ML19259C273

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Supplements 790507 Response to IE Bulletin 79-07. Safety-related Piping Meets Seismic Sys Criteria
ML19259C273
Person / Time
Site: Millstone Dominion icon.png
Issue date: 05/07/1979
From: Counsil W
NORTHEAST UTILITIES
To: Grier B
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
TAC-46174, NUDOCS 7906140524
Download: ML19259C273 (1)


Text

'

W NORTHI!AST IFFII.ITil!S r,c e c w e m re" "

P.O. BOX 270

)s[d[$[5YrMch.,, HARTFORD, CONNECTICUT 06101 L L A SbbkN5?!?5b??b::l May 7, 1979 Docket No. 50-336 Mr. Boyce Grier Director, Region 1 Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission King of Prussia, Pennsylvania 19406

Reference:

(1) W. G. Counsil letter to Boyce Grier, dated April 24, 1979.

Dear Mr. Grier:

Millstone Nuclear Power Station, Unit No. 2 I&E Bulletin 79-07 In Reference (1), Northeast Nuclear Energy Company (NNECO) responded to the con-cerns identified in I&E Bulletin 79-07, and outlined the methods employed for seismic analyses of safety-related piping at Millstone Unit No. 2. Reference (1) also indicated that the re-analysis of the affected installations was in progress and that a supplement would be submitted prior to the start of Cycle 3 operation.

Accordingly, the following information is provided in fulfillment of that commit-ment.

Reference (1) indicated that a preliminary analysis of the piping systems using the SRSS technique of combining responses due to orthogonal earthquake motion in ADLPIPE had revealed that the resultant stress levels remained within acceptable limi ts . Additional analyses have substantiated the preliminary results. Analyses of piping restraints and equipment attachments for the six systems identified in Reference (1) have been completed. All supports were found capable of carrying the seismic-induced loads within acceptable stress limits. In all cases, the existing installation has been found to remain acceptable.

In summary, the systems previously identified have been found to meet the criteria for seismic systems delineated in the Millstone Unit No. 2 FSAR and are acceptable for continued use. We trust that you find the above information, coupled with the information provided in Reference (1), responsive to your concerns.

Very truly yours, 2282 242 NORTHEAST NUCLEAR ENERGY COMPANY l,,l '

f.  !@72GA' W. G. Counsil Vice President 70061407