ML082110382
| ML082110382 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 08/04/2008 |
| From: | Farideh Saba NRC/NRR/ADRO/DORL/LPLII-2 |
| To: | Waldrep B Carolina Power & Light Co |
| Saba F 301-465-1447 | |
| Shared Package | |
| ml082110166 | List: |
| References | |
| Download: ML082110382 (5) | |
Text
August 4, 2008 Mr. Benjamin Waldrep, Vice President Brunswick Steam Electric Plant Carolina Power & Light Company Post Office Box 10429 Southport, North Carolina 28461
SUBJECT:
BRUNSWICK STEAM ELECTRIC PLANT, UNIT 2 - FINAL ACCIDENT SEQUENCE PRECURSOR ANALYSIS OF NOVEMBER 1, 2006, OPERATIONAL EVENT
Dear Mr. Waldrep:
The enclosure provides the final results of the Accident Sequence Precursor (ASP) analyses of an event, which occurred at the Brunswick Steam Electric Plant (BSEP), Unit 2 as documented in Licensee Event Report 324/06-001 on November 1, 2006. Additionally, Region II reviewed the event during baseline and supplemental inspections and issued three Inspection Reports, namely: 05000324/2007008, 05000324/2007009, and 05000324/2007010; discussing the event and documenting the findings for BSEP, Units 1 and 2. The ASP analysis calculated a mean conditional core damage probability of 6x10-6.
The U.S. Nuclear Regulatory Commission (NRC) established the ASP Program in 1979 in response to the Risk Assessment Review Group Report (NUREG/CR-0400, dated September 1978). The ASP Program systematically evaluates nuclear power plant operating experience to identify, document, and rank the operating events that were most likely to have led to inadequate core cooling and severe core damage (precursors), accounting for the likelihood of additional failures.
The NRC currently uses the ASP Program to:
Monitor performance against the safety goal established in the agencys Strategic Plan (see NUREG-1100, Volume 24, Performance Budget: Fiscal Year 2009, issued February 2008).
Provide feedback to improve Standardized Plant Analysis Risk models.
Evaluate the generic implications of precursors and trend industry performance.
Support generic safety issue resolution.
For more information about the ASP program, see the annual ASP program report at http://www.nrc.gov/reading-rm/doc-collections/commission/secys/2007/secy2007-0176/2007-0176scy.pdf
The enclosure is provided for your information and no response is requested. If you have any questions please contact me at 301-415-1447 Sincerely,
/RA/
Farideh E. Saba, Senior Project Manager Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-324
Enclosure:
Final ASP Analysis cc w/encl: See next page
The enclosure is provided for your information and no response is requested. If you have any questions please contact me at 301-415-1447 Sincerely,
/RA/
Farideh E. Saba, Senior Project Manager Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-324
Enclosure:
Final ASP Analysis cc w/encl: See next page DISTRIBUTION:
Public LPL 2-2 R/F RidsNrrDorlLPL2-2 RidsNrrPMFSaba RidsNrrLACSola RidsOgcRp CLui, RES RidsAcrsAcnwMailCenter RidsRgnIIMailCenter ADAMS ACCESSION NOS: Package: ML082110166; Letter: ML082113082 Transmittal of Final ASP Analyses: ML081560691
- By memo dated OFFICE LPL2-2/PM LPL2-2/LA RES/DRA LPL2-2/BC NAME FSaba CSola CLui (JMonninger for)*
TBoyce DATE 08 / 04 /2008 08 / 04 /2008 06/11/2008 08 / 04 /2008 OFFICIAL RECORD COPY
Carolina Power & Light Company Brunswick Steam Electric Plant Unit 2 cc:
David T. Conley Associate General Counsel II -
Legal Department Progress Energy Service Company, LLC Post Office Box 1551 Raleigh, North Carolina 27602-1551 Mr. William M. Sue, Chairperson Brunswick County Board of Commissioners Post Office Box 249 Bolivia, North Carolina 28422 Resident Inspector U. S. Nuclear Regulatory Commission 8470 River Road Southport, North Carolina 28461 Mr. John H. ONeill, Jr.
Pillsbury Winthrop Shaw Pittman, LLP 2300 N Street NW.
Washington, DC 20037-1128 Ms. Beverly Hall, Section Chief Division of Radiation Protection N.C. Department of Environment and Natural Resources 3825 Barrett Dr.
Raleigh, North Carolina 27609-7721 Mr. Edward L. Wills, Jr.
Plant General Manager Brunswick Steam Electric Plant Carolina Power & Light Company Post Office Box 10429 Southport, North Carolina 28461-0429 Public Service Commission State of South Carolina Post Office Drawer 11649 Columbia, South Carolina 29211 Ms. Margaret A. Force Assistant Attorney General State of North Carolina Post Office Box 629 Raleigh, North Carolina 27602 Mr. Robert P. Gruber Executive Director Public Staff - NCUC 4326 Mail Service Center Raleigh, North Carolina 27699-4326 Director, Site Operations Brunswick Steam Electric Plant Carolina Power & Light Company Post Office Box 10429 Southport, North Carolina 28461-0429 Sandra Spencer, Mayor City of Southport 201 East Moore Street Southport, North Carolina 28461 Mr. Warren Lee Emergency Management Director New Hanover County Department of Emergency Management Post Office Box 1525 Wilmington, North Carolina 28402-1525 Mr. J. Paul Fulford Manager, Performance Evaluation and Regulatory Affairs PEB5 Carolina Power & Light Company Post Office Box 1551 Raleigh, North Carolina 27602-1551
Enclosure FINAL ACCIDENT SEQUENCE PRECURSOR ANALYSIS OF NOVEMBER 1, 2006, OPERATIONAL EVENT BRUNSWICK STEAM ELECTRIC PLANT (BSEP), UNIT NO. 2 DOCKET NO. 50-324 Reactor Trip and Loss of Offsite Power Caused by Line-to-Ground Fault on the Startup Auxiliary Transformer (November 2006) at BSEP, Unit 2: This event is documented in Licensee Event Report 324/06-001. Additionally, Region II reviewed the event during baseline and supplemental inspections and issued three inspection reports, namely: 05000324/2007008, 05000324/2007009, and 05000324/2007010; discussing the event and documenting the findings for both units.
Condition Summary: On November 1, 2006, at 1823 BSEP, Unit 2 (the unit) experienced a loss of the units Startup Auxiliary Transformer (SAT) resulting in a loss of reactor forced circulation and subsequent manual reactor trip. Due to the loss of the SAT, offsite power to the unit's emergency busses was lost when the units main generator tripped. The four emergency diesel generators (EDGs) properly started and EDGs 3 and 4 supplied the units emergency busses.
EDGs 1 and 2 continued to run unloaded, per design, until, at approximately 0400 on November 2, 2006 (i.e., after approximately 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> and 37 minutes of run time), EDG 1 tripped.
EDGs 3 and 4 were unaffected by the tripping of EDG 1 and continued to supply the units emergency busses until offsite power was restored to the emergency busses via backfeed through the units auxiliary transformer at 1745 on November 2, 2006.
Results; This initiating event resulted in a point estimate conditional core damage probability (CCDP) of 5.2x10-6. An uncertainty analysis for this operating condition was also performed resulting in a mean CCDP of 6x10-6 with 5 percent and 95 percent uncertainty bounds of 1x10-6 and 2x10-5, respectively. The ASP analysis can be accessed from the NRCs Agencywide Documents Access and Management System through Accession No. ML081350025.
Principal Contributor: Christopher Hunter Date: August 4, 2008