ML19250C272
| ML19250C272 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 11/05/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Arenal A SOUTHERN CALIFORNIA EDISON CO. |
| References | |
| NUDOCS 7911230129 | |
| Download: ML19250C272 (1) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION o
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REGION V o, i 1990 N. CALIFORNIA BOULEVARD O
SulTE 202, WALNUT CREEK PLAZA o
WALNUT CREEK, CALIFORNIA 94596 November 5, 1979 Docket Nos. 50-206 50-361 50-362 Southern California Edison Company P. O. Box 800 2244 Walnut Grove Avenue Rosemead, California 91770 Attention: Mr. A. Arenal, Vice President Advanced Engineering Gentlemen:
This Information Notice is provided as an early notification of a possibly significant matter.
It is expected that recipients 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,
$WmWL R. H. Engelken Director
Enclosures:
1.
IE Information Notice No. 79-26 2.
List of IE Information Notices Issued in the Last Six Months 13'>6 235 cc w/ enclosures:
J. M. Curran, SCE J. T. Head, SCE J. H. Drake, SCE 7911230/
SSINS:
6870 Accession No:
7908220133 UNITED STATES NUCLEAR REGULATORY C0'#41SSION OFFICE OF INS %CTION AND ENFORCEMENT WASHINGTON, D. C.
20555 November 5, 1979 IE Information Notice No. 79-26 BREACH OF CONTAINMENT INTEGRITY Description of Circumstances:
On September 14, 1979, the Consumers 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 manual 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 imorocerly oositioned since April,1978, when an efficiency test of the bypass line filters was performed. The plant has operated at power for the major portion of that time oeriod.
The valve misalignment had no actual inoact on the public health.
However, in the event of a desian basis accident wherein fuel damace and release of oricary coolant inside the containment are postulated, the ooen valves would provide a significant oath for a radioactive release from the containment.
The initial desiqn ourpose for the bypass system was to provide a lora term hydrogen control capability for the containment atnosohere 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 cerrit ventina, this systen would be nanually valved to vent the containnent atmosohere, throuah high efficiency and charcoal filters, to the exhaust stack.
Thus the conoonents in the bypass lire beyond the two manual isolation valves were not designed for the severe service they would be exoosed to with the valves ooen during 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 nake immediate closing of the manual isolaticn valves, even if identified as the source of leakaae, an extremelv hazardous coeration.
The orincipal cause for this event was i proner use and oositioning of these valv DUPLICATE DOCUMENT valve line-up checklist, which is perfor Entire document previously 1/ Current NRC requirements call for th entered into system under:
fiydronen builduo.
Palisades has reconbi 1306 236 u
No. of pages:
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