ML19291C141
| ML19291C141 | |
| Person / Time | |
|---|---|
| Issue date: | 01/07/1980 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | Ahearne J, Gilinsky V, Kennedy R NRC COMMISSION (OCM) |
| References | |
| NUDOCS 8001230016 | |
| Download: ML19291C141 (2) | |
Text
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WASHINGTON, D. C. 20S55 J4N 7 ;930 MEMORANDUM FOR: Chainnan Ahearne Comissioner Gilinsky Comissioner Kennedy Comissioner Hendrie Comissioner Bradford THRU:
Executive Direc* nr for Operations (SIEn'd) T A Refud FROM:
Harold R. Denton, Director Office of Nuclear Reactor Regulation
SUBJECT:
RESPONSE FROM WESTINGHOUSE REGARDING ECCS EVALUATION MODELS As a result cf our ongoing review of vendor ECCS models for fuel cladding rupture, strain and flow blockage, the Westinghouse Electric Corporation provided further information to us by letter dated December 7, 1979.
From the December 7, 1979 submittal and from subsequent discussions with Westinghouse, we have learned that use of the proposed staff fuel cladding models by themselves could impact the LOCA analyses for Westinghouse supplied plants in such a way as to dictate a reduction in peaking factor (Fq) of up to 0.17.
We have also determined, however, that there is additional margin available in another part of the Westinghouse ECCS evaluation model. Specifically, the application of a more detailed, hydraulic model* during the blowdown portion of the analysis would result in increases of the permissible peak linear heat rate of up to 0.20 in F.
For each specific Westinghouse supplied plant we have q
evaluated the impact of the use of the proposed staff fuel cladding models. We have determined that additional margin, based on approved UHI ECCS models, is sufficient to offset any potential penalty that would result from use of the staff's proposed model.
Consequently, no existing plant-specific Fo limit requires adjustment at this time to assure compliance with the limifs of 10 CFR 50.46.
The staff is in the process of assessing the need for model changes based upon the Oak Ridge data and probably will not arrive at a final position for another couple of months.
In summary, the previously approved calculations for all Westinghouse plants show compliance with 10 CFR 50.46 using the approved models and further, they also indicate compliance with 10 CFR 50.46 when our new interim fuel cladding
- Model improvements include adoption of a refined steam / water slip velocity model and concomitant addition of a containment node to the blowdown (SATAN) analyses.
Application of these improvements have been formally approved for W upper head injection (UHI) plants.
Contact:
R. L. Tedesco, X27980 1791 100 8 0012 3 0 O\\ h
a The Comission -
models are utilized if taken in conjunction with other staff model improvements that have been approved. Accordingly, no further action on Westinghouse supplied plants is anticipated pending development of the staff's revised fuel evaluation model.
We have reviewed the earlier submittal from the other vendors and believe that the infonnation they provided remains adequate with regard to assuring compliance with the provisions of 10 CFR 50.46.
We will keep the Comission informed of related events as they develop.
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Harold R. Denton, Director Office of Nuclear Reactor Regulation cc: OGC OPE SECY 1791 101