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APR 7883
. . . . . m /7,8,9,1011:1hl:2:3 A A6r9 APR 7 1983 MEMORANDUM FOR: J. J. ay, Chairman Advisory Comittee on Reactor Safeguards FROM: Harold R. Denton, Director Office of Nuclear Reactor Regulation ggj
SUBJECT:
ACRS COMMENTS ON SEISMIC DESIGN MARGINS This is in response to the ACRS letter of January 11, 1983 concerning quantification of seismic design margins. Significant activity has taken place or is underway in each of the areas recommended by the committee. We liew the January 11, 1983 letter as a call for consolidation of these efforts into a systematic appraisal of seismic risk. We concur that both the concept and time frame of the committee's recommendations are apprepriate.
We also believe that there should be continued strong NRC support of the U.S. programs in the geosciences. We have consolidated many of the ongoing.NRC sponsored programs dealing with eastern U.S. geology and seismicity to provide a more focused effort in tne appraisal of the seismic hazard at eastern U.S. reactor sites. These consolidated programs should fulfill, in large measure, the committee's recommendations.
The committee's recomendations with regard to generic studies of seismic risk, seismic review of specific plants, and seismic safety research, represent a group of activities that cut across every engineering discipline involved in seismic design and involve considerable industry participation. We concur in principle with the committee's recommendations. However, the recommendations are necessarily general and extensive discussion with the appropriate ACRS subcommittees will be necessary to define the specific programs that are feasible considering the availability of data and resources.
NRR will take the lead in planning and coordinating activities related to seismic margin study programs. A meeting with the ACRS Subcommittee on Extreme External Phenomenon is currently scheduled for mid April, 1983. The staff and industry representatives will be prepared to a *^
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4 J. J. Ray discuss the geoscience programs now contemplated or underway. We shall also be prepared to discuss the scope of proposed programs to address other aspects of the ACRS concerns related to seismic margin studies.
In the closing paragraph of the January 11, 1983 letter, the ACRS notes that a generic study such as recommended, given sufficient priority, could be an appropriate substitute for case specific studies of seismic design margins recomended in previous letters. The staff also believes that most aspects of seismic contribution to risk, including seismic design margins, are most appropriately studied on a generic basis. We plan to take action, wherever feasible, to make the staff and industry efforts related to case specific studies an integral part of a more generic program.
l n Harold R. Denton, Director Office of Nuclear Reactor Regulation cc: Chairman Palladino Comissioner Gilinsky Comissioner Ahearne Comissioner Roberts Comissioner Asselstine OPE OGC SECY l
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