ML19289E428

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Responds to Commissioner Kennedys 781102 Query Re Combination of Dynamic Loads as a Regulatory Design Basis. ACRS Has Established Subcommittee to Continue Review of Question & Will Rept When Appropriate
ML19289E428
Person / Time
Issue date: 03/14/1979
From: Carbon M
Advisory Committee on Reactor Safeguards
To: Hendrie J
NRC COMMISSION (OCM)
References
ACRS-R-0823, ACRS-R-823, NUDOCS 7904170546
Download: ML19289E428 (1)


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g NUCLEAR REGULATORY CCf4 MISSION 3,Q

. 'h j ADVISORY Mn4MITTEE ON REACTOR SAFEGUARDS

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g WASHf NGToN, D, C. 20555 fiarch 14, 1979 Honorable Joseph M. Hendrie Chairman U.S. Nuclear Regulatory Commission Washington, D. C. 20555

SUBJECT:

COMBINATION OF DYNAMIC LOADS AS A REULATORY DESIGN BASIS

Dear Dr. Hendrie:

This letter is in response to Commissioner Kennedy's question at the November 2, 1978 meeting between the Commissioners and the ACRS, con-cerning the combination of dynamic loads as a design basis fer nuclear facilities.

'Ihe NRC Staff is considering the use of " Square Root of the Sum of the Squares" methodology when combining LOCA and seismic loadings for the primary coolant system boundary. %is may eliminate some possibly unde-sirable conservatism in load combination methodology; however, it ad-dresses only a small portion of the issues in question. W e treatment of structural supports for example, is not, at present, considered sim-ilarly.

The ACRS is aware of a number of technical programs addressing load-com-binations which have been initiated by the Office of Nuclear Reactor Reg-ulation under technical assistance contracts and through requests to the Office of Nuclear Regulatory Research. These may ultimately alter the Staff position on combined loads. However, their presently incomplete sta-tus makes a full commentary premature at this time.

The ACRS has established a Subcommittee to continue review of this ques-tion and will report to you at an appropriate time.

Sincere:.y, Max W. Carbon Chairman 79041705 %