ML19250C273
| ML19250C273 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 11/05/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| References | |
| NUDOCS 7911230131 | |
| Download: ML19250C273 (1) | |
Text
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UNITED STATES NUCLEAR REGULATORY COMMISSION y *.,,
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.- c REGION V S
1990 N. CAllFORNIA BOULEVARD
'Nd SUITE 202, WALNUT CREEK PLAZA
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WALNUT CREEK, CALIFORNI A 94596 November 5, 1979 Docket No. 50-312 Sacramento Municipal Utility District P. O. Box 15830 Sacramento, California 95813 Attention: Mr. John J. Mattimoe Assistant General Manager Gentlemen:
This Information Notice is provided as an ea ly notification of a possibly significant matter.
It is expected that rec pients will review the information for possible applicability to their facilities.
No specific action or response is requested at this time.
If further NRC evaluations so indicate, an IE Circular, Bulletin or NRR Generic Letter will be issued to recommend or request specific licensee actions.
If you have questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely, f W
,ci L R. H. Engelken Director
Enclosures:
1.
IE Information Notice No. 79-26 2.
List of IE Information Notices Issued in the Last Six Months cc w/ enclosures:
R. J. Rodriguez, SMUD L. G. Schwieger, SMUD 1396 237 7911230 l
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6870 Accession f:o:
7908220133 UNITED STATES NUCLEAR REGULATORY C0!f11SSION OFFICE OF INSPECTION AND ENFORCEMENT WASHIflGTON, D. C.
20555 t1ovember 5, 1979 IE Information Notice No. 79-26 BREACH OF CONTAINMENT INTEGRITY Description of Circunstances:
On Seotenber 14, 1979, the Consuners Power Conoany (CPC) notified the NRC of discovery at the Palisades Nuclear Generating Plant of a valve misalignment that had resulted in containnent integrity being breached for an indeterminate length of time.
While preparing to perform a Type "C" leak test between two aanual valves in a 3" bypass line around the main 48" containment ourge valve, plant personnel dis-covered that both of these manual isolation valves were locked in the open oosi-tion. These valves should have been locked closed.
Investication : / the licensee indicated that the valves may have been incrocerly positioned since April,1978, when an efficiency test of the bypass line filters was perforned. The plant has operated at oower for the major portion of that time oeriod.
The valve risalianment had no actual inoact on the public health.
However, in the event of a desian basis accident wherein fuel damaae and release of orinary coolant inside the containment are postulated, the ooen valves would provide a sianificant oath for a radioactive release from the containnent.
The initial desiqn ourpose for the bypass system was to provide a long tem hydrogen control cacability for the containment atnoschere following a design basis accident.l_/ It was intended that after approximately 30 days following an accident, when containment oressure and activity levels dropped sufficiently to permit ventina, this systen would be nanually valved to vent the containnent atmosohere, throuch high efficiency and charcoal filters, to the exhaust stack.
Thus the conoonents in the bypass line beyond the two ranual isolation valves were not designed for the severe service they would be exoosed to with the valves ooen durina the initial pressure surge of the desian basis accident, and signif-icant uncontrolled release would result. High radiation in the vicinity of the bypass line would also make immediate closing of the manual isolation valves.
even if identified as the source of leakaoe, an extrenely hazardous ooeratirn.
The princioal cause for this event was i proner use and nositioning of these vah valve line-up checklist, which is perfor DUPLICA'IE DOCUMENT Entire document previously 1/ Current NRC requirements call for th entered into system under:
fiydrocen builduo.
Palisades has reconbi p
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