Westinghouse Two-Loop NSSS (Generic Letter 79-18)

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

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.

Mr. Robert H. Groce              - 2 -           May 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 
.

                              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. 
.

Mr. Eugene R. Mathews             - 2 -          May 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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