ML20213E256

Forwards Request for Addl Info Re Applicability of Square Root of Sum of Squares Combination of Dynamic Responses

ML20213E256
Person / Time
Site:	Columbia
Issue date:	09/10/1982
From:	Knight J Office of Nuclear Reactor Regulation
To:	Novak T Office of Nuclear Reactor Regulation
References
CON-WNP-0544, CON-WNP-544 NUDOCS 8209300356
Download: ML20213E256 (3)

Text

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Jaras P. Knight, Assistant Diractor for Cenpenents & Structures Engineering, DE

SUBJECT:

REQUEST FOR ADDITIONAL INFCFf:ATION C0f:CEPfill;G APPLICATION OF SPSS COMBIf!ATI0fl 0F DY?'Af!IC RESPCPSES FOR WilP-2

References:

1.

Letter from G. D. Bcuchey to A. Schwencer, "f4uclear Projectf:0. 2 Application of SRSS Rule for Steel Containtrent", dated July 28, 1982 2.

Report, Sf'A 12109.01-P001, " Study to Denonstrate the Gereric /policability of SkSS Cctbiratior of Dynaric Rospenses for t' ark III fluclear Stear Sunply Systen rnd Balarce-nf-Plant Pipino and Equiprent Corponents",

General Electric Ccmpenv. dated t'ovember 24, 1981.

3.

Report, f!EDE-24010-P, " Technical Bases for the use of tha Squarn-Root-of-the-Sur-of-Squarne (SPSS) fiethed for Ccebining Dyranic Loads for l' ark II Plents", Ceroral Elec.tric Company, dated July 1977.

In Sectier 3.9.3.1 of the Safety Evaluation P.epert for Uf.'P-2 (flVPEG-OP9M, we identified a ccnfirratory issue concerning the aoplicability of SPSS carbiration of dyraric responses for the WhP-2. Tha staff's specific concern is that the primary contairrent for the UtiP-2 plar.t is a free-starding stcel pressure vessel ard the plant is in a hicher roismic zere. Cased en a review of the applicant's tubnittal (refererca

1) dated.luly TP, lor 2, we have daternined that sore areas in the applicant's responses have not been addressed adeouately.

Please transnit the atti.-hed request for additional information to the applicant at your earliest convenience.

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Jares P. Knight, Arsistant Director for

(' ef5-ADOCK - 05000397 Corponerts & Structures Ergineering 8209300356 820910' O-Division of Engineerina.

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P. Vollrer R. Auluck R. Bosrak H. Rrarrer A. Schwoncar S. Ucu

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MECHANICAL EllGINEERING BRANCH REQUEST FOR ADDITI0flAL INFORMATION WilP-2 00CKET N0. 50-397 In order to assess the applicability of SRSS combination of dynamic responses for WNP-2, the applicant reviewed the data of the 26 response combinations pertaining to the free-standing steel containment contained in Tables 3-6, 3-9 and 3-13 of Reference 2.

Based on a review of these data the applicant concluded that the use of SRSS method is adequate for WNP-2 (Reference 1).

We reviewed the information in References 1, 2 and 3 and determined that the applicant has not provided adequate information required to reach a quantitative conclusion on the applicability of SRSS combination of dynamic responses.

The sample number of cases mentioned above is not large or convincing enough (only 26 cases, and many of the 26 cases have NEP levels of the SRSS combined responses which are only marginal) to justify an across-the board application of SRSS for all mechanical systems and components in an application which differs significantly from other Mark II and Mark III plants.

Additional quantitative evidence is necessary to support SRSS applicability based on the actual dynamic responses and containment structure ccnfiguration of WNP-2 since (1) the configuration of the Mark II containment and the hydrodynamic loads used in WNP-2 differ significantly from those of ffark III plants on which the mentioned sample cases were based. (2) the carthquake level used in the WNP-2 design is higher than the levels used in the referenced Mark III plants.

Thus the seismic responses of systems and components in WNP-2 cannot be expected to duplicate those in Mark III plants, and may differ significantly from them.

It is reccmmended that the applicant choose one of the following options in demonstrating the applicability of SRSS.

1.

Generate CDFs and show that the NEPs of SRSS combiactions of responses at selected sample locations exceed 84%.

The number and distribution of sample locations shculd be sufficient by compre-hensive to cover all essential systems and components as shewn in Ref. 2 and 3.

2.

Verify that the dynamic loads to be combined are conservatively defined at the 84th percentile or greater.

Generate CDFs and show that the NEPs of SRSS combination of responses at selected sample locations are at or exceed 50% and the NEPs of 1.2 SRSS are at or exceed 84%.

.- 3.

Verify quantitatively the similarity of response characteristics of systems and conpanents in WMP-2 to those in Mark II or III as indicated in Ref. 2 & 3, such that the same conclusion on SRSS applicability may be justified for WNP-2.

Such an effort might include comparisons of containment modal frequencies and the nature of the dynamic loads, such as the general shapes and durations of the earthquake and the suppression pool dynamic loads.

4 Combine dynamic responses by absolute summation.

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