ML20035H782

Responds to to Chairman,Commenting on Staff Research Program Re Environ Qualification of Digital I&C Sys.Informs That Staff Will Reassess Direction of Program to Prioritize Stressors in Terms of Significance

ML20035H782
Person / Time
Issue date:	12/10/1992
From:	Taylor J NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO)
To:	Shewmon P Advisory Committee on Reactor Safeguards
References
ACRS-GENERAL, NUDOCS 9305070097
Download: ML20035H782 (2)

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UNITED STATES S

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December 10, 1992

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Mr. Paul Shewmon, Chairman Advisory Committee on Reactor Safeguards 1

U.S. Nuclear Regulatory Commission Washington, D.C. 20555

SUBJECT:

ENVIRONMENTAL QUALIFICATION FOR DIGITAL INSTRUMENTATION AND SYSTEMS I am responding to your November 12, 1992 letter to the Chairman in which you commented on the staff's research program related to the environmental qualification of digital instrumentation and control (I&C) systems.

Specifically, you expressed concern about the staff's lack of a coherent rationale for emphasizing electromagnetic and radio frequency interference (EMI/RFI) over other environmental stressors, and the fact that it did not draw on the experiences of others, particularly the military, in this area.

j It is true that in establishing the direction of its research program, the staff did not systematically prioritize the environmental stressors associated with nuclear plant digital I&C systems. However, as discussed during the meeting, the staff emphasized EMI/RFI over the other stressors based on the relatively larger number of nuclear power plant operating events in which l

EMI/RFI played a role. We agree that in terms of overall plant safety, some of the other stressors may be just as important. Therefore, the staff will i

reassess the direction of its digital I&C environmental qualification research program to prioritize the stressors (and its resources) in terms of their relative safety significance.

Also, as discussed during the meeting, the staff has taken advantage of some of the work done by the military in this area. Specifically, the staff has i

assessed the applicability of Mil. Std. 461C. " Electromagnetic Emission and Susceptibility Requirements for Control of Electromagnetic Interference," and.

Mil. Std. 462, " Measurement of Electromagnetic Interference Characteristics,"

to nuclear plant digital I&C systems. Nevertheless, we agree that it could and should do much more. Therefore, the staff will more diligently pursue the nn-9305070097 921210 I

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Paul Shewmon work of others, particularly the military, in this area and assess the applicability of the work to nuclear plant digital I&C systems.

Original Signed By James M. Taylor James M. Taylor Executive Director for Operations i

cc: The Chairman Comissioner Rogers Comissioner Curtiss i

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