ML070380083
| ML070380083 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 02/07/2007 |
| From: | Moroney B NRC/NRR/ADRO/DORL/LPLII-2 |
| To: | Singer K Tennessee Valley Authority |
| Moroney B, NRR/DORL, 415-3974 | |
| Shared Package | |
| ML070380113 | List: |
| References | |
| Download: ML070380083 (4) | |
Text
February 7, 2007 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:
WATTS BAR NUCLEAR PLANT, UNIT 1 - AUDIT REPORT OF NEW STRAINER DESIGN IN RESPONSE TO GENERIC LETTER 2004-02 AND GENERIC SAFETY ISSUE-191 The enclosed report provides the results of the U.S. Nuclear Regulatory Commission (NRC) staff audit of the design, and the associated analysis and testing of the new sump strainer design at the Tennessee Valley Authoritys (the licensee) Watts Bar Nuclear Plant, Unit 1 (WBN).
The audit report includes a review of the design of the planned sump modifications, the evaluation of upstream and downstream blockage, and other post-accident debris effects identified in Generic Letter (GL) 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation during Design Basis Accidents at Pressurized-Water Reactors. It also provides detailed feedback on each section of the licensees sump performance evaluation (e.g., debris generation, debris transport, head loss), identifying areas that were adequately addressed, as well as areas for which further analysis or justification may be warranted. Overall, the staffs impression is that the WBN new sump modifications appear to be robust with sufficient design margin. However, the final conclusions regarding the adequacy of the licensees corrective actions for GL 2004-02 will be based on the staffs review of open items resulting from this audit and on any other supplemental responses to GL 2004-02.
This was the first of several audits to be conducted by the NRC staff to help verify the adequacy of corrective actions to address GL 2004-02. The WBN staff was very supportive during the audit. In particular, the NRC staff appreciates the effort to obtain detailed reactor vessel internal structure hydraulic data. This first audit was a learning process for both the licensee and the NRC staff, and the licensees flexibility and cooperation were crucial in the successful completion of the audit.
In addition to providing feedback on the WBN sump performance evaluation, the report also documents staff findings that have significant generic implications. Thus, the report will serve as a vehicle to inform other licensees of the staffs technical positions. The staff provided the draft audit report to the licensee on November 28, 2006, and requested that it be reviewed for any proprietary information. On January 25, 2007, Mr. James Smith, WBN Licensing Manager, informed the staff that no proprietary information was found in the report.
K. Singer Therefore, the report will be made available to the public in the NRCs Agencywide Document Access and Management System (Accession Number ML062120469) and through the NRC public web site (www.nrc.gov).
If you have any questions, please contact me at (301) 415-3974.
Sincerely,
/RA/
Brendan T. Moroney, Project Manager Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-390
Enclosure:
Audit Report cc w/o enclosure: See next page
ML070380083 Package: ML070380113 NRR-106 OFFICE LPL2-2/PM LPL2-2/LA SSIB/BC LPL2-2/BC (A)
NAME BMoroney RSola MScott MChernoff DATE 02/07/07 02/07/07 02/07/07 02/07/07
Mr. Karl W. Singer Tennessee Valley Authority WATTS BAR NUCLEAR PLANT cc:
Mr. Ashok S. Bhatnagar, Senior Vice President Nuclear Operations Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. Preston D. Swafford, Senior Vice President Nuclear Support Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. Larry S. Bryant, Vice President Nuclear Engineering & Technical Services Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. Michael D. Skaggs, Site Vice President Watts Bar Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Spring City, TN 37381 General Counsel Tennessee Valley Authority 6A West Tower 400 West Summit Hill Drive Knoxville, TN 37902 Mr. John C. Fornicola, Manager Nuclear Assurance Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. Robert H. Bryan, Jr., General Manager Licensing and Industry Affairs Tennessee Valley Authority 4X Blue Ridge 1101 Market Street Chattanooga, TN 37402-2801 Ms. Beth A. Wetzel, Manager Corporate Nuclear Licensing and Industry Affairs Tennessee Valley Authority 4X Blue Ridge 1101 Market Street Chattanooga, TN 37402-2801 Mr. James D. Smith, Acting Manager Licensing and Industry Affairs Watts Bar Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Spring City, TN 37381 Mr. Michael J. Lorek, Plant Manager Watts Bar Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Spring City, TN 37381 Senior Resident Inspector Watts Bar Nuclear Plant U.S. Nuclear Regulatory Commission 1260 Nuclear Plant Road Spring City, TN 37381 County Executive 375 Church Street Suite 215 Dayton, TN 37321 County Mayor P. O. Box 156 Decatur, TN 37322 Mr. Lawrence E. Nanney, Director Division of Radiological Health Dept. of Environment & Conservation Third Floor, L and C Annex 401 Church Street Nashville, TN 37243-1532 Ms. Ann P. Harris 341 Swing Loop Road Rockwood, TN 37854