ML17037B534

Letter Regarding NRC Staff Review of Addendum 3 to the Mark I Containment Evaluation Short Term Program Report Which Was Submitted on 08/17/1976 by GE Company on Behalf of the Mark I Owner'S Group

ML17037B534
Person / Time
Site:	Nine Mile Point
Issue date:	09/14/1976
From:	Lear G Office of Nuclear Reactor Regulation
To:	Rhode G K Niagara Mohawk Power Corp
References
Download: ML17037B534 (8)

Text

r,'SEP 1 4576 Docket No.50-220-Niagara Mohawk Power Corporation ATTN: Mr.Gerald K.Rhode Vice President-Engineering 300 Erie Boulevard 1/est Syracuse, Hew York 13202 Gentlemen:

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'ACRS (16)DRoss The NRC staff has completed its review of Addendum 3 to the Hark I Containment Evaluation Short Term Program Report (NEDC-20989-P) which was submitted to the NRC on August 17, 1976 by General Electric Company on behalf of the Mark I Owner's Group.The Addendum 3 report describes the methods used to determine the vent header and vent pipe pool swell impact loads which were considered in the"Plant Unique Analysis Report For Torus Support System and Attached Piping For Nine Mile Point Nuclear Power Station" dated July 26, 1976.'lfe have concluded that the methods used to determine plant unique pool swell velocities from the reference plant velocity, as described in Addendum 3, are, acceptable; however, we have further concluded that the determination of vent-header and vent pipe impact loads using impulse/velocity data obtained from 1/12 scale test facility strain gage measure-ments is not acceptable since we believe these strain gage measurements do mot provide an adequate arid reliable data base.Consequently, we require that you provide a supplement to the Nine Mile Point Unit No.1 plant unique analysis report which considers vent header and vent pipe impact loads which have been determined using the impulse/velocity relationship derived from the Mark III-Pressure Suppression Text Facility (PSTF)data.In order for us'o complete our review of the Mark I Containment Short Term-Program in a timely manner, we require that you provide your written response'.,'y October l.1976.One signed original and 39 copies of your response will be necessary.

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Niagara t5ohawk Power Corporation ATTN: ter.Gerald K.Rhode Vice President-Engineering 300 Erie Boulevard West Syracuse, Hew York 13202 In a June 18, 1976 letter from ter.E.A.Ilughes, General Electric Company (GE), to ftr.V.Stello of the NRC staff, GE!provided responses on behalf of the Hark I Owner's Group to NRC staff questions on the Mark I Containment Evaluation Short Term Program final report.The response to Containment Systems Branch (CSB)guestion No.9 provided information regarding potential damage to critical torus internal structures and components from missiles generated as a result of post-LOCA pool swell impact loads on the solid catwaTk, inside the f<ine tiile Point Unit No.1 (t<HP-1)suppression pool (torus).In your letter of July 23, 1976 you stated that, although containment integrity would be maintained for the most probable missile impact orientations and target areas, NtlPC would remove the solid catwalk at Nt<P-1 and replace it with a grating catwalk during the scheduled Spring 1977 refueling outage in order to alleviate the potential for damage.In order to complete our review and evaluation of the continued use of a solid catwalk at HtlP-1 until Spring 1977, the HRC staff requires that you provide a study which determines the probability of loss of contain-ment integrity at HMP-1 due to a postulated LOCA and subsequent catwalk missile damage.The study should consider the probability of a pipe break resulting in a LOCA which in turn results in the failure of the solid catwalk.It should also consider the orientations of the catwalk missiles which result in failure of the torus wall, vent pipe and bellows assembly.Since much of the catwalk may fail.the study should include the effects of multiple missiles.In order to complete our review of the Mark I Containttletft Short Term Progi.am in a timely fashion, we require that the abovementi ed information be provided by October 1, 1976.One signed original and opies of your response will be necessary.

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4 Niagara f<ohawk Power Corporation SEP 1 4$76 If you have any questions regarding the requested information, we would be pleased to meet with you.Sincerely, Origina(sign g i, y George Lear, Chief Operating Reactors Branch 83 Division of Operating Reactors cc: Arvin E.Upton, Esquire LeBoeuf, Lamb, Leiby 5 HacRae 1757 N Street, H.W..Washington, D.C.20036 Anthony Z.Roisman,'squire Roisman, Kessler and Cashdan 1712 N Street, N.W.Washington, D.C., 20036 Oswego City Library 120 E.Second Street Oswego, New York 13126 RB 83......CRa.....,9...IJ'.orrIcc3r SVRNAMC3r'ATc3r PoIm hEC-318 (ReT.9-S3)hZCM 0240 ORB 0'3 ORB 8 J.Gui.bert.:mj

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