ML082460906

Dam Safety Inspection Results and Future Scheduling

ML082460906
Person / Time
Site:	Watts Bar
Issue date:	08/29/2008
From:	Brandon M Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML082460906 (14)

Text

Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381-2000 AUG 2 9 2008 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Gentlemen:

In the Matter of the

)

Docket Nos. 50-390 Tennessee Valley Authority

)

50-391 WATTS BAR NUCLEAR PLANT (WBN) - DAM SAFETY INSPECTION RESULTS AND FUTURE SCHEDULING In response to the teleconference held on July 21, 2008, provided in the Enclosure is a copy of the most recent Dam Safety Inspection report for the Yard Holding Pond on site at WBN.

The future inspections of this dam are being tracked in the Enterprise Maintenance Planning and Control (EMPAC) system for intervals of 2.5 years and 5 years. In addition, TVA has reviewed the applicable criteria and determined that no structures at Sequoyah Nuclear Plant or Browns Ferry Nuclear Plant qualify under the Federal Guidelines as dams.

There are no regulatory commitments associated with this submittal. If you have any questions concerning this matter, please call Rusty Tompkins, Dam Safety Manager, at (423) 751-6111.

Sincerely, M. K. Brandon Manager, Site Licensing and Industry Affairs Enclosure cc: See Page 2 k~O

U.S. Nuclear Regulatory Commission Page 2 AUG 2 9 2008 Enclosures cc (Enclosures):

U.S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303 ATTN: George A. Wilson U.S. Nuclear Regulatory Commission OWFN 9 E3 Washington, DC 20555-0001

ENCLOSURE Watts Bar Nuclear Plant Dam Safety Inspection Report E-1

Dam Safety Inspection Report - Class A File Number: 91-00 Watts Bar Hydro Plant EDMS Number: J22 080807 001 Special, Nuclear Yard Drainage Holding Pond UNID: WBH-00-INSP-333 -DAM Report ID: ROOWBHCLA082008 Date of Inspection: 05/28/04 Headwater: N/A Tailwater: N/A Inspection

Participants:

Dam Safety: Scott Kramer, Rusty Tompkins WBN Nuclear: Darrin Hutchison, Environmental Tech Support Manager Features Inspected:

Yard Drainage Holding Pond Spillway Dam Attachments to this Inspection Memorandum:

Exhibit 1: Recommendations Exhibit 2: Inspection Procedure, Checklist, Observations Exhibit 3: Photographs Exhibit 4: Drawing 10N225, 10N226, 10W227, 17W303-2 Summary:

A yard drainage holding pond is located at Watts Bar Nuclear plant, which is included in the National Inventory of Dams (NID). The size of the reservoir is such that an embankment dam located at the Southwest corner of the holding pond meets the definition of a dam per the Federal Guidelines for Dam Safety; therefore Dam Safety inspections of this dam are required. This was the first such inspection performed at this facility.

The dam is in satisfactory condition and only some minor maintenance is recommended in Exhibit 1.

Original signed by Scott Kramer, PE Principal Dam Safety Inspection Engineer Original signed by Lynn Petty, PE Manager, Civil Engineering Distribution: Senior Manager, RO Support Services, Gene Gibson; Senior Manager, River Scheduling, Charles Bach, Carol Eimers; Manager, Dam Safety, Russell Tompkins; Manager, Civil Engineering, Lynn Petty; WBN Nuclear, Darrin Hutchison; Facilities Management, Darrel Reed; Dam Safety, Kim Barrett; Chattanooga Dam Safety Files (Hard Copy), BSL (Diana Miles)

E-2

Exhibit 1, Recommendations Watts Bar Hydro Plant Special, Nuclear Yard Drainage Holding Pond Maintenance & Repair Items to be Handled by Other Organizations:

1. PM - Remove the trees located on the upstream and downstream side of the small embankment dam and spillway. Include all trees within 20' of the toe and groin areas.

Responsible Organization: Facilities Maintenance, Darrel Reed Estimated Cost:

$4,000.00 Estimated Completion Date: 3/30/09

2.

PM - Fill the small hole that is undermining the left side of the spillway slab just downstream from the crest of the dam with small 1/2" washed stone.

Responsible Organization: Facilities Maintenance, Darrel Reed Estimated Cost:

$500.00 Estimated Completion Date: 3/30/09 Maintenance & Repair Items:

None Pending Proiects:

None Follow-up Tasks:

None Exhibit 1, Page 1 E-3

Exhibit 2, Inspection Procedure and Checklist Watts Bar Hydro Plant Special, Nuclear Yard Drainage Holding Pond

1. Inspection Procedure:

1.1. See procedure:..\\..\\Inspection Procedures, Civil\\lP2.0 General, Intermediate Civil Inspections.doc 1.2. Equipment Requirements: PPE, Camera

2.

Inspection Checklist:

2.1. Holding Pond Embankment Dam (Including Abutment):

2.1.1.Upstream Face:

2.1.1.1. Slope Protection 2.1.1.2. Erosion 2.1.1.3. Sinkholes, Depressions 2.1.1.4. Vegetation 2.1.1.5. Low Level Outlet Structure 2.1.2. Downstream Face (Including Abutment):

2.1.2.1. Slope Protection 2.1.2.2. Erosion 2.1.2.3. Sinkholes, Depressions 2.1.2.4. Vegetation 2.1.2.5. Seeps 2.2. Spillway Section:

2.2.1.Crest and Downstream Face:

2.2.1.1. Surface Condition of concrete 2.2.1.2. Cracks/ Spalls 2.2.1.3. Block Movement at Joints 2.2.1.4. Leakage 2.2.1.5. Erosion 2.2.1.6. Undermined Holes along Edges Exhibit 2, Page 1 E-4

Exhibit 2, Inspection Procedure and Checklist Watts Bar Hydro Plant Special, Nuclear Yard Drainage Holding Pond

3.

Inspection Observations:

A small yard holding pond of 190 acre-feet is located on the south side of the Watts Bar Nuclear plant, which collects discharge water from the cooling towers during periods of high river water temperatures. A small embankment dam with a concrete overflow spillway is located at the southwest side of the pond. For an overall plan view of the pond and dam, see the attached drawing 10N225. Details of he embankment dam and spillway can be found on drawing 10N226. Since the size of the reservoir is larger than the 50 acre-feet, this dam meets the definition of a dam per the Federal Guidelines for Dam Safety and Dam Safety inspections are required. This dam is classified as a low hazard.

An embankment crosses over the pond in front of the embankment dam, which creates a small pond in front of the actual dam. There are (5) 24" diameter pipes and (1) 24" pipe that directly connects the larger pond with the smaller pond, which acts as a skimmer between the main pond and the smaller pond. Details for the skimmer embankment are located on drawing 1 0W227. This particular feature is not considered as a dam.

An additional embankment separates another small pond at the northwest end of the main pond. A pipe allows water to flow from the smaller pond to the larger pond, therefore this embankment is also not considered as a dam.

Two small aluminum sludge settling ponds are located on the north side of the main yard pond, but these are too small.to be considered as dams.

Also see procedure:..\\..\\Inspection Procedures, Civil\\IP1.5 CivilPost Inspection Activities.doc 3.1. Embankment Dam:

The embankment dam is estimated at 350' long and 19' high above natural ground elevation. A 25' wide uncontrolled concrete overflow spillway is located in the center section.

An inlet structure is located on the upstream left side ofthe embankment dam, from which a 48" diameter pipe is routed in the direction of the Tennessee River. This pipe tees into a 72" pipe that runs from the cooling towers downstream to an outlet structure on the river.

The embankment dam is in satisfactory condition. Numerous trees will require removal per Dam Safety requirements. See Exhibit 1 for recommendations.

3.2. Spillway Section:

The spillway section is in satisfactory condition. A small undermined area is located on the left side of the spillway slab, which allows water to flow underneath the slab. This hole should be filled with small 1/2" stone. See Exhibit 1 for recommendations.

Exhibit 2, Page 2 E-5

Exhibit 3, Inspection Photographs Watts Bar Hydro Plant Special, Nuclear Yard Drainage Holding Pond Figure 1 View of main yard holding pond looking eastward towards the cooling towers.

Figure 2 View of main holding pond taken from same spot at Figure 1, looking towards the Southeast.

Figure 3 View of main holding pond looking towards the northwest and at the location of the photo taken in Figure 2.

Exhibit 3, Page 1 E-6

Exhibit 3, Inspection Photographs Watts Bar Hydro Plant Special, Nuclear Yard Drainage Holding Pond Figure 4:

View of upstream side of dam with the concrete spillway. Note numerous trees that will need to be removed.

Figure 5:

View of crest of dam and upstream edge of concrete spillway. A weir for measuring flow is located on the upstream end of the spillway.

Figure 6:

View of downstream slope of dam, with concrete spillway slab. Note trees located along the toe which will require removal.

Exhibit 3, Page 2 E-7

Exhibit 3, Inspection Photographs Watts Bar Hydro Plant Special, Nuclear Yard Drainage Holding Pond Figure 7:

View of concrete spillway slab on downstream slope.

Figure 8:

View of a small hole that has undermined the concrete spillway slab.

Figure 9:

View of small whirlpool above inlet structure for 48" outlet pipe.

Exhibit 3, Page 3 E-8

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