NRC Generic Letter 79-66, Additional Information Re 11/09/79 Letter on ECCS Calculations

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GL79066

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555

November 27, 1979

(LETTER TO ALL OPERATING LIGHT WATER REACTORS)

Gentlemen:

Letters, dated November 9, 1979, were sent to all the licensees requesting information concerning the new fuel cladding strain and fuel assembly blockage models and compliance with 10 CFR 50.46. Subsequently further infornation was provided by the NSSS vendors and fuel suppliers regarding the impact of cladding heating-rate dependent burst temperature effects on rupture time and rupture strain/blockage and consequently on calculated peak cladding temperatures. The vendors and fuel suppliers supplied additional information by letters to the staff.

Copies of these additional letters are enclosed. This new information should be used in preparing your response to the November 9, 1979 request.

Sincerely,

Darrell G. Eisenhut, Acting Director Division of Operating Reactors

Enclosures:

1. Letter from Babcock & Wilcox, dated November 20, 1979

2. Letter from Combustion Engineering, dated November 16, 1979

3. Letter from Exxon Nuclear Co., dated November 16, 1979

4. Letter from General Electric Co., dated November 16, 1979

5. Letter from Westinghouse Electric Co., dated November 16, 1979

6. Letter from Yankee Atomic Electric Co., dated November 20, 1979

80 010703-276