ML063130442

RAI, Technical Specification Change Request for Ultimate Heat Sink

ML063130442
Person / Time
Site:	Sequoyah
Issue date:	11/22/2006
From:	Pickett D NRC/NRR/ADRO/DORL/LPLII-2
To:	Singer K Tennessee Valley Authority
Paige, Jason, NRR/JCP4
References
TAC MD2621, TAC MD2622
Download: ML063130442 (4)

Text

November 22, 2006 Mr. Karl W. Singer Chief Nuclear Officer and Executive Vice President Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801

SUBJECT:

SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION REGARDING TECHNICAL SPECIFICATION CHANGE REQUEST FOR ULTIMATE HEAT SINK TEMPERATURE (TAC NOS. MD2621 AND MD2622)

Dear Mr. Singer:

By letter dated July 12, 2006, the Tennessee Valley Authority (TVA, the licensee) submitted Technical Specification Change Request, Section 3.7.9.1, Ultimate Heat Sink (UHS)

Temperature Increase and Elevation Changes, for Sequoyah Nuclear Plant, Units 1 and 2.

This revision will change the minimum UHS water elevation in Section 3.7.5.a from 670 feet to 674 feet. The essential raw cooling water temperature requirement in Section 3.7.5b will be increased from 83 degrees Fahrenheit (°F) to 87 °F.

In order for the staff to complete its review of the information provided by the licensee, we request that TVA provide responses to the enclosed request for additional information (RAI).

Based on discussions with your staff, we understand that you plan to respond to the enclosed RAI within 60 days of receipt of this letter. If you have any questions about this material, please contact me at (301) 415-1364.

Sincerely,

/RA/

Douglas V. Pickett, Senior Project Manager Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-327 & 50-328

Enclosure:

Request for Additional Information cc: See next page

ML063130442 NRR-088 OFFICE LPLI2-2 LPL2-2/PM LPL2-2/LA EGCB/BC LPL2-2/BC (A)

NAME JPaige DPickett RSola RKaras as DPickett (A)LOlshan for signed on DATE 11/ 20 /06 11/ 21 /06 11 / 20 /06 10 / 30 /06 / 11/22 /06 REQUEST FOR ADDITIONAL INFORMATION SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2, TECHNICAL SPECIFICATION CHANGE REQUEST FOR ULTIMATE HEAT SINK TEMPERATURE DOCKET NOS. 50-327 AND 50-328

1. While the applicant assumed a Chickamauga earthdam breach width of 400 feet which is about 5 times dam height as suggested by the U.S. Bureau of Reclamation (1998), a recent study by Wahl (2004; "Uncertainty of Predictions of Embankment Dam Breach Parameters," ASCE J. of Hydraulic Engr. V.130, No. 5) argued that the uncertainties in breach width estimates are widely recognized to be large. For large storage dams, breach width is a function of both breach height and reservoir storage volume.

Therefore, the applicant should consider both breach width and storage volume in estimating breach width. It is expected that the licensees estimate of breach width will consider reasonable assurance for protection of ultimate heat sink (UHS) volume and intake head.

2. Please clarify that there is enough margin to ensure the provision of at least 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of river level above 670 feet following a loss of downstream dam considering the uncertainty in the reservoir recession (drawdown) curves (Graph on Page E1-15) caused by the uncertainty in estimating breach width.

3. Please revise the recession curves in Page E1-15 by taking into account the backwater effect at the Sequoyah Nuclear Plant emergency raw cooling water intake site, which is located about 14 miles upstream of Chickamauga Dam.

4. For the staff to perform its confirmatory analysis, please provide input, output, and source code of the simulated open channel hydraulics model used to construct the tailwater rating curve at the Chickamauga Dam site.

5. While the initial pool level of the Chickamauga reservoir is very sensitive to the rate of reservoir recession, the applicant should justify the use of an initial pool level of 680 feet in simulating reservoir recession curves. Or, please explain why one of driest/wettest water levels should not be used as an initial condition to be conservative.

6. Page 4 in reference #8 of Enclosure 1 states that the reservoir levels are lower at other times of the year, but the ultimate heat sink limit is not approached during this time, which is from December to March. The applicant should verify this statement based on historical water temperatures, water levels, and recorded UHS shutdowns.

7. Please clarify the condition of simulation for the recession curve in Page 18 of Reference #8.

Enclosure

Mr. Karl W. Singer SEQUOYAH NUCLEAR PLANT Tennessee Valley Authority cc:

Mr. Ashok S. Bhatnagar, Senior Vice President Mr. Glenn W. Morris, Manager Nuclear Operations Corporate Nuclear Licensing Tennessee Valley Authority and Industry Affairs 6A Lookout Place Tennessee Valley Authority 1101 Market Street 4X Blue Ridge Chattanooga, TN 37402-2801 1101 Market Street Chattanooga, TN 37402-2801 Mr. Larry S. Bryant, Vice President Nuclear Engineering & Technical Services Mr. Paul L. Pace, Manager Tennessee Valley Authority Licensing and Industry Affairs 6A Lookout Place ATTN: Mr. James D. Smith 1101 Market Street Sequoyah Nuclear Plant Chattanooga, TN 37402-2801 Tennessee Valley Authority P.O. Box 2000 Mr. Robert J. Beecken, Vice President Soddy Daisy, TN 37384-2000 Nuclear Support Tennessee Valley Authority Mr. David A. Kulisek, Plant Manager 6A Lookout Place Sequoyah Nuclear Plant 1101 Market Street Tennessee Valley Authority Chattanooga, TN 37402-2801 P.O. Box 2000 Soddy Daisy, TN 37384-2000 Mr. Randy Douet Site Vice President Senior Resident Inspector Sequoyah Nuclear Plant Sequoyah Nuclear Plant Tennessee Valley Authority U.S. Nuclear Regulatory Commission P.O. Box 2000 2600 Igou Ferry Road Soddy Daisy, TN 37384-2000 Soddy Daisy, TN 37379 General Counsel Mr. Lawrence E. Nanney, Director Tennessee Valley Authority Division of Radiological Health ET 11A Dept. of Environment & Conservation 400 West Summit Hill Drive Third Floor, L and C Annex Knoxville, TN 37902 401 Church Street Nashville, TN 37243-1532 Mr. John C. Fornicola, Manager Nuclear Assurance and Licensing County Mayor Tennessee Valley Authority Hamilton County Courthouse 6A Lookout Place Chattanooga, TN 37402-2801 1101 Market Street Chattanooga, TN 37402-2801 Ms. Ann P. Harris 341 Swing Loop Road Rockwood, Tennessee 37854