ML25195A151

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03-14-79 Combination of Dynamic Loads as a Regulatory Design Basis
ML25195A151
Person / Time
Issue date: 03/14/1979
From: Carbon M
Advisory Committee on Reactor Safeguards
To: Hendrie J
NRC/Chairman
References
Download: ML25195A151 (1)


Text

UNITED STATES NUCLEAR REGULATORY COMMISSION ADVISORY COMMITTEE ON REACTOR SAFEGUARDS WASHINGTON, D. C. 20555 Honorable Josep-i M. Hendrie Chairman U.S. Nuclear Regulatory Commission Washington, D. C. 20555 March 14, 1979

SUBJECT:

ca-tBINATION OF DYNAMIC LOAIS AS A REXiUIATORY 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 for nuclear facilities.

The 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. 'Ibis may eliminate some possibly unde-sirable conservatism in load combination methodology; however, it ad-dresses only a small portion of the issues in question. 'lhe treatment of structural supports for example, is not, at present, considered siin-ilarly.

The ACRS is aware of a number of technical programs addressing load-can-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 9f this ques-tion and will report to you at an appropriate time.

2636 Max w. carbon Chairman