ML20148H167

Requests re-evaluation of ECCS Cooling Performance Using NRC Approved Model That Does Not Use Nucleate Boiling Heat Transfer Correlation During Blowdown After Critical Heat Flux Predicted by Approved Correlation

ML20148H167
Person / Time
Site:	Yankee Rowe
Issue date:	12/10/1976
From:	Schwencer A Office of Nuclear Reactor Regulation
To:	Groce R YANKEE ATOMIC ELECTRIC CO.
References
NUDOCS 8011170330
Download: ML20148H167 (2)

Text

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MC 101975 g ff Docket No. 50-29 .

1 Yankee Atomic Electric Company ATTU: fir. Robert H. Groce E Licensing Engineer 20 Turnpike' Road Westboro, flassachusetts 01581 Gentlemen:

0 RE: YAtlKEE NUCLEAR POWER STATION (YANKEE-ROWE) .. g ..

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During the course of our review of emergency core cooling system (ECCS) P evaluation modbls, it has come to our attention that the Exxon Nuclear Company (ENC) ECCS evaluation model, which was used for your facility, uses a nucleate boiling heat transfer correlation during blowdowr. after '

critical heat flux -(CHF) is first predicted. This may not conform to the requirements of Appendix K to 10 CFR 50. The criteria for compliance .

with Appendix K have been established by the NRC staff and discussed with EHC representatives. Enclosed is a copy of our letter dated December 2,  :

1976, to ENC requesting that a corrected ECCS model be submitted for ,"

our evaluation as soon as possible. ,~.

This matter is similar to one identified with respect to another nuclear steam system supplier's evaluation model; and, based on our experience in connection with developing a correction for that model, we have concluded that there are acceptable correlations which can be used and -

which have a small effect on the calculated peak clad temperature. It is expected that the effect on calculated peak clad tenperature would be small enough so that modification of your Technical Specifications will not be required; however, this must be verified for your facility by reevaluation of the ECCS cooling performnce using a corrected model.

Accordingly, submit as soon as possible, a reevaluation of your ECCS cooling performance using an NRC staff approved model that does not use a nucleate  ;

boiling heat transfer correlation auring blowdown after CHF has been predicted by the approved CHF correlation.

Sincerely, Original signed by .. n gc(3 -

A. Schwancer, Chief N

THIS DOCUMENT C0:ITAWS '

Operating Reactors Branch #1 P00R QUAUTY PAGES Division of Operating Reactors  ;

Enclosure and cc:

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!!RC ltr dtd 12/02/76 cc w/ enc 1: R Mr. Donald G. Allen, President Yankee Atolic Electric Company 20 Turnpike Road

}lestboro, l',assachusetts 01581 Grecqficid Public Library 402 l'ain Street Greenfield, Massachusetts 01581 i.

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