ML19224B894
| ML19224B894 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/18/1979 |
| From: | Tedesco R Office of Nuclear Reactor Regulation |
| To: | Mattson R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7906270142 | |
| Download: ML19224B894 (2) | |
Text
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NUCLEAR REGULA TC.W COM.".ilSSION
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IGY 181379 I:EliORANDU1 FOR: Roger J. ifattson, Director, Division of Systems Safety FR0ti:
Robert L. Tedesco, Assistant Director for Reactor Safety, DSS
SUBJECT:
BWR PRESSURE RELIEF VALVES I have made a preliminary review of some data on BWR pressure relief valves with regard to failure rate, f.e., either inadvertec.t actuation or actuation with subsequent stuck-open condition.
The results are summarized belcw:
1.
Appendix y of NAS!!-1400 indicates a failure probability of 10-I Joe ilurphy believes that this was a reasonable number but that an updating was needed.
2.
TiUREG-0462 (July 1978) [ Period 1969 - April 1978]
Of the 49 BWR inadvertent bicwdown events reported, 25 involved the spurious opening of an SRV valve with subsequent failure to reseat; 12 SRis opened during a pressure-transient with sub -
sequent failure to properly reseat; and 11 events involved manual SRV opening during testing with subsequent failure to rescat.
Comparable data are given for other pressure relief valves.
The report discusses corrective actions being taken to reduce the frequency of SRV events; however, it does not appear reasonable to expect a significant reduction such that the prob-ability of failure would be made very small.
3.
I talked to G. Sherwood at
.c about the SRV situation and he gave
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me a number of 4 x 10-4 pc, event which is low.
I have asked for the basis of this value based on NUREG-0462 information.
On the basis of the foregoing, it appears that we have a similar situation with BWR SRVs that we have with the B&W PORVs.
This raises the same question regarding GDC 14.
In NUREG-0560, we indicated that we would look into such events that frequently challenge the plant safety system (8.2.5).
I believe that it is necessary that we meet promptly with GE on this matter.
It appears that we may need a GG review group soon.
d Pfmm Robert L. Tedesco, Assistant Director for Reactor Safety
_I Division of Systems Safety 4 }/+
cc: See next page.
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