ML20148A524
| ML20148A524 | |
| Person / Time | |
|---|---|
| Issue date: | 12/19/1978 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | Ahearne, Bradford, Gilinsky, Hendrie, Kennedy NRC COMMISSION (OCM) |
| References | |
| REF-GTECI-A-09, REF-GTECI-SY, RTR-NUREG-0460, RTR-NUREG-460, TASK-A-09, TASK-A-9, TASK-OR NUDOCS 7812290071 | |
| Download: ML20148A524 (2) | |
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[ % UNITED STATES y" NUCLEAR REGULATORY COMMISSION g WASHINGTON, D. C. 20555
- ' DEC 191978 MEMORANDUM FOR: Chairman Hendrie Commissioner Gilinsky Commissioner Kennedy Commissioner Bradford Commissioner Ahearne THRU: Lee V. Gossi:., Executive Director for Operations '
FROM: Harold R. Denton, Director Office of Nuclear Reactor Regulation
SUBJECT:
ANTICIPATED TRANSIENTS WITHOUT SCRAM (ATWS)
Enclosed for your information is a copy of Volume 3 to NUREG-0460, the NRC staff report on ATWS. It is being transmitted today to the ACRS and the Regulatory Requirements Review Committee for their ongoing reviews.
The first two volumes of the report were 1ssued in April,1978. (See April 19, 1978 memo from Acting Director of NRR to Commission.) Since then, additional information and insights on ATWS have become available.
Industry representatives and the NRC staff have made presentations to the ACRS and its subcommittee on ATWS. In addition, the Review Committee on the Reactor Safety Study has issued its findings and recommendations to the NRC.
On the basis of this new information, the NRR staff has reevaluated the recommendations in the first two volumes of NUREG-0460. The new report reflects the staff's current view that a numerical safety objective is not satisfactory for use in nuclear. regulatory decisionmaking at this time, although quantitative risk assessments are valuable supple-ments to the engineering evaluation of ATWS. This supplement to NUREG-0460 considers various alternative plant modifications for ATWS ranging from none to those needed to satisfy the proposed licensing criteria ,
for new plants in NUREG-0460 Volumes 1 and 2. The staff has analyzed the corresponding degrees of assurance of safety that the modifications i
The Commissioners . DEC 19197g are judged to provide and selected a mix of ATWS prevention and mitiga-tion measures for several classes of nuclear power plants that will provide an acceptable level of safety. Subject to confirmatory generic analyses, the staff has concluded, for plants now operating or under construction, that these measures would provide substantial, additional protection which is required for the public health and safety.
The ACRS and the RRRC will meet in early January to consider this supple-ment to NUREG-0460. The RRRC will include in its deliberations an assess-ment of the staff's reliance on risk assessment techniques. Pending the concurrence of the RRRC, we plan to issue requests for the industry to supply generic analyses of ATWS mitigation capability and other informa-tion needs. Following the approach outlined in Section 5 of the report, we anticipate coming to the Commission in May 1979 with our recommenda-tions for its actions to resolve the ATWS issue.
We are taking action to assure installation of recirculation pump trip on the operating BWRs that do not now have it. All but one of these plants had previously committed to install recirculation pump trip.
Harold R. Denton, Director Office of Nuclear Reactor Regulation
Enclosure:
NUREG-0460, Volume 3 cc: NRC Public Document Room -
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