ML070380083

Audit Report of New Strainer Design in Response to Generic Letter 2004-02 and Generic Safety Issue-191

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: ML070380083
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 Ms. Beth A. Wetzel, Manager Nuclear Operations Corporate Nuclear Licensing and Tennessee Valley Authority 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. Preston D. Swafford, Senior Vice President Nuclear Support Mr. James D. Smith, Acting Manager Tennessee Valley Authority Licensing and Industry Affairs 6A Lookout Place Watts Bar Nuclear Plant 1101 Market Street Tennessee Valley Authority Chattanooga, TN 37402-2801 P.O. Box 2000 Spring City, TN 37381 Mr. Larry S. Bryant, Vice President Nuclear Engineering & Technical Services Mr. Michael J. Lorek, Plant Manager Tennessee Valley Authority Watts Bar Nuclear Plant 6A Lookout Place Tennessee Valley Authority 1101 Market Street P.O. Box 2000 Chattanooga, TN 37402-2801 Spring City, TN 37381 Mr. Michael D. Skaggs, Site Vice President Senior Resident Inspector Watts Bar Nuclear Plant Watts Bar Nuclear Plant Tennessee Valley Authority U.S. Nuclear Regulatory Commission P.O. Box 2000 1260 Nuclear Plant Road Spring City, TN 37381 Spring City, TN 37381 General Counsel County Executive Tennessee Valley Authority 375 Church Street 6A West Tower Suite 215 400 West Summit Hill Drive Dayton, TN 37321 Knoxville, TN 37902 County Mayor Mr. John C. Fornicola, Manager P. O. Box 156 Nuclear Assurance Decatur, TN 37322 Tennessee Valley Authority 6A Lookout Place Mr. Lawrence E. Nanney, Director 1101 Market Street Division of Radiological Health Chattanooga, TN 37402-2801 Dept. of Environment & Conservation Third Floor, L and C Annex Mr. Robert H. Bryan, Jr., General Manager 401 Church Street Licensing and Industry Affairs Nashville, TN 37243-1532 Tennessee Valley Authority 4X Blue Ridge Ms. Ann P. Harris 1101 Market Street 341 Swing Loop Road Chattanooga, TN 37402-2801 Rockwood, TN 37854