ML051430398
| ML051430398 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 05/25/2005 |
| From: | Jaffe D NRC/NRR/DLPM/LPD3 |
| To: | Domonique Malone Nuclear Management Co |
| Jaffe D, NRR/DLPM, 415-1439 | |
| References | |
| Download: ML051430398 (4) | |
Text
May 25, 2005 Mr. Daniel J. Malone Site Vice President Palisades Nuclear Plant Nuclear Management Company, LLC 27780 Blue Star Memorial Highway Covert, MI 49043-9530
SUBJECT:
PALISADES PLANT - RE: FINAL ACCIDENT SEQUENCE PRECURSOR ANALYSIS OF 2003 OPERATIONAL EVENT
Dear Mr. Malone:
Enclosed for your information is the final Accident Sequence Precursor (ASP) analysis of an operational event which occurred at the Palisades Plant in March 2003. The condition was reported by Licensee Event Report No. 255/03003, dated May 20, 2003, and documented in U.S. Nuclear Regulatory Commission (NRC) Inspection Report No. 05000255/2004005, dated April 8, 2004. This is being issued as a final analysis since it is a non-controversial, lower risk precursor for which the ASP results are consistent with the results from the Significance Determination Processs final evaluation of the same condition. Elimination of the review and comment resolution for this event will reduce the burden for the NRC staff and the licensee.
Sincerely,
/RA/
David H. Jaffe, Acting Project Manager, Section 1 Project Directorate III Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-255
Enclosure:
ASP Analysis cc: See next page
ML051430398 OFFICE PDIII-1/(A)PM PDIII-1/LA PDIII-1/SC NAME DJaffe THarris LRaghavan DATE 5/25/05 5/24/05 5/25/05
SUMMARIES OF FINAL ACCIDENT SEQUENCE PRECURSOR (ASP) ANALYSIS Loss of Shutdown Cooling and Emergency Diesel Generator Start at Palisades (March 2003.) This is the ASP analysis of operational conditions documented in License Event Report 255/03-003, dated May 20, 2003, and Inspection Report 05000255/2004005, dated April 8, 2004.
Condition summary: On March 25, 2003, plant maintenance workers were installing signposts in the parking lot to designate parking spaces. One of the signposts was driven into a conduit and damaged a cable which contained protective relay circuitry for all sources of offsite power. An alert was declared due to the loss of offsite power combined with the loss of shutdown cooling. The alert was downgraded to an Unusual Event after about 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> when shutdown cooling was restored.
The reported event, loss of offsite power, occurred during a refueling outage, when the reactor vessel head was open, and the cavity was flooded. The decay heat was being removed by decay heat removal (DHR) system. The event caused temporary disconnection of the alternating current (ac) power from the grid (switchyard power disconnect event) which stopped the running DHR train and auto-started emergency diesel generators.
Results: The mean conditional core damage probability (CCDP) of this event is calculated as 3 x10-6 with 5 percent and 95 percent uncertainty bounds of 3 x10-7 and 8 x10-6, respectively.
This relatively low CCDP is due to factors such as ease of proceduralized recovery of ac power to the buses if the diesel generators did not start; long time window for core damage to occur, and various credible (but not proceduralized) recovery processes available if the DHR system did not restart. One insight that can be derived from this analysis is to proceduralize backup processes in case the normal DHR system fails during shutdown operations.
SDP/ASP comparison. The risk significance of this event has also been analyzed under the Significance Determination Process (SDP). The result was a white finding with a delta core damage frequency of 1x10-6. Thus, the ASP and SDP results are consistent.
A sensitivity analysis made as part of the ASP analysis to determine the CCDP if this event had occurred during power operation, shows that the event importance could have been as high as 4x10-5, even when credit is given for easy ac power recovery operator action in this particular case.
The ASP analysis can be found at ML051190504. If you have any questions about the analysis, please contact Selim Sancaktar (415-8184).
Palisades Plant cc:
Robert A. Fenech, Senior Vice President Nuclear, Fossil, and Hydro Operations Consumers Energy Company 1945 Parnall Rd.
Jackson, MI 49201 Arunas T. Udrys, Esquire Consumers Energy Company 1 Energy Plaza Jackson, MI 49201 Regional Administrator, Region III U.S. Nuclear Regulatory Commission 801 Warrenville Road Lisle, IL 60532-4351 Supervisor Covert Township P. O. Box 35 Covert, MI 49043 Office of the Governor P. O. Box 30013 Lansing, MI 48909 U.S. Nuclear Regulatory Commission Resident Inspector's Office Palisades Plant 27782 Blue Star Memorial Highway Covert, MI 49043 Michigan Department of Environmental Quality Waste and Hazardous Materials Division Hazardous Waste and Radiological Protection Section Nuclear Facilities Unit Constitution Hall, Lower-Level North 525 West Allegan Street P.O. Box 30241 Lansing, MI 48909-7741 Michigan Department of Attorney General Special Litigation Division 525 West Ottawa St.
Sixth Floor, G. Mennen Williams Building Lansing, MI 48913 Manager, Regulatory Affairs Nuclear Management Company, LLC 27780 Blue Star Memorial Highway Covert, MI 49043 Director of Nuclear Assets Consumers Energy Company Palisades Nuclear Plant 27780 Blue Star Memorial Highway Covert, MI 49043 John Paul Cowan Executive Vice President & Chief Nuclear Officer Nuclear Management Company, LLC 700 First Street Hudson, WI 54016 Jonathan Rogoff, Esquire Vice President, Counsel & Secretary Nuclear Management Company, LLC 700 First Street Hudson, WI 54016 Douglas E. Cooper Senior Vice President - Group Operations Palisades Nuclear Plant Nuclear Management Company, LLC 27780 Blue Star Memorial Highway Covert, MI 49043 October 2003