ML19322A067

Forwards Newark-Kennedy Criteria for Combinations of Earthquake &/Or Other Transients Responses. Believes Criteria Justify Use of Square Root of the Sum of the Squares Methodology for Generic Nuclear Power Station Design

ML19322A067
Person / Time
Site:	Black Fox
Issue date:	12/20/1978
From:	Fate M PUBLIC SERVICE CO. OF OKLAHOMA
To:	Varga S Office of Nuclear Reactor Regulation
Shared Package
ML19322A068	List: ML19322A067
References
NUDOCS 7901020159
Download: ML19322A067 (4)

Text

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6 212 DIN 8 -014-002

-PUBLIC SERVICE COMPANY OF OKLAHOMA A CENTRAL AND SOUTH WEST COMPANY P.O. BOX 201/ TULSA, OKLAHOMA 74102 / (918) 583-3611 arrin s. rare, ./r.

December 20, 1978 sucur/w vice pressant File: 6212.125.3500.21L Public Service Company of Oklahoma Black Fox Station:

Methodology for Combining Dynamic Responses of Structures, Systems and Components Important to Safety Docket STN 50-556 and STN 50-557 Office of Nuclear Reactor Regulation Division of Project Management Light Water Reactors Branch No. 4 U.S. Nuclear Regulatory Commission Washington, D. C. 20555 Attn: Steven A. Varga, Chief Gentlemen:

A working grou, of the NRC Staff issued a report in September 1978 (NUREG-0484) that reviewed and discussed the present methods used by nuclear power station designers for combining various load combinations. As a result of the NUREG-0484 analysis, the NRC Staff approved the application of the SRSS methodology for combining SSE and LOCA dynamic loads within the reactor coolant pressure boundary and its supports. This application of the SRSS methodology was in addition to uses previously approved by the NRC Staff, i.e., the combining of certain modal combinations and direction combination responses caused by earth-quakes, and the combining of LOCA and SSE loads in the analysis of PWR fuel bundles.

Significantly, NUREG-0484 recognized that the NRC Staff is actively considering the application of SRSS methodology to the evaluation of Mark I and Mark II contain-ment dynamic loads, and suggested - the development of the justification to expand the application of SRSS methodology on a generic basis.

Since the publication of NUREG-0484, a significant new development has occurred with the creation of the criteria justifying the generic use of SRSS in combining

-loads for reactor design by Dr. Nathan Newmark and Dr. R. P. Kennedy (hereinafter referred to as the "Newmark-Kennedy Criteria"). A copy of the criteria is attached.

They were most recently discussed during a meeting of the ACRS Fluid liydraulic Dynamic Effects Subcommittee on November 28-30, 1978.

MiWOM CENTRAL AND SOUTH WEST SYSTEM \

gntral Pgwgrgn,d, Light gb,hc e,ryge, Company of Oklahorna guthw stern Elegnc Power ',Ngtgs Utihties

Page 2 December 20, 1978 We believe the criteria justify the use of SRSS methodology for generic nuclear power station design, and that the criteria can and should serve as a basis for complying with your October 31, 1978 request for a PSAR commituent on load combina-tion methodology for.the design of the Black Fox Station. In view of the foregoing, the Applicants are prepared to submit an amendment to the PSAR for the Black Fox Station which would provide:

A. Although we believe that the above Criteria allow the use of the SRSS methodology for structures, the absolute summation method will be used to combine dynamic loads as defined in Appendix 3C of the PSAR, as amended through Amendment 13, in connection with the design of structures.

If these loads are subsequently redefined in a significant manner, or if loads for structures other than those defined in Appendix 3C are defined, the loads may be combined as provided in B. below or by absolute summation.

B. The SRSS load combination method will be used to combine dynamic loads defined in connection with the design of piping and components for the entire Black Fox Station provided that each load can be shown to meet criterion 1. or each load combination can be shown to meet criterion 2.

af the Newmark-Kennedy Criteria. Applicants agree to cooperate with the NRC Staff during the implementation of the Newmark-Kennedy Criteria, including the opportunity to review the actual application of the criteria by Applicants' NSSS upplier and Architect / Engineer.

C. In the unlikely event the application of the SRSS load combination method-ology for any particular load or load combination,.specified in A or B above, results in a failure to meet both criteria 1. and 2. of the Newmark-Kennedy Criteria, Applicants agree to cooperate with the NRC Staff to determine an acceptable load combination method.

We would be' pleased to meet with you to explain and discuss further the details of our proposal.

I Sincerely, m

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> ;s-cii MEF:VLC:1h Attachment cc: Black Fox Station Service List

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2 October 1978 CRITERIA FOR COMBINATIONS OF EARTHQUAKE AND/0R OTHER TRANSIENT RESPONSES Preamble.

The intent of the methods proposed fpr combinations of transient, dynamic responses is to achieve a non-exceedance probability of approx-imately 84 percent for the peak combined response of the system, com-ponent, or element considered. This goal is achieved by compliance with any one of the following criteria, or any alternative method that meets the intent stated above, provided that the intensity of loads or acceler-ations for each input are conservatively represented (approximately at the level of the 84th percentile, or the mean plus one standard deviation, of the expected input intensity).

1. Criterion.

Dyaamic or transient responses of structures, components and equipment arising from combinations of dynamic loading or motions may be combined by SRSS provided that each of the dynamic inputs or responses has characteristics similar to those of earthquake ground motions, and that the individual component inputs can be considered to be relatively uncorrelated; i.e., the individual dynamic inputs or responses considered are either from independent evente or have random peak phasing. This similarity involves a limited number of peaks of force or acceleration (not more than 5 exceeding 75 percent of the maximum, or not more than 10 exceeding 60 percent of the maximum), with approximately zero mean and a total duration of strong motion (i.e., exceeding 50 percent of the maximum) of 10 seconds or less.

Explanation.

i Since earthquake motions in various directions produce responses which are combined conservatively by the use of SRSS, the descriptions of l

dynamic or transient inputs are based on those applicable to earthquake A-1 l

l