ML080720484
| ML080720484 | |
| Person / Time | |
|---|---|
| Site: | Boiling Water Reactor Owners Group |
| Issue date: | 03/14/2008 |
| From: | Michelle Honcharik NRC/NRR/ADRO/DPR/SPB |
| To: | Bunt R BWR Owners Group, Southern Nuclear Operating Co |
| Michelle Honcharik, 415-1774 | |
| References | |
| NEDO-33148, Rev 2, TAC MD2917 | |
| Download: ML080720484 (6) | |
Text
March 14, 2008 Mr. Randy C. Bunt, Chair BWR Owners= Group Southern Nuclear Operating Company 40 Inverness Center Parkway/Bin B057 Birmingham, AL 35242
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION RE: BOILING WATER REACTOR OWNERS= GROUP (BWROG) LICENSING TOPICAL REPORT (LTR) NEDO-33148, REVISION 2, SEPARATION OF LOSS OF OFFSITE POWER FROM LARGE BREAK LOCA (TAC NO. MD2917)
Dear Mr. Bunt:
By letter dated August 25, 2006 (Agencywide Documents Access and Management System Accession No. ML062480327), the BWROG submitted for U.S. Nuclear Regulatory Commission (NRC) staff review LTR NEDO-33148, Revision 2, Separation of Loss of Offsite Power from Large Break LOCA [loss-of-coolant accident]. Upon review of the information provided, the NRC staff has determined that additional information is needed. The NRC staff requires your response to the enclosed Request for Additional Information (RAI) questions within 60 days from the date of this letter. If you have any questions regarding the enclosed RAI questions, please contact me at 301-415-1774.
Sincerely,
/RA by JThompson for /
Michelle C. Honcharik, Senior Project Manager Special Projects Branch Division of Policy and Rulemaking Office of Nuclear Reactor Regulation Project No. 691
Enclosure:
RAl questions cc w/encl: See next page
Mr. Randy C. Bunt, Chair March 14, 2008 BWR Owners= Group Southern Nuclear Operating Company 40 Inverness Center Parkway/Bin B057 Birmingham, AL 35242
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION RE: BOILING WATER REACTOR OWNERS= GROUP (BWROG) LICENSING TOPICAL REPORT (LTR) NEDO-33148, REVISION 2, SEPARATION OF LOSS OF OFFSITE POWER FROM LARGE BREAK LOCA (TAC NO. MD2917)
Dear Mr. Bunt:
By letter dated August 25, 2006 (Agencywide Documents Access and Management System Accession No. ML062480327), the BWROG submitted for U.S. Nuclear Regulatory Commission (NRC) staff review LTR NEDO-33148, Revision 2, Separation of Loss of Offsite Power from Large Break LOCA [loss-of-coolant accident]. Upon review of the information provided, the NRC staff has determined that additional information is needed. The NRC staff requires your response to the enclosed Request for Additional Information (RAI) questions within 60 days from the date of this letter. If you have any questions regarding the enclosed RAI questions, please contact me at 301-415-1774.
Sincerely,
/RA by JThompson for/
Michelle C. Honcharik, Senior Project Manager Special Projects Branch Division of Policy and Rulemaking Office of Nuclear Reactor RegulationProject No. 691
Enclosure:
RAl questions cc w/encl: See next page DISTRIBUTION:
PUBLIC PSPB Reading File RidsNrrDpr RidsNrrDprPspb RidsNrrPMMHoncharik RidsNrrLADBaxley RidsOgcMailCenter RidsAcrsAcnwMailCenter RidsNrrDss RidsNrrDe RidsNrrDra RidsNrrDci RidsNrrDssSrxb RidsNrrDssSnpb RidsNrrDssSbpb RidsNrrDeEeeb RidsNrrDraApla RidsNrrDciCptb Robert Wolfgang Stephen Dinsmore Steven Laur Vijay Goel Benjamin Parks Richard Dudley SRosenberg (HardCopy)
ADAMS Accession No: ML080720484 NRR-106
- No substantive changes OFFICE PSPB/PM PSPB/LA APLA/BC*
EEEB/BC PSPB/BC NAME MHoncharik DBaxley MRubin GWilson JThompson for SRosenberg DATE 3/ 14 /08 3/ 13 /08 3/6/08 3/13/08 3/ 14 /08
OFFICIAL RECORD COPY
ENCLOSURE REQUEST FOR ADDITIONAL INFORMATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION LICENSING TOPICAL REPORT (LTR) NEDO-33148, REVISION 2, SEPARATION OF LOSS OF OFFSITE POWER FROM LARGE BREAK LOCA BOILING WATER REACTOR OWNERS= GROUP PROJECT NO. 691 The U.S. Nuclear Regulatory Commission (NRC) staff is concerned about the potential safety impact of a loss-of-coolant accident (LOCA) followed by delayed loss of offsite power (LOOP) that might occur while the load sequencer is in the process of adding emergency loads to the vital buses. In real world scenarios, some delay in LOOP is credible. Such an event might continue with offsite power remaining unavailable, or possibly with its recovery.
The NRC staff continues to assess the risk associated with large break LOCAs (LBLOCAs) and delayed LOOPs. The "bounding" risk assessment described in the LTR assumes that all LOCA/LOOP sequences go to core damage at a 1x10-6 (E-6) frequency and a large early release frequency (LERF) of E-8 even though (1) a delayed LOOP is a subset of all LOCA/LOOP sequences and (2) not all LOOP events occur after LOCAs. To facilitate this assessment, the BWROG is requested to supplement the LTR by answering the following questions:
- 1.
What factors lead the BWROG to conclude that this assessment is bounding?
- a.
What factors can be considered as being conservative in their treatment?
- b.
What factors can be considered as being not conservative?
- c.
The assumed conditional probability of LERF following LOCA core damage is estimated at E-2. How is this bounding for all BWR and containment designs that might implement this LTR.
- 2.
Has the BWROG made a realistic assessment of this risk?
- a.
If so, how much smaller would the BWROG expect the realistic risk to be, relative to the bounding assessment?
- b.
Discuss in detail why no further licensee actions are required with respect to a LOCA with a delayed LOOP?
- 3.
The bounding risk assessment described in the LTR uses core damage as a consequence metric. What extent of core damage is presumed in this assessment (e.g., partial core damage (like occurred at Three Mile Island), complete core meltdown)?
BWR Owners= Group Project No. 691 Mr. Doug Coleman Vice Chair, BWR Owners= Group Energy Northwest Columbia Generating Station Mail Drp PE20 P.O. Box 968 Richland, WA 99352-0968 DWCOLEMAN@energy-northwest.com Mr. Richard Libra Executive Vice Chair, BWR Owners= Group DTE Energy - Fermi 2 M/C 280 OBA 6400 North Dixie Highway Newport, MI 48166 librar@dteenergy.com Mr. Richard Anderson BWROG, Executive Chair FPL Energy (DAEC)
Duane Arnold Energy Center 3277 DAEC Road Palo, IA 52324 richard_l_anderson@fpl.com Mr. James F. Klapproth GE Energy M/C A50 3901 Castle Hayne Road Wilmington, NC 28401 james.klapproth@ge.com Mr. Joseph E. Conen Regulatory Response Group Chair BWR Owners= Group DTE Energy-Fermi 2 200 TAC 6400 N. Dixie Highway Newport, MI 48166 conenj@dteenergy.com Mr. J. A. Gray, Jr.
Regulatory Response Group Vice-Chair BWR Owners= Group Entergy Nuclear Northeast 440 Hamilton Avenue Mail Stop 12C White Plains, NY 10601-5029 JGray4@entergy.com Mr. Ken A. McCall, Program Manager GE Energy M/C F12 3901 Castle Hayne Road Wilmington, NC 28401 kenneth.mccall@ge.com Mr. Tim E. Abney GE Energy M/C A-16 3901 Castle Hayne Road Wilmington, NC 28401 tim.abney@ge.com Oscar Limpias Entergy Nuclear Northwest Echelon One 1340 Echelon Parkway.
Jackson, MS 39213-8202 olimpia@entergy.com Joe Donahue Progress Energy Inc.
410 S. Wilmington St. (M/S PEB6A)
Raleigh, NC 27601-1849 joe.w.donahue@pgnmail.com Paul J. Davison Hope Creek Nuclear Station P.O. Box 236 Hancocks Bridge, NJ 08038 paul.davison@pseg.com Dennis Madison, Vice President Southern Nuclear Operating Co.
Edwin I. Hatch Nuclear Plant 11028 Hatch Parkway North Baxley, GA 31515-2010 drmadiso@southernco.com 3/13/08