ML072910733
| ML072910733 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 10/29/2007 |
| From: | John Hughey NRC/NRR/ADRO/DORL/LPLI-2 |
| To: | Christian D Virginia Electric & Power Co (VEPCO) |
| Sanders, Carleen, NRR/DORL 415-1603 | |
| Shared Package | |
| ML072910721 | List: |
| References | |
| IR-06-002 | |
| Download: ML072910733 (4) | |
Text
October 29, 2007 Mr. David A. Christian President and Chief Nuclear Officer Virginia Electric and Power Company Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711
SUBJECT:
MILLSTONE POWER STATION, UNIT NO. 2 - RE: FINAL ACCIDENT SEQUENCE PRECURSOR ANALYSIS OF FEBRUARY 23, 2006, OPERATIONAL EVENT
Dear Mr. Christian:
The enclosure provides the final results of the Accident Sequence Precursor (ASP) analyses of an event which occurred at Millstone Power Station, Unit No. 2 (MPS2) as documented in Licensee Event Report 336/06-002, dated April 21, 2006, and Inspection Report 05003366/2006002, dated May 5, 2006. These documents are publicly available through the Agencywide Document Access Management System, Accession Numbers ML061220573 and ML061250262, respectively. The subject matter event occurred at MPS2 on February 23, 2006, during which a manual reactor trip was initiated due to both steam generator feed pumps tripping following an instrument air leak. Following the trip, the plant experienced an abnormal cool down in part due to excessive auxiliary feed water flow. The ASP analysis calculated a point estimate conditional core damage probability (CCDP) of 8 x 10-6. The event is categorized as a low risk event (<1 x 10-4), in accordance with Regulatory Issue Summary 2006-24, Revised Review of Transmittal Process for Accident Sequence Precursor Analyses, therefore, this is an informal analysis review.
The U.S. Nuclear Regulatory Commission (NRC or Agency) established the ASP Program in 1979 in response to the Risk Assessment Review Group report (see NUREG/CR-0400, dated September 1978). The ASP Program systematically evaluates U.S. 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 ASP Program has the following objectives:
Provide a measure for trending nuclear power plant core damage risk.
Provide a partial check on dominant core damage scenarios predicted by probabilistic risk assessments.
Provide feedback to regulatory activities.
Evaluate the adequacy of NRC programs.
The NRC also uses the ASP Program to monitor performance against the safety goal established in the agency's Strategic Plan. (See NUREG-1100, Vol. 21, dated February 2005.)
For more information about the ASP program, see the annual ASP program report at http://www.nrc.gov/reading-rm/doc-collections/commission/secys/2005/secy2005-0192/2005-0192scy.pdf.
The enclosure is provided for your information and no response is requested. If you have any questions please contact me at 301-415-3204 Sincerely,
/RA/
John D. Hughey, Project Manager Plant Licensing Branch I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-336
Enclosure:
Final ASP Analysis cc w/encl:
See next page
The NRC also uses the ASP Program to monitor performance against the safety goal established in the agency's Strategic Plan. (See NUREG-1100, Vol. 21, dated February 2005.)
For more information about the ASP program, see the annual ASP program report at http://www.nrc.gov/reading-rm/doc-collections/commission/secys/2005/secy2005-0192/2005-0192scy.pdf.
The enclosure is provided for your information and no response is requested. If you have any questions please contact me at 301-415-3204 Sincerely,
/RA/
John D. Hughey, Project Manager Plant Licensing Branch I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-336
Enclosure:
Final ASP Analysis cc w/encl:
See next page DISTRBUTION:
Public RidsNrrDorlLpl1-2 RidsNrrLAABaxter RidsNrrPMJHughey RidsOgcMailCenter RidsAcrsAcnwMailCenter RidsRgn1MailCenter LPL1-2 R/F FEltawila ADAMS ACCESSION NOS: Package: ML072910721 Letter: ML072910733 Final ASP: ML071910721*By Memorandum dated OFFICE LPL1-2/GE LPL1-2/PM LPL1-2/LA RES/DRASP LPL1-2/BC NAME CSanders JHughey ABaxter FEltawila*
HChernoff DATE 10/24/07 10/24/07 10/23/2007 08/08/2007 10/29/07 OFFICIAL RECORD COPY
Millstone Power Station, Unit No. 2 cc:
Lillian M. Cuoco, Esquire Senior Counsel Dominion Resources Services, Inc.
Building 475, 5th Floor Rope Ferry Road Waterford, CT 06385 Edward L. Wilds, Jr., Ph.D.
Director, Division of Radiation Department of Environmental Protection 79 Elm Street Hartford, CT 06106-5127 Regional Administrator, Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 First Selectmen Town of Waterford 15 Rope Ferry Road Waterford, CT 06385 Charles Brinkman, Director Washington Operations Nuclear Services Westinghouse Electric Company 12300 Twinbrook Pkwy, Suite 330 Rockville, MD 20852 Senior Resident Inspector Millstone Power Station c/o U.S. Nuclear Regulatory Commission P.O. Box 513 Niantic, CT 06357 Mr. J. Alan Price Site Vice President Dominion Nuclear Connecticut, Inc.
Building 475, 5th Floor Rope Ferry Road Waterford, CT 06385 Mr. J. W. "Bill" Sheehan Co-Chair NEAC 19 Laurel Crest Drive Waterford, CT 06385 Mr. Evan W. Woollacott Co-Chair Nuclear Energy Advisory Council 128 Terry's Plain Road Simsbury, CT 06070 Ms. Nancy Burton 147 Cross Highway Redding Ridge, CT 00870 Mr. Chris L. Funderburk Director, Nuclear Licensing and Operations Support Dominion Resources Services, Inc.
Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711 Mr. David W. Dodson Licensing Supervisor Dominion Nuclear Connecticut, Inc.
Building 475, 5th Floor Rope Ferry Road Waterford, CT 06385 Mr. Joseph Roy, Director of Operations Massachusetts Municipal Wholesale Electric Company Moody Street P.O. Box 426 Ludlow, MA 01056