ML19250C266
| ML19250C266 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay, Diablo Canyon |
| Issue date: | 11/05/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Crane P PACIFIC GAS & ELECTRIC CO. |
| References | |
| NUDOCS 7911230123 | |
| Download: ML19250C266 (1) | |
Text
lb pa at%q'o, UNITED STATES e8'y).-q ',g NUCLEAR REGULATORY COMMISSION n e REGION V 5.gb o, i Mi
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1990 N. C ALIFORNI A BOULEVARD
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,8 SulTE 202, WALNUT CREEK PLAZA
- ,,,o WALNUT CR EEK, CALIFORNIA 94596 November 5, 1979 Docket Nos. 50-133 50-275 50-323 Pacific Gas and Electric Company 77 Beale Street San Francisco, California 94106 Attention: Mr. Philip A. Crane, Jr.
Assistant General Counsel Gentlemen:
This Information Notice is provided as an early notification of a possibly significant matter.
It is expected that recipients will rr/iew the information for possible applicability to their facilitie',.
No specific action or response is requested at this time.
If furthe. NRC evaluations so indicate, an IE Circular, Bulletin or NRR Generic l_etter 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, 0(1md k 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:
W. Barr, PG&E W. Raymond, PG&E R. Ramsay, PG&E, Diablo Canyon 13 f) 200 E. Weeks, PG&E, Humboldt Bay J. Worthington, PG&E 7911230 /
3 SSIt!S :
6870 Accession t'o:
7903220133 UNITED STATES NUCLEAR REGULATORY CO*dISSI0il 0FFICE OF INSDECTION AND ENF00. CEMENT UASHINGTON, 9. C.
20555 November 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..alve nisalignment that had resulted in containnent integrity being breached for an indeterminate lenqth of time.
While prenaring to perform a Type "C" leak test between two nanual 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 posi-tion. These valves should have been locked closed.
Investiaation by the licensee indicated that the valves may have been incrocerly oositioned since April,1978, when an efficiency test of the bypass line filters was perforned. The plant has operated at power for the major portion of that tine oeriod.
The valve risaliqnment had no actual inoact on the public health.
However, in the event of a desien basis accident wherein fuel danace and release of oricary coolant inside the containment are postulated, the ooen valves would orovide a significant cath for a radioactive release from the containnent.
The initial desiqn ourpose for the bypass system was to provide a long tem hydrogen control capability 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 dropoed sufficiently to pernit venting, this systen would be nanually valved to vent the containnent atmosohere, throuah high efficiency and charcoal filters, to the exhaust stack.
Thus the connonents in the bypass line beyond the two manual isolation valves were not designed for the severe service they would be exoosed to with the valves onen durina the initial oressure surge of the desian basis accident, and sionif-icant uncontrolled release would result.
Hiah radiation in the vicinity of the byoass line would also make imediate closing of the manual isolation valves, even if identified as the source of leakaae, an extremely hazardous ooeration.
The orincipal cause for this event was i proper use and ocsitionina of these valv valve line-up checklist, which is perfon DUPLICATE DOCUMENT Entire document previously 1/ Current NRC requirements call for th entered into system under:
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