ML20236J127
| ML20236J127 | |
| Person / Time | |
|---|---|
| Issue date: | 07/20/1987 |
| From: | Sheron B NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Neils G NORTHERN STATES POWER CO., NUCLEAR ENERGY INSTITUTE (FORMERLY NUCLEAR MGMT & |
| References | |
| REF-GTECI-A-45, REF-GTECI-DC, TASK-A-45, TASK-OR NUDOCS 8708060056 | |
| Download: ML20236J127 (2) | |
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Jul. 2 01987 Dr. Gerald Neils, Chairman NUMARC Working Group on DHR Northern States. Power Company t
414 Nicollet Mall Minneapolis, Minnesota 55401
Dear Dr. Neils:
I received a copy of your June 22, 1987 communication to Dr. David Ericson on the subject of our USI A-45 Program on Shutdown Decay Heat Removal Requirements.
Sandia National Laboratories (SNL) is in the process of studying these comments in detail; however, we are particularly interested in your indication that a separate PRA of one of the SNL Case Studies was sponsored by EPRI, the Westinghouse Owners Group, and Wisconsin Electric Power and concludes that core melt risk is about ten times lower than the SNL Case Study for the same plant.
Since we perceive that this industry-sponsored study represents your quantification of the differing views outlined in your June 22nd letter, it would assist es in our deliberations to better understand your technical-basis for these differences.
Therefore, we ask that you identify the' major items in your recent PRA study which contribute to the factor of ten difference in core melt probability, and present the technical basis for the value(s) selected (e.g., referenceable operating ~ experience data base, human factor studies, component. reliability data, external event initiating frequencies, etc).
We also dsh to acknowledge the creation of the NUMARC Working Group to study the DHR issue, and we look forward to interfacing with members in the near future.
Since our draft Regulatory Analysis on USI A-45 is still pre-decisional, perhaps we can consider a first meeting to focus on our review of the items you will identify as key contributors to the factor of ten difference in the core melt probability between the two PRAs.
We appreciate the technical. attention that NUMARC has apparently devoted to review of the six Case Studies, as indicated by Enclosure 1 of your June 22nd letter, and we intend to work with SNL to consider your comments.
Sincerely, Br!@d riped M Briaa W. Sh9f03 Brian W. Sheron, Director Division of Reactor and Plant Systems Office of Nuclear Regulatory Research cc:
D. Ericson 0FC :DRPS:RPSIB : DRPS: RPSIB :DRPS:DD
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- BSheron DATE :07/17/87^
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DISTRIBUTION J(JL 2 0 i007 RES CIRC /CHRON DRPS C/F RPSIB R/F A. Marchese G. Mazetis K. Kniel W. Minners B. Sheron T. Speis E. Beckjord
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