ML20134E266

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Discusses 10CFR50.54(f) Re Nu Developing Design & Licensing Bases Documentation Packages for Sys W/Highest Contribution to Core Melt Frequency
ML20134E266
Person / Time
Site: Millstone Dominion icon.png
Issue date: 08/22/1996
From: Blanch P
AFFILIATION NOT ASSIGNED
To: Zwolinski J
NRC
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ML20134D719 List:
References
NUDOCS 9611010088
Download: ML20134E266 (1)


Text

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From: PAUL M. BLANCH <PMBLANCH@ix.netcom.com>

To: JZ <JAZWOL9aol.com>

Date: 8/22/96 4:25am

Subject:

10CFR50.54(f)

From a friend.

Paul:

As part of its 10CFR50.54(f) response efforts, NU is developing design and licensing bases documentation packages for the systems with the highest contribution to core melt frequency. As I understand the reason for the 10CFR50.54(f) letters, NU had lost configuration control such that the as-built configuration of the plants did not match the UFSAR and controlled drawir- Given this rather significant discrepancy, how can the plant specif a rHAs be meaningful? Granted, the top ten ' risk' systems will probably be the same if the PRAs are revisited with the actual plant configurations, but there could be some surprises. In any event, it would seem prudent (if not mandatory) that NU revise the plant specific PRAs after they figure out the actual plant configurations. The NRC does not rely too i heavily on absolute PRA numbers, but they do place greater reliance on the  ;

, relative difference between PRA results. For example, if the M111 stone-3  ;

core melt frequency increased 50% simply due to using the as-built configuration instead of the as-thought-to-be-built configuration, the NRC would then have a measure of the safey impact of Millstone-3 operating outside its design / licensing bases over the years. If on the other hand the M111 stone-3 core melt frequency decreases, one shouldn't make the argument I that the forced shutdown lessened safety, since risk was always dependent on the as-built configuration.

Food for thought, Paul M. Blanch Energy Consultant 135 Hyde Rd.

West Hartford CT 06117 Voice 860-236-0326 l Fax 860-232-9350 1

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9611010088 961024 PDR ORG NRRA PDR