ML20028D505
| ML20028D505 | |
| Person / Time | |
|---|---|
| Issue date: | 12/26/1979 |
| From: | Rosztoczy Z NRC - TMI-2 BULLETINS & ORDERS TASK FORCE |
| To: | Ross D NRC - TMI-2 BULLETINS & ORDERS TASK FORCE |
| Shared Package | |
| ML20027A678 | List:
|
| References | |
| FOIA-82-543, RTR-NUREG-0635, RTR-NUREG-635 NUDOCS 8301190210 | |
| Download: ML20028D505 (2) | |
Text
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DEC 2 61979 MEMORANDUM FOR:
D. F. Ross, Jr., Director, Bulletins & Orders Task Force FROM:
Z. R. Rosztoczy, Chief, Bulletins & Orders Task Force
SUBJECT:
GENERIC EVALUATION OF SMALL BREAK LOSS-OF-COOLANT ACCIDENT BEHAVIOR FOR COMBUSTION ENGINEERING OPERATING PLANTS The Analysis Group has completed the review and evaluation of information received from Combustion Engineering and the Combustion Engineering Owners
, Group on small break loss-of-coolant accidents. Our evaluation, conclusions and recu.1mendations are presented in the attached draft report. This report has been prepared as Appendix VIII of NUREG-0635.
The most important findings are:
The small break evaluation presented by Combustion Engineering is appropriate for use in operator training, however, improvements are required before it could be used to show compliance with 10 CFR 50.46.
The. reactor protection system and the engineered safety features do not prqyide automatic protection in case of a small break LOCA. Prompt t
operator action is required to protect public health and safety.
The Combustion Engineering plants are protected for small breaks if only a single failure is postulated and if the operators perform as required.
All of the Combustion Engineering plants are probably not protected for
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either of the following two events:
(1) loss of main feedwater and auxiliary feedwater at the same time; and (2) loss of natural circulation.
The Combustion Engineering evaluation relied on equipment which is not i
considered part of the safety systems and is not qualified for operation in the post-LOCA environment.
The Combustion Engineering evaluation also relied on two-phase. natural circulation in the reactor coolant system, a mode of heat removal that s
has not yet been demonstrated experimentally.
The challenge rate of relief valves per reactor year of operation could be rather large for Combustion Engineering plants, comparable to the challenge rate of relief valves on B&W plants prior to 4-25-79, and an order of magnitude higher than the challenge rate of B&W plants in their present mode of operation.
8301190210 821122 PDR FOIA SHOLLY62-543 PDR
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D. F. Ross, Jr. DEC 2 61979 Appropriate corrections have been recommended in the report.for the existing shortcomings. The recommendation, if implemented, will provide reasonable assurance that continued operation of the Combustion Engineering plants does not endanger public health and safety.
The Analysis Group performed its work during the past seven months in parallel with the work of other task forces.
I am certain that some of our recommendations are similar to recommendations coming from other groups. Nevertheless, the reasons for the recommendations, and the urgency and importance of the rec-ommendations might be different in the various evaluations.
I would like to urge you to include Appendix VIII in NUREG-0635 in its entirety.
If NRC is not ready yet to implement some of the recommendations or if some of the recommendations need to be considered on a broader basis than the small break LOCA alone, these considerations should be mentioned in the main part of the report, rather than eliminating the recommendations in c,uestion from the appendix.
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Zoltan R. Rosztoczy, C Bulletins & Orders Task Force Distribution w/o
Enclosure:
T. Noeck.
W. Kane P. Norian R. Audette J. Guttmann W. Jensen B. Shero'n E. Throm R. Frahm l
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