ML16344A080

ACRS Comments on the NRC Staff Proposal for the Resolution of USI A-44, Station Blackout

ML16344A080
Person / Time
Issue date:	03/12/1985
From:	Banks M Advisory Committee on Reactor Safeguards
To:	Dircks W NRC/EDO
References
Download: ML16344A080 (2)

Text

D850312 Mr. William J. Dircks Executive Director for Operations U. S. Nuclear Regulatory Commission Washington, D. C. 20555

SUBJECT:

ACRS COMMENTS ON THE NRC STAFF PROPOSAL FOR THE RESOLUTION OF USI A-44, "STATION BLACKOUT" During its 299th meeting, March 7-9, l985, the Advisory Committee on Reactor Safeguards reviewed the resolution of USI A-44, "Station Black-out," that is being proposed by the NRC Staff. A Subcommittee also discussed this issue with the NRC Staff on February 26, l985. We com-mented earlier on this issue in a letter to you dated July l3, l983. We also had the benefit of the documents referenced.

We observe that the NRC Staff has taken appropriate account of ACRS recommendations contained in the July l3, l983 letter.

We reaffirm our conclusion that the proposed recommendations of the NRC Staff are appropriate. We believe that if followed they will reduce risk to the public and to operating plants.

The NRC Staff is currently contemplating implementing their recommendations for the resolution of USI A-44 by recommending a rulemaking to the Commission.

We recommend that effort be made to seek a method of implementing these recommendations that will require a minimum of Staff and licensee resources. If a rule is adopted, we recommend that implementing guides permit analyses appropriate to each plant and that the process be kept to the minimum necessary for the appropriate resolution of USI A-44. If a better alternative than rulemaking is advanced, we recommend that it be given serious consideration.

As mentioned in our letter of July l3, l983, we urge that actions considered in the resolution of this issue be closely coordinated with recommendations which may emerge from the ongoing work on resolving USI A-45, "Shutdown Decay Heat Removal Requirements."

Additional comments by ACRS Member David Okrent are presented below.

Sincerely, David A. Ward Chairman Additional Comments by ACRS Member David Okrent It is my understanding that the current approach to the resolution of USI A-44 was constrained in its consideration of earthquakes to those

equivalent to the safe shutdown earthquake, or less. I recommend that, during the period of public comment, the NRC Staff examine the possible impact of more severe earthquakes than the SSE on the likelihood of loss of all AC power for extended periods of time in order to ascertain whether such effect would have any significant impact on their current conclusions.

References:

l. U. S. Nuclear Regulatory Commission, "Evaluation of Station Blackout Accidents at Nuclear Power Plants, Technical Findings Related to Unresolved Safety Issue A-44," draft NUREG-l032, dated January 30, l985

2. U. S. Nuclear Regulatory Commission, "Station Blackout Accident Analyses," NUREG/CR-3226, dated May l983

3. U. S. Nuclear Regulatory Commission, "Reliability of Emergency AC Power Systems at Nuclear Power Plants," NUREG/CR-2989, dated July l983

4. U. S. Nuclear Regulatory Commission, "Cost Analysis for Potential Modifications to Enhance the Ability of a Nuclear Plant to Endure Station Blackout," NUREG/CR-3840, dated July l984