ML20203N091
| ML20203N091 | |
| Person / Time | |
|---|---|
| Issue date: | 09/17/1986 |
| From: | Ward D Advisory Committee on Reactor Safeguards |
| To: | Stello V NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| References | |
| ACRS-R-1218, TAC-61519, TAC-61520, NUDOCS 8609230137 | |
| Download: ML20203N091 (2) | |
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NUCLEAR.9EGULATORY COMMISSION
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ADVISORY COMMr. TEE ON REACTOR FAFEGUARDS wasmworow, o.c.nosse o
September 17, 1986 Mr. Victor Stello, Jr.
Executive Director for Operations U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Mr. Stello:
SUBJECT:
ACRS COMMENTS ON PROPOSED RESOLUTION OF GENERIC ISSUE 124,
" AUXILIARY FEEDWATER SYSTEM RELIABILITY" i
During its 317th meeting, September 11-13, 1986, the Advisory Committee on Reactor Safeguards met with representatives of the Office of Nuclear Reactor Regulation (NRR) to discuss a proposed resolution approach for Generic Issue 124
" Auxiliary Feedwater System Reliability."
The Comittee initially commented on this issue in a December 10, 1985 letter to W. J. Dircks, EDO.
Since that time, subcomittee meetings were held on this issue on March 26 and September 9, 1986.
As we noted in our December 10, 1985 letter, we believe the issue of auxiliary feedwater (AFW) system reliability is important and deserves attention by the NRC Staff on a high-priority basis.
l During the March 26, 1986 ACRS subcommittee meeting, NRR described a l
resolution approach that would require P acceptable AFW system reliability ( <10"p licensees to demonstrate an unavailability on demand) as stipulated in the Standard Review Plan (NUREG-0800).
Demonstration of acceptable reliability would be shown by a probabilistic assessment, and continuing system reliability would be assured by a periodic (five-year) analysis of component failure data for the AFW system at a given plant.
Systems which could not be demonstrated to have suitable reliability
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would require modification to assure compliance.
The Office of Nui: lear Reactor Regulation has now revised its resolution approach. As discussed with the Comittee, the new approach involves an intensive review of the AFW system reliability for seven older operating units. These units have two-train AFW systems which were judged to have questionable reliability, based on a review required after the TMI accident.
As we understand the new NRR approach, the reliability of each plant's AFW system will be evaluated by an NRC Review Team.
The team will use infomation obtained from the Office of Inspections &
Enforcement inspections, plant visits, and other relevant data sources.
The owner of one of the plants under review, Prairie Island, has con-ducted an extensive reliability analysis of its AFW system.
NRR indi-l cated that the Prairie Island analysis will be a sort of benchmark against which the other plants will be measured, but no objective criteria for judging acceptability have been established.
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Mr. Victor Stello, Jr. September 17, 1986 While the above studies will provide useful data, we are concerned with the lack of a definitive criterion for judging the acceptability of AFW systems at these plants. Absent an objective benchmark or standard of acceptability, we believe a plant-to-plant comparison of the relative AFW system reliabilities may not provide a satisfactory approach for resolving this issue. We recommend that the.NRC Staff consider return-ing to the review process it described during the March 1986 subcom-mittee meeting.
Sincerely, D.
d David A. Ward Chairman
.