ML071500398
| ML071500398 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar, Sequoyah  |
| Issue date: | 06/15/2007 |
| From: | Catherine Haney Plant Licensing Branch III-2 |
| To: | Campbell W Tennessee Valley Authority |
| Haney C, NRC/NRR/DORL, 415-1453 | |
| References | |
| GI-189 | |
| Download: ML071500398 (6) | |
Text
June 15, 2007 Mr. William R. Campbell, Jr.
Chief Nuclear Officer and Executive Vice President Tennessee Valley Authority 1101 Market Street Chattanooga, TN 37402-2801
SUBJECT:
SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2, AND WATTS BAR NUCLEAR PLANT, UNIT 1 - COMMITMENT FOR HYDROGEN IGNITER BACKUP POWER SUPPLY AND CLOSURE PROCESS FOR GENERIC ISSUE 189, SUSCEPTIBILITY OF ICE CONDENSER AND MARK III CONTAINMENTS TO EARLY FAILURE FROM HYDROGEN COMBUSTION DURING A SEVERE ACCIDENT
Dear Mr. Campbell:
This letter acknowledges your March 6, 2007, letter committing to changes at the Sequoyah Nuclear Plant (SQN), Units 1 and 2, and the Watts Bar Nuclear Plant (WBN), Unit 1, that will enhance plant capabilities to mitigate the potential for early containment failure from hydrogen combustion. The proposed changes involve revising procedures to supply power to one train of igniters for each unit using existing backup generators.
The U.S. Nuclear Regulatory Commission (NRC) staff agrees that the proposed changes will resolve concerns related to Generic Issue 189 (GI-189), Susceptibility of Ice Condenser and Mark III Containments to Early Failure from Hydrogen Combustion During a Severe Accident, and provide benefits for certain security scenarios. The NRC staff understands that your commitment will enhance the electrical independence of the containment hydrogen igniter system. This action is warranted for pressurized water reactors with ice condenser containments because many systems that prevent core damage rely on the same power supplies and electrical distribution system as the hydrogen igniters. This enhancement mitigates the potential for early containment failure by allowing control of hydrogen within containment following certain beyond-design-basis events that may progress to core damage and preclude operation of the hydrogen igniters from the normal power supply. The NRC staff expects this enhancement will provide hydrogen igniter system electrical independence commensurate with the expected frequency, challenges, and uncertainties associated with these beyond-design-basis events.
Consistent with the guidelines of NRC Management Directive 6.4, Generic Issues Program, the NRC staff will perform verification inspections at SQN and WBN. These inspections will include elements to verify that you establish procedures to provide backup power to the hydrogen igniters, train appropriate staff in the procedures, and institute appropriate controls on the reliability and availability of necessary equipment. Procedures that allow trained personnel to establish backup power to the igniters within 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> are fully consistent with goals to
W. R. Campbell, Jr. mitigate potential hydrogen accumulation. The NRC staff understands that implementation of vendor recommended maintenance and existing procedures will ensure adequate availability and reliability of the backup power supplies. In addition, NRC licensing project managers may verify the integrity of your commitments over time through established review procedures for your commitment management program.
Verification of your committed actions and those of other affected licensees will provide the basis by which the NRC will close out GI-189. The NRC staff will perform the verification inspections at a time consistent with the implementation date specified in your letter.
Accordingly, please keep the NRC staff informed of any changes in the scope of modifications or the implementation date.
Sincerely,
/RA/
Catherine Haney, Director Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-327, 50-328, and 50-390 License Nos. DPR-77, DPR-79, and NPF-90 cc: See next page
W. R. Campbell, Jr. mitigate potential hydrogen accumulation. The NRC staff understands that implementation of vendor recommended maintenance and existing procedures will ensure adequate availability and reliability of the backup power supplies. In addition, NRC licensing project managers may verify the integrity of your commitments over time through established review procedures for your commitment management program.
Verification of your committed actions and those of other affected licensees will provide the basis by which the NRC will close out GI-189. The NRC staff will perform the verification inspections at a time consistent with the implementation date specified in your letter.
Accordingly, please keep the NRC staff informed of any changes in the scope of modifications or the implementation date.
Sincerely,
/RA/
Catherine Haney, Director Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos.: 50-327, 50-328, and 50-390 License Nos.: DPR-77, DPR-79, and NPF-90 cc: See next page DISTRIBUTION:
PUBLIC LPL2-2 R/F RidsNrrDorlLpl2-2 RidsNrrPMBMoroney RidsNrrLACSola RidsRgn2MailCenter RidsNrrDorl RidsNrrDss RidsNrrDssSbpb RidsNrrDprPgcb ADAMS Letter: ML071500398 OFFICE DSS/SBPB DSS/SBPB:BC DSS:D DPR/PGCB DIRS:D DORL/LPL2-2:LA DORL/LPL2-2:PM DORL:D NAME SJones JSegala JWermiel JGolla ECollins RSola BMoroney CHaney DATE 06/04/07 06/05/07 06/05/07 06/05/07 06/08/07 06/11/07 06/11/07 06/15/07
W. R. Campbell, Jr.
OFFICIAL RECORD COPY Page 1 of 2 William R. Campbell, Jr.
SEQUOYAH NUCLEAR PLANT Tennessee Valley Authority WATTS BAR NUCLEAR PLANT cc:
Mr. Ashok S. Bhatnagar, Senior Vice President Nuclear Generation Development and Construction 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. Walter M. Justice, II Interim 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 Mr. Randy Douet, Site Vice President Sequoyah Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Soddy Daisy, TN 37384-2000 General Counsel Tennessee Valley Authority ET 11A 400 West Summit Hill Drive Knoxville, TN 37902 Mr. John C. Fornicola, General 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. Glenn W. Morris, Manager Licensing and Industry Affairs Sequoyah Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Soddy Daisy, TN 37384-2000 Mr. David A. Kulisek, Plant Manager Sequoyah Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Soddy Daisy, TN 37384-2000 Senior Resident Inspector Sequoyah Nuclear Plant U.S. Nuclear Regulatory Commission 2600 Igou Ferry Road Soddy Daisy, TN 37379 County Mayor
W. R. Campbell, Jr.
Hamilton County Courthouse Chattanooga, TN 37402-2801 Page 2 of 2 William R. Campbell, Jr.
SEQUOYAH NUCLEAR PLANT Tennessee Valley Authority WATTS BAR NUCLEAR PLANT cc:
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 Mr. Masoud Bajestani Vice President Watts Bar Unit 2 Watts Bar Nuclear Plant Tennessee Valley Authority
W. R. Campbell, Jr.
Page 3 of 3 P.O. Box 2000 Spring City, TN 37381