ML20028D515
| ML20028D515 | |
| Person / Time | |
|---|---|
| Issue date: | 12/19/1979 |
| 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-0565, RTR-NUREG-565 NUDOCS 8301190213 | |
| Download: ML20028D515 (2) | |
Text
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g WASHINGTON. D. C. 20555 3l DEC 191979 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-0F-COOLANT ACCIDENT BEHAVIOR FOR BABC0CK & WILC0X OPERATING PLANTS The Analysis Group has completed the review and evaluation of information received from B&W and the B&W Owners Group on small break loss-of-coolant accidents. Our evaluation, conclusions and recommendations are presented in the attached draft report. This report has been prepared as NUREG-0565.-
The most important findings are:
The small break evaluation presented by B&M 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 provide automatic protection in case of a small break LOCA. Prompt ogenator action is required to protect public health and safety.
The B&W plants are protected for small breaks if only a single failure is postulated and if the operators perform as required.
One of the B&W plants (Davis Besse Unit 1) is probably not protected for either of the following two events:
(1). loss of main feedwater and
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auxiliary feedwater at the same time in the event of a LOCA; and (2) l loss of natural circulation.
The B&W evaluation relied on equipment which is not considered part of the safety systems and is not qualified for operation in the post LOCA environment.
The B&W evaluation also relied on two-phase natural circulation in the reactor coolant system, a mode of heat removal that has not yet been demonstrated experimentally.
Tiie challenge rate of relief valves per reactor year of operation has I
been substantially reduced by changes in reactor trip and PORV pressure setpoints and anticipatory reactor trips, i
Appropriate corrections have been recommended in the report for the existing shortcomings. The recommendations, if implemented, will provide reasonable l
assurance that continued operation of the B&W plants does not endanger public health and safety.
B301190213 821122 1
SHOLLY82-543 PDR L
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D.'F. Ross, Jr. DEC 191979 e
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 recomnendations are similar to recommendations coming from other groups. Nevertheless, the reasons for the recommendations, and the urgency and importance of the recommendations might be different in the various evaluations.
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 could be mentioned in the report. We are prepared to work with you on appropriate changes is such are needed, t
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Zoltan R. Rosztoczy, Chief Bulletins & Orders Task For Distribution w/o
Enclosure:
T. Novak W. Kane P. Norian R. Audette J. Guttmann W. Jensen B. S1eron.
E. TYIo~m R. Frahm S
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