NRC Generic Letter 79-18, Westinghouse Two-Loop NSSS

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GL79018

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

May 15, 1979

Docket No. 50-29

Mr. Robert H. Groce Licensing Engineer Yankee Atomic Electric Company 20 Turnpike Road Westboro, Massachusetts 01581

Dear Mr. Groce:

Enclosed for your information is a copy of a letter sent to one of the licensees of a Westinghouse two loop plant. A similar letter has been sent to the licensees of the other Westinghouse two loop plants. Note that the use of the rod bank exchange program has not yet been approved for other than these two loop plants.

Sincerely,

Dennis L. Ziemann, Chief Operating Reactors Branch #2 Division of Operating Reactors

Enclosure:

As Stated

cc: See next page

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Mr. Robert H. GroceMay 15, 1979

cc Mr. Lawrence E. Minnick, President Yankee atomic Electric Company 20 Turnpike Road Westboro, Massachusetts 01581

Greenfield Community College 1 College Drive Greenfield, Massachusetts 01301

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

May 15, 1979

Docket No. 50-305

Mr. Eugene R. Mathews, Vice President Power Supply and Engineering Wisconsin Public Service Corporation P.O Box 1200 Green Bay, Wisconsin 54305

Dear Mr. Mathews:

The Nuclear Regulatory Commission staff has reviewed information submitted by the Westinghouse Corporation and two licensees of two loop plants regarding the use of the rod bank exchange (rod swap) method to verify shutdown margin for two loop Westinghouse nuclear steam supply systems. Based on our review, we approve the use of this method as an alternative to the boron exchange method of verifying shutdown margin for these two loop NSSSs providing the following conditions are met:

1. The analysis for predicting rod worths and shutdown margin is performed by Westinghouse using the technique proposed to the NRC at the September 1978 meeting.

2. All rod banks are measured.

3. Written approval is obtained from the NRC prior to use of the rod exchange method. Approval will based on NRC review of your review and acceptance criteria for these rod exchange tests. Once we approve your review and acceptance criteria, they need not be resubmitted unless changed.

4. The test procedure for this method is that identified in a Westinghouse letter to NRC dated April 24, 1979.

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Mr. Eugene R. MathewsMay 15, 1979

5. Within 45 days after the first verification of shutdown margin using the rod bank exchange method, the test data is formally submitted to the NRC.

This approval is only for plants with a two loop NSSS. Additional information and further review will be required before we can reach a conclusion on the use of this method for three and four loop plants.

Sincerely,

A. Schwencer, Chief Operating Reactors Branch #1 Division of Operating Reactors

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