NRC Generic Letter 79-28, Evaluation of Semi-Scale Small Break Experiment

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GL79028

July 10, 1979

Mr. David Holt B&W Owner's Group Systems Engineer - Licensing Steam Production Department Duke Power Company Charlotte, North Carolina 28242

Dear Mr. Holt:

SUBJECT: EVALUATION Of SEMISCALE SMALL BREAK EXPERIMENT

As part of the current effort to develop improved guidelines for handling potential small break loss-of-coolant accidents, you are performing computer calculations to assess the course of such events. The computer programs used in these analyses have been compared to only a limited amount of experimental data. The results of the evaluations were not conclusive and further verification with experimental data is required. Accordingly, it is requested that you perform an evaluation of the recent Semiscale small break experiment (5-07-10B) with your small break computer program. To be useful in this current effort it is essential that the work be completed by approximately September 1, 1979.

The test details necessary to perform these calculations have already been forwarded to the reactor vendors. The analysis of the Semiscale test relates to our previous requests regarding small breaks. If further information regarding the experiment is need, please contact L. E. Phillips (301) 492-

7588.

Sincerely,

Derwood F. Ross, Jr., Director Bulletins & Orders Task Force Office of Nuclear Reactor Regulation

cc: B&W Owner's Group Licensees