EL 1537.51540>C0 153515300-jTOP OF GATES: EL 1526U 1525z0> 152015151510 .........1505-SPILLWAY CREST: EL 1503.515000 50 100 150 200DISCHARGE -1000 CFSSEQUOYAI-FIN/ANALYDischarge RatinFigure 2.4.3Figure 2.4.3-7 Discharge Rating Curve, Hiwassee Dam (Sheet 16 of 17)NUCLEAR PLANT,L SAFETY'SIS REPORTg Curve, Hiwassee Dam3-7 (Sheet 16 of 17)2.4-164 SQN-0CDz-JU)uJ0U)4I-U)UJ204U)-jU)181018051800179517901785178017751770-TOP OF DAM: EL 1807.5-TOP OF GATES: EL 1780 ____-SPILLWAY CREST: EL 17 75 _____________0 20 40 60 80 100 120 140 160 180 20DISCHARGE -1000 CFS00SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTDischarge Rating Curve, Nottely DamFigure 2.4.3-7 (Sheet 17 of 17)Figure 2.4.3-7 Discharge Rating Curve, Nottely Dam (Sheet 17 of 17)2.4-165 SQN-fo DouglaS DiffR .F6RM3230'lfolilcoDamrvfWm 0.30 4Chilhowee Duni SEQUOYAH NUCLEAR PLANT33.60. FINAL SAFETYANALYSIS REPORTFort Loudoun -Tellico SOCHUnsteady Flow Model SchematicFigure 2.4.3-8Figure 2.4.3-8 Fort Loudoun -Tellico SOCH Unsteady Flow Model Schematic2.4-166 SQN-Ia'.OR IWItft4C..pMaThkI7W7n IWn W73 W11 3 3MW7 3P&W73 X?3fDATESEQUOYAH NUCLEARFINAL SAFETYANALYSIS REPOFUnsteady Flow Model Fort lReservoir March 1973 FFigure 2.4.3-9 (Sheet 1Figure 2.4.3-9 Unsteady Flow Model Fort Loudoun Reservoir March 1973 Flood (Sheet I of 2)PLANTLoudounFloodof 2)2.4-167 SQN-940m2020................................................ ......................Alm ODm im.... -41"MNRhl 0 DoTaM~slm17331M197MOM973117m7 3*19DATE1173MWIAM 3M21*3SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTUnsteady Flow Model Fort LoudounReservoir March 1973 FloodFigure 2.4.3-9 (Sheet 2 of 2)Figure 2.4.3-9 Unsteady Flow Model Fort Loudoun Reservoir March 1973 Flood (Sheet 2 of 2)2.4-168 SQN-I"8S14813lmeal= w~lmmmsaft LitW1U026111L= WM3 M3 &= =3 SO=103 WM MM M3 W1 8 WNW $M1G3 103 811733 W8DATESEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTUnsteady Flow Model Fort Loudoun -TellicoReservoir May 2003 FloodFigure 2.4.3-10 (Sheet 1 of 3)Figure 2.4.3-10 Unsteady Flow Model Fort Loudoun -Tellico Reservoir May 2003 Flood (Sheet I of 3)2.4-169 SQN-maaS, 0Ina M 0m 3... ....DATfb4WTWg1p-=3SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTUnsteady Flow Model Fort Loudoun -TellicoReservoir May 2003 FloodFigure 2.4.3-10 (Sheet 2 of 3)Figure 2.4.3-10 Unsteady Flow Model Fort Loudoun -Tellico Reservoir May 2003 Flood (Sheet 2 of 3)2.4-170 SQN-an1mWs.M "-" % tt R II811DATEumaoHWdTWDBOW43~SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTUnsteady Flow Model Fort Loudoun -TellicoReservoir May 2003 FloodFigure 2.4.3-10 (Sheet 3 of 3)Figure 2.4.3-10 Unsteady Flow Model Fort Loudoun -Tellico Reservoir May 2003 Flood (Sheet 3 of 3)2.4-171 SQN-Melton Hill DamtRM 601 .1F.ort'Loud6udh Dam- Mile,q602.-3RiverLTIRM,107.TRM 520.9SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTWatts Bar SOCH UnsteadyFlow Model SchematicFigure 2.4.3-11Figure 2.4.3-11 Watts Bar SOCH Unsteady Flow Model Schematic2.4-172 SQN-m~766DATE760 Udo*Unsead Flo Mode aat aFWmevwyigFlW MarchS1973F~~DUEFINA SAFETYFINALYSSAFEPOTYUnsteady Flow Model Watts BarReservoir March 1973 FloodFigure 2.4.3-12Figure 2.4.3-12 Unsteady Flow Model Watts Bar Reservoir March 1973 Flood2.4-173 SQN-ITMMImmMLUTWLTOob--~ "--:::...lamm533614103 5/15163 510103 S763 51 6103 5616#3 6t1103 5126 511303 51/4103 51161035116103 51171/03 511603DAT_ _SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTUnsteady Flow Model Watts BarReservoir May 2003 FloodFigure 2.4.3-13Figure 2.4.3-13 Unsteady Flow Model Watts Bar Reservoir May 2003 Flood2.4-174 SQN-Watt inTRV4499-tChadeston GaugehýH-RM I .9ý-ChioK'a'mi-U'gi! DWmRM 471A`yRM480!5,SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTChickamauga SOCH UnsteadyFlow Model SchematicFigure 2.4.3-14Figure 2.4.3-14 Chickamauga SOCH Unsteady Flow Model Schematic2.4-175 SQN-M6"67ft~wOV~S114* oMa1mmd Iftm 11TWs=*r, m T* W1N4W~----VN""MlMi4UU.W3114M7 311113 311117 3117ff3 311113 311113DATE=in17SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTUnsteady Flow Model ChickamaugaReservoir March 1973 FloodFigure 2.4.3-15Figure 2.4.3-15 Unsteady Flow Model Chickamauga Reservoir March 1973 Flood2.4-176 SQN-700Ig"soT~WWTW1W.1 ftam~wp4neDATE W ?X l WS2UC1,SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTUnsteady Flow Model ChickamaugaReservoir May 2003 FloodFigure 2.4.3-16Figure 2.4.3-16 Unsteady Flow Model Chickamauga Reservoir May 2003 Flood2.4-177 SQN-F-9aVOa(""000"~S-VA1"7104470 46 486 me0 M0 mEWESMSM MM MILESEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTChickamauga Steady StateProfile ComparisonsFigure 2.4.3-17Figure 2.4.3-17 Chickamauga Steady State Profile Comparisons2.4-178 SQN-on 6 o 1 6 10 1236 1266 14m "DOCAE(" SEQUFigure 2.4.3-18 Tailwater Rating Curve, Watts Bar DamI 1in no 460 6NOOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTrailwater Rating Curve,Wafts Bar DamFigure 2.4.3-182.4-179 SQN-1,250,0o01,000.0o0o750o000(n0PEAKQ 1,088, 62I.2§-- -- --- ---- ----- ---1- -- --------- -------------------------------------------------------- ----------------------------------500,000250,0000-3d163/16 3117 3/18ý3/19 3/20 3121DATE3/22 3/233/2431253r26 3/27SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTPMF Discharge Hydrograph atSequoyah Nuclear PlantFigure 2.4.3-19Figure 2.4.3-19 PMF Discharge Hydrograph at Sequoyah Nuclear Plant2.4-180 SQN-Security-Related Information -Withheld Under IOCFR2.390Figure 2.4.3-20 West Saddle Dike Location Plan and Section2.4-181 SQN-725720715P4ak Elev: 719.74ftOwl100/710705U.j//I./ItII700695690685680------/1j/Sequoyah Nuclear PlantFinal Safety Analysis ReportPMF Elevation Hydrograph atSequoyah Nuclear Plant3/16Figure 2.4.3-216753/153/173/183/19Date3/20 3/21 3/22 3/233/24Figure 2.4.3-21 PMF Elevation Hydrograph at Sequoyah Nuclear Plant2.4-182 SQN-70 .1"'~ Q91RolI, h _£~~~~ L; ____I 1"L :I.. i .........I~~~~~ I MR,.TS'1'(tOFigure 2.4.3-22 General Grading for Site Drainage2.4-183 SQN-Figure 2.4.3-23 Not Used2.4-184 SQN-... .. -~-,, ..:., :--.,?.,.. ,.: .' .. ¢ : o i"&xk 1:40. ."p ,, -',Q Wind from N\N W "--" * ,"i. ",.-;-N U C L E A R P L A N T.."' ,f -----...." -: .., o .< \ s~t .... ..'- ' .\k... .",-,'Nw.... .",-LEVEL JA * \'" NU LA"L N -'N- ,"Q.AFiur 2 4Sqoa NcerPatNW idWv ec---- --v Q w-.i 'KI SCL .0020 00FEFigure 2.4.3-24 Sequoyah Nuclear Plant NNW Wind Wave Fetch2.4-185 SQN-10"JWind from N E --.Fetch I. 5 m iles ' ,iti.. .., ", "k--,.- " "' " f1, .:d, r= .rI , ' ",-. .iI"1_ .-., 1.' -. Jr. I ,-r ..SEQUOYAH"NUCLEAR PLANTkC -."/ -\_JZ/SEQUOYAH NUCLEAR PLANTNE WIND WAVE FETCH .SCALE 0 1000 2000 3000 FEETI:2"..-..1 .-.... J' _.Figure 2.4.3-25 Sequoyah Nuclear Plant NE Wind Wave Fetch2.4-186 SQN-A-~ / S4~ (sat,---I-----0. r. ~e.r -srcr Oý A.2I.-,~ '4'.5ISewOV cN"--* a Ins--an, so *(S flip~r1~o 8-Figure 2.4.3-26 Topography Surrounding Diesel Generator Bldg and Cooling Towers2.4-187 SQN-SECC /ON -PWERHOUSE "0 w I/Pt/FT DIAGRAM V CMce Disifld SOO9 :PI/PUt77DI0AGRAM4 Vl C5 NUv4.5%' ACT(W VR ~ ASWMI IVAREAvlyo 069ijPOiIIl PQrSScLQC ASSuMED M c v/0ra610AEA-0rlY.ttebýH Nio Th* 60'eAo SE-d AWAa a',Sam bd up the~~~~r. ~ ~ ~ 1 A ~ f~si~e A c0frechA.7 .a,~v fkn Vd to 040't8.s.44y' ffeare ,.va/d,/ *qA#)- CPIN A~ddh '0 Wtr MedrPA Roh ofEiASlllr .0rh mq Lcess of Mot' rogdktr3501415'1 ' d~eejos of Sapfety of/. LIIII1Zi2I26i.5f PIAN AT I, 1:57025545- PRCSSURES157'I 0See.s~~-----gap r.ee, Q.I1's CoekgdaIo onlo shv&--frothi%64SF PA'(S3LIRE foevMM/0 0. A TZ's uuod" e87r a.~a!1Scole 1°.dO'!L1 I A, '4e .5.q I.W ~ ,uTJ/ I ifoIWarm5 Reedfri~ Wjiv k ' NI/IAvg.2~~~.232'9 O.r. AM 2.57 4,.s, ýIZ?.;*JV ji 0 Ls______________________________ 447 15,03"A0 19SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTResults of Analysis For OperatingBasis Earthquake- Watts Bar DamFigure 2.4.4-1Figure 2.4.4-1 Powerhouse & Spillway Results of Ananlysis For Operating Basis Earthquake -Watts Bar Dam2.4-188 SQN-....~ ~ ~ ~ Y 7- V... .MAZ iFI T 6A, Og.U E1,71.. ,A4CI OV /O,9af /Afr2A V I" ,c- Ii /00;' KW 0F1A- .1, be> AS' / A 175corA-sl /4,,'Aie"f.O/Cdetedoled fo.T 'IAL /LLP~ ~7~A" J 7ff"4/A /T 4I Je01/PL IF PPRSS"P A 5SSUALe TO.ACT LW 420 C AA'&V.544,' P4.A'Cl 7.Vn 7546 ' _L Lt ..9.it -ý 7)4' M* --l -W 1/%'--aW0 v!Sy*W.10.11C~ Me "Ip.Oi,ob#w.ya 4s e'e oAof 4bt~t#o aI ? Me 04.A fova" --d Ile,,MoS~.fO,8A 41 P0ASSU,,-'S-111- --4-- --.- -1-k-1-- --7 Vh~ !.V 4,9, 'S -VV 0 is.'7.'~i',d/ 5t9 ~ .f/~ o ; /S 26 si ,4d~/0/1 01 H~ v 1-d 1/1724oo 9iil.VSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTResults of Analysis For OperatingBasis Earthquake- Fort Loudoun DamFigure 2.4.4-2Figure 2.4.4-2 Powerhouse & Spillway Results of Analysis For Operating Basis Earthquake -Fort Loudoun Dam2.4-189 SQN-o~ .s'~e7r,* /~ )6N,NN.,NNNIi,1Cy 40Zt, 00 4 ie AOg~04 0.L~f14 ,1 i9i/ #.% J* *SAM W W.Vd3 improvements have icreasedthe etecdive height of theembankment to a nonmium El836 (See Foil Loudoun ProtectDrawing 10W222-1) Fiekdsurveys ndi:ate a minrtlqrrheight Ei 836.9 was achievedT YPICAL e-(MAAe-*r sec rlayo~SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTEmbankment Results For OperatingBasis Earthquake, Fort Loudoun DamFigure 2.4.4-3Figure 2.4.4-3 Embankment Results Of Analysis For Operating Basis Earthquake -Fort Loudoun Dam2.4-190 SQN-Security-Related Information -Withheld Under IOCFR2.390Figure 2.4.4-4 Analysis For OBE & 1/2 PMF Assumed Condition of Dam After Failure of Norris Dam2.4-191 SQN-L A /36.9r, I A..,,YRP/CAL SPILLWAY SECrTIK atta.y 3 s .-.11.9e% 4I dte/05.tte , of oocspe00Of It M base SQ os$od 00tow/Y o lftbp.6 t//,,ott top.O,,M/ aSM If A.O60'eOt. 00 -s dlotoo00 '&T5 #54 'S~js=;rgSo oota'Cc sUPLIFT D/4GRA9M &I 9VUPLIft PRESS1A.' Ac r -OV / a'- a45f A4eA"0 .34S6' PLANA'A elP3W,10,7'co/csj/ale"df t sher.formtdo, a. ,6 i sOssattd' o t cwhro /ca..i 05Shear S/osreq,d for 0'.'Ctt4S'd'tCr-t po00'Co Of Pose ';7Ot-OtI Y.' XAi , to,ý 50e 1 *,I,,'1_or on,.,s' SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTSpillway & Nonoverflow Results OfAnalysis For OBE, Cherokee DamFigure 2.4.4-5Figure 2.4.4-5 Spillway & Nonoverflow Results of Analysis For Operating Basis Earthquake -Cherokee Dam2.4-192 SQN-I/¢////J/r~-L t/.'r c' !ArryA'AyA2kD-~6, (.0J~.sr ~jd~ ~09a ,~ ,c~o4to, I7Muffect hjutjN of Mew vnibanfkw'n1.fr to El1091 uf grealef bsee CtioroIko HydroP'o4ecl Uramwngt, 10W222-1,21~&~Sr //5.6rtt ~TYP~'CAt E'.f 4WMet4'7 SfCtc,~-SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTEmbankment Results Of AnalysisFor OBE, Cherokee DamFigure 2.4.4-6Figure 2.4.4-6 Embankment Results of Analysis For Operating Basis Earthquake -Cherokee Dam2.4-193 SQN-Security-Related Information -Withheld Under 10CFR2.390Figure 2.4.4-7 Assumed Condition Of Dam After Failure OBE & 112 Probable Max Flood -Cherokee Dam2.4-194 SQN-7YPIC.4i SP/LLMAWY S6CT,'OAS d-MN(e.Fut11jqgSS1J,9eS ASS0ME4ro ACTe r o /00 % olP8&4se Wr,4I-Nore.S:x&,ftrae/~.Meifý .ft .009d. A.IIItO O .4.. t£.ASC P~t.SSURCdssa,,,d /. 6e e.* t,com~press~mion mseaW efem',re64$d e-ed.X y X/ A vq -5 'fe.9 ."1 *096xr A' v IO565 V'~'I *~ PooA,4.ASEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTSpillway & Nonoverflow Results OfAnalysis For OBE, Douglas DamFigure 2.4.4-8Figure 2.4.4-8 Spillway & Nonoverflow Results of Analysis For Operating Basis Earthquake -Douglas Dam2.4-195 SQN-rPcaTCq ao- sAP!Try4..10:194"4- _ NIH ~&QT/C~ HA7OP OP DAM (10/7 1 .1I'99 7 iLL1 i,955 II /1O~Z0A'r&935i0q0.2 ';Uf O06v 010,a9 01.4 a "17 0.I69, 0.189AsswieD A4CCPLL'9Ar7-/NN~rC.S:1A.dlys's ,vozMcWe 4,4.772 ,Sh-.,s~~,~Mso nk//somc as o0 ~~dd~~dly3,S.~-A.-szwAI4 swrwiArwa L/4'eC'0;T CIqCLe,-I-, O~SADDL( DAM No.SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTSaddle Dam No. 1 Results OfAnalysis For OBE, Douglas DamFigure 2.4.4-9Figure 2.4.4-9 Saddle Dam No. 1 Results of Analysis For Operating Basis Earthquake -Douglas Dam2.4-196 SQN-Security-Related Information -Withheld Under 1 OCFR2.390Figure 2.4.4-10 Douglas Dam Assumed Condition of Dam After Failure OBE & 1/2 Probable Maximum Flood -Douglas Project2.4-197 SQN-Security-Related Information -Withheld Under 10CFR2.390Figure 2.4.4-11 Fontana Dam Assumed Condition of Dam After Failure OBE & 1/2 PMF2.4-198 SQN-ixamx(TVAKInqUNUNL"IrIC0AmwU N29svftetwaterV PC .ClaulmWillm cýý-ý'. bET QL e0n1le 40,& 16 Vemon JOF Al MANplainEtekwal 0N,M"AMAARILA0ýERCIKEmuRVII________ -I Oa,.dIWg*GROATAM.YM ANATIONA 0S6Itcamoo ORM Ubme4 .LA v r:atomE RME 00V fTlrMASCALE IN MILES9 :;tU0 10 20ýA Im4IAl oIoza i l --rl "" -- Ir= "I T Figure 2.4.4-12 OBE with Epicenter Within Area Shown2.4-199 SQN-T#V'Sd/hw r. TYLI/F /ARM 11111upupT', P,?eSSCWZASSUA~eD 7ACTf ON /OVfrOf BASE e ARA ,dfO-fro,~Io, 0.67 JJ'SA4, A/sB0ASE R4AN ./ AMOAt hi: Ia/ jceo/eew W," .r VVFdj/ base dsslIM00d to be d2/4eBy dpzn*m'coo/yadelr,,,,,. /. A. 9U~4,7a/k2.At/~.0/I dC00.I/0Oofa,6o~i M,- bose wo-sd/ondto he 09.-gV8/ Agat S ',/.'y9 s esswe0d oPe4, ,O Mis' IA,,eoys.4.BA.S PRe4SSUR4("IA424At5 4, ps2 ~ -A 0.9SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTSpillway Results Of Analysis ForSSE Earthquake. Fort Loudoun DamFigure 2.4.4-13Figure 2.4.4-13 Spillway Results of Analysis For SSE Earthquake Fort Loudoun Dam2.4-200 SQN-PA(r~ ~ 5A~fTy,As -a~'NNN'Nedg 0d/0S7.90;,To7.10AS S WAE ACCr~eA4 Ir'cwo -V'Ir'stImp ijl matits huj)I 1 t,4Sce Flot Lodi Pr~c IOravvug tOW222- Il~ Fieldhoeytt oi El 636 9,a ciwTYPICAL EMBANKMENTSECTIONSEQUOYAH NUCLEARFINAL SAFETYANALYSIS REPOIEmbankment Results Of AnSSE Earthquake, Fort LoudFigure 2.4.4-14Figure 2.4.4-14 Embankment Results of Analysis For SSE Earthquake Fort Loudoun DamPLANTRTalysis Foroun Dam2.4-201 SQN-Security-Related Information -Withheld Under 10CFR2.390Figure 2.4.4-15 Fort Loudoun Dam Assumed Condition of Dam After Failure SSE Combined with a 25 Year Flood -Fort Loudoun2.4-202 SQN-Security-Related Information -Withheld Under 10CFR2.390Figure 2.4.4-16 Norris Dam SSE & 25 Year Flood Judged Condition of Dam After Failure -Norris Dam2.4-203 SQN-*A " 'AAl °.LOG"¢ L_" k.SEWA eSiot-_ -i SECFigure 2.4.4-17 SSE With Epicenter in North Knoxville Vicinity:UOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTSSE With Epicenter InNorth Knoxville VicinityFigure 2.4.4-172.4-204 SQN-710705700695 4I-LUwLI.zzO 690LU685680675670PEAK ELEV, = 708.56I, I4 -----r ----- ----------- ------ ------ ----4 --------- -------- --------LL Iee---------....j- ------L --------------L ------1 --------- -----3/15 3/16 3/17 3/18 3/19 3/20 3/21 3/22 3/23 3/24 3/25 3/26 3/27DATE3/28 3/29SEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTSeismic Combinatinon With Failure OfCherokee, Douglas & Tellico InOBE withl/2 PMFFigure 2.4.4-18Figure 2.4.4-18 OBE Failure Of Cherokee, Douglas & Tellico With 1/2 PMF2.4-205 SQN-.... -' -.-.-"B w, jo ~ -.. "T -., ..sI -cPOA c. :* ---,_ , 'T -..--"- Ei/ lar-A,-D7vaaE CAUL~ca cm_ _ _ _Figure 2.4.4-19 SSE With Epicenter In West Knoxville Vicinity3EQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTSSE With Epicenter InWest Knoxville VicinityFigure 2.4.4-192.4-206 SQN-Security-Related Information -Withheld Under IOCFR2.390Figure 2.4.4-20 Tellico Dam Assumed Condition of Dam After Failure SSE Combined With a 25 Year Flood Tellico Project2.4-207 SQN-... i.-=--I-. ' vZ " ---.... -"- --' i ,,,5-T.,~L.L~.S. q ;,,A IRSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTLocation Of The SSE For SimultaneousFailure Of The Douglas & Fontana DamsFigure 2.4.4-21Figure 2.4.4-21 Location Of SSE For Simultaneous Failure Of The Douglas & Fontana Dams2.4-208 SQN-No03 1dno~rida shlp corc' /aMthod.2 Thbr Me origiow itebiffyftar ~oi sw est$ .idSobd stwyAvioj4 Mi, 1/ft Vor rtf hJ Veo sfivqjhs of rvwlatioalAoNJ3.-, A sSiJ"ied Co~3obo~/~/ -~-y.S&C r/(N Al-Al(SrA 30 0601)f7?OAIf OHý'GOVAL AA/A4,YS/SS35c&/e / "3O'WeAev c, isweakesr circleSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTEmbankment Watts Bar Dam,Results of Analysisfor OBEFigure 2.4.4-22Figure 2.4.4-22 Embankment Watts Bar Dam, Results of Analysis for OBE2.4-209 SQN-/. 5 V/ (5' ( ~~-f.*?dq" ý' I "jZ4EL H2d,EL 600EL 760OAP 07 M 1-Z S'20ELEL74;720027 1.0,q, 1204q 06gOL 009 0V 0/29F 0 /4d 0/4/6g C/Sq4 5 5lE AL([L R.4 r/ON'1t4SS1,111 -4,WEL 67A1z I'vea/J AL/,A/ff~~~t'~j EL7912 '61, o(, 2"',C*2~c25Ao,,'eq)I of,,,fr,5/0c; 45~, C.6... /7AfE ST (/'/CLECEL 72d7 ~P~.W7Y~T-YP/IC,4Zi-EMAA'/fMC/V SZ-CT/ONSEQUOYAH NUCLEAR PLANTFINAL SAFETYANALYSIS REPORTEmbankment Tellico Dam,Results of Analysisfor OBEFigure 2.4.4-23Figure 2.4.4-23 Embankment Tellico Dam, Results of Analysis for OBE2.4-210 SQN-I? NE(S) T M51(4.. (0 *U*00 -AR-c O -PC.ER R4ELIEF TO S.PET WAKE -U TANK 400 GAL(Z LI. ES)L TO UL IT/UpT (2 LINES)N I.... ... .- 1-- srt tuDEMI.101(0 POOL lL 511 CHA RGING 0 UN41ITPAUX FEED 0-(Z LINEOS PER UNIT) I ..0-INIT)810 4 L ' ....... _ P U IT)-t,-s 1 --r.r --.1 T "A ,TO 011E0101 PIN/ANENULUS PUMPS RC Mae AUX 01ARGi4GI~~~~~~~ Wý',.'LL i ..... T -.-I -=] i('clII .~(t'EPRS LO"SS-04ESSURIZER 0 0 P P PUMPS,/U.,T).1E( /,04AT)"__-_"__ MPL0400000 BL DGrot, OTLES N' SAOR[BAY OL INTAKE PUMPING DORS IAT IAIN-"),AND INTE CHANNEL STATION (TRUC FUR( r S*/uRIT) DT L OEAL RETLO S5(01(05~"i RP0 PRELIEFAEIIIADLo ..O 1V (VLVV(E VAULT R)ACTORCOOLANT(ZLNES-S ..M TAN 14.I CVI-T 1 L fLSSURIZEIR J AET BLDGCV-D-~wt --TAI- ;LINES) C21 NoGft- ES-M (0 L.Fi .W I n S i in O i -NDOES NRAI INCLUDEU~lDVEN UILATION SYS., EMERGIENCY POWER SYS..SAMPLINIG SYS., 0(:TAILS 0F EFICý LOADS.SCREENS SP ý-OL PIECE CONNECTlOýS.K C UOY A H NUCLEAR FLANII F 7.NAt SAFET IYSAN/ALYSIS5 REPORT-0* D 13 AIZý,."! : [I W) ) , OI L:- 1 1 owS,-A I WN I N OPIEIRA I .13N; Ný IU A-0joEpJD ZN ;51Figure 2.4.14-1 Flow Diagram -Flood Protection Provisions with New ERCW Intake Station in Operation -Natural Convection Cooling2.4-211 SQN--(, LENE--AU24LIARY ISOR04Tot TO WA AE-UP TAN 000 GALU L PIT I/PLANT)~$E- (?C LINES)~~c CS -(Z LIK ES) 41u-PC.ARGING *,'UNIT)1CPBI 11ooL AAAC WIT)PIT FNII LLACRAE- ( -2 " LINUSU5E'T.LIrNN EON SETTLING AUX. U K PR NNITUNIT01;PUMPS115 EICSG ;,IWA IR-qý, C PUMP (?/UNIr) ,X CHARGINGI I '/ T ? -' EA ! I P W 'OCFT No. II , SC,,A) ... IN.,r P ý P : 2 WEAl. NQ ..... SEA *'"7 r.FOREBA I POOL INTAOE PUMPING rIA0 C Dt U I ot .. R O CU LNO INTLAKE KA I OtL ST-CATION S7RUCTURf VESSEL RIEDSCSAA.4PLIPPOWE RE05., DEAIS f EA OAS,,, <, .R ,<,, R O0J ISR OUATSIST ',lE ANDTCANLc D / AFTln!IL10G PUMSCAG POD11Ue)G- L RI AfI PRSURZRNEIF AK NCNOTES: IC(_T- 1 TIR ....... CODESE IL .......LDGA =..DRWING DOES NOT I I : I I. SDRAIN REACTAR CLTILATIO SYS. EMERGENCY OWER SYS- LOADSDRAINUIN AsAM" PLING SYS., DETAILS Of ERIC. LOADS, E r A LYSANSPOOL PIECE. COWIT 'Ajuil 1(2IL =TIF OUTSIDAE'IC llAL(A21 IIES SIPIIC REATO BLDG'FUEL TRAICNCI DRAINA r SUMPFigum- F d Pn P viis wh Nw E W I keUin SMPS(2 VOL (/UNIT)ENR PIPINGSEOU0'YAH NUCLLAR PLAN1S F '"iNAL SAF E iYS ANALYSI S REPORT1 4l~lr 1U IN 0Pr.I;AI:,_tr Cll,7tNR! 0001. 1CFigure 2.4.14-2 Flow Diagram -Flood Protection Provisions with New ERCW Intake Station in Operation -Open Reactor Cooling2.4-212 SQN-SiI3".Iý. 105t'-l~,,.... /0 3~.07oI/IIo7.30-0 01.3.I TI ~ -(1- 710307,9W0 Sq. Mi. 11,lls Gap CenteredMarch Flood EventAdopted Rainfall DistributonlSeqooyah Nuclear plant0 *TRM 485.0T---.. Rive., Elevation.Qbor. l .00no~~+,5aav,*haavs , On 07 e*.0..Sýqov iC .i.U 1 72 'a4 M8.ANOTE: Times shown allow 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months for communications and forecast computations.& ~ ~ ~ ~ ~ ~ ~ 0 C.70710 ////392221,430 Sq. Mi3. Dowunr..oo.Centered, Mardh Flood Event4Adopted P.Infalo Distributionloquoyrrh Nod.. Plan, IF TRM 46S.0Teon-.. 30.. Elevationo0 /2 /0 3 0/ 0 2 ý ' 0 .ý " ý ,I, ..... -21,400 Sq. Ml. Do-t-o rea.m C-dmo , Maoch10- H i.g9 IHa OUrn rbDbMn=Soq.oy.h Nod.. Plint 0 TRM 45S.0Tanetat River Elevation11 1ý 41 1 Too......1111.1. -Mgo-g!'nFigure 2.4.14-3 (Sheet I of 2) -Sequoyah Nuclear Plant Rainfall Flood Warning Time Basis for Safe Shutdown For Plant Flooding -Winter Events2.4-213 SQN-7,9110 Sq. Mi. Boll Gap Ceotm~djoo.Flood OnmaHe."o LatDa Sy 04onribonlo.Seeloyoh Nuclear Plant 0 TRIM 4505O fnto..Ro, Umoatio.63r 12. 18to 04 72tSotl loto" A234 11 .7,910 Sq. MI. Boll, Gop Cette.dion. E~ot10" HMen Lent Day OI1t-butlooSqomoyA h Nude., Plant 0 TRM 411S.0Tennuso. Rioer Eleotlon0 12 28 24 4Z '. 42 44 M % 18 32i 88 14 12,, '8 2 38NOTE: Times shown allow 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months for communications and forecast computations.F.!l,9110 5q. Mi.B~t Gap Centerd une Flood EvetAdopted Rainfall Distribution5.q-oyah Nuclear Plaint 0 TRIM 42S.0Tan-ese River ElevtionBFigure 2.4.14-3 (Sheet 2 of 2) -Sequoyah Nuclear Plant Rainfall Flood Warning Time Basis for Safe Shutdown For Plant-Flooding -Summer Events2.4-214 ENCLOSURE 2EVALUATION OF ISSUES FROM PRE-APPLICATION MEETINGOn March 29, 2012, a Category I public meeting was held between the U.S. NuclearRegulatory Commission (NRC) and representatives of the Tennessee Valley Authority (TVA) atNRC Headquarters, One White Flint North, 11555 Rockville Pike, Rockville, Maryland. Thepurpose of the meeting was to discuss TVA's planned submittal of a license amendmentrequest to revise the licensing and design basis for hydrologic engineering as described in theWatts Bar Nuclear Plant (WBN), Unit 1 Updated Final Safety Analysis Report (UFSAR).Following this pre-application meeting, the NRC Staff published a meeting summary, "Summaryof March 29, 2012, Pre-Application Meeting with Tennessee Valley Authority on Changing theLicensing Basis for Hydrologic Engineering (TAC No. ME8200)," dated April 11, 2012 (ADAMSAccession No. ML12097A306). In this letter, the NRC Staff recommended that TVA consideraddressing the following issues in the submittal. Any issue only related to WBN Unit 1 or forwhich the response is the same as that for WBN Unit 1 as described in the TVA submittal to theNRC Document Control Desk, "Application to Revise Watts Bar Nuclear Plant Unit 1 UpdatedFinal Safety Analysis Report Regarding Changes to Hydrologic Analysis, TAC No. ME8200(WBN-UFSAR-12-01)," is noted below.1. The chronology and basis for the changes made to the hydrologic engineering designbasis from 1995 to 1998 to 2009.This response is the same as WBN Unit 1 except for references to the applicable site, andapplies to the hydrologic analysis for Sequoyah Nuclear Plant (SQN) Units 1 and 2.The probable maximum flood (PMF) for SQN Units 1 and 2 at the time of Operating Licenseissuance was elevation 722.6 ft, and included assumptions based on the existingunderstanding of dam structural stability and capability during seismic and extreme floodevents in the 1970's. In the 1980's and 1990's, TVA implemented a Dam Safety Program(DSP) that resulted in dam safety modifications that increased dam structural stability andcapability Between 1995 and 1998, TVA completed a hydrologic reanalysis to credit theresults of the dam safety modifications that had been completed. This reanalysis resulted inlowering the SQN Units 1 and 2 calculated PMF to elevation 719.6 ft, but no physicalchanges to SQN Units 1 and 2 site flooding protection features were implemented as aresult of the decreased design basis flood (DBF) elevations. In 2009, TVA completed ahydrologic reanalysis to address closure of issues involving the hydrologic analysis for theapplication for a combined operating license '(COLA) for the proposed Bellefonte NuclearPlant (BLN) Units 3 and 4, in accordance with 10 CFR 52. This reanalysis resulted in raisingthe SQN Units 1 and 2 calculated PMF to elevation 722.0 ft. Although this was not higherthan the original PMF but is higher than the earlier revised PMF, no physical changes toSQN Units 1 and 2 site flooding protection features were required based on the changes toPMF alone. However, because of the updates to the Design Basis Flood (DBF) levelsbased on the most recent wind-wave runup calculations, the Spent Fuel Pit Pump Motorsand equipment required for flood mode operation located in the Diesel Generator Buildingare affected. Temporary compensatory measures are in place and documentation changesand permanent plant modifications are planned to provide adequate flooding protection forthis equipment. This is described in Section 1.0 of Enclosure 1, Summary Description.Page 1 of 14 ENCLOSURE2EVALUATION OF ISSUES FROM PRE-APPLICATION MEETING2. An update of the status of TVA's resolution of long-term hydrology issues, per thestaff's request in the NRC letter dated January 25, 2012.This response is the same as WBN Unit 1 except for references to the applicable site, andapplies to the hydrologic analysis for SQN Units 1 and 2.On May 31, 2012, a Category 1 public meeting was held between the NRC staff andrepresentatives of the IVA at NRC Headquarters, Two White Flint North, 11545 RockvillePike, Rockville, Maryland. The purpose of the meeting was to discuss (1) the currentlicensing basis for flooding at WBN Unit 1 and SQN Units 1 and 2, (2) the status of TVA'scurrent licensing basis reanalysis, (3) flooding protection and flood mode operation at WBNand SQN, (4) modular flood barriers at TVA dams, and (5) TVA's flooding reevaluation planregarding the NRC's Fukushima 50.54(f) letter dated March 12, 2012.Following this senior management meeting, the NRC Staff published a meeting summary,"Summary of May 31, 2012, Senior Management Meeting with Tennessee Valley Authorityon the Licensing Basis for Flooding/Hydrology," dated June 6, 2012 (ADAMS Accession No.ML12157A457). The TVA slide presentation is provided in ADAMS Accession No.ML12156A076. In the meeting summary, the NRC Staff acknowledged the following relatedto the status of TVA's resolution of long-term hydrology issues:a. TVA discussed the challenges faced with the complexities of the revised hydrologymodeling used for the licensing basis re-analysis, and TVA acknowledged the lack oftimeliness in resolving the flooding issue.b. TVA discussed the management commitment for regaining safety margin for floodingand updating the current licensing basis through a high quality analysis, ensuring plantoperability, and improved timeliness.c. TVA made a number of commitments at the end of the presentation. Thesecommitments have now been formalized in the TVA submittal to the NRC DocumentControl Desk, "Commitments Related to Updated Hydrologic Analysis Results forSequoyah Nuclear Plant, Units 1 and 2, and Watts Bar Nuclear Plant, Unit 1," datedJune 13, 2012 (ADAMS Accession No. ML12171A053).Therefore, the NRC Staff including senior management has been provided an updatedstatus based on the TVA presentation, responses provided by TVA during the presentation,and the commitments provided by TVA regarding future actions to complete the hydrologicanalysis and applicable documentation changes and permanent plant and damembankment modifications. With the exception of implementing the commitments providedto the NRC, there are no other actions required for this issue for SQN Units 1 and 2.3. The relationship and use of the 25-year flood level versus the May 2003 flood level inTVA's new analysis.This response is the same as for WBN Unit'1 and applies to the hydrologic analysis for SQNUnits 1 and 2.As described in the second paragraph of Section 3.2 of Enclosure 1, Uncertainties, perNUREG/CR-7046 the only manner to address the uncertainty in the hydrologic analysis isPage 2 of 14 ENCLOSURE2EVALUATION OF ISSUES FROM PRE-APPLICATION MEETINGthrough calibration of the model to historic flood events or sensitivity analyses. TVAcalibrated the model to historic flood events using the two highest recent flood events wheredata exists. The floods used for calibration are March 1973 and May 2003 storms. TheMay 2003 flood event was a much larger flood than the 25-year flood. The May 2003 floodreached a maximum elevation of 657.2 feet on May 8, 2003 on the Tennessee River at theWalnut Street gage at Tennessee River Mile (TRM) 464.2. This compares with theMarch 1973 flood, the maximum flood of record since regulation by the TVA system, whichreached a maximum elevation of 658.06 feet on March 18, 1973. Based on the floodfrequency elevations at the Walnut Street gage the May 2003 flood was about a 100-yearevent as shown in the tabulation below.The flood frequency elevations at the Walnut Street gage TRM 464.2 are as follows:Flood Elevation (ft.)11 -year 644.02-year 649.25-year 650.610-year 653.450-year 655.9100-year 657.0500-year 663.61 National Geodetic Vertical Datum (NGVD) 1929Based on review of observed elevations at key locations in the vicinity of SQN, theMay 2003 flood event was about a 100-year event over the reach of interest with May 2003maximum elevations exceeding flood of record elevations at some locations. A comparisonof the maximum elevations reached during the May 2003 flood at key locations is shown inthe tabulation below.Location Maximum Elevation (ft.) NGVD 1929Flood of Record May 2003Chickamauga Dam Headwater 686.99 5/9/84 687.13 5/7/2003Watts Bar Dam Tailwater 696.95 3/17/1973 694.17 5/7/2003Using the calibrated model based upon the two highest recent flood events where dataexists (i.e., March 1973 and May 2003), the 25-year flood event specified in RG 1.59 wasused for application with the postulated Safe Shutdown Earthquake (SSE) failure ofupstream dams as described in Section 2.1 of Enclosure 1, Proposed Changes, under thesubheading Section 2.4.4, Potential Dam Failures, Seismically Induced. The 25-year floodmagnitude was developed using flood volume frequency relationships. The inflowhydrographs were developed using the March 1973 flood, the flood of record, and a largeregional flood, scaled by the ratio of the 25-year volume to the 1973 volume. This providesan estimate of the 25-year flood based on historical watershed experience.4. The justification for the proposed combinations of dam failure scenarios used inTVA's new analysis.This response is the same as WBN Unit 1 except for references to the applicable site, andapplies to the hydrologic analysis for SQN Units 1 and 2.Page 3 of 14 ENCLOSURE 2EVALUATION OF ISSUES FROM PRE-APPLICATION MEETINGThe methodology used to develop the controlling seismic/flood condition at SQN is the sameas previously followed for the site evaluations described in the SQN Units 1 and 2 UFSARas follows:1. A ground motion attenuation function was generated to describe the peak horizontalacceleration of rock at the free surface versus distance from the epicenter.2. Using the attenuation relationship, the seismic base accelerations for various damshaving large stored inventory (reservoir storage) and low spatial separation weredetermined.3. The seismic stability of the dams for the seismic event centered at the dam (maximumbase acceleration) and seismic events which cause dam failures at adjacent dams (lessthan maximum base acceleration) were then determined.4. Based on the predicted seismic stability of the dams (individually and in combination)and reservoir storage, the potential seismic failure/flooding combinations were screenedto identify the controlling case for SQN.5. Hydrological routing for the potential controlling cases was then performed.The ground motion attenuation functions to permit evaluation of simultaneous failure of twoor more dams were based on the attenuation characteristics of an Operating BasisEarthquake (OBE) and a SSE occurring in the geographic area encompassing theTennessee Valley above Guntersville dam. Utilizing historical earthquake data fromlocations near the Tennessee Valley, an attenuation curve was developed. Using thisOBE/SSE relationship, a representation of the earthquake was developed in the form ofconcentric circles radiating from a center 0.09g (OBE) or 0.1 8g (SSE) acceleration with eachcircle representing decreasing levels of base acceleration as the distance from the epicenterincreased. The concentric circles centered at an acceleration of 0.09g/0.18g were thenstrategically moved around the dams above Guntersville Dam to determine potentialmulti-site critical base acceleration levels.The dams above Guntersville were examined for seismic stability based on baseacceleration level. During the period from 1970 to 1988, the initial seismic stability analyseswere performed on the concrete dam sections and the earth embankments of critical dams.In this evaluation, some of the concrete dams such as Apalachia, Fort Patrick Henry, MeltonHill and Ocoee No. 3 were not analyzed due to their relatively small storage volume andwere postulated to fail. In other cases, more detailed seismic evaluations were performed,such as at Norris Dam. The more detailed evaluation of Norris dam concluded that the damwould not fail in OBE (coincident with one-half PMF) or SSE (coincident with 25-year flood).However, for purposes of the seismic failure combinations Norris dam was conservativelypostulated to fail with only the resulting debris field impeding flow.Using the dam base accelerations and seismic stability evaluations (or failure assumptions)as screening criteria, various flood-seismic failure combinations were identified. Cases to beevaluated further were selected based on the potential reservoir flood volume released inseismic failures, the relative timing of those releases, and in some cases results of previousflood routing analysis.Page 4 of 14 ENCLOSURE 2EVALUATION OF ISSUES FROM PRE-APPLICATION MEETINGThe impact of multiple failures of the large reservoir dams identified in the screeningevaluations bound the effects of a single dam failure. Thus, single dam failures were notfurther evaluated.Using the earthquake attenuation function, the seismic stability determinations, reservoirvolume, flood wave timing, and informal routing methods, the following cases were definedas having the potential to control at SQN for OBE coincident with one-half PMF:1. Simultaneous failure of Norris and Tellico Dams: Melton Hill Dam located below NorrisDam is not failed with the OBE in this scenario to maximize the downstream impact ofthe seismic failure wave from Norris Dam that overtops and fails Melton Hill Dam whichis judged to be more critical.2. Simultaneous partial failure of Fontana Dam and complete failure of Hiwassee,Apalachia, Blue Ridge, and Tellico Dams due' to an OBE at a location betweenHiwassee and Fontana: Fort Loudoun and Watts Bar Dams are seismically stable atOBE base accelerations for this epicenter.3. Simultaneous partial failure of Fontana Dam and complete failure of Tellico Dam: FortLoudoun and Watts Bar Dams are seismically stable at base OBE accelerations.At least three other failure combinations evaluated in the original SQN Units 1 and 2 UFSARstudies and judged not to be controlling were not re-evaluated as a part of the new analysissince they were not controlling in the original analysis.The following failure combinations for the SSE coincident with the 25-year flood weredefined as having the potential to control at SQN using the evaluation criteria:1. Simultaneous failure of Norris, Cherokee, Douglas and Tellico Dams with SSE epicenterlocated in the North Knoxville vicinity: For this combination, Fort Loudoun, Watts Barand Fontana Dams do not fail since the attenuated base acceleration at these dams isless than the base acceleration for which the dams are seismically stable. Melton HillDam is not failed seismically to maximize the downstream impact by allowing Melton HillDam to overtop and fail due to the Norris Dam failure wave.2. Simultaneous failure of Norris, Douglas, Fort Loudoun and Tellico Dams: For thiscombination, Cherokee, Fontana and Watts Bar Dams do not fail since the attenuatedbase acceleration at these dams is less than the base acceleration for which the damsare seismically stable. Melton Hill Dam is not failed seismically to maximize thedownstream impact by allowing Melton Hill to overtop and fail due to the Norris Damfailure wave.At least seven other failure combinations evaluated in the original SQN Units 1 and 2UFSAR studies and judged not to be controlling were not re-evaluated as a part of the newanalysis.Flood simulations for the five failure combinations described above were performed todefine the maximum bounding elevation at SQN. This is further described in Section 2.1 ofPage 5 of 14 ENCLOSURE2EVALUATION OF ISSUES FROM PRE-APPLICATION MEETINGEnclosure 1, Proposed Changes, under the subheading Section 2.4.4, Potential DamFailures, Seismically Induced.5. The purpose of the finite element analysis on the Fontana Dam.This response is the same as WBN Unit 1, and applies to the hydrologic analysis for SQNUnits 1 and 2.As part of TVA's DSP and consistent with the Federal Guidelines for Dam Safety, TVAperformed a review of Fontana Dam in the mid-1980s to determine if the dam was capableof withstanding a maximum credible earthquake (MCE) (Reference: Fontana Project DamSafety Analysis Report, April 1986). The evaluation determined that Fontana Dam wascapable of safely passing the PMF but the dam's ability to withstand earthquake loading wasnot assured. As a result of this finite element analysis, reinforcement of the upper portion ofthe non-overflow dam was recommended and subsequently implemented to ensure the damwould remain stable for the MCE.Since this original finite element analysis did not consider the alkali aggregate reaction(AAR) expansion issues at Fontana Dam, additional analyses were performed to evaluatethe seismic/hydrostatic stability of the dam and the impacts of stresses associated with AARexpansion in the dam structure.Patterned cracking was first observed in the dam in 1949. Also, it was noted that the damwas beginning to tilt in the upstream direction at that time. In 1972, cracking was observedin the walls of the drainage gallery in the curved concrete blocks of the dam. A six-inch wideslot with a depth of about 95 feet was cut between November 1975 and July 1976 at thejoint of Blocks 32/33 to relieve some of the stress. The slot had completely closed at the topof dam by October 1983. The top third (35 feet) of this slot required re-cutting to a width offive inches between October 1983 and January 1984. Slot closure measurements indicatedthat the slot closed gradually over time and would require re-cutting in the next severalyears. The third slot cutting to a width of six inches was performed between February -May1999 and January -May 2000.Clearance problems were first detected in the spillway gates of the main spillway in 1967.Pier tilting due to concrete growth was causing binding of the gates when they were beingopened. The gates were trimmed four times between 1967 and 1989. In the late 1990's, itwas concluded that slot cuts on each end of the spillway would help reduce the tilting of theend piers of the spillway. Two slots with the same width of about 0.6 inches, and withdepths of 82 and 57 feet at joint Blocks 34/35 and 41/42 respectively, were cut in January1999. In November 1999, re-cutting of the spillway slots was undertaken. However, slots34/35 and 41/42 had closed during the summer season at the top of the slot by 2001.In summary, three slots have been cut in Fontana Dam (Blocks 32/33, Blocks 34/35, andBlocks 41/42) to address problems associated with AAR. The first slot was cut at Blocks32/33 in 1975. The slot was required to eliminate the longitudinal force from the longstraight portion of the dam. The longitudinal force was tending to push the curved blocksupstream, thus creating the observed cracks. The two spillway slots located at each end ofthe spillway (Blocks 34/35 and Blocks 41/42) were installed to help control tilting of the piersinto the spillway.Page 6 of 14 ENCLOSURE2EVALUATION OF ISSUES FROM PRE-APPLICATION MEETINGA finite element analysis was used to evaluate the existing slots in either the open or closedcondition, the effects of cutting deeper slots, the effects of cutting additional slots, and toprovide recommendations for long-term slot cutting strategy for best management of theFontana Dam AAR problem. An August 2006 seismic/hydrostatic stability analysisperformed by Acres International which considered the combined impacts of stressesassociated with AAR expansion of the dam structure concluded that although the minimumsliding factor of safety is less than 1.0 for the critical section (FS = 0.814) when subjected toa sustained acceleration of 0.26g, the post-earthquake stability of the dam is acceptable.6. Discuss whether approvals for the dam and river operations modifications arerequired from other agencies (e.g., U.S. Army Corps of Engineers).This response is the same as WBN Unit 1, and applies to the hydrologic analysis for SQNUnits 1 and 2.TVA was created as a Federal agency by the Tennessee Valley Authority Act of 1933 withspecific responsibilities for the unified development of the Tennessee River system.Approval is not required from other agencies for TVA's modifications to its dam and riversystem operations. However, modifications must be consistent with procedures set forth bythe National Environmental Policy Act (NEPA), which is the same requirement for otherfederal agencies.As a procedural act, NEPA calls for Federal agencies to make informed decisions, consideralternatives, to have decision-making processes that consider the environmental impacts oftheir proposed actions, and provide full disclosure of the process as applied. The level ofenvironmental review required for a given action depends on the expected impact on theenvironment and/or when the proposed action is likely to be controversial.The most recent environmental reviews that effected modification of the WVA river systemwere completed as Environmental Impact Statements (EIS) as follows:1. Tennessee River and Reservoir System Operation and Planning Review, TVA,December 1990. Record of Decision issued February 1991.2. Reservoir Operations Study, TVA, February 2004. Record of Decision issued May 2004.The U.S. Army Corps of Engineers (USACE) and U.S. Fish and Wildlife Service werecooperating agencies on this EIS.As a part of the NEPA process, other Federal agencies and the public are invited toparticipate in the process. Consistent with the NEPA process, the final decision on anyaction to be taken as a result of the environmental review rests with the initiating Federalagency. In the case of reviews that have a potential impact resulting in modification ofTennessee River system operation, WVA makes the final decision on what actions areadopted for implementation.The Act further gave TVA the power to construct dams and reservoirs on the TennesseeRiver and its tributaries to provide for navigation and control floods on the Tennessee andMississippi River basins. To date, TVA has either acquired or constructed 49 dams locatedin seven different states as a part of the unified development of the region. The power givenPage 7 of 14 ENCLOSURE2EVALUATION OF ISSUES FROM PRE-APPLICATION MEETINGto TVA for construction of dams and reservoirs in the Tennessee River basin is much likethe authority given to the USACE on other river systems.TVA has had a DSP since the first dams were acquired and/or built. Dam safety ensuresthat the impoundments and dams are designed, constructed, operated and maintained assafely and reliable as is practical. The DSP was formalized in 1982 to ensure consistencywith the Federal Guidelines for Dam Safety which was issued in 1979. The guidelines applyto management practices for dam safety of Federal agencies responsible for the planning,design, construction, operation, or regulation of dams. Today, the Dam Safety Governance(DSG) procedures define TVA's dam safety responsibilities to ensure compliance with theFederal guidelines.Since the DSP was formalized in 1982, TVA has systematically evaluated its dams forhydrologic and seismic adequacy which has resulted in several dams being physicallymodified. These modifications and operational changes as described above have beencompleted consistent with NEPA procedures.The one location on the WVA system where an operational change would require theconcurrence of the USACE is at Kentucky Dam. Kentucky Dam, located about 23.0 milesabove the confluence of the Tennessee River with the Ohio River, is connected by anavigation canal located just above each dam to Barkley Reservoir, owned by the USACE.Thus, the Kentucky and Barkley Dams have to be operated in tandem. Further, the USACEhas the authority to direct the operation of Kentucky reservoir during critical flood operationson the lower Ohio and Mississippi Rivers. The physical location and the large flood storageavailable allows Kentucky reservoir to provide significant flood reduction benefits on thelower Ohio and Mississippi Rivers.There have been no operational changes proposed at Kentucky Dam that would requireTVA to obtain concurrence from the USACE.7. Discuss the overall uncertainties in TVA's revised analysis calculations.This response is the same as WBN Unit 1, and applies to the hydrologic analysis for SQNUnits 1 and 2.The primary standards followed for development of the PMF are American NationalStandards Institute/American Nuclear Society (ANSI/ANS) 2.8 and RG 1.59. Theseguidance documents state that the PMF be derived from the combination of circumstancesthat collectively represent a risk probability that is acceptable for nuclear plant accidents.Each element in the development of the PMF is based on best available data including PMPestimates from the National Weather Service, rain-runoff relationships developed fromhistorical storms, time distribution of PMP consistent with storms in the region, seasonal andareal considerations of rainfall, current reservoir operations, and verification of runoff andstream course models against large historic floods. Per regulatory guidance, thedesign-basis flood for nuclear power plants is an estimation. The calculations which supportthe PMF analysis document assumptions and approaches which are consistent withregulatory guidance. The PMF analysis is a best estimate and is consistent with currentguidelines. However, it is realized that various elements of the analysis can result indifferent elevations, some higher and some lower, and those elements are discussed inPage 8 of 14 ENCLOSURE2EVALUATION OF ISSUES FROM PRE-APPLICATION MEETINGfurther detail in Section 3.2 of Enclosure 1, Uncertainties, in order to explain why the PMFanalysis is a reasonable best estimate.8. Justification for the use of any compensatory measures as a result of TVA's revisedanalysis.This response is the same as WBN Unit 1 except for references to the applicable site, andapplies to the hydrologic analysis for SQN Units 1 and 2.The updated DBF analysis for SQN, indicated that some upstream dam earth embankmentscould be overtopped during the PMF. Four dams were identified as having embankmentsthat could be overtopped during the PMF: Cherokee; Fort Loudoun; Tellico; and Watts Bar.Once these earth embankment overtopping events were identified, actions were taken toprevent overtopping to ensure continued SQN operability. An evaluation of temporary floodbarriers that could be installed in a short period of time and had a proven performancerecord for dependability led to the use of HESCO Concertainer units filled with stone. A totalof approximately 18,000 feet of temporary flood barriers are installed at Cherokee, FortLoudoun, Tellico and Watts Bar Dams. This installation was completed by the end ofDecember 2009. The temporary flood barriers are located on the top of the earthembankments and/or on saddle dams as appropriate at each of the four dams. Thetemporary flood barrier configuration consists of HESCO Concertainer units from three feetin height to HESCO Concertainer units stacked based on manufacture recommendation upto seven feet.The maintenance of the temporary flood barriers and closure of openings during emergencyevents is a River Operations (RO) -Asset Owner (AO) responsibility, as defined by DamSafety procedure RO-SPP-27.0. The purpose of the Dam Safety procedure is to protectupstream and downstream lives and property by ensuring that impoundments and dams aredesigned, constructed, operated and maintained as safely and reliable as is practical. Thisprocedure describes the methods by which the RO Senior Vice-President (AO) willaccomplish compliance with Federal Guidelines for Dam Safety and DSG.As a part of the RO DSP, the temporary flood barriers are inspected on a regular basis.They are inspected during plant monthly and quarterly inspections and during the 15 monthcomprehensive site inspections. Any noted damage to the HESCO Concertainer units fromthese inspections that would compromise the structural integrity or functionality of thetemporary flood barriers is repaired promptly. Since completion of installation in December2009, only minor repairs such as small holes up to three inches in diameter have had to berepaired. Also, as committed to in the TVA submittal to the NRC Document Control Desk,"Commitments Related to Updated Hydrologic Analysis Results for Sequoyah Nuclear Plant,Units 1 and 2, and Watts Bar Nuclear Plant, Unit 1," dated June 13, 2012 (ADAMSAccession No. ML12171A053), TVA's Nuclear Power Group will issue and initially performprocedures for semi-annual inspections of the temporary HESCO flood barriers installed atCherokee, Fort Loudoun, Tellico, and Watts Bar reservoirs by August 31, 2012. Theseinspections will:a. Ensure the temporary HESCO flood barriers remain in place and are not structurallydegraded as specified by the manufacturer's written specifications andrecommendations;Page 9 of 14 ENCLOSURE2EVALUATION OF ISSUES FROM PRE-APPLICATION MEETINGb. Verify the inventory and staging of the material required to fill the gaps that exist; andc. Ensure that adequate physical security (e.g., fences and locks) is provided for thestaged material against theft.These inspections will continue until a permanent modification is implemented to preventovertopping the Cherokee, Fort Loudoun, Tellico, and Watts Bar dams due to the PMF.For each of the dams, Cherokee; Fort Loudoun; Tellico; and Watts Bar Dams, where thetemporary flood barriers have been installed, a supplement to the project Emergency ActionPlan (EAP) has been issued which describes the emergency notification responsibilities andprocedures. The River Forecast Center has responsibility for identification of events whichcould exceed critical elevations at each dam consistent with their Emergency Notificationprocedure and notification to the AO of the flooding condition. The AO declares a DamSafety emergency which following the Dam Safety procedure (RO-SPP-27.0) implementsthe Project PMF Barrier Closure Plan. Each of the four dams has openings in the temporaryflood barriers which have to be closed. The EAP supplement details the methods to beused by TVA's construction partner GUBMK Constructors for closure of the openings. Theclosure of the opening can be accomplished by setup of the HESCO Concertainer unitslinked to the existing HESCO Concertainer units already in place or by overlap of thetemporary flood barriers at a given location as appropriate. At each dam where material forclosure of the temporary flood barriers is required, the materials (HESCO Concertainer unitsand stone) are stockpiled in a designated fenced enclosure as described in the supplementto the EAP.Experience data on the use of the selected temporary flood barriers during historic floodsand the vendor documentation on barrier testing were evaluated prior to selection and use.The USACE has also tested the HESCO Concertainer units by performing hydrostatictesting, wave-induced hydrodynamic testing, overtopping testing, and structural debrisimpact testing with a floating log. The debris impact testing was based-on two different logsizes: 12 inch and 17 inch diameter logs (12 feet long) with an impact speed of five mph.The results of the laboratory testing showed that the HESCO Concertainer units were notdamaged by the loading conditions used in the testing program.Stability analysis of the temporary flood barriers was performed for seismic and hydrostatic(PMF) loadings. The analysis showed that the temporary flood barriers are stable under theseismic and PMF loading conditions. This is described in the proposed revision toSQN Units 1 and 2 UFSAR Subsection 2.4.3.4, which states that while the flood barriers aretemporary structures, there is a structural analysis for the headwater loading behind thetemporary flood barriers that verifies that failure would not occur. Additionally, a seismicevaluation completed on the flood barriers (without headwater behind the barriers) verifiesthat failure of the temporary flood barriers would not occur.A potential exists for runaway barges to float downstream and impact the temporary floodbarriers at two of the four dams where the barriers are in place. Barges along thesereservoirs are typically tied off at barge terminals or mooring cells during high flow events,such as a PMF event. The mooring facilities, however, are not designed for PMF elevationsand velocities, so the barges could break loose. There is no barge traffic on CherokeeReservoir, so no potential for impact exists. The Fort Loudoun Reservoir has limited tomoderate barge traffic. Using typical barge dimensions, the barge would have to weigh lessPage 10 of 14 ENCLOSURE2EVALUATION OF ISSUES FROM PRE-APPLICATION MEETINGthan 70-80% of full load capacity in order to strike the barriers. However, the earthenembankments of the dam where the temporary flood barriers are placed are located at adistance from the main channel. The stream flow during a high flow event is directed towardthe concrete overflow portion of the dam, and the barges would be carried by the currentaway from the temporary flood barriers. At the Tellico Reservoir, there is very infrequentbarge traffic. Conservatively assuming there will be a barge on the reservoir, and usingtypical barge dimensions, the barge would have to weigh less than 40-50% of full loadcapacity in order to strike the barriers. However, the earthen embankments of the damwhere the temporary flood barriers are placed are located at a distance from the mainchannel. The stream flow during a high flow event is directed toward the concrete overflowportion of the dam, and the barges would be carried by the current away from the temporaryflood barriers. There is limited to moderate barge traffic at the Watts Bar Reservoir. Anevaluation using typical barge dimensions for the Tennessee River, and conservativelyassuming barges are empty (less draft allows for the barge to run closer to the top of thedam), demonstrates that barges are not likely to impact the temporary flood barriers. Aspatial analysis shows that the closest edge of the temporary flood barrier would have to beat least 9.0 ft away from the upstream edge of the earthen embankment in order to preventimpact. The temporary flood barriers are located at least this distance from the edge of theearthen embankment, ensuring that there is no potential for barge impact.As discussed in the NRC letter to TVA, "Tennessee Valley Authority (TVA) Long-TermHydrology Issues for Operating Nuclear Plants -Browns Ferry Nuclear Plant, Units 1, 2,and 3 (TAC Nos. ME5026, ME5027, and ME5028); Sequoyah Nuclear Plant, Units 1 and 2(TAC Nos. ME5029 and ME5030); and Watts Bar Nuclear Plant, Unit 1 (TAC No. ME5031),"dated January 25, 2012, Accession No. ML11241A166, the NRC Staff found that the sandbaskets [temporary flood barriers] are not capable of resisting debris impact. The NRC Stafffurther states that "documents, [provided by TVA] neither discuss the ability of sand basketsto withstand debris impact, or mention whether the baskets are designed for impact ofdebris loads. The NRC staff is unable to conclude that these sand baskets were designedto withstand impacts from large debris during a flood. If a design flood were to occur, thereis a high likelihood that significant debris would accompany the flood waters which couldimpact the baskets. There is the potential for this debris to damage the baskets or push theindividual baskets.apart causing a breach. There would be no time to repair the basketsbecause the flood would already be in progress. Therefore, sand baskets that are notdesigned and constructed to withstand impacts from large debris are not acceptable as along-term solution."To resolve this issue, as committed to in the TVA submittal to the NRC Document ControlDesk, "Commitments Related to Updated Hydrologic Analysis Results for Sequoyah NuclearPlant, Units 1 and 2, and Watts Bar Nuclear Plant, Unit 1," dated June 13, 2012 (ADAMSAccession No. ML12171A053), TVA will implement permanent modifications to preventovertopping of the embankments of the Cherokee, Fort Loudoun, Tellico, and Watts BarDams due to the PMF. The final solution will be established in an evaluation conducted incompliance with the National Environmental Policy Act (NEPA) Environmental ImpactStatement (EIS). Based on the current NEPA EIS schedule, these permanent modificationsare scheduled to be installed by October 31, 2015.Based on TVA RO procedures for the maintenance of the temporary flood barriers andclosure of openings during emergency events; TVA RO and TVA's Nuclear Power Groupperiodic inspections of the temporary flood barriers and additional materials required forPage 11 of 14 ENCLOSURE 2EVALUATION OF ISSUES FROM PRE-APPLICATION MEETINGclosure of openings; experience data on the use of the HESCO temporary flood barriersduring historic floods; stability analysis of the temporary flood barriers for seismic andhydrostatic (PMF) loadings; USACE tests of the HESCO Concertainer units includinghydrostatic testing, wave-induced hydrodynamic testing, overtopping testing, and structuraldebris impact testing with a floating log; and TVA's qualitative assessment of the potentialfor runaway barges to float downstream and impact the temporary flood barriers; it isconcluded that use of the temporary flood barriers for the period of time required toimplement the permanent modifications to prevent overtopping of the embankments of theCherokee, Fort Loudoun, Tellico, and Watts Bar Dams is adequate.The use of the temporary flood barriers is described in Section 2.1 of Enclosure 1, ProposedChanges, under subheading Subsection 2.4.3, Probable Maximum Flood (PMF) on Streamsand Rivers. The credit or lack of credit for the temporary flood barriers in the hydrologicanalysis is described in Section 2.1 of Enclosure 1, Proposed Changes, under subheadingsSubsection 2.4.3, Runoff and Stream Course Model, and Subsection 2.4.4, Dam FailurePermutations, respectively. In the proposed SQN Units 1 and 2 UFSAR Subsection 2.4.3,the increase in the height of the embankments are included in the discharge rating curvesfor Cherokee, Fort Loudoun, Tellico, and Watts Bar Dams that are used in the hydrologicanalysis for rainfall-induced PMF events. Increasing the height of embankments at thesefour dams prevents embankment overflow and failure of the embankment. The vendorsupplied temporary flood barriers were shown to be stable for the most severe PMFheadwater/tailwater conditions using vendor recommended base friction values. In theproposed SQN Units 1 and 2 UFSAR Subsection 2.4.4, the temporary flood barriers areassumed to fail in the hydrologic analysis for seismically-induced dam failures for the caseswhere reservoir levels would increase to the top of the embankments, and are thus notcredited for increasing the height of the embankments.9. Discuss the temporary modification to the thermal barrier booster pump flood barrierprotection in the UFSAR.This issue was specific to WBN Unit 1. However, the temporary compensatory measuresapplicable to SQN Units 1 and 2 are discussed in Section 3.3 of Enclosure 1, Margins.As committed to in the TVA submittal to the NRC Document Control Desk, "CommitmentsRelated to Updated Hydrologic Analysis Results for Sequoyah Nuclear Plant, Units 1 and 2,and Watts Bar Nuclear Plant, Unit 1," dated June 13, 2012 (ADAMS AccessionNo. ML12171A053), TVA will implement a documentation change to require the Spent FuelPit Cooling Pump Enclosure caps as a permanent plant feature for flooding protection, andwill install permanent plant modifications to 'provide adequate flooding protection withrespect to the DBF level for the Diesel Generator Building, by March 31, 2013.10. Discuss any impact on TVA's individual plant examination of external events or finalenvironmental impact statement due to the revised flood analysis.This issue was specific to WBN Unit 1 and to the initial licensing of WBN Unit 2, and is notapplicable to SQN Units 1 and 2.11. Discuss whether any flood barriers at the plant are impacted by the revised PMF level.Page 12 of 14 ENCLOSURE 2EVALUATION OF ISSUES FROM PRE-APPLICATION MEETINGOnly two distinct changes to the physical flooding protection features of SQN Units 1 and 2are required.As discussed further in Section 3.3 of Enclosure 1, the SQN Units 1 and 2 Spent Fuel PitCooling Pump Enclosure caps in the Auxiliary Building are now required to maintainadequate flooding protection of the Spent Fuel Pit Cooling Pump Motors during flood mode.The DBF surge level within flooded structures is elevation 722.5 ft. The Spent Fuel PitCooling Pump Motors platform is located at elevation 721.0 ft, but is located in an enclosurethat provides flooding protection up to elevation 724.5 ft. However, the Spent Fuel PitCooling Pump Enclosure caps were not originally intended to be permanently installed. Torestore margin for the Spent Fuel Pit Cooling Pump Motors, installation of the caps at anytime prior to or during the event of a Stage I flood warning has been established as acompensatory measure. A documentation change is planned to require the SQN Units 1and 2 Spent Fuel Pit Cooling Pump Enclosure caps as a permanent plant feature forflooding protection.As discussed further in Section 3.3 of Enclosure 1, the lowest floor of the common SQNUnits 1 and 2 Diesel Generator Building is at elevation 722.0 ft with its doors on the uphillside facing away from the main body of flood water. This elevation is lower than theupdated DBF level of elevation 723.2 ft. Therefore, flood levels exceed the floor level atelevation 722.0 ft. The entrances into safety-related areas and mechanical and electricalpenetrations into safety-related areas are sealed to prevent major leakage into the buildingfor water up to the grade elevation of 722.0 ft. Additionally, redundant sump pumps areprovided within the building to remove minor leakage. As a result of this increase, stagedsandbags to be constructed into a berm at the entrances to the Diesel Generator Building atany time prior to or during the event of a Stage I flood warning has been established as acompensatory measure. These sandbags will be constructed into a berm at least three ft inheight (elevation 725.0 ft) to prevent water intrusion inside the building. Permanent plantmodifications are planned to provide adequate flooding protection features for the commonSQN Units 1 and 2 Diesel Generator Building.As committed to in the TVA submittal to the NRC Document Control Desk, "CommitmentsRelated to Updated Hydrologic Analysis Results for Sequoyah Nuclear Plant, Units 1 and 2,and Watts Bar Nuclear Plant, Unit 1," dated June 13, 2012 (ADAMS AccessionNo. ML12171A053), TVA will implement a documentation change to require the Spent FuelPit Cooling Pump Enclosure caps as a permanent plant feature for flooding protection, andwill install permanent plant modifications to provide adequate flooding protection withrespect to the DBF level for the Diesel Generator Building, -by March 31, 2013.12. Discuss the use and control of sand baskets (e.g., at the WBN recreational area).This response is the same as WBN Unit 1, and applies to the hydrologic analysis for SQNUnits 1 and 2.Refer to the response to Issue 8 for more detailed description of use of the HESCOConcertainer units as a temporary flood barrier.The temporary flood barriers installed in the vicinity of the recreational area at Watts BarDam are in place to prevent overtopping of the earth embankment during a PMF. There arethree locations where closure of the access openings in the temporary flood barrier wouldPage 13 of 14 ENCLOSURE2EVALUATION OF ISSUES FROM PRE-APPLICATION MEETINGbe required to complete the floodwall in advance of a PMF event. A supplement to theEmergency Action Plan for Watts Bar Dam has been issued to address procedures to befollowed during such an event.The HESCO Concertainer units (20-3'x3'x15' baskets) and stone (approximately 210 tons)needed to complete closure of the floodwall are stored in a designated fenced area near thecampground and in proximity to the access points where they would be used. The HESCOConcertainer units are stored on pallets in a folded position.The TVA River Forecast Center has responsibility for identification of events which couldexceed critical elevations at the dam consistent with their Emergency Notification procedureand notification to the RO Senior Vice-President (AO) of the flooding condition. The AOdeclares a dam safety emergency which following the procedures implements the Watts BarDam PMF Barrier Installation Plan. The supplement details the methods, material andequipment to be used by TVA's construction partner GUBMK for closure of the openingsthrough the floodwall. The closure of the opening can be accomplished by setup of theHESCO Concertainer units linked to the existing HESCO Concertainer units already in placeor by overlap of the temporary flood barriers at a given location as appropriate.Similar requirements for the use and control of the HESCO temporary flood barriers exist forCherokee, Fort Loudoun, and Tellico Dams.The use of the temporary flood barriers, and credit or lack of credit for the temporary floodbarriers in the hydrologic analysis, is discussed further in the response to Issue 8.As committed to in the TVA submittal to the NRC Document Control Desk, "CommitmentsRelated to Updated Hydrologic Analysis Results for Sequoyah Nuclear Plant, Units 1 and 2,and Watts Bar Nuclear Plant, Unit 1," dated June 13, 2012 (ADAMS AccessionNo. ML12171A053), TVA will implement permanent modifications to prevent overtopping ofthe embankments of the Cherokee, Fort Loudoun, Tellico, and Watts Bar Dams due to thePMF. The final solution will be established in an evaluation conducted in compliance withthe NEPA EIS. Based on the current NEPA EIS schedule, these permanent modificationsare scheduled to be installed by October 31, 2015.13. Discuss the impact on any safety-related equipment other than the thermal barrierbooster pumps.This issue was specific to WBN Unit 1, and is not applicable to SQN Units 1 and 2.14. Discuss the impact of TVA's five proposed combinations of dam failure scenarioswithin its revised flood analysis.This response is the same as WBN Unit 1, and applies to the hydrologic analysis for SQNUnits 1 and 2.As discussed in the response to Issue 4, the methodology used to develop the controllingseismic/flood condition at SQN is the same as previously followed for the site evaluationsdescribed in the SQN Units 1 and 2 UFSAR. This is further described in Section 2.1 ofEnclosure 1, Proposed Changes, under the subheading Section 2.4.4, Potential DamFailures, Seismically Induced.Page 14 of 14

v t e Letter Sequence Request
TAC:ME8200, (Open)
Initiation Request, Request, Request, Request, Request, Request, Request, Request Acceptance... Supplement, Supplement Administration Meeting, Meeting Questions Answers Results Approval... Other: ML12276A375
MONTHYEAR2012-04-11 [Table View]

ML12226A563

Text

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