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| {{Adams | | {{Adams |
| | number = ML13197A118 | | | number = ML13169A212 |
| | issue date = 07/15/2013 | | | issue date = 06/18/2013 |
| | title = Supporting Documentation for July 22, 2013, Regulatory Conference to Discuss Inspection Report 05000266/2013011 and 05000301/2013011, Preliminary Yellow Finding | | | title = NRC Integrated Inspection Report 05000266-13-011 and 05000301-13-011, Preliminary Yellow Finding |
| | author name = Meyer L | | | author name = Reynolds S |
| | author affiliation = NextEra Energy Point Beach, LLC | | | author affiliation = NRC/RGN-III/DRP |
| | addressee name = | | | addressee name = Meyer L |
| | addressee affiliation = NRC/Document Control Desk, NRC/NRR | | | addressee affiliation = NextEra Energy Point Beach, LLC |
| | docket = 05000266, 05000301 | | | docket = 05000266, 05000301 |
| | license number = DPR-024, DPR-027 | | | license number = DPR-024, DPR-027 |
| | contact person = | | | contact person = |
| | case reference number = EA-13-125, IR-13-011, NRC 2013-0069 | | | case reference number = EA-13-125 |
| | document type = Letter, Report, Miscellaneous | | | document report number = IR-13-011 |
| | page count = 45 | | | document type = Inspection Report, Letter |
| | | page count = 17 |
| }} | | }} |
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| {{#Wiki_filter: | | {{#Wiki_filter:June 18, 2013 |
| [[Issue date::July 15, 2013]]
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| U.S. Nuclear Regulatory Commission ATTN: Document Control Desk 11555 Rockville Pike Rockville, MD 20852 Point Beach Nuclear Plant, Units 1 and 2 Dockets 50-266 and 50-301 Renewed License Nos. DPR-24 and DPR-27 NEXT era POINT BEACH NRC 2013-0069 Supporting Documentation for July 22. 2013. Regulatory Conference to Discuss Inspection Report 05000266/2013011 and 05000301/201301 Preliminary Yellow Finding References:
| | ==SUBJECT:== |
| 1) U.S. Nuclear Regulatory Commission, Point Beach Nuclear Plant, Units 1 and 2 NRC Integrated Inspection Report 05000266/2013011 and 05000301/2013011; Preliminary Yellow Finding, dated June 18, 2013. (ML 13169A212)
| | POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 NRC INTEGRATED INSPECTION REPORT 05000266/2013011 AND 05000301/2013011, PRELIMINARY YELLOW FINDING |
| 2) Point Beach letter NRC-2013-0054 Response to Inspection Report 050000266/2013011; Preliminary Yellow Finding, dated June 28, 2013. (ML 13179A333)
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| On June 18, 2013, the Nuclear Regulatory Commission (NRC) provided NextEra Energy Point Beach, LLC (NextEra)
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| with the results of the Temporary Instruction (TI) 2515-187, "Inspection of Near-Term Task Force Recommendation 2.3 Flooding Walk Downs," conducted at the Point Beach Nuclear Plant (PBNP) during the first quarter of 2013, describing a performance deficiency related to the PBNP implementation of certain procedures intended to mitigate postulated flooding events (Reference 1 ). The Reference 1 letter further informed NextEra that NRC had preliminarily determined that the significance of the identified performance deficiency was yellow. On June 28, 2013, NextEra requested a Regulatory Conference to discuss the significance determination (Reference 2). The requested Regulatory Conference has been scheduled for July 22, 2013. NextEra has thoroughly reviewed the issue raised in the Reference 1 letter, and has concluded that the Individual Plant Examination for External Events (IPEEE) contains estimates and assumptions that are overly conservative and it is not appropriate to use in the safety significance determination for this performance deficienc Therefore, NextEra has performed substantial additional analyses utilizing more recent best-available information and modeling to more accurately determine the potential safety significance of the identified performance deficienc Using the updated external flooding analysis and Probabilistic Risk Assessment NextEra Energy Point Beach, LLC, 6610 Nuclear Road, Two Rivers, WI 54241 Document Control Desk Page 2 (PRA) models of the effects of postulated flooding is the correct tool for assessing the safety significance of the performance deficiency
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| .. The results of the updated analyses clearly demonstrate that the safety significance of the performance deficiency is very low. As requested in Reference 1, NextEra has provided both a summary description of the updated analyses and an explanation of the results in the Enclosure to this letter. Attachment 1 conta i ns the updated wave run-up analysis performed by NextEra's independent contracto Attachment 2 is an updated safety significance determination analysis showing that the safety significance of the performance deficiency is very low, with margin. Attachment 3 prov i des an explanation of the PBNP design, showing that the r unning Service Water pumps would continue to operate following a loss of DC control power. Finally, Attachment 4 is an analysis of the rates of rise of Lake Michigan during various postulated flooding events, showing that PBNP would have more than eight weeks to respond to pre-storm level changes before the station's license basis flood level would occur. NextEra looks forward to discussing these documents, together with our assessment of the very low safety significance of the performance deficiency , in greater detail during the upcoming Regulatory Conference. This letter contains no new Regulatory Commitments and no revisions to existing Regulatory Commitment If you have any questions or require additional information, please contact Mr. Ron Seizert , Licensing Supervisor at (920)755-750 Very truly yours, NextEra Energy Point Beach, LLC L c Site Vice President Enclosure cc: Administrator , Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC Branch Chief, Plant Support, Division of Reactor Safety, Region Ill, USNRC ENCLOSURE NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT UPDATED FLOODING ANALYSIS AND SIGNIFICANCE DETERMINATION Executive Summary The NRC preliminary significance determination for the performance deficiency (Reference 1) was based on determining the change in Core Damage Frequency (CDF) using the Individual Plant Examination of External Events (IPEEE). NextEra has developed an updated , more accurate storm surge/wave run-up analysis which provides a more reliable analytical basis for assessing the associated safety significance of the postulated flooding event. The application of this more accurate approach shows that the identified performance deficiency is of very low safety significance, with margin. Description of the Updated Flooding Analysis and Resulting Significance Determination The external flooding analysis for Point Beach Nuclear Plant (PBNP) contained in the station's IPEEE is dominated by overly conservative estimations and assumption These estimations and assumptions include the resultant water elevations, environmental conditions, equipment elevations, and site configuration and topograph The cumulative effect of these overly conservative assumptions results in significantly overestimating the impact of external flooding events, including wave run-up. In order to better determine the safety significance of the identified performance deficiency, NextEra retained an expert independent engineering firm to update the station's external flooding analysis utilizing more recent and more accurate data. The updated analysis assumes the same initiating still water level frequencies as those used in the IPEEE. Further, the updated analytical model utilizes actual plant structures, configuration, topography, and near-shore bathymetric survey data in calculating the range of water levels and associated wave run-up condition The updated model included no off-setting credit for any of the flood/wave run-up mitigation actually in place at PBNP to determine water levels outside of the Turbine Buildin The calculated water level provides the effective driving head for any potential water intrusion into the Turbine Buildin NextEra performed analysis of the potential water flow paths in the Turbine Building to determine the time it takes to accumulate sufficient water to impact safety significant equipmen A computer model was used to conduct this analysis, based on plant flow paths and rates, which were validated by walk-downs. Water flow rates were determined by calculating flow under doors, over curbs, and through other building characteristics. It would take greater than three hours for water outside the turbine building to impact the Residual Heat Removal (RHR) Pumps and their suction valves from Containment Sump B. However, for the purpose of simplification and to build additional margin into the analysis, the water was assumed to reach equilibrium inside and outside the buildings at time zero for the purpose of determining impact to equipmen Finally, the calculated water level outside the Turbine Building was used as an input to the PBNP Probabilistic Risk Assessment (PRA) to evaluate the risk significance of the postulated Page 1 of 8 flooding/wave run-up scenario This updated risk significance determination assumed that the external flooding wave run-up protection mitigation features described in the PBNP Final Safety Analysis Report (FSAR) were not in place. The resulting significance determination, using the updated analysis and conservative assumptions described above, demonstrate that the safety significance of the performance deficiency is very low, with margin. Evaluation of Flood/Wave Run-Up, Water Levels and Potential Equipment Impacts The PBNP external flooding analysis had been updated to more accurately predict the potential flooding/wave run-up impact on PBNP and the result of the revised analysis was used to assess the potential impact of the calculated water levels on plant equipmen The equipment impact analysis utilizes the same initial conditions contained in the FSAR, updated to include actual site topography, offshore bathymetry and the as-built shore-line configuration to calculate expected wave phenomena at various lake levels, including those of very long recurrence intervals (e.g., high lake levels). The resultant wave phenomena were then used as input data for the DELFT3D computer model, a state of the art model that can simulate both two dimensional (in either the horizontal or vertical plane) and three dimensional flow, to analyze Lake Michigan behaviors during external flooding events and to determine the resulting effect of wave run-up at PBNP. The DELFT3D model has been accepted by industry experts and industry organizations including more than 70 countries world-wide that use DEL TARES hydrology modeling programs and is being used extensively for post-Fukushima flood hazard analyse The DELFT3D model has also been recently used by several other nuclear plants to demonstrate compliance with NRC requirements, including:
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| * South Texas Project, Units 3 and 4 COLA and FSAR (Delft3D-FLOW) for breach and wave modeling * Turkey Point Units 6 and 7 (Delft3D-FLOW), tsunami wave analysis * Turkey Point Units 3 and 4 flood hazard reevaluation
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| * Nine Mile Point (NMP) (DELFT-SWAN), for near shore wave heights and periods * Calvert Cliffs used DELFT for storm surge for COLA and flood hazard reevaluation
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| * Victoria County Station Early Site Permit Application (Delft3D-FLOW)
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| for Cooling Basin Breach Analysis Accordingly, NextEra is confident that its updated engineering evaluation of potential wave run-up effects at PBNP provides the best available information to use for safety significance determination Comparison of the Updated Storm Surge/Wave Run-up Analysis to the PBNP IPEEE Analysis The most limiting flooding from Lake Michigan is a function of the still water lake level plus wind generated waves. To estimate the frequency of flooding at PBNP, the IPEEE utilized a statistical frequency distribution that was estimated from Lake Michigan gauge data. This still Page 2 of 8 water lake level has also been used in the updated Storm Surge/Wave Run-up Analysis (Updated Wave Run-Up Analysis)
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| as a starting point for the modelin However, although the IPEEE utilizes an estimated wave run-up, it does not describe the estimation methodology utilized to determine its results. It is clear, however, that the IPEEE estimation methodology does not take into account site specific shoreline and near-shoreline configurations, which are very important for an accurate determination of the storm effects. The Updated Wave Run-Up Analysis, on the other hand, utilizes state of the art modeling and analytical methods, and updated site-specific input data to determine wave set-up and wave run-up. Like the IPEEE, the Updated Wave Run-Up Analysis also utilizes conservative assumptions for evaluating the depth of water between the Turbine Building and Pumphous Specifically, both analyses assume the following:
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| * Yard drains do not contribute to runoff from floodin * There are no relief paths from flooding (e.g., Turbine Building floor drains and Pumphouse relief paths). The IPEEE utilizes simplified, conservative estimates for the amount of water that would accumulate between the Turbine Building and the Pumphouse from wave run-up, but again the IPEEE does not describe the estimation methodology used to determine the presented results. The Updated Wave Run-Up Analysis incorporates license basis deep water wave heights, more extensive local and offshore bathymetry, and the as-built shore-line configuration and characteristics to calculate expected wave response at various still water levels. In determining the equipment impacted, the internal water levels were assumed conservatively to equal the calculated outside water levels at time zero. A comparison of the overly conservative IPEEE and the more accurate Updated Wave Run-Up Analysis showing the differences in calculated water level between the PBNP Turbine Building and Pumphouse, is presented below. Summary of Water Levels IPEEE vs. PBNP Updated Analysis Water Level Resulting Frequency of Extrapolated from Calculated Water Water Level in Still Water Level Still Water the IPEEE Level (With Wave Turbine (ft-IGLD 1955) Level Estimates (ft-Run-up) Building (yr-1) (ft-IGLD 1955) (inches above IGLD 1955) floor) 583.00 1.4E-02 587.60 583.96 0 585.00 3.2E-04 588.37 585.84 0 586.00 5.4E-05 588.73 587.24 0 587.00 4.2E-06 589.24 588.51 3.7" 587.64 9.9E-07 589.53 588.89 8.3" Page 3 of 8 These results demonstrate that the IPEEE was overly conservative in estimating the water level between the Turbine Building and Pumphouse and is not appropriate for use in assessing safety significance because it is not the best-available informatio The result of the Updated Wave Run-Up Analysis is appropriate input to determine the safety significance of the performance deficienc The following Figure shows the levels resulting from the updated analysi Page 4 of 8 Simplified PBNP Plant Elevation with Calculated Water Level (Not to Scale) Turbine Building I PEEE Describes Lake L evel of 587' and Wave Run-Up to 596' with Frequency of 4.2E-6. Updated analysis of lake leve l of 587' with wave run-up, results in calculated water l evel of 588.51'. PU M PHOUSE VSR I EDG 588.2'-Turbine Building Floor 588.51' -Calculated Water Level @ Turbine Building [ 587'-IPEEE Still Lake ] I 581.9'-Des i gn Bas i s Fl ood 580.7' -I nsta ll Je rs ey B a rri ers 576'-Appro xi m a t e C u rre n t La k e Mich i gan Lev e l Page 5 of 8 Results of the Updated Wave Run-Up Analysis The Updated Wave Run-Up Analysis shows that the calculated water levels between the Turbine Building and Pumphouse would be 588.51 feet of water IGLD 1955 for the event frequency of 4.2E-06/year-much less severe than estimated in the IPEEE. The detailed engineering evaluation supporting NextEra's Updated Wave Run-Up Analysis is provided in Attachment 1. Point Beach Revised External Flood PRA The still water level flood exceedance frequencies from the IPEEE were utilized in Next E ra's updated analysis so that the impacts from this updated analysis could be compared to the same flood frequencies used by the NRC. With the results from the updated external flooding analyses, conditional core damage probability was calculated using the updated RG 1.200 internal events model. Point Beach letter NRC-2013-0054 Response to Inspection Report 50000266/2013011 (Reference 2) provided a list of potentially vulnerable equipment impacted by accumulating water up to 589.2 feet (IGLD 1955). NextEra's updated analysis conservatively assumed an internal water level of 588.51 feet (IGLD 1955) based on the same calculated water level outside the Turbine Buildin This internal water level impacts only the Residual Heat Removal (RHR) pumps and RHR pump suction from Containment Sump B, therefore this equipment is not available in the revised PRA evaluation. Based on the equipment impacts described above , the PRA results indicate that the risk due to external flooding (without barriers)
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| is very low, with a Core Damage Frequency (CDF) equal to 2.83E-07/year. The associated change in risk with and without barriers was also determined to be ve r y low, with a change in CDF equal to ?E-09/yea The NRC's preliminary significance determination of the performance deficiency was based on the 1995 Point Beach IPEEE inputs and assumption This determination calculated a conditional core damage probability of 2. ?E-02/y and a change in CDF of 1.8E-05/y NextEra's updated analysis demonstrates that the IPEEE assumptions of wave run-up levels and final water levels at and in the Turbine Building were overly conservativ Principle contributors to the differences in overall safety significance include the site topography, the existing site layout and features, equipment elevations, and environmental condition Each of these items has been considered in the updated detailed modeling described herein. Attachment 2 provides the supporting information associated with the PRA evaluatio Continued Service Water Pump Availability with Loss of DC Control Power A significant contributor to the difference between the NextEra and the NRC staff estimated change in CDF with failure of equipment up to 589.2 feet IGLD 1955 is the PRA modeling of Service Water (SW) pump availability upon loss of DC control power. NRC's SPAR model contains a presumption that the SW pump becomes unavailable upon loss of DC power. Page 6 of 8 The SW pumps remain available throughout this event. If operating at the time DC power is lost, the SW pumps would continue to operate, because DC power is required to open the breaker supplying AC power to the pumps. In other words, if DC power is lost, the breakers cannot open to turn off the running SW pumps. If the pumps are not operating at the time DC power is lost, operators can start pumps by either realigning DC control power supplies and/or through local manual operation of their respective breaker Both actions are directed by existing site procedures upon loss of DC power. The actions for switching to the alternate DC control power source and local operation of SW pumps, including flow control, are directed by site procedures. These actions were re-validated by walk-downs with Auxiliary Operators and observed by independent Nuclear Oversight (NOS) observation The validation indicated that the actions can be completed within one hour. Finally, these actions are included in Operator training and evaluation program Attachment 3 provides the supporting information associated with SW pump availability. Lake Michigan Level Rate of Rise Lake Michigan is a very large body of water and changes in level are very slow in comparison to river level changes. The PBNP original Final Facility Description Safety Analysis Report (FFDSAR) section discussing flooding does not address a rate of rise for the lake, so an evaluation was performed to establish the time that is available to respond to rising lake levels. The rate of rise in lake level was calculated using National Oceanographic and Atmospheric Administration (NOAA) historical lake data for the 95 year period from 1918 through 2013. During this period, the greatest increase in Lake Michigan level during a single month was 0.85 ft. The evaluation concluded that the time available to respond to rising Lake Michigan prestorm levels would be approximately eight weeks from the level at which PBNP procedures require wave run-up barrier construction initiation (580. 7 feet IGLD 1955) until conditions for the license basis maximum wave run-up could be reached. With respect to the identified performance deficiency, this eight week time period provides significant opportunity to identify and correct deficiencies with flood barrier The updated analysis performed in support of this evaluation contains significant margin, including that the PRA analysis does not account for the significant time available for Operators to take actions in response to rising lake levels. Attachment 4 provides the supporting information associated with the rate of change in Lake Michigan water level and required Operator actions. Conclusion The updated external flooding analysis shows that the frequency of reaching a calculated water level that impacts safety related equipment is very low. The PRA analysis, using the calculated water levels, determined that affected equipment results in a very low CDF. Therefore, the failure to establish adequate procedure requirements to implement external flooding wave run-up protection features as described in the FSAR has very low safety significance, based on the calculated change in CDF of 7E-09/y The Individual Plant Examination for External Events (IPEEE) contains estimates and assumptions that are overly conservative and it is not appropriate to use in the safety significance determination for this performance deficienc The IPEEE estimated that water levels would be substantially higher with the same input assumptions, because of the many simplifications that were used at the Page 7 of 8 time. With more accurate site information and a more rigorous tool for analysis, the conservatisms of the IPEEE were shown to be excessiv Attachments 1) Calculated Average External Water Levels at Turbine Building 2) Point Beach Revised External Flood Safety Significance Determination 3) Continued Service Water Pump Availability with Loss of DC Control Power 4) Lake Michigan Level Rate of Rise Page 8 of 8 ATTACHMENT 1 NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT CALCULATED AVERAGE EXTERNAL WATER LEVELS AT TURBINE BUILDING 20 Pages Follow CALC. NO. CALCULATION COVER SHEET FPL-076-CALC-004 N E RC O N REV. 1 PAGE NO. 1 of 20 Title: Calculated external average water levels at turbine building Client: NextEra Energy (NEE) Project: FPLPB025 Item Cover Sheet Items Yes No 1 Does this calculation contain any assumptions that require confirmation?
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| X (If YES, identify the assumptions)
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| 2 Does this calculation serve as an "Alternate Calculation"? (If YES, identify the X design verified calculation.)
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| Design Verified Calculation No. 3 Does this calculation supersede an existing calculation? (If YES, identify the X superseded calculation.)
| | ==Dear Mr. Meyer:== |
| | This letter refers to the inspection conducted from April 4, 2013 through June 6, 2013 for your Point Beach Nuclear Plant. The purpose of the inspection was to follow-up on issues identified during completion of Temporary Instruction (TI) 2515/187, Inspection of Near-Term Task Force Recommendation 2.3 Flooding Walk Downs. The issues were classified as a finding for the licensees lack of procedural requirements to appropriately implement external flooding wave run-up protection design features as described in the Final Safety Analysis Report. The finding was classified as an apparent violation with significance to be determined and was documented in NRC Inspection Report 05000266/2013002 and 05000301/2013002 (ML13133A356). The enclosed report documents the results of the follow-up efforts of this inspection, which were discussed on June 6, 2013, with you. |
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| Superseded Calculation No. Scope of Revision:
| | Based on the results of this inspection, the NRC has preliminarily determined the finding to be a Yellow finding with substantial safety significance that will result in additional NRC inspections and potentially other NRC action. As described in Section 4OA5, the inspection-identified finding involved the licensees lack of procedural requirements to appropriately implement external flooding wave run-up protection design features as described in the Final Safety Analysis Report. Specifically, the licensees procedure, as implemented, would not have protected safety-related equipment in the turbine building or pumphouse. |
| Text revised on Page 15 Revision Impact on Results: No impact to results. Text only. Study Calculation D Final Calculation Safety-Related Non-Safety Related D (Print Name and Sign) Originator:
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| Shaun W. Kline . o , Date: 0 7/1 Si z_n 1 3 Design Verifier:
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| Justin Pistininzi (;16-
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| ......._...
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| Date: o ? /1 1.-/ ":l '0/J Approver:
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| Paul Martlnchlch
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| / '-:J.z (j AA ... Date: t7 7 J1 0 J U)3 /
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| CALC. NO. CALCULATION FPL-076-CALC-004 REV. 1 REVISION STATUS SHEET PAGE NO. 2 of 20 CALCULATION REVISION STATUS REVISION DATE DESCRIPTION 1 July 15, 2013 Initial Issue PAGE REVISION STATUS PAGE NO. REVISION PAGE NO. REVISION All pages 1 REVISION STATUS Attachment NO. PAGE NO. REVISION NO. Attachment NO. PAGE NO. REVISION NO. All Attachments All Pages 1 CALC. NO * .. CALCULATION FPL-076-CALC-004 I j I E N ERC ON DESIGN VERIFICATION PLAN REV. 1 AND SUMMARY SHEET PAGE NO. 3 of20 Calculation Design Verification Plan: Apply CSP Number 3.01, Revision 6, Section 4.5.a, Design Review Method and to include at a minimum: 1. Review and verify the design inputs, references and tables to ensure that the Calculations Results, as they conform to the design methodology and design guidance, are correct. (Print Name and Sign for Approval-mark "NIA" if not required)
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| Approver:
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| Paul Martinchich Date: 07/ >:s-)"A?J J 3 Calculation Design Verification SummarY':
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| After reviewing this calculation and all related documents for Revision 0, I have come to the following conclusions:
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| 1. The methodology, design inputs and approach are appropriate for the derivation of all calculated results. 2. The results of the Calculation are reasonable based on verified input values. 3. The report text and general flow of the document is clear and concise. Based on the above summary, the calculation is determined to be acceptable. (Print Name and Sign) Design Verifier:
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| Justin Pistininzi S/eZJ_p/-_ Date: 0 7/tr::-/ 'J-o£3. Others: N/A ?/"' Date: I I CALC. NO. FPL-076-CALC-004 I W EN E RCON CALCULATION DESIGN VERIFICATION REV. 1 CHECKLIST PAGE NO. 4 of20 Item Cover Sheet Items Yes No N/A 1 Design Inputs -Were the design inputs correctly selected, referenced (latest X revision), consistent with the design basis and incorporated in the calculation?
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| 2 Assumptions- Were the assumptions reasonable and adequately described, X justified andfor verified, and documented?
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| 3 Quality Assurance- Were the appropriate QA classification and requirements X assigned to the calculation?
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| 4 Codes, Standard and Regulatory Requirements- Were the applicable codes , X standards and regulatory requirements, including issue and addenda, properly identified and their requirements satisfied?
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| 5 Construction and Operating Experience
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| -Has applicable construction and X operating exper i ence been considered?
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| 6 Interfaces- Have the design interface requirements been satisfied, including X interactions with other calculations?
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| 7 Methods -Was the calculation methodology appropriate and properly applied X to satisfy the calculation objective?
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| 8 Design Outputs-Was the conclusion of the calculation clearly stated, did it X correspond directly with the objectives and are the results reasonable compared to the inputs? 9 Radiation Exposure-Has the calculation properly considered radiation X exposure to the public and plant personnel?
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| 10 Acceptance Criteria -Are the acceptance criteria incorporated in the X calculation sufficient to allow verification that the design requirements have been satisfactorily accomplished?
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| 11 Computer Software -Is a computer program or software used, and if so, are X the requirements of CSP 3.02 met? COMMENTS: (Print Name and Sign) Design Verifier:
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| Justin Plstlnlnzi Date: D7 It s/ J..o£3. Others: N/A ,?/ Date: I E N ERCO N CALCULATION CONTROL S H EE T T AB L E O F C ONT E NT S C ALC. NO. F PL-076-CALC-004 R E V. 1 PAG E NO. 5 of 20 1. PURPOSE AND SCOPE ............................................................
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| ....... 6 2. SUMMARY OF RESULTS AND CONCLUSIONS
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| 6 3. REFERENCES
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| .................................................................................................................... 9 4. ASSUMPTIONS
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| .......................... 10 5. DESIGN INPUTS ..............................................
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| ..................... 10 6. METHODOLOGY
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| .......... 11 7. CALCULATIONS
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| .................................................................... 14 List of Figures FIGURE 1-1: COASTAL INUNDATION COMPONENTS
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| .... 6 FIGURE 2-1: OBSERVATION POINTS AT POINT BEACH NUCLEAR PLANT (PBNP) .....................
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| 8 FIGURE 6-1: EFFECTIVE RUNUP SCHEMATIC
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| .................................. 14 FIGURE 7-1: MAXIMUM WAVE BREAKING DISTANCE OF THE LARGEST WAVES NORMAL TO THE SOUTHWEST CORNER OF THE PUMP HOUSEfTURBINE BUILDING AT POINT BEACH NUCLEAR PLANT (PBNP) ........................................................................................................
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| ........................... 18 FIGURE 7-2: SCHEMATIC OF RESULTS FROM TABLE 7-3 FOR SWL=587.00 FT-IGLD55 USING TH9 MEAN WAVE SETUP .......................
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| ....... 19 List of Tables TABLE 5-1: INCIDENT WAVE RUN UP AND WATER ELEVATION CALCULATION INPUTS ........................ 10 TABLE 7-2: CALCULATION RESULTS FOR THE MAXIMUM STRUCTURAL LOADING ANALYSIS ...........
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| 16 TABLE 7-3: CALCULATION RESULTS FOR THE AVERAGE EXTERNAL WATER LEVEL PROXIES ON THE TURBINE BUILDING ...................................................................................................
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| ................. 17 E N ERCO N CALCULATION CONTROL SHEET 1. Purpose and Scope CALC. NO. FPL-076-CALC
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| -004 REV. 1 PAGE NO.6 of 20 This calculation is performed under NextEra Energy (NEE) contract order 02306247 to determine a(n) * average water level proxy at the turbine building for the PRA leakage analysis, and * maximum water level proxy at the turbine building for a structural loading analysis on the turbine building's rollup doors and the jersey barriers due to effects of storm surge in Lake Michigan at the Point Beach Nuclear Plant (PBNP). The purpose of this calculation is to provide a calculation by empirical relationship of incident wave run up elevations beyond the standing water elevation, which is comprised of the still water level (SWL) and wave setup (FEMA, 2005; Dean and Dalrymple, 2007; USACE, 2011). The initial SWL is prescribed and the wave setup is computed by the DELFT3D model (ENERCON , 2013a). Wave runup includes many simultaneous processes , and is the sum of static wave setup, dynamic wave setup, and incident wave runup (swash), as shown in Figure 1-1. To adequately address the water elevations on critical infrastructure at PBNP, an empirical relationship computation of the latter parameter (incident wave runup) is require Proxies for critical total water elevations (which include the combined effects of SWL, wave setup, and individual wave swash) on the turbine building are also computed. Results and conclusions from this calculation can be used to determine the effect of waves and flooding on the turbine building at PBNP. For instance, the calculated average water levels can be used to compute water leakage into the building and the maximum water level can be used to determine the highest forces against the turbine building rollup doors. In ci dent I ************** ****** Coastal Inundation Components (adapted from USACE. 2012) I ********************************************...
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| .......... ':::.::::.:.:**************** .. . Wav e Setup ******************** \ \. .... ** ******** Stand i ng Water Eleva l i on .. 2 J _ / ** ............ ** Still Wa t er level SWL Wind S elul level)
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| Pre-slormAnl e cedent ----Water level (of la k e Mich i gan) G) Determined In CLB (FSAR & IPEEE) Calculated by Numerical Modeling (DELFT3D)
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| @ Hand-Calculated by Empirical Relationships (FEMA & USACE) Note: Drawing not lo s ca le Figure 1-1: Coastal Inundation Components 2. Summary of Results and Conclusions Conservative parameters were used whenever available in this analysis. Where conservative values were not available, reasonable inputs in accordance with industry standard practice and justification were used. Therefore, the results of this analysis are bound i ng for PBN ENERCON CALCULATION CONTROL SHEET CALC. NO. FPL-076-CALC-004 REV. 1 PAGE NO.7 of 20 This analysis first considered incident wave runup, which empirically has been shown to be a function of deep-water characteristics and beachface slope (Stockdon, 2006; FEMA, 2005; Dean and Dalrymple, 2007; USAGE, 2011 ), to help determine a total water elevation above the still water level and wave setup components modeled in DELFT3D (ENERCON, 2013a). Beach/beachface characteristics and breaking wave locations were found near the southwest corner of the pump house adjacent to the turbine building (observation point BP2, see Figure 2-1), where ponding occurs in the most severe cases (ENERCON, 2013a). We also provide a water elevation proxy considering the mean setup, rather than the peak surge level simulated in DELFT3D (ENERCON, 2013a). The calculated average setup method produces a maximum mean water level proxy of 0.31 feet on the turbine building (588.51 ft-IGLD) during the case IPEEE still water level elevation of 587 ft-IGLD55 (PBNP, 1995; PBNP, 2013). This value can be used to determine the effective water leakage experienced into the turbine building from pooling water against the doors. We find an incident wave run up greater than 1.65 feet will occur for less than 2% of the storm duration (ENERCON, 2013a). Accordingly , a wave bore exceeding 2.19 feet (590.39 ft-IGLD55)
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| could be expected less than 2% of the storm at the turbine building in the most severe IPEEE still water level case of 587 feet-International Great Lakes Datum 1955 (henceforth IGLD55) (PBNP, 1995; PBNP, 2013). For an initial water level of 586 ft-IGLD, maximum runup may reach the turbine building, but mean water level proxies indicate no persistent water present. This calculation can support analyses of door, building, and barrier stability in the presence of increased water level and/or wave attack. The results in this calculation are applicable for a small, yet critical range of the turbine building near the southwest corner of the pump house. Conservative methods were applied to account for uncertainties related to the inputs. This incident runup calculation and total water elevation proxies can be applied to other PBNP locations, but the methodology and assumptions presented should be considered first. The total water elevations are expected to be lower at other PBNP turbine building locations of interest, since the maximum setup of the observations in Figure 2-1 was selected for this analysis (ENERCON, 2013a).
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| ENERCON CALCULATION CONTROL SHEET Shoreline CALC. NO. FPL-076-CALC-004 REV. 1 PAGE NO.8 of 20 .fo4LN3 0 Observation points that provided water levels (wave setup) used in the wave runup calculation. Approximate Scale: 1" = 200' Figure 2-1: Observation Points at Point Beach Nuclear Plant (PBNP).
| | The finding does not present an immediate safety concern because the licensee has taken corrective action and revised the procedure to implement the wave run-up protection features. |
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| E N ERC ON CALCULATION CONTROL SHEET 3. References CALC. NO. FPL-076-CALC-004 REV. PAGE NO. 9 of 20 3.1 Dean and Dalrymple, 2007, "Water Wave Mechanics for Engineers and Scientists," World Scientifc , 353 pp. 3.2 Deltares, 2012, Deltares Systems, "DELFT3D-WAVE User Manual," updated 2012. 3.3 ENERCON, 2013a, ENERCON Services, Inc. (ENERCON), "DELFT3D Modeling of Surge and Wave Runup, Revision 0," Calculation Number FPL076-CALC-003 , 2013. 3.4 ENERCON, 2013b, ENERCON Services, Inc. (ENERCON), "Mean Wave Flow, Revision 0," Calculation Number FPL-076-CALC
| | Specifically, the licensees procedure has been revised to direct the installation of jersey barriers in conjunction with the use of sandbags, existing jersey barriers have been modified, and sandbags and additional jersey barriers have been purchased and pre-staged. This finding was assessed based on the best available information, using the applicable significance determination process (SDP). The basis for the NRCs preliminary significance determination is described in the enclosed report. This finding is also an apparent violation of NRC requirements and is being considered for escalated enforcement action in accordance with the NRC Enforcement Policy. The current Enforcement Policy is included on the NRCs Web site at http://www.nrc.gov/about-nrc/regulatory/enforcement/enforce-pol.html. |
| -006, 2013. 3.5 FEMA, 2005, Federal Emergency Management Administration (FEMA), "Guidelines and Specifications for Flood Hazard Mapping Partners," D.4.5 Wave Setup, Runup, and Overtoppin .6 FEMA, 2007, Federal Emergency Management Administration (FEMA), "Guidelines and Specifications for Flood Hazard Mapping Partners," D.2.8 Wave Runup, and Overtoppin .7 FEMA, 2012, Federal Emergency Management Administration (FEMA)," FEMA Great Lakes Coastal Guidelines, Appendix D.3 Update," D.3 Coastal Flooding Analyses and Mapping: Great Lakes. 3.8 Mase , 1988, "Spectral Characterisitcs of Random Wave Runup," Coastal Engineering, Vol. 12, No.2, pp.175-189. 3.9 Melby, 2012, United States Army Corps of Engineers, Coastal and Hydraulic Laboratory, "Wave Runup Prediction for Flood Hazard Assessment (Draft)." 3.10 PBNP, 1995, Point Beach Nuclear Plant (PBNP), "Point Beach Nuclear Plant Individual Plant Examination of External Events (IPEEE) for Severe Accident Vulnerabilities
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| -Summary Report ," Wisconsin Electric Power Company, June 30, 1995. 3.11 PBNP, 2013, Point Beach Nuclear Plant (PBNP) Design Information Transmittal (OfT), Modification Process, " Still Water Elevations (IGLD55) to be used for the FPL-076 series of calculations in the PBNP wave analysis to match up with existing event probabilities," July 11, 2013. 3.12 S&L, 1967, Sargent and Lundy (S&L), "Maximum Deep Water Waves & Beach Run-up at Point Beach," 1967. 3.13 Stockdon, 2006, "Empirical parameterizat i on of setup, swash, and runup," Coastal Engineering, Vol. 53, No. 2 , pp. 573-588. 3.14 USAGE, 2011, United States Army Corps of Engineers (USACE), "Coastal Engineering Manual," EM 1110-2-1100 , updated 2011. 3.15 USACE, 2012, United States Army Corps of Engineers (USACE), "Statistical Analysis and Storm Sampling for Lakes Michigan and St. Clair," 201 E N E R C ON CALCULATION CONTROL SHEET 4. Assumptions CALC. NO. FPL-076-CALC-004 REV. 1 PAGE NO. 10 of 20 4.1 No reduction factors due to differing surface roughnesses have been applied. The beach/beachface extent includes predominately sand, grass, gravel, and asphalt, which require no reduction (FEMA, 2005). Applying no reduction factors is the most conservative approach for wave runup calculation .2 The conversion from 2% incident wave runup elevation to 50% incident wave runup elevation is based on an empirical relationship applied to total run up for i rregular waves (Mase, 1988; USACE, 2011 ). It is assumed that the conversion applies equivalently for wave setup and incident runup and that the conversion is valid for waves modeled in FPL-076-CALC-00 Given the conservative method of calculating incident runup and the lack of accepted industry standards for calculating mean incident runup heights, this is a reasonable approac .3 An effective runup elevation, or average elevation of the wave runup bore over its entire wavelength (wave period), is determined by assuming the runup bore maintains a sinusoidal shape above the mean water surface, which is a conservative approach for a linear wave form. An effective (average)
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| height for this bore is used to provide a proxy for mean effective incident runup elevations. Although breaking waves become nonlinear and lose their sinusoidal shape (Dean and Dalrymple, 2007), this approach provides an approximation of the average (effective)
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| runup height. It is a reasonable and conservative approach given the lack of industry standard in the derivation of such a paramete .4 Wave setup is assumed to be a constant value near the turbine buildin The maximum or mean water level at observation points (BP2, SS4, or SS5) near the turbine building are used to determine the wave setup value (height above the initial still water level). This calculation provides a value of water levels near the southwest corner of the pump house and may differ at other PBNP locations. However, the calculated level bounds the expected level at the turbine buildin . Design Inputs The design inputs are listed in Table 5-1 below. A maximum wave period of 10 seconds was used to account for the maximum wind-generated periods determined in FPL-076-CALC-003 (Enercon, 2013a). Table 5-1: Incident Wave Run up and Water Elevation Calculation Inputs Value Units Source(s)
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| Ho 23.5 ft ENERCON, 2013a T 10 s ENERCON, 2013a Wave 120 degrees ENERCON, 2013a Direction Wind 90 degrees ENERCON, 2013a Direction PBNP, 2012 m 0.025 ft/ft S&L, 1976 ENERCON, 2013a 587.64 587 PBNP, 1995 SWL 586 ft-IGLD55 585 PBNP, 2013 583 CALCULATION CONTROL SHEET 6. Methodology 6.1 Runup CALC. NO. FPL-076-CALC-004 REV. PAGE NO. 11 of 20 Run up (R) is the maximum elevation of wave uprush above the still water level, consisting of wave setup (11). the elevation of the water surface due to wave action, and oscillatory wave swash from breaking waves (USAGE, 2011 ): R = 1J + R/Nc (FEMA, 2005 , 0.4.5-1) where: R = total runup (ft) 11 = combined static and dynamic wave setup (ft) R1Nc = incident wave run up due to oscillatory wave swash (ft) Physically, R is the local maximum in water elevation (USAGE, 2011 ). No reliable theoretical formulations for run up exist currently because the controlling processes are complex and nonlinea Rather, empirically derived relationships are used to estimate runup (USAGE, 2011). Many of these formulae relate total runup (R) to wave characteristics and beachface morphology (i.e. slope). For the purposes of this analysis, however, such a computation would not be required. Computed OELFT30 water levels (in FPL-076-CALC-003)
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| include wave setup (11). Thus, the only additional increase to the maximum water elevation is the oscillatory wave swash, RING. 6.2 Incident wave runup and maximum water levels for stability analysis FEMA defines the 2% incident wave run up (RING 2%), the oscillatory water elevations attributable to wave swash that is to exceed less than 2% of the time, as where: 111 R1Nc 2% = 0.6 f!!Q Ho -.ITO (FEMA, 2005, 0.4.5-11) R1Nc 2% = incident wave run up elevation beyond water surface exceeded by <2% of waves (ft) m = beach slope (dimensionless)
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| Ho = deep-water wave height (ft) Lo = deep-water wavelength (ft) Thus, maximum incident runup occurs on steep beaches for large, long waves. Equation 0.4.5-11 was developed empirically along the Pacific coast (FEMA, 2005). It was chosen for this calculation for two major reasons: 1) it provided a clear evaluation of the incident wave run up, rather than the combined effects of incident runup and setup, and 2) it is conservative approach, since frictional dissipation over a wide, sloped dissipative beach, like Lake Michigan , would yield lower incident runup heights than the steeper, narrower surf zones of the Pacific coast (Stockdon, 2006). FEMA (2012) does provide unofficial (draft) guidelines for the flood mapping on the Great Lakes, and promotes the use of Melby's (2012) compilation of wave runup formulations when applicabl However, equations therein reference a total run up elevation (Melby, 2012, Figure 1 ). FEMA (2012) defines run up as a "statistic associated with a group of waves or a particular storm," indicating that the equations do not separate setup from individual wave swash. Runup formulations for structures are also provided (FEMA, 2012), but are irrelevant when the largest waves modeled in FPL-076-CALC-003 break far seaward of PBNP and do not E N ERCO N CALCULATION CONTROL SHEET CALC. NO. FPL-076-CALC-004 REV. PAGE NO. 12 of 20 directly impact any vertical infrastructur Hence, Equation 0.4.5.11 is the best known, applicable, yet conservative estimate of only incident wave swash. The beach is defined as the area between wave breaking and the landward extent of wave runup (FEMA, 2005). The landward extent of the beach is defined as the turbine building near the southwest corner of the pump house (observation point BP2) where ponding was predicted in the most severe cases (ENERCON, 2013a; Table 7-2). Additionally, the turbine building would interrupt runup flow and is the structure of top importance. The elevation of the bottom of the turbine building door is 588.2 ft-IGLD55. At PBNP, the seaward extent of the beach was located where wave breaking occurred, as predicted by the DELFT30-WAVE model (ENERCON, 2013a). Larger waves began breaking -700 feet from the turbine building, whereas smaller wind-generated waves, which produce significantly less incident runup broke approximately
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| -250 feet from the BP2 observation point (ENERCON, 2013a). In deep-water, wavelengths are directly related to the wave period (T): (FEMA, 2005, 0.4.5-10)
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| where: T =wave period (s) Incident runup heights thus become a function of deep-water wave height and period, as well as the beach slope. The largest incident wave run up values occur on steep beachfaces for waves that are large {Ho) and long (T). Thus, the simulations with the largest Ho and T values along the deep-water boundaries would produce the highest incident wave run up elevation The water elevation given by SWL +I"JMAX+RINC 2% (Wl2%) is a proxy for the maximum water level reached during the storm. It is the value used in stability analysis used of the turbine building's rollup doors and jersey barrier .3 Effective incident runup to determine external water levels on turbine building The incident wave runup (RINC) is only an instantaneous water elevation (Figure 6-1). To better understand the time-averaged, mean total water level, an average runup elevation proxy may be developed. At PBNP, the mean water level is an important factor in the leakage experienced in the turbine buildin After a wave breaks, it continues as a bore up the beachface until gravity limits its upward swash rush or it is interrupted by a hard structure. For sinusoidal bores that are equally spaced (i.e. the length of the bore is equal to the space between bores, the mean elevation can be given in two parts. The first part is the same calculation performed in FPL-076-CALC-006, and the result from that analysis (Equation 6-2 in FPL-076-CALC-006)
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| is provided here: where: A = n1Nc2%L BORE 2 1f AsoRE = area under the wave bore (ft 2) L = wavelength (ft) (6-1) The average height of that bore is given by dividing by half of the nearshore wavelength, L/2 (see Figure 6-1 ): where: -h -_ A BORE _ RINC 2% BORE -Lj2 --lf-hBoRE = average height of the bore (ft) (6-2)
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| ENERCON CALCULATION CONTROL SHEET CALC. NO. FPL-076-GALC-004 REV. 1 PAGE NO. 13 of 20 Note that the height of the wave bore is not a true wave height; rather, it is a wave amplitude, since the trough of the bore is neglected. The second part of the calculation is the space between bores, which is assumed to be at the standing water elevation (Figure 6-1). Since the 'bore' has a height of zero in this range, the overall effective height of the bore, and subsequently of the incident run up (REFF 2%), if the next bore is assumed to follow the profile in Figure 6-1, is given by: R _ hBoRE _ R/Ncz% EFF2% (6-3) where: REFF 2% = effective run up height (ft) This value (REFF 2%) is used as a proxy of the wave runup provided by the incident runup (RJNc) predicted by Equation 0.4.5-11 from FEMA (FEMA, 2005). This approximation is a conservative approach of the linear wave profile since the wave trough is neglecte Additionally, the USAGE (2011) provides empirical formulas for various total run up thresholds (e.g. RMAx, R2%, R) for irregular waves (USAGE, 2011 ). If incident wave run up and wave setup, the two components of total wave runup, are assumed to vary equally (i.e. increase/decrease by the same percentage)
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| between these various thresholds, then a comparison of the empirical formulas will allow for a conversion of REFF 2%, derived from applying Equation 6-3 to an R1Nc 2% computation, to an equivalent REFF 5o% proxy for R, the mean run up calculation (USAGE, 2011): where: R o.aaR EFF 50% = l.0 6 EFF 2% REFF 50% = effective run up height proxy for R (ft) REFF 2% = effective run up height proxy for R1Nc (ft) (6-4) The coefficients in Equation 6-4 (0.88 and 1.86) are found in Section 11-4-4 of USAGE (2011 ). This value (Rm 5o%) can be used as a proxy for average runup elevation, although it should be noted that this elevation is not static and the instantaneous level oscillates around this value, as shown in Figure 6-1. Physically, REFF so% is equivalent to the average height that run up will reach 50% of the time. Similarly, REFF 2% is the average height that runup will reach 2% of the time. Thus, SWL +i]+REFF 50% (WL50% EFF) where iJ is the mean wave setup, can be thought of as a proxy for the mean water level. Instantaneous water elevations range between the standing water level and the maximum extent of run up. WLso% EFF is used to compute mean water leakage into the turbine buildin E N ERCO N Turbine building Note: drawing not to scale U2 CALC. NO. FPL-076-CALC-004 CALCULATION CONTROL SHEET REV. L PAGE NO. 14 of 20 Instantaneous water level Standing water elevation (SWL + fl*) Floor elevation (588.2 ft-IGLD55)
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| * Note: wave setup (fl) was considered either as a maximum modeled level (flMAX), which was used in calculations for the structural loading analysis, or a mean level (ij), which was used in the computations for average external water level proxies at the turbine building. Figure 6-1: Effective Run up Schematic 7. Calculations These cases examine the incident wave run up for the largest (significant wave height, Hs = Ho = 23.5 feet) and longest (T = 10 seconds) deep-water waves with no barriers present and each evaluated SWL, shown in Table 7-1 (ENERCON, 2013a). From Equation 0.4.5-10, the deep-water wavelength (Lo) of these waves would be 512.32 feet. These parameters provide a worst-case flooding scenario for each initial SWL; all input values are shown in Table 5-1. For these deep-water wave conditions, the maximum wave setup ('lMAX) was 1.74 feet, corresponding to the still water level of 587 ft-IGLD55, as found in FPL-076-CALC-003 (ENERCON, 2013a). For the lower still water levels, the maximum wave setup narrowly ranged between 1.20 and 1.28 feet (ENERCON, 2013a). This result is likely attributable to the relatively steep sloping bathymetry at the seaward edge of PBNP. For the highest still water level, 587.64 ft-IGLD55, the maximum setup at BP2 was 1.46 feet. Above a threshold water level (between 586 and 587 ft-IGLD55), waves and accompanying setup make it close to the turbine building; below it, the wave setup height appears to be quite stable. Please refer to FPL-076-CALC-003 for a more comprehensive discussion and presentation of the DELFT3D setup results. Mean wave setup (i]) ranged from 1.12 to 1.39 feet (ENERCON, 2013a). If observation point BP2 was submerged , then it was used to determine the maximum and average wave setup, as it was d i rectly adjacent to the turbine building (see Figure 2-1). If that point was dry for the entire simulation, then observation point 884 or 885, the next closest inundated points, were used. The mean wave setup was computed for only the durations in which BP2 (or neighbor observation point) experienced flooding, which often lagged the start of the model by several minutes (ENERCON, 2013a).
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| ENERCON CALCULATION CONTROL SHEET CALC. NO. FPL-076-CALC-004 REV. 1 PAGE N0.15 of 20 The largest waves, responsible for the highest incident run up elevations, break furthest seaward of the turbine building (Figure 7-1). The slope of the beach/beachface for this calculation was divided into two segments, after the methodology shown in Figure 0.2.8-1 of FEMA (2007). The landward segment extended from near the turbine building (observation point BP2, see Figure 2-1) out to the edge of the topographic map of PBN. The elevation of the BP2 is 587.35 feet-IGLD55 and the elevation at the seaward edge of the topographic map is 573.35 feet-IGLD5 The distance between these points is 350 feet, providing an upper beach slope of 0.04. Seaward of this segment, the beach slope is 0.01 out to 1,000 feet from the turbine building (S&L, 1976). The DELFT3D model showed wave breaking initiating
| | In accordance with NRC Inspection Manual Chapter (IMC) 0609, we intend to complete our evaluation using the best available information and issue our final determination of safety significance within 60 days of the date of this letter. The significance determination process encourages an open dialogue between the NRC staff and the licensee; however, the dialogue should not impact the timeliness of the staffs final determination. Before we make a final decision on this matter, we are providing you with an opportunity (1) to attend a Regulatory Conference where you can present to the NRC your perspective on the facts and assumptions the NRC used to arrive at the finding and assess its significance, or (2) submit your position on the finding to the NRC in writing. If you request a Regulatory Conference, it should be held within 30 days of the receipt of this letter and we encourage you to submit supporting documentation at least one week prior to the conference in an effort to make the conference more efficient and effective. If a Regulatory Conference is held, it will be open for public observation. If you decide to submit only a written response, such submittal should be sent to the NRC within 30 days of your receipt of this letter. If you decline to request a Regulatory Conference or submit a written response, you relinquish your right to appeal the final Significance Determination Process determination, in that by not doing either, you fail to meet the appeal requirements stated in the Prerequisite and Limitation sections of Attachment 2 of Inspection Manual Chapter 0609. |
| -700 feet from the turbine building (Figure 7-1), so the horizontal extent of this segment is 350 feet. A weighted average of the overall beach slope was computed to yield an average value of 0.025. This beach slope (m) was used in all of the wave runup calculations, since only minor shifts (-20 feet) occurred in wave breaking locations due to different initial still water levels. From the calculated beachface slopes and deep-water wave conditions, the incident wave runup (RINc) was calculated to be 1.65 feet. This oscillatory swash operates on top of the wave setup (11), so this result must be added to the SWL (583, 585, 586, 587, OR 587.64 ft-IGLD55)
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| and modeled maximum or mean setup. Thus, the water elevation (SWL +11MAx+R1Nc 2%) which would be exceeded less than 2% of the storm is 590.39 IGLD55 in the 587 ft-IGLD55 SWL case, the most severe still water level in the IPEEE (PBNP, 1995; PBNP, 2013). For this incident wave runup, an instantaneous water depth of up to 2.19 feet at 590.39 ft-IGLD55 (Table 7-2) when SWL = 587 ft-IGLD55 could be realized at the turbine building. This water depth may be used to calculate loading against the turbine doors. Physically, this elevation is a close proxy for the maximum water elevation for the provided still water level, wind, and wave characteristics, but could be exceeded less than 2% of the storm. The effective runup (Rm 2%), calculated from Equation 6-3, is 0.26 feet. The effective height that 50% of individual wave run ups will exceed (REFF so%), calculated from Equation 6-4, is 0.12 feet. Using inputs from Table 5-1 and the calculated R1Nc, REFF2%, and REFFSo% from section 6.2 and 6.3, water level proxies were computed for turbine building's east wall. Results are shown in Table 7-3, and the most severe IPEEE case is shown schematically in Figure 7-2 (PBNP, 1995; PBNP, 2013). The incident runup remains the same in each case, but the overall water elevation proxies differ (Table 7-3). When the BP2 observation point was dry, the next closest submerged observation point (SS4 or SS5) was used to determine the maximum or mean wave setup (see Figure 2-1 and ENERCON, 2013a). The mean water surface proxy (WLso% EFF) is above the elevation of the turbine building floor during only the most elevated initial still water levels, 587 and 587.64 ft-IGLD5 For the 586 ft-IGLD55 case, runup would be expected to impact the structure less than 0.65 feet (588.85 ft-IGLD55)
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| for 98% of the storm. The effective runup elevations indicate no permanent ponding due to wave setup and swash. In the other two initial water level cases, 583 and 585 ft-IGLD55, more than 98% of the incident wave runups would not reach the turbine building floor; similarly, the mean water surface elevation proxy indicates no persistent water on the building doors. A maximum mean setup (if) also was used to calculate the total effective water elevation proxies used to determine leakage into the turbine building. The mean water level proxy (WLsoo;, EFF) is above the turbine building floor elevation by 0.31 feet in the most severe IPEEE case, SWL = 587.00 ft-IGLD55 (PBNP, 1995; PBNP, 2013). No standing water is predicted for the SWL = 586 ft-IGLD55 case, with WLso% EFF = 587.24 IGLD55. Further, no standing water and less than 2% of incident wave runup is expected for the initial SWL = 583 or 585 ft-IGLD55 case **--------CALC. NO. FPL -076-CALC-004 E N ERCO N CALCULATION CONTROL SHEET REV. 1 PAGE N0.16 of 20 Table 7-2: Calculation Results for the Maximum Structural Loading Analysi Inputs for Maximum Incident Runup (Rmc2%) and Setup (I"JMAX) for each SWL Case. Output is a Dynamic Total Water Level (WL2%). Ho T (s) m RiNC2% SWL Frequency of I'] MAX SWL + I']MAX Wl:z% (ft) (ft/ft) (ft) (ft-IGLD55)
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| SWL (yr 1)* (ft) ** (ft-IGLD55) (ft-IGLD55)
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| 23.50 10.00 0.025 1.65 587.64 9.9E-07 1.46 589.10 590.75 23.50 10.00 0.025 1.65 587.00 4.2E-06 1.74 588.74 590.39 23.50 10.00 0.025 1.65 586.00 5.4E-05 1.20 587.20 588.85 23.50 10.00 0.025 1.65 585.00 3.2E-04 1.21 586.21 587.86 23.50 10.00 0.025 1.65 583.00 1.4E-02 1.28 584.28 585.93 * SWL frequencies are provided by PBNP (2013), formulated from data i n PBNP (1995). ** maximum setup values (r]MAX), measured at either observation point BP2 or SS5 (if BP2 was dry), obtained from DELFT3D simulations (FPL-076-CALC-003)
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| corresponding to still water levels (SWL) and deep-water wave conditions of Ho = 23.5 feet and direction=
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| 120 °. Note: This table represents a temporary condition that would induce maximum wave runup for use in calculating structural loading on the turbine buildin *-------------------------------------------------------------
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| CALC. N FPL -076-CALC-004 E i!" J E N ERCON CALCULATION CONTROL SHEET REV. 1 PAGE N0.17 of20 Table 7-3: Calculation Results for the Average External Water Level Proxies (WLso.,. EFF) on the Turbine Buildin Inputs for Highest Effective In cident Run up (REFF so%) and Mean Setup (7]) for each SWL Case. Ho T (s) m REFFSO% SWL Frequency of i] (ft) -SWL+i] Wlso%EFF (ft) (ftlft) (ft) (ft-IGLD55)
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| SWL (yr 1) '* (ft-IGLD55) (ft-IGLD55)
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| 23.50 10.00 0.025 0.12 587.64 9.9E-07 1.13 588.77 588.89 23.50 10.00 0.025 0.12 587.00 4.2E-06 1.39 588.39 588.51 23.50 10.00 0.025 0.12 586.00 5.4E-05 1.1 2 587.12 587.24 23.50 10.00 0.025 0.12 585.00 3.2E-04 0.72 585.72 585.84 23.50 10.00 0.025 0.12 583.00 1.4E-02 0.84 583.84 583.96 * SWL frequencies are provided by PBNP (2013), formulated from data in PBNP (1995) . .. mean setup values (ij') averaged over the entire simulation when flooding occurred, measured at either observation point BP2 or SS4 (if BP2 was dry), obtained from DELFT3D simulations (FPL-076-CALC-003)
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| corresponding to still water levels (SWL) and deep-water wave condit i ons of Ho = 23.5 feet and direction
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| = 120 °. Note: This table represents average water level proxies at the turbine buildin . -* ---------.... -.. -... 1:1 E N ERCO N *ru .. -,..-;:;-*
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| -" ..... 44.2835 44.283 44.2825 t §: 44.282 "' .5 .., 0 44.2815 0 <.> >-44.281 44.2805 44.28 44.2795 -87.538 CALCULATION CONTROL SHEET -87.537 -87.536 -87.535 CALC. NO. FPL-076-CALC-004 REV. 1 PAGE NO. 18 of 20 --87.534 -87.533 -87.532 x coordinate (m) Figure 7-1: Maximum Wave Breaking Distance of the Largest Waves Normal to the Southwest Comer of the Pump House/Turbine Building at Point Beach Nuclear Plant (PBNP). Percent Breaking (Oo/o=No Breaking, 1=100% Breaking)
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| i s Shown in the Color Map Abov Turbine building Note: drawing not to scale CALCULATION CONTROL SHEET CALC. NO. FPL-076-CALC-004 REV. 1 PAGE NO. 19 of 20 SWL = 587 ft-IGLD55 Mean setup ________________
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| Wlsocro...£fu588.51 tt-IGLD55)"" i REFFSO%
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| Standing water elevation, SWL + i'j (588.39 ft-IGLD55)
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| Door/floor elevation (588.2 ft-IGLD55)
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| Results for deep-water wave height= 23.5 ft. deep-water wave direction=
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| 120 °, SWL = 587 ft-IGLD55, and no barriers present. Legend R 1 Nc = max. incident wave run up ReFF = effective wave run up ('time-averaged'
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| R 1 Nc) SWL = still water level (587 ft-IGLD55)
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| fj =mean wave setup at BP2 (ft) Wlso% EFF = 'average'
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| water elevation proxy including ReFF soo/o Figure 7-2: Schematic of Results from Table 7-3 for SWL=587 .00 ft-IGLD55 using the Mean Wave Setup. The WLr;. EFF and EFFWL 2% are the Effective Water Level Proxies Used to Determine Water Leakage into the Turbine Buildin E N E R C ON CALCULATION CONTROL SHEET CALC. NO. FPL-076-CALC-004 REV.1 PAGE NO. 20 of 20 Attachment A (On DVD) Pages/ Worksheets/
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| File Name (References)
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| Revision File Dean and Dalrymple, 2007 NA File Delatres, 2012.pdf NA File ENERCON, 2013a 0 File ENERCON, 2013b 0 File FEMA, 2005 NA File FEMA, 2007 NA File FEMA, 2012 NA File Mase, 1988 NA File Melby, 2012 NA File PBNP, 1995 NA File PBNP, 2013 NA File S&L, 1967 NA File Stockdon, 2006 NA File USACE, 2011.pdf NA File USACE, 2012.pdf NA File ATTACHMENT 2 NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT POINT BEACH REVISED EXTERNAL FLOOD SAFETY SIGNIFICANCE DETERMINATION Performance Deficiency The licensee failed to establish appropriate procedural requirements to implement external flooding wave run-up protection design features as described in the FSAR. Executive Conclusion The safety significance of this issue is assessed to be of very low with margin for Units 1 and 2. Table 4 provides the core damage frequency (CDF) with and without barriers as well as the change in core damage frequency with and without the barrier The basis of this conclusion is that a detailed wave run-up analysis results in a calculated water level much lower than the water levels previously evaluated in the IPEEE. The PRA analysis based on the updated engineering analysis confirms that the IPEEE water levels were dominated by estimates and assumptions that resulted in excessive conservatism for the 4.2E-06/yr frequency event. These lower water levels from the updated engineering analysis result in fewer equipment impacts. Background The IPEEE response to GL 88-20, "Individual Plant Examination for Severe Accident Vulnerabilities," evaluated external flood hazards for PBNP. This evaluation was based in part on the analysis for external flood events conducted in conjunction with the NRC's TAP A-45 study. In order to evaluate the safety significance of this issue, the data provided in the IPEEE was used to evaluate the change in CDF and large early release frequency (LERF). For the purpose of this evaluation the "change" being considered is the plant with and without the barrier protection to 589.2 (IGLD-1955), as described in the IPEEE report. To perform this evaluation, some simplifying conservative assumptions, providing margin, are made: 1) Above 589.2 ft. IGLD 1955 (+9ft.), the impact of the flood is the same with and without barrier ) For the purposes of the PRA calculations, the water level inside the buildings was assumed to equal the water level outside the Turbine Building at time zero. 3) Below 588.2 ft. IGLD 1955 (+8ft.), there is no impact from the flood (with or without barriers). 4) The PRA evaluation assumes a concurrent dual unit loss of offsite power (LOOP) due to the storm which is conservative because the postulated storm does not reach sustained wind speeds that are expected to cause damage to offsite power distributio Page 1 of 8 Risk Assessment PBP PRA Model Rev. 5.02 was used for this assessmen Since this evaluation will be applying the frequency of the external flood outside of the PRA model, all initiators in the internal events model were set to 0.0 with the exception of the weather-centered LOOP initiator (INIT-T1W).
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| By doing this, the value being quantified is the conditional core damage probability (CCDP), i.e., the core damage probability assuming the initiator (external flood in this case) occurs The following steps were taken to evaluate the significance of this issue: 1) Run CAFTA cases (average Testing & Maintenance)
| | Please contact Mr. Jamnes Cameron at 630-829-9833 and in writing within 10 days from the issue date of this letter to notify the NRC of your intentions. With this notification you are requested to provide a list of equipment that is impacted by the flood levels of interest (wave run-up from 592 to 596 feet mean sea level (MSL), impounding up to 2 feet of water at the turbine building grade level), the basis for the list of equipment, and a discussion of any differences between assumed flood impacts documented in the Individual Plant Examination of External Events (IPEEE), the internal flooding Probabilistic Risk Assessment (PRA) notebook, and the Flooding Vulnerability Report, dated October 26, 2012. This information will allow us to refine our current significance determination. If we have not heard from you within 10 days, we will continue with and finalize our significance determination and enforcement decision. The final resolution of this matter will be conveyed in separate correspondence. |
| for Units 1 and 2 with an E-10 truncation limit with flags set to account for the postulated equipment failures. The results of the cases representing the CCDPs for the five bins comprising varying depths of water on the Turbine Building floor are shown in Table 1. For simplicity, only the maximum CCDP for each bin will be carried through the rest of this calculatio ) In order to calculate .LlCDF for the water height ranges in this report , flood event frequencies had to be derived. That was done by defining a relationship between calculated water levels and still water levels from Attachment 1. This relationship is shown in Table 2. 3) The results of the curve-fit of the flood exceedance frequencies from Table 5.2.5-2 of the IPEEE are presented in Table 3. Note that due to the data, two curve fits are presente The first curve fit represents still water elevations s585.1 ft IGLD 1955 and the second curve fit represents still water elevations
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| > 585.1 ft IGLD 1955. 4) By using these developed relationships, a frequency is derived for a given calculated flood level by determining the associated still water level from Table 2 and then using it to determine the frequency from Table 3. 5) The CDF is calculated by multiplying the Incremental Flood Frequency (determined from the relationships in Tables 2 and 3, by the CCDP and is presented in Table 4. 6) The .LlCDF was calculated by subtracting the CDF with barriers from the CDF without barriers for each bin. The Total .LlCDF was obtained by subtracting the CDF Total with barriers from the CDF Total without barrier This information is also presented in Table 4. Note that based upon previous evaluations and the very small CDF values, values for LERF were not calculate Due to the nature of the initiating event, i t is judged that there is no unique challenge to L E RF. Thus , the .LlLERF for this evaluation is judged to be well below 1 E-09 /yr. The final calculation of .LlCDF for this issue is determined to be ?.E-09 /yr, which is of very low safety significance , with margin. Page 2 of 8 Margin The flood consequence is considered to be bounding and conservative for the following reasons: 1) All equipment affected by the flood is assumed to be failed at time zero. Based on engineering evaluations, the water accumulation inside various areas of the plant would take over three hours prior to affecting any safety significant equipmen ) No credit for flood mitigation actions taken in response to rising water levels throughout the plant has been modeled. Due to the relatively slow progression of the postulated flood, there should be time for the operators or plant staff to respond to the rising water level and to protect and/or realign equipmen ) No credit for recovery actions taken in response to equipment issues in the plant has been modeled. It is expected that some equipment may be able to be recovered and that other means to provide decay heat removal could be used, e.g., pumper trucks, B.5.b equipment, and portable generator ) The concrete barriers installed at a lake level of 580.7 ft. (IGLD 1955), in accordance with PC 80 Part 7, "Lake Water Level Determination," are assumed to be ineffective in limiting the quantity of water. Page 3 of 8 Ta bl e 1 Maximum Conditional Co r e Damage P robability vs. Water Level Range Bins Range of Water Level CCDP (max) Bin on Turbine Equipment Assumed Failed (1,7) Building Floor (4) (inches) (2,3) Offsite power assumed lost, Offsite Power Transformers (1 X-01/03, 1 0 to <4.0 2X-01/03), 4.25 E-05 RHR Pumps (1/2P-1 OAIB), RHR Pump Suction from Containment Sump B (1/2SI-851AIB) Charging Pumps (1 CV-2AIB/C and 2CV-2 4.0 to <8.0 2AIB/C), 6.87 E-04 Station Battery Chargers (D-07/D-08/D-09)
| | Because the NRC has not made a final determination in this matter, no Notice of Violation is being issued for the inspection finding at this time. In addition, please be advised that the number and characterization of the apparent violation described in the enclosed inspection report may change as a result of further NRC review. In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter, its enclosure, and your response (if any) will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records System (PARS) |
| A Train Emergency Diesel Generators (G-01, G-02), G-01/G-02 EDG Alarm & Electrical Panels (C-34/C-35), G-01/G-02 EDG DC Power Transfer Control Panels (C-78/C-79), 3 8.0 to <12.5 4.16 KV Switchgear ( 1/2A-03/04
| | component of NRC's Agencywide Document Access and Management System (ADAMS). |
| ), 7.70 E-03 (5) 4.16 KV Vital Switchgear A Train (1/2A-05), 1/2HX-11A, B RHR HX Shell Side Inlet Valves (1/2CC-738AIB), Non-Safety Related 480V MCCs (B-33, 8-43), Steam Generator Feedwater Pump Seal Water Injection Pumps (1/2P-99AIB)
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| 480 V Vital MCCs A Train (1/2B-32), 4 Safeguards Batteries (D-01, D-02), (6) 12.5 to <17 Service Air Compresso r (K-3B,) 8.92 E-02 Diesel Driven Fire Pump (P-35B), Instrument Air Compressors (K-2AIB) Condensate Pumps (1/2P-25AIB), Feedwater Pumps (1/2P-28AIB), Service Water Pumps (P-32AIB/C/D/E/F), DC Distribution Panels (D-63, D-64 ), Stand-by Steam Gene r ator Pumps 5 (P-38AIB), 1.00 Turbine Driven Auxiliary Feedwater Pumps (1/2P-29), Motor Driven Auxiliary Feedwater Pumps (1/2P-53), Service Air Compressor (K-3A), Safety Injection Pumps (1/2-P12AIB)
| | ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room). |
| Page 4 of 8 Notes: (1) "Equipment Assumed Failed" for each range of water levels greater than 588.2 ft. IGLD 1955 is based on the elevation of the limiting vulnerable subcomponen (2) "Range of Water Level" is based on inches of water on the turbine building floor. (3) "Range of Water Level" 0 inches equals 588.2 ft. IGLD 1955. (4) The maximum CCDP from either unit is used in the downstream calculation (5) It has been identified that P-35A, Electric Fire Pump, may fail at an elevation in Bin 3. Since this bin already fails 1A-05 (which powers 1 B-03, which powers the electric fire pump), there is no additional consequence of this component failure. (6) It has been identified that a control panel associated with the 2P-29, Turbine Driven Aux Feedwater Pump low suction pressure trip, may fail at an elevation in Bin 4. A sensitivity case was run that showed that the CCDP value would increase slightly to 9.0E-2. This small difference compared to the CCDP value used for Bin 4 is not significant in the conclusions of this evaluatio (7) Equipment failures at the water level elevations have been validated against the most recent walk-downs as documented in EC 279398. Page 5 of 8
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| -l.() l.() m ..--I 0 _J <.9 :S (ii > Q) _J '-Q) ..... ro s "0 Q) -m ::J .2 ro l) Table 2 Calculated Water Level Based on Still Water Lake Elevation Still Water Elevation to Calculated Water Level Relationship St ill Water Lake Calculated Water Ele v ation Leve l (ft.IGLD-(ft. IGLD-1955) * 1955) 587.64 588.89 587.00 588.51 586.00 587.24 585.00 585.84 583.00 583.96 Relationship Between Still Water Lake Elevation and Calculated Water Level (Level Against Turbine Hall) 590 589 588 587 586 585 584 583 582 583 584 585 586 587 Still Water Elevation (ft IGLD-1955) | | Sincerely, |
| 588 NOTE: *Calculated Water Level is taken from Table 7-3 of Enercon Calculation FPL-076-CALC-004 Page 6 of 8 Annual Frequency (per yr) 3.69E-02 2.53E-04 3.45E-07 8.25E-11 Table 3 Annual Frequency Based on Still Water Elevation
| | /RA/ |
| [Derived from Information in IPEEE] Flood Frequency
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| -Curve Fit Equat ions Frequency- Curve Fit (per yr) Still Water Elevation IPEEE (ft IGLD 1955) from IPEEE StiiiWaterFREQ1 StiiiWaterFREQ2 IPEEE Table 5.2.5-2 582.5 3.7E-02 585.1 2.7E-04 4.8E-04 588.0 4.1 E-07 591.0 2.9E-10 Note where two values are provided, IPEEE StillWater FREQ2 was used. (.J 1: (!) ::J C" E LL Ill ::J 1: 1: Point Beach Flood Hazard Frequency (from IPEEE Table 5.2.5-2) 1.E-01 ,-----------------------
| | Steven A. Reynolds, Director |
| ---, <( 1.E-06 1.E-07 1.E-10 +-----,--------.-----,--------.----.---L----J 580.0 582.0 58 .0 588.0 590.0 592.0 Still Water Flood Elevation (ft IGDL-1955)
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| Page 7 of 8 Tab le 4 .t.CDF Calcu l a t ion With and Without Barriers {1 'lH' t-t*n r:l:Iffl'm Effective Flood Incremental Still Water Water Bin Frequency Flood Lake Level CCDP CDF CCDP CDF ACDF1 Frequency Elevation (Range) (1) peryr peryr ft (IGLD-peryr peryr peryr 1955) inches 1 5.6E-06 2.9E-06 586.93 0 to <4.0 4.25E-05 1.23E-1 0 O.OOE+OO O.OOE+OO 1.23E-10 2 2.7E-06 1.4E-06 587.23 4.0 to <8.0 6.87E-04 9.54E-10 O.OOE+OO O.OOE+OO 9.54E-10 587.53 8.0 to 3 1.3E-06 7.3E-07 <12.5 7.70E-03 5.60E-09 O.OOE+OO O.OOE+OO 5.60E-09 4 5.7E-07 3.2E-07 587.87 12.5 t o<17 8.92E-02 2.8 4 E-08 8.92E-02 2.84E-08 O.OOE+OO 5 2.5E-07 2.5E-07 588.21 >17 1.00E+OO 2.48E-07 1.00E+OO 2.48E-07 O.OOE+OO CDF CDF Total 2.83E-07 Total 2.76E-07 7.E-0 9 (1) E ff ect i ve wate r level is t he level o f water in the t urbine build i ng. Page 8 o f 8 ATTACHMENT 3 NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT CONTINUED SERVICE WATER PUMP AVAILABILITY WITH LOSS OF DC CONTROL POWER As discussed in Reference 2, a significant contributor to the difference between initial NextEra and NRC staff estimated changes in Core Damage Frequency (CDF) with failure of equipment up to 589.2 feet of water IGLD 1955 is the PRA modeling of Service Water (SW) pump availability upon loss of DC control power. NRC's SPAR model contains a presumption that the SW pump becomes unavailable upon loss of DC power. (It is important to note that NextEra's updated analysis does not result in water levels which would impact DC power.) With a Loss of Offsite Power (LOOP), all four installed Emergency Diesel Generators (EDGs) will start and energize their associated buses. All six Service Water (SW) pump supply breakers will then sequence onto their respective AC load centers. With respect NRC's SPAR model assumption that SW would be unavailable upon loss of DC power, an interruption in DC control power does not cause re-positioning of breaker DC control power provides remote breaker operation of the 480 volt SW supply breakers by momentarily energizing either the opening or closing solenoid coils. The overcurrent protective device is not dependent on DC control power and remains functional without DC control power. Once a breaker is closed, a loss of DC control power will not cause it to open, and the connected load will continue to be energize Therefore, the operating SW pumps will remain in operation if DC control power is lost. DC control power supplies the starting circuit of the EDGs, the power to initially flash the field on an EDG that is starting, and provides the ability to remotely adjust the electric governor setpoint, and to adjust the voltage regulator setpoin If an operating EDG suffers a complete loss of DC control power, the electronic governor will fail to full fuel demand, and the backup mechanical governor will take over speed regulatio The exciter and voltage regulator are self-energized from the generator output, and will fail to the as-set voltage. The ability to locally adjust frequency on the running generator will remain availabl The pending loss of DC control power due to flooding would be anticipated, and would be acted upon by the Operator before the actual loss occurre Each battery charger would initiate a trouble alarm when it failed, providing a minimum of 1 hour notice of the loss of the supplied bus. The one hour time is based on the minimum capacity of the batteries, and provides time to align the DC control power supplied to running EDGs, 4 kV switchgear, and 480 V Load Centers prior to the complete loss of control power. Abnormal Operating Procedure AOP-0.0 directs the Operator to realign control power from the normal source to the alternate DC control power source. This includes realigning the DC control power for Emergency Diesel Generators and 4 kV switchgear, and the direction would be exercised in anticipation of the loss of the busses when the inability to recover the overheated chargers became evident. Page 1 of 2 If a running "B" train EDG were lost for any reason, the remaining "B" train EDG would be aligned to re-energize the bus previously supplied by the lost EDG using either ECA-0.0 (loss of AC power) or OI-35A (standby emergency power alignment).
| | Division of Reactor Projects |
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| | Docket Nos. 50-266; 50-301 License Nos. DPR-24; DPR-27 |
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| | ===Enclosure:=== |
| | Inspection Report 05000266/2013011 and 05000301/2013011 w/Attachment: Supplemental Information |
| | |
| | REGION III== |
| | Docket Nos: |
| | 50-266, 50-301 License Nos: |
| | DPR-24, DPR-27 Report No: |
| | 05000266/2013011; 050000301/2013011 Licensee: |
| | NextEra Energy Point Beach, LLC Facility: |
| | Point Beach Nuclear Plant Location: |
| | Two Rivers, WI Dates: |
| | April 4, 2013 through June 6, 2013 Inspectors: |
| | S. Burton, Senior Resident Inspector |
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| | D. Betancourt, Acting Senior Resident Inspector |
| | |
| | M. Thorpe-Kavanaugh, Resident Inspector |
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| | L. Kozak, Senior Reactor Analyst |
| | |
| | Approved by: |
| | J. Cameron, Branch Chief |
| | |
| | Branch 6 |
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| | Division of Reactor Projects |
| | |
| | =SUMMARY OF FINDINGS= |
| | IR 05000266/2013011; 050000301/2013011; 04/03/2013 - 06/06/2013; Point Beach Nuclear |
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| | Plant, Flood Protection This report covers the circumstance behind the failure to establish a procedure to implement external flooding wave run-up design features. The NRC staff identified one finding, preliminarily determined to be |
| | : '''Yellow.''' |
| | The preliminary Yellow finding is associated with a violation of NRC requirements. The significance of inspection findings is indicated by their color (i.e., greater than Green, or Green, White, Yellow, Red) and determined using Inspection Manual Chapter (IMC) 0609, Significance Determination Process, dated June 2, 2011. The cross-cutting aspect is determined using IMC 0310, Components Within the Cross-Cutting Areas, dated October 28, 2011. All violations of NRC requirements are dispositioned in accordance with the NRC's Enforcement Policy dated January 28, 2013. The NRC's program for overseeing the safe operation of commercial nuclear power reactors is described in NUREG-1649, "Reactor Oversight Process," Revision 4, dated December 2006. |
| | |
| | ===NRC-Identified=== |
| | and Self-Revealed Findings |
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| | ===Cornerstone: Mitigating Systems=== |
| | * Preliminary Yellow: A finding and an apparent violation of 10 CFR Part 50, Appendix B, |
| | Criterion V, Instructions, Procedures, and Drawings, was identified by the inspectors in that from January 19, 1996 until March 13, 2013, the licensee failed to have a procedure appropriate to the circumstances to address external flooding as described in the Final Safety Analysis Report (FSAR.) Specifically, Procedure PC 80 Part 7, as implemented, would not protect safety-related equipment in the turbine building or pumphouse because the procedure (1) did not appropriately prescribe the installation of barriers such that gaps in or between the barriers were eliminated to prevent water intrusion, (2) did not protect equipment by requiring barriers to be placed in front of the doors, from 1996 to 2008, as described in the FSAR, and (3) did not require the barriers to protect the plant to an elevation of at least 9 feet (589 foot elevation) as described in the FSAR. |
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| | The performance deficiency was screened against the Reactor Oversight Process per the guidance of lMC 0612, Appendix B, and determined to be more than minor because the finding was associated with the Mitigating Systems Cornerstone attributes of Protection Against External Factors (Flood Hazard) and Procedure Quality, and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences (i.e. core damage). Specifically, the licensees failure to procedurally control and maintain external flooding design features and to provide procedural controls for external events could negatively impact mitigating systems ability to respond to an external flooding event. The inspectors evaluated the finding using IMC 0609, |
| | Attachment 0609.04, Tables 2 and 3, and Appendix A, and determined a detailed risk evaluation was needed. This finding does not present an immediate safety concern, in that, the licensee has taken corrective action and revised procedures implementing wave run-up protection features. Specifically, the licensees procedure has been revised to direct the installation of jersey barriers in conjunction with the use of sandbags, existing jersey barriers have been modified, and sandbags and additional jersey barriers have been purchased and pre-staged. These issues are being characterized as an apparent violation in accordance with the NRC's Enforcement Policy, with its final significance to be dispositioned in separate future correspondence. This finding has a cross-cutting aspect in the area of problem identification and resolution, corrective action program, because the licensee failed to thoroughly evaluate problems such that the resolutions address causes and extent of conditions [P.1(c)]. (Section 4OA5) |
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| | B. |
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| | Licensee-Identified Violation None |
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| | =REPORT DETAILS= |
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| | ==OTHER ACTIVITIES== |
| | Cornerstones: Mitigating Systems {{a|4OA5}} |
| | |
| | ==4OA5 Other Activities== |
| | ===.1 Failure to Establish an Adequate Procedure to Implement External Flooding Wave Run-=== |
| | Up Design Features |
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| | ====a. Inspection Scope==== |
| | The inspectors and the Senior Reactor Analyst (SRA) completed their inspection and assessment of a finding classified as an apparent violation with significance to be determined that was previously documented in NRC Inspection Report 05000266/2013002 and 05000301/2013002 (ML13133A356). The inspection and assessment included the review of procedures and information to preliminarily determine the significance of the finding and apparent violation. |
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| | b. |
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| | Introduction A finding of potential substantial safety significance (Preliminary Yellow) and an apparent violation of 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, was identified by the inspectors in that from January 19, 1996 until March 13, 2013, the licensee did not have a procedure that provided for Final Safety Analysis Report (FSAR) design criteria for external flooding wave run-up protection. |
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| | Specifically, the licensees procedure, as implemented, would not protect safety-related equipment in the turbine building or pumphouse. |
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| | Description The description of the finding was documented in NRC Inspection Report 05000266/2013002 and 05000301/2013002 (ML13133A356) and is reproduced here for convenience. |
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| | As an extent of condition review from URI 05000266/2012002 01; 05000301/2012002 01, and in response to TI-187, the inspectors reviewed the licensing basis information and found that the FSAR described external flooding design features and mitigating strategies to protect against a wave run-up flooding event. This flooding event is postulated to occur when waves from Lake Michigan break over the bank entering the circulating water pumphouse and turbine buildings through existing non-watertight doors in each structure. The FSAR states that the site would protect the turbine building and pumphouse by using sandbags, concrete jersey barriers, or equivalent barriers placed on the north and south sides of the circulating water pumphouse just to the west of the walkway. |
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| | Licensee procedure PC 80 Part 7, Lake Water Level Determination, implemented these features as described in the FSAR. The inspectors reviewed PC 80 Part 7 and found that guidance was only provided for installation of concrete jersey barriers. |
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| | The licensee performed a walkthrough of the sites flooding procedure in response to the NRCs 50.54(f) Near-Term Task Force Review of Insights from the Fukushima Dai-Ichi Accident, letter which requested flood area walkdowns and procedure walkthroughs. During the performance of TI-187, the inspectors reviewed the licensees Wave Run-Up Mitigation Package and observed the PC 80 Part 7 walkthrough. During the walkthrough, the licensee discovered that the jersey barriers could not be installed as described in the procedure. |
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| | Specifically, that the area where the jersey barriers were to be installed was not a hardened flat surface; therefore, when the jersey barriers were installed, the barriers were not flush with the ground, and a 4-inch gap was created, which allowed water intrusion past the barriers. The licensee also discovered that the jersey barriers could not be installed against one another due to the existence of rebar at either end of the barriers. This created a gap between each barrier that allowed water intrusion between each of the barriers. Also, the bottom of the jersey barriers were cut to allow them to be moved by use of a forklift creating holes in the bottom of each barrier that allowed water intrusion past the barriers. |
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| | Additionally, the length of the barriers was insufficient to provide protection as needed. An additional 8.42-foot jersey barrier on each side of the pumphouse would need to be installed beyond what was previously identified to provide the needed protection against wave run-up. Finally, the barriers were to be installed in areas that were identified as B.5.b equipment staging areas and consideration of the design interfaces was not assessed. The licensee entered the identified deficiencies into the CAP as AR01809095, AR01824582, AR01807841, and AR01806402. |
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| | Although the licensee identified this issue described above in response to the NRCs 50.54(f) letter, the inspectors found that the licensee did not assign prompt corrective actions to fix the deficient barriers until prompted by inspectors; the licensee did not consider the amount of time needed to erect the barriers until prompted by inspectors; and the licensee did not recognize the need to perform additional evaluations for crediting the use of sandbags and jersey barriers until prompted by inspectors. The licensee documented these concerns in AR01853775, AR01853779, and AR01849522, as well as updated the above-listed CRs and corrective actions due dates to ensure the wave run-up design features were fully evaluated. Therefore, this finding will be characterized as NRC identified because the inspectors added value in the identification of previously unknown weakness in the licensees initial classification, evaluation, and corrective actions associated with this issue. |
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| | The licensee initiated AR01856327 in response to the inspectors concerns. |
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| | Analysis |
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| | The initial analyses of the finding were documented in NRC Inspection Report 05000266/2013002 and 05000301/2013002 (ML13133A356) and are reproduced here for convenience. The additional analyses performed are documented after the reproduced sections. |
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| | The inspectors determined that the licensees failure to establish appropriate procedural requirements to implement external flooding wave run-up protection design features as described in the FSAR was a performance deficiency warranting further evaluation. |
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| | The inspectors determined that this finding was more than minor in accordance with IMC 0612, Appendix B, because the finding was associated with the Mitigating Systems Cornerstone attributes of Protection Against External Factors (Flood Hazard) and Procedure Quality, and adversely affected the Cornerstone objective to ensure the availability reliability, and capability of systems that respond to initiating events to prevent undesirable consequences (i.e. core damage). Specifically, the licensees failure to procedurally control and maintain external flooding design features, and provide appropriate procedure directions for responses to external events, could negatively impact mitigating systems ability to respond to an external flooding event. |
| | |
| | The inspectors evaluated the finding using IMC 0609, Attachment 0609.04, Tables 2 and 3, and Appendix A for the Mitigating Systems Cornerstone. The inspectors answered Yes to the Appendix A, Exhibit 2.B question for external event mitigating systems (Seismic/Fire/Flood/Severe Weather Protection Degraded), because it represented loss or degradation of equipment designed to mitigate a flooding event. Specifically, the jersey barriers were determined to not be of sufficient length to provide protection and allowed water intrusion past the barriers. The inspectors answered No to Exhibit 4, Question 1, because, if it is assumed the barrier was completely failed or unavailable, the loss of the barrier by itself during the event it was intended to mitigate, would not cause a plant trip or initiating event, would not degrade two or more trains, and would not degrade one train of a system that supports a risk significant system or function. The inspectors answered Yes to Exhibit 4, Question 2, because the finding involved the loss of any safety function identified by the licensee through IPEEE analysis. |
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| | Specifically, the licensees IPEEE credits sandbags to protect against external flooding events. Since the licensee substituted the use of jersey barriers in place of sandbags, the jersey barriers were determined to not be able perform the safety function as described. Therefore, the inspectors determined that a detailed risk evaluation was needed. |
| | |
| | The RIII SRA performed a preliminary detailed risk evaluation using the external flooding baseline risk evaluation from the licensees Individual Plant Examination of External Events (IPEEE), dated June 30, 1995. The SRA also considered additional risk information provided by the licensee PRA staff in a document titled, Point Beach External Flood Safety Significance Determination dated April 26, 2013. The preliminary change in core damage frequency (CDF) was estimated to be 1.8E-5, which is a finding of substantial safety significance (Yellow). |
| | |
| | The FSAR described flood protection measures to protect the plant to the 589 foot elevation which provided for a small margin from the design basis wave run-up event of 588.62 foot elevation. In the IPEEE, the licensee evaluated the risk of external flooding due to high still water lake level plus wave run-up. The IPEEE credited the use of sandbags built to the 589 foot elevation which is a height of one foot around the turbine building grade level and two feet around the circulating water pumphouse. The IPEEE further assumed that flooding in the buildings would occur if the sandbags were overtopped by wave run-up by one foot. |
| | |
| | The sandbagging method of flood protection was replaced in 1996 by a method using concrete jersey barriers. To model the performance deficiency, the SRA assumed that no flood protection was installed (i.e., no sandbags, jersey barriers, or equivalent installed). The baseline risk was estimated using the IPEEE information which credited sandbag protection. The CDF was estimated by calculating the risk of external flooding with no flood protection and subtracting the baseline risk. |
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| | The IPEEE analysis assumed that to fail safety-related equipment in the plant, 6 to 12 inches of water must accumulate above plant grade in between the circulating water pumphouse and the turbine building. Plant grade was assumed to be 588.2 ft. One foot of water was assumed to accumulate for a wave run-up event to the 592 ft. elevation and two feet of water was assumed to be impounded for a wave run-up event to 596 ft. |
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| | elevation. With this information, the SRA determined that the sandbagging method provided some protection for a wave run-up event between 592 ft. and 596 ft. This was the range of wave run-up events used in the preliminary detailed risk analysis. The IPEEE analysis further assumed that the sandbags must be overtopped by 1 ft. of water to result in flooding necessary to fail safety-related equipment. Table 5.2.7-1 of the IPEEE lists the critical equipment assumed to be rendered unavailable if the buildings are flooded, The licensee derived the flood frequencies for various wave run-up levels from the IPEEE and documented this in their safety significance determination. The SRA used these values in the preliminary detailed risk evaluation. The frequency of a wave run-up event exceeding 592 ft. was estimated to be 7.3E-4/yr. For the baseline risk estimate, the SRA assumed that the sandbagging method of protection had a failure probability of 0.1. If sandbagging failed, water would enter the turbine building, control building and circulating water pumphouse and impact plant equipment. For the performance deficiency risk estimate, the flood protection features were assumed to be failed. |
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| | The SRA assumed that the wave run-up event was concurrent with a weather-related loss of offsite power (LOOP) event. The flood itself does not cause the LOOP to occur; it is assumed that the wind and weather necessary to cause the wave run-up also causes a LOOP. The SRA used a modified version of the current Point Beach Standardized Plant Assessment Risk model to estimate a conditional core damage probability (CCDP) assuming a weather-related LOOP occurs and the flood impacts mitigating equipment in the turbine building, control building, and the circulating water pumphouse. To calculate the CCDP, the SRA used the list of equipment impacted by the flood as defined by the licensee in their safety significance determination. The SRA determined through discussion with the licensee PRA staff that the source of the list of equipment impacted was a recently issued Internal Flooding PRA notebook. The SRA calculated a CCDP of 2.7E-2. Using this CCDP and the other inputs described above results in a CDF result of 1.8E-5/yr, which is a finding of substantial safety significance (Preliminary Yellow). The dominant sequence was a wave run-up flood event with a concurrent weather-related LOOP, followed by the failure of auxiliary feedwater and the failure of feed and bleed. The failure of auxiliary feedwater is in part due to flood effects and in part due to random failures of other equipment or operator actions necessary to maintain a long term auxiliary feedwater suction source. |
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| | To complete the final significance determination, the NRC has determined that additional review of the flood effects on equipment is necessary because several sources of relevant information reviewed contained conflicting information regarding the vulnerability of plant components to internal building water levels. Specifically, the NRC plans to perform additional reviews of available plant information on the impact of flooding in the turbine building, control building, and circulating water pumphouse. |
| | |
| | =====Enforcement:===== |
| | A preliminary safety significant (Yellow) finding and an apparent violation of 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, was identified by the inspectors in that from January 19, 1996 until March 13, 2013, the licensee failed to have a procedure appropriate to the circumstances to address flooding as described in the FSAR. Specifically, procedure PC 80 Part 7, as implemented, would not protect safety-related equipment in the turbine building or pumphouse because the procedure |
| | : (1) did not appropriately prescribe the installation of barriers such that gaps in or between the barriers were eliminated to prevent water intrusion, |
| | : (2) did not protect equipment by requiring barriers to be placed in front of the doors, from1996 to 2008, as described in the FSAR, and |
| | : (3) did not require the the barriers to protect the plant to an elevation of at least 9 feet (589 foot elevation elevation) as described in the FSAR. |
| | |
| | The licensee entered this issue into the CAP as AR01856327. Completed corrective actions include: procedure revision; installation of jersey barriers in conjunction with the use of sandbags; modified existing jersey barriers; and, sandbags and additional jersey barriers have been purchased and pre-staged. This is being characterized as an AV in accordance with the NRC's Enforcement Policy, and its final significance will be dispositioned in separate future correspondence (AV 05000266/2013002-10; 05000301/2013002-10, Failure to Establish A Procedure to Implement Wave Run-Up Design Features).) |
| | |
| | {{a|4OA6}} |
| | |
| | ==4OA6 Management Meetings== |
| | ===.1=== |
| | ===Exit Meeting Summary=== |
| | On June 6, 2013, the inspection results were presented to Mr. L. Meyer. The licensee acknowledged the issues presented. None of the potential report input discussed was considered proprietary. |
| | |
| | {{a|4OA7}} |
| | |
| | ==4OA7 Licensee-Identified Violations== |
| | None. |
| | |
| | ATTACHMENT: |
| | |
| | =SUPPLEMENTAL INFORMATION= |
| | |
| | ==KEY POINTS OF CONTACT== |
| | Licensee |
| | : [[contact::L. Meyer]], Site Vice President |
| | Ron Seizert, Licensing Supervisor |
| | Anil Julka, PRA Engineer, NextEra Energy |
| | Jon Leiker, PRA Engineer, Point Beach |
| | Nuclear Regulatory Commission |
| | : [[contact::J. Cameron]], Branch Chief |
| | |
| | ==LIST OF ITEMS== |
| | ===OPENED, CLOSED AND DISCUSSED=== |
| | ===Discussed=== |
| | : 05000266/2013002-10; |
| | : 05000301/2013002-10 AV Failure to Establish A Procedure to Implement Wave Run-Up Design Features |
| | |
| | ==LIST OF DOCUMENTS REVIEWED== |
|
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| This would ensure the availability of power to all 3 "B" train SW pumps. In the event that a SW pump needs to be started on an energized bus , but does not have DC control power available to effect remote operation, the procedural direction to "start pumps as necessary" will cause the Operator to start the pump by closing the breaker locally. The low service water pressure alarm response procedure would direct this action, as would di r ection in the various abnormal operating and emergency operating procedure Based on these considerat i ons, it is concluded that the postulated combination of a LOOP, loss of the "A" train buses, and loss of the D-07 , D-08, D-09 battery chargers does not limit the plant to only a single SW pump during long term operation. The actions for switching to alternate DC Control power are as follows: * The operators will respond to control room alarms based on degrading DC voltage * AOP 0.0 Vital DC System Malfunction, entry conditions would be satisfied and direct switching to alternate DC Control power for G-04 EDG. * If G-04 E DG would lose DC control power, guidance for local speed control is provided in E CA 0.0, Loss of all AC, for hydraulic governor operation. * AOP 1 OA, Safe Shutdown local control procedure, provides guidance for local operation of the Service Water pump breakers, if local operation, is require * A Nuclear Oversight Observer completed a satisfactory observation of the above actions in the field by 3 Auxiliary Operator * The above field actions were timed and validated to be completed in aggregate of <1 hour. * These Operator actions are part of the IN PO accredited training programs for both initial and continuing training for the Auxiliary Operators. Local operation of these breakers is trained on, tested, and evaluated by our Operator Initial and Continuing Training program Conclusion If a Service Water Pump is operating when DC Control Power is lost it will continue operating and if it is not operating when DC Control Power is lost, the Operators are trained and are procedurally directed to start the pumps locally. If DC Control Power is lost to G-04 EDG , the operators are trained and have procedural guidance to locally control G-04 EDG's speed with the hydraulic governo Page 2 of 2 ATTACHMENT 4 NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT PBNP TIME TO RESPOND TO RATES OF RISE IN LAKE MICHIGAN WATER LEVEL Purpose The purpose of this evaluation is to establish the time available to respond to rising levels in Lake Michigan before the design basis flood threat may be reached. This evaluation does not rigorously reevaluate the point at which there is a threat from rising water. Design and Licensing Basis No flood height elevation has been calculated for anything but the vertical wall on the east side of the forebay to date. This value is stated in the FSAR (Section 2.5) as 8.42 feet plant elevatio It is based on a maximum undisturbed lake level of +1.7 ft. plant elevation plus a wave run-up of 6.55 feet against a vertical surface, and a sustained level change of +0.17 feet of water based on conservative value of sustained easterly wind velocity of 40 mph over a fetch length of 70 miles and average depth of 465 feet of water. Thus, the maximum expected run-up on a vertical structure would be 6.72 feet above the normal water level (resulting in a plant elevation of 8.42 feet) and somewhat less on a riprap slope. Plant Reaction to Lake Level Changes Prior to Revision 4 (issued March 14, 2013) Point Beach procedure PC 80 Part 7 required installation of pre-cast concrete barriers within 3 weeks when the level of Lake Michigan reached a reported level of 580. 7ft. IGLD 1955. The detailed directions in the procedure on how to obtain this information would have resulted in using the currently accepted International Great Lakes Datum ("IGLD") of 1985. This elevation equates to -0.2 feet plant elevatio This procedure is performed monthly and ensures advance preparation in anticipation of a potential high water event. Historical Lake Level Changes To determine how much advance notice it would have ensured, the historical lake data archived by the National Oceanographic and Atmospheric Administration (NOAA) was reviewe The data for monthly average lake level contained data from January 1918 through March 2013 was converted to feet, and the difference between successive months calculated to obtain the monthly rate of level change. As shown in the histogram below, the distribution of level change is asymmetrica Page 1 of 4 Histogram of Rate of Level Change 140 9 0.00% 120 . 80.00% 100 70.00% 6 0.00% > 80 v c Gl :I .... 5 0.00% 60 ... 40.00% 40 3 0.00% 20.00% 20 0 Rate of Lake Level Change (ft/month)
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| Because the lake level as a function of time cannot be replicated by any meaningful function, it is instructive to calculate the maximum historical one month and two month level changes. On one occasion, the rate of rise in the lake reached 0.85 ft in a single month (April, 1960). The next highest rate of rise ever observed was 0.69 ft/month during two successive months (April and May 1929). As the length of the period increases, the monthly average rate of rise decrease The maximum monthly rate of rise for a three month period is 0.55 ft!month, and for a four month period it has been 0.48 ft!mont A full listing of the data is appended to this evaluatio IPEEE Trigger Points From Table 3-3 in the TAP A-45 report (recreated in the IPEEE submittal), the combination of lake level and wave run-up which gets to the 8ft plant elevation (588.2ft IGLD 1955) occurs with a still lake level of about 582ft IGLD 1955. Since 580.2 IGLD 1955 corresponds to 0.0 feet plant elevation, the still lake level at which the wave run-up reaches 8.0 feet , is 1.8 feet plant elevatio Using this as the lake level at which the threat from rising water materializes , there is 2 feet between the "install barriers" trigger point contained in PC 80 Part 7 and the threat level. Using the maximum historical rise rates for one, two, three, and four months to consume the entire 2 foot margin (height differential)
| |
| would require a period (denoted as " available time period") of: ( 2ft ) weeks T = * 4.33-----,--
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| Rate (n Months) month Page 2 of 4 Using this formulation, the following results are obtained:
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| Rate of Rate Period Available Rise Time Period Height From Differential (ft) ft!month months weeks Trigger Point (Weeks) 2 0.48 4 17.3 18.1 2 0.55 3 13.0 15.8 2 0.69 2 8.7 12.6 2 0.85 1 4.3 10.2 In all cases, the available time period for the 2 foot rise exceeds the highest historical value for that same time period. Therefore, the rate of rise and the available time for each case is conservative. This indicates that even in the "worst case" where lake level were rising at the most rapid historic 1 month rate of 0.85 ft!month, and sustained it for an unprecedented 10 weeks, it would still take a little more than those 10 weeks to consume the 2 feet of margin from the time that the trigger point is reached until the threat level was reached. However, the surveillance is only performed monthly. So it is possible that the reported lake level could be just below (e.g., 0.1 foot less than) the "trigger point" level of 580.7 ft at the time that the procedure is performe It would then take another month (4.3 weeks) to discover that the trigger point level had been exceede Under this postulation, it is appropriate to use the rise rate for n+1 months to determine time to achieve the total rise. T = [( 2 ft ) -1 month] * 4.33 _w_e_e_k.,...s Rate (n + 1 Months) month Using this formulation, the following results are obtained:
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| Rate of Rate Period Available Rise Time Period Height From Differential (ft) ft!month months weeks Detection to Threat Level (Weeks) 2 0.48 4 17.3 -2 0.55 3 13.0 13.7 2 0.69 2 8.7 11.4 2 0.85 1 4.3 8.2 Using the conservative approach described above, it would still leave at least 8.2 weeks, after discovery that the trigger point had been exceeded, to complete preparations for high water, even if the first opportunity had been missed. The procedure allows three weeks for installation so that there would be 5.2 weeks available to address barrier deficiencies before lake level reaches the design basis flood level. At the time that the barriers would have been set, the deficiencies in setting, placement, gaps, etc. would have been self-evident, just as they were when the station performed a trial placement in 2012. Page 3 of 4 Station Actions related to increasing lake levels: * Weather Conditions are monitored daily by the Shift Technical Advisor and inputted into Safety Monitor * Weekend look ahead by Work Week manager for weather effects on weather impact for weekend on Safety Monitor * Procedurally directed Monthly Recording of Lake Level per PC 80 Part 7 "Lake Level Determination" * Per PC 80 Part 7 at a Lake Level (580.7 ft.') the Jersey Barriers are installed
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| * At a lake level of greater than or equal to 588.2 ft the plant will declare an Unusual Event (HU 1.7) * At a lake level of greater than or equal to 589.2 ft the plant will declare an Alert (HA 1.6) As described previously, it has been calculated that, with the maximum historical lake rise, it would take greater than 8 weeks to reach the CLB lake level of 581.9 ft. from a starting level of 580.7 ft. The jersey barriers , including approximately 1000 sand bags, was installed and inspected in less than 24 hours. Conclusion The time available to respond to rising Lake Michigan pre-storm levels would be at least 8.2 weeks from the time of discovery until the license basis flood level could be attaine During 2012 , when the barriers were installed, it took less than 8 hours. Additionally , installation of the modified barrier (which includes approximately 1000 sand bags) was completed in less than 24 hours. Therefore, there is ample time to install the barriers and take appropriate additional actions. Page 4 of 4
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| }} | | }} |
Text
June 18, 2013
SUBJECT:
POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 NRC INTEGRATED INSPECTION REPORT 05000266/2013011 AND 05000301/2013011, PRELIMINARY YELLOW FINDING
Dear Mr. Meyer:
This letter refers to the inspection conducted from April 4, 2013 through June 6, 2013 for your Point Beach Nuclear Plant. The purpose of the inspection was to follow-up on issues identified during completion of Temporary Instruction (TI) 2515/187, Inspection of Near-Term Task Force Recommendation 2.3 Flooding Walk Downs. The issues were classified as a finding for the licensees lack of procedural requirements to appropriately implement external flooding wave run-up protection design features as described in the Final Safety Analysis Report. The finding was classified as an apparent violation with significance to be determined and was documented in NRC Inspection Report 05000266/2013002 and 05000301/2013002 (ML13133A356). The enclosed report documents the results of the follow-up efforts of this inspection, which were discussed on June 6, 2013, with you.
Based on the results of this inspection, the NRC has preliminarily determined the finding to be a Yellow finding with substantial safety significance that will result in additional NRC inspections and potentially other NRC action. As described in Section 4OA5, the inspection-identified finding involved the licensees lack of procedural requirements to appropriately implement external flooding wave run-up protection design features as described in the Final Safety Analysis Report. Specifically, the licensees procedure, as implemented, would not have protected safety-related equipment in the turbine building or pumphouse.
The finding does not present an immediate safety concern because the licensee has taken corrective action and revised the procedure to implement the wave run-up protection features.
Specifically, the licensees procedure has been revised to direct the installation of jersey barriers in conjunction with the use of sandbags, existing jersey barriers have been modified, and sandbags and additional jersey barriers have been purchased and pre-staged. This finding was assessed based on the best available information, using the applicable significance determination process (SDP). The basis for the NRCs preliminary significance determination is described in the enclosed report. This finding is also an apparent violation of NRC requirements and is being considered for escalated enforcement action in accordance with the NRC Enforcement Policy. The current Enforcement Policy is included on the NRCs Web site at http://www.nrc.gov/about-nrc/regulatory/enforcement/enforce-pol.html.
In accordance with NRC Inspection Manual Chapter (IMC) 0609, we intend to complete our evaluation using the best available information and issue our final determination of safety significance within 60 days of the date of this letter. The significance determination process encourages an open dialogue between the NRC staff and the licensee; however, the dialogue should not impact the timeliness of the staffs final determination. Before we make a final decision on this matter, we are providing you with an opportunity (1) to attend a Regulatory Conference where you can present to the NRC your perspective on the facts and assumptions the NRC used to arrive at the finding and assess its significance, or (2) submit your position on the finding to the NRC in writing. If you request a Regulatory Conference, it should be held within 30 days of the receipt of this letter and we encourage you to submit supporting documentation at least one week prior to the conference in an effort to make the conference more efficient and effective. If a Regulatory Conference is held, it will be open for public observation. If you decide to submit only a written response, such submittal should be sent to the NRC within 30 days of your receipt of this letter. If you decline to request a Regulatory Conference or submit a written response, you relinquish your right to appeal the final Significance Determination Process determination, in that by not doing either, you fail to meet the appeal requirements stated in the Prerequisite and Limitation sections of Attachment 2 of Inspection Manual Chapter 0609.
Please contact Mr. Jamnes Cameron at 630-829-9833 and in writing within 10 days from the issue date of this letter to notify the NRC of your intentions. With this notification you are requested to provide a list of equipment that is impacted by the flood levels of interest (wave run-up from 592 to 596 feet mean sea level (MSL), impounding up to 2 feet of water at the turbine building grade level), the basis for the list of equipment, and a discussion of any differences between assumed flood impacts documented in the Individual Plant Examination of External Events (IPEEE), the internal flooding Probabilistic Risk Assessment (PRA) notebook, and the Flooding Vulnerability Report, dated October 26, 2012. This information will allow us to refine our current significance determination. If we have not heard from you within 10 days, we will continue with and finalize our significance determination and enforcement decision. The final resolution of this matter will be conveyed in separate correspondence.
Because the NRC has not made a final determination in this matter, no Notice of Violation is being issued for the inspection finding at this time. In addition, please be advised that the number and characterization of the apparent violation described in the enclosed inspection report may change as a result of further NRC review. In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter, its enclosure, and your response (if any) will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records System (PARS)
component of NRC's Agencywide Document Access and Management System (ADAMS).
ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).
Sincerely,
/RA/
Steven A. Reynolds, Director
Division of Reactor Projects
Docket Nos. 50-266; 50-301 License Nos. DPR-24; DPR-27
Enclosure:
Inspection Report 05000266/2013011 and 05000301/2013011 w/Attachment: Supplemental Information
REGION III==
Docket Nos:
50-266, 50-301 License Nos:
DPR-24, DPR-27 Report No:
05000266/2013011; 050000301/2013011 Licensee:
NextEra Energy Point Beach, LLC Facility:
Point Beach Nuclear Plant Location:
Two Rivers, WI Dates:
April 4, 2013 through June 6, 2013 Inspectors:
S. Burton, Senior Resident Inspector
D. Betancourt, Acting Senior Resident Inspector
M. Thorpe-Kavanaugh, Resident Inspector
L. Kozak, Senior Reactor Analyst
Approved by:
J. Cameron, Branch Chief
Branch 6
Division of Reactor Projects
SUMMARY OF FINDINGS
IR 05000266/2013011; 050000301/2013011; 04/03/2013 - 06/06/2013; Point Beach Nuclear
Plant, Flood Protection This report covers the circumstance behind the failure to establish a procedure to implement external flooding wave run-up design features. The NRC staff identified one finding, preliminarily determined to be
- Yellow.
The preliminary Yellow finding is associated with a violation of NRC requirements. The significance of inspection findings is indicated by their color (i.e., greater than Green, or Green, White, Yellow, Red) and determined using Inspection Manual Chapter (IMC) 0609, Significance Determination Process, dated June 2, 2011. The cross-cutting aspect is determined using IMC 0310, Components Within the Cross-Cutting Areas, dated October 28, 2011. All violations of NRC requirements are dispositioned in accordance with the NRC's Enforcement Policy dated January 28, 2013. The NRC's program for overseeing the safe operation of commercial nuclear power reactors is described in NUREG-1649, "Reactor Oversight Process," Revision 4, dated December 2006.
NRC-Identified
and Self-Revealed Findings
Cornerstone: Mitigating Systems
Criterion V, Instructions, Procedures, and Drawings, was identified by the inspectors in that from January 19, 1996 until March 13, 2013, the licensee failed to have a procedure appropriate to the circumstances to address external flooding as described in the Final Safety Analysis Report (FSAR.) Specifically, Procedure PC 80 Part 7, as implemented, would not protect safety-related equipment in the turbine building or pumphouse because the procedure (1) did not appropriately prescribe the installation of barriers such that gaps in or between the barriers were eliminated to prevent water intrusion, (2) did not protect equipment by requiring barriers to be placed in front of the doors, from 1996 to 2008, as described in the FSAR, and (3) did not require the barriers to protect the plant to an elevation of at least 9 feet (589 foot elevation) as described in the FSAR.
The performance deficiency was screened against the Reactor Oversight Process per the guidance of lMC 0612, Appendix B, and determined to be more than minor because the finding was associated with the Mitigating Systems Cornerstone attributes of Protection Against External Factors (Flood Hazard) and Procedure Quality, and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences (i.e. core damage). Specifically, the licensees failure to procedurally control and maintain external flooding design features and to provide procedural controls for external events could negatively impact mitigating systems ability to respond to an external flooding event. The inspectors evaluated the finding using IMC 0609,
Attachment 0609.04, Tables 2 and 3, and Appendix A, and determined a detailed risk evaluation was needed. This finding does not present an immediate safety concern, in that, the licensee has taken corrective action and revised procedures implementing wave run-up protection features. Specifically, the licensees procedure has been revised to direct the installation of jersey barriers in conjunction with the use of sandbags, existing jersey barriers have been modified, and sandbags and additional jersey barriers have been purchased and pre-staged. These issues are being characterized as an apparent violation in accordance with the NRC's Enforcement Policy, with its final significance to be dispositioned in separate future correspondence. This finding has a cross-cutting aspect in the area of problem identification and resolution, corrective action program, because the licensee failed to thoroughly evaluate problems such that the resolutions address causes and extent of conditions P.1(c). (Section 4OA5)
B.
Licensee-Identified Violation None
REPORT DETAILS
OTHER ACTIVITIES
Cornerstones: Mitigating Systems
4OA5 Other Activities
.1 Failure to Establish an Adequate Procedure to Implement External Flooding Wave Run-
Up Design Features
a. Inspection Scope
The inspectors and the Senior Reactor Analyst (SRA) completed their inspection and assessment of a finding classified as an apparent violation with significance to be determined that was previously documented in NRC Inspection Report 05000266/2013002 and 05000301/2013002 (ML13133A356). The inspection and assessment included the review of procedures and information to preliminarily determine the significance of the finding and apparent violation.
b.
Introduction A finding of potential substantial safety significance (Preliminary Yellow) and an apparent violation of 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, was identified by the inspectors in that from January 19, 1996 until March 13, 2013, the licensee did not have a procedure that provided for Final Safety Analysis Report (FSAR) design criteria for external flooding wave run-up protection.
Specifically, the licensees procedure, as implemented, would not protect safety-related equipment in the turbine building or pumphouse.
Description The description of the finding was documented in NRC Inspection Report 05000266/2013002 and 05000301/2013002 (ML13133A356) and is reproduced here for convenience.
As an extent of condition review from URI 05000266/2012002 01; 05000301/2012002 01, and in response to TI-187, the inspectors reviewed the licensing basis information and found that the FSAR described external flooding design features and mitigating strategies to protect against a wave run-up flooding event. This flooding event is postulated to occur when waves from Lake Michigan break over the bank entering the circulating water pumphouse and turbine buildings through existing non-watertight doors in each structure. The FSAR states that the site would protect the turbine building and pumphouse by using sandbags, concrete jersey barriers, or equivalent barriers placed on the north and south sides of the circulating water pumphouse just to the west of the walkway.
Licensee procedure PC 80 Part 7, Lake Water Level Determination, implemented these features as described in the FSAR. The inspectors reviewed PC 80 Part 7 and found that guidance was only provided for installation of concrete jersey barriers.
The licensee performed a walkthrough of the sites flooding procedure in response to the NRCs 50.54(f) Near-Term Task Force Review of Insights from the Fukushima Dai-Ichi Accident, letter which requested flood area walkdowns and procedure walkthroughs. During the performance of TI-187, the inspectors reviewed the licensees Wave Run-Up Mitigation Package and observed the PC 80 Part 7 walkthrough. During the walkthrough, the licensee discovered that the jersey barriers could not be installed as described in the procedure.
Specifically, that the area where the jersey barriers were to be installed was not a hardened flat surface; therefore, when the jersey barriers were installed, the barriers were not flush with the ground, and a 4-inch gap was created, which allowed water intrusion past the barriers. The licensee also discovered that the jersey barriers could not be installed against one another due to the existence of rebar at either end of the barriers. This created a gap between each barrier that allowed water intrusion between each of the barriers. Also, the bottom of the jersey barriers were cut to allow them to be moved by use of a forklift creating holes in the bottom of each barrier that allowed water intrusion past the barriers.
Additionally, the length of the barriers was insufficient to provide protection as needed. An additional 8.42-foot jersey barrier on each side of the pumphouse would need to be installed beyond what was previously identified to provide the needed protection against wave run-up. Finally, the barriers were to be installed in areas that were identified as B.5.b equipment staging areas and consideration of the design interfaces was not assessed. The licensee entered the identified deficiencies into the CAP as AR01809095, AR01824582, AR01807841, and AR01806402.
Although the licensee identified this issue described above in response to the NRCs 50.54(f) letter, the inspectors found that the licensee did not assign prompt corrective actions to fix the deficient barriers until prompted by inspectors; the licensee did not consider the amount of time needed to erect the barriers until prompted by inspectors; and the licensee did not recognize the need to perform additional evaluations for crediting the use of sandbags and jersey barriers until prompted by inspectors. The licensee documented these concerns in AR01853775, AR01853779, and AR01849522, as well as updated the above-listed CRs and corrective actions due dates to ensure the wave run-up design features were fully evaluated. Therefore, this finding will be characterized as NRC identified because the inspectors added value in the identification of previously unknown weakness in the licensees initial classification, evaluation, and corrective actions associated with this issue.
The licensee initiated AR01856327 in response to the inspectors concerns.
Analysis
The initial analyses of the finding were documented in NRC Inspection Report 05000266/2013002 and 05000301/2013002 (ML13133A356) and are reproduced here for convenience. The additional analyses performed are documented after the reproduced sections.
The inspectors determined that the licensees failure to establish appropriate procedural requirements to implement external flooding wave run-up protection design features as described in the FSAR was a performance deficiency warranting further evaluation.
The inspectors determined that this finding was more than minor in accordance with IMC 0612, Appendix B, because the finding was associated with the Mitigating Systems Cornerstone attributes of Protection Against External Factors (Flood Hazard) and Procedure Quality, and adversely affected the Cornerstone objective to ensure the availability reliability, and capability of systems that respond to initiating events to prevent undesirable consequences (i.e. core damage). Specifically, the licensees failure to procedurally control and maintain external flooding design features, and provide appropriate procedure directions for responses to external events, could negatively impact mitigating systems ability to respond to an external flooding event.
The inspectors evaluated the finding using IMC 0609, Attachment 0609.04, Tables 2 and 3, and Appendix A for the Mitigating Systems Cornerstone. The inspectors answered Yes to the Appendix A, Exhibit 2.B question for external event mitigating systems (Seismic/Fire/Flood/Severe Weather Protection Degraded), because it represented loss or degradation of equipment designed to mitigate a flooding event. Specifically, the jersey barriers were determined to not be of sufficient length to provide protection and allowed water intrusion past the barriers. The inspectors answered No to Exhibit 4, Question 1, because, if it is assumed the barrier was completely failed or unavailable, the loss of the barrier by itself during the event it was intended to mitigate, would not cause a plant trip or initiating event, would not degrade two or more trains, and would not degrade one train of a system that supports a risk significant system or function. The inspectors answered Yes to Exhibit 4, Question 2, because the finding involved the loss of any safety function identified by the licensee through IPEEE analysis.
Specifically, the licensees IPEEE credits sandbags to protect against external flooding events. Since the licensee substituted the use of jersey barriers in place of sandbags, the jersey barriers were determined to not be able perform the safety function as described. Therefore, the inspectors determined that a detailed risk evaluation was needed.
The RIII SRA performed a preliminary detailed risk evaluation using the external flooding baseline risk evaluation from the licensees Individual Plant Examination of External Events (IPEEE), dated June 30, 1995. The SRA also considered additional risk information provided by the licensee PRA staff in a document titled, Point Beach External Flood Safety Significance Determination dated April 26, 2013. The preliminary change in core damage frequency (CDF) was estimated to be 1.8E-5, which is a finding of substantial safety significance (Yellow).
The FSAR described flood protection measures to protect the plant to the 589 foot elevation which provided for a small margin from the design basis wave run-up event of 588.62 foot elevation. In the IPEEE, the licensee evaluated the risk of external flooding due to high still water lake level plus wave run-up. The IPEEE credited the use of sandbags built to the 589 foot elevation which is a height of one foot around the turbine building grade level and two feet around the circulating water pumphouse. The IPEEE further assumed that flooding in the buildings would occur if the sandbags were overtopped by wave run-up by one foot.
The sandbagging method of flood protection was replaced in 1996 by a method using concrete jersey barriers. To model the performance deficiency, the SRA assumed that no flood protection was installed (i.e., no sandbags, jersey barriers, or equivalent installed). The baseline risk was estimated using the IPEEE information which credited sandbag protection. The CDF was estimated by calculating the risk of external flooding with no flood protection and subtracting the baseline risk.
The IPEEE analysis assumed that to fail safety-related equipment in the plant, 6 to 12 inches of water must accumulate above plant grade in between the circulating water pumphouse and the turbine building. Plant grade was assumed to be 588.2 ft. One foot of water was assumed to accumulate for a wave run-up event to the 592 ft. elevation and two feet of water was assumed to be impounded for a wave run-up event to 596 ft.
elevation. With this information, the SRA determined that the sandbagging method provided some protection for a wave run-up event between 592 ft. and 596 ft. This was the range of wave run-up events used in the preliminary detailed risk analysis. The IPEEE analysis further assumed that the sandbags must be overtopped by 1 ft. of water to result in flooding necessary to fail safety-related equipment. Table 5.2.7-1 of the IPEEE lists the critical equipment assumed to be rendered unavailable if the buildings are flooded, The licensee derived the flood frequencies for various wave run-up levels from the IPEEE and documented this in their safety significance determination. The SRA used these values in the preliminary detailed risk evaluation. The frequency of a wave run-up event exceeding 592 ft. was estimated to be 7.3E-4/yr. For the baseline risk estimate, the SRA assumed that the sandbagging method of protection had a failure probability of 0.1. If sandbagging failed, water would enter the turbine building, control building and circulating water pumphouse and impact plant equipment. For the performance deficiency risk estimate, the flood protection features were assumed to be failed.
The SRA assumed that the wave run-up event was concurrent with a weather-related loss of offsite power (LOOP) event. The flood itself does not cause the LOOP to occur; it is assumed that the wind and weather necessary to cause the wave run-up also causes a LOOP. The SRA used a modified version of the current Point Beach Standardized Plant Assessment Risk model to estimate a conditional core damage probability (CCDP) assuming a weather-related LOOP occurs and the flood impacts mitigating equipment in the turbine building, control building, and the circulating water pumphouse. To calculate the CCDP, the SRA used the list of equipment impacted by the flood as defined by the licensee in their safety significance determination. The SRA determined through discussion with the licensee PRA staff that the source of the list of equipment impacted was a recently issued Internal Flooding PRA notebook. The SRA calculated a CCDP of 2.7E-2. Using this CCDP and the other inputs described above results in a CDF result of 1.8E-5/yr, which is a finding of substantial safety significance (Preliminary Yellow). The dominant sequence was a wave run-up flood event with a concurrent weather-related LOOP, followed by the failure of auxiliary feedwater and the failure of feed and bleed. The failure of auxiliary feedwater is in part due to flood effects and in part due to random failures of other equipment or operator actions necessary to maintain a long term auxiliary feedwater suction source.
To complete the final significance determination, the NRC has determined that additional review of the flood effects on equipment is necessary because several sources of relevant information reviewed contained conflicting information regarding the vulnerability of plant components to internal building water levels. Specifically, the NRC plans to perform additional reviews of available plant information on the impact of flooding in the turbine building, control building, and circulating water pumphouse.
Enforcement:
A preliminary safety significant (Yellow) finding and an apparent violation of 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures, and Drawings, was identified by the inspectors in that from January 19, 1996 until March 13, 2013, the licensee failed to have a procedure appropriate to the circumstances to address flooding as described in the FSAR. Specifically, procedure PC 80 Part 7, as implemented, would not protect safety-related equipment in the turbine building or pumphouse because the procedure
- (1) did not appropriately prescribe the installation of barriers such that gaps in or between the barriers were eliminated to prevent water intrusion,
- (2) did not protect equipment by requiring barriers to be placed in front of the doors, from1996 to 2008, as described in the FSAR, and
- (3) did not require the the barriers to protect the plant to an elevation of at least 9 feet (589 foot elevation elevation) as described in the FSAR.
The licensee entered this issue into the CAP as AR01856327. Completed corrective actions include: procedure revision; installation of jersey barriers in conjunction with the use of sandbags; modified existing jersey barriers; and, sandbags and additional jersey barriers have been purchased and pre-staged. This is being characterized as an AV in accordance with the NRC's Enforcement Policy, and its final significance will be dispositioned in separate future correspondence (AV 05000266/2013002-10; 05000301/2013002-10, Failure to Establish A Procedure to Implement Wave Run-Up Design Features).)
4OA6 Management Meetings
.1
Exit Meeting Summary
On June 6, 2013, the inspection results were presented to Mr. L. Meyer. The licensee acknowledged the issues presented. None of the potential report input discussed was considered proprietary.
4OA7 Licensee-Identified Violations
None.
ATTACHMENT:
SUPPLEMENTAL INFORMATION
KEY POINTS OF CONTACT
Licensee
- L. Meyer, Site Vice President
Ron Seizert, Licensing Supervisor
Anil Julka, PRA Engineer, NextEra Energy
Jon Leiker, PRA Engineer, Point Beach
Nuclear Regulatory Commission
- J. Cameron, Branch Chief
LIST OF ITEMS
OPENED, CLOSED AND DISCUSSED
Discussed
- 05000266/2013002-10;
- 05000301/2013002-10 AV Failure to Establish A Procedure to Implement Wave Run-Up Design Features
LIST OF DOCUMENTS REVIEWED