ML19254F671
| ML19254F671 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 11/05/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Bryan J UNION ELECTRIC CO. |
| References | |
| NUDOCS 7911160236 | |
| Download: ML19254F671 (1) | |
Text
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m UNITED STATES E' by#( ','n NUCLEAR REGULATORY COMMISSION E
REGION lil e[
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GLEN ELLYN. lLLINOIS 60137 Docket No. 50-483 NOV 5 1979 Docket No. 50-486 Union Electric Company ATTN:
Mr. John K. Bryan Vice President - Nuclear P. O. Box 149 St. Louis, MO 63166 Gentlemen:
This Information Notice is provided as an early notification of a possibly significant matter.
It is expected that recipients will review the infor-mation for possible applicability to their facilities. No specific action or response is requested at this time.
If further NRC evaluations so indi-cate, an IE Circular, Bulletin, or NRR Generic Letter will be issued to recommend or request specific licensee actions.
If you have questions regarding the matter, please contact the Director of the appropriate hTC Regional Office.
Sincerely, na b
~
ames G. Ke p r Director
Enclosure:
IE Information Notice No. 79-26 cc w/ encl:
Mr. W. H. Weber, Manager, Nuclear Construction Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC Region I & IV Ms. K. Drey Mr. Ronald Fluegge, Utility Division, Missouri Public Service Commission
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SSINS:
6870 Accession No:
7908220133 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION 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 Company (CPC) notified the NRC of discovery at the Palisades Nuclear Generating Plant of a valve misalignment that had resulted in containment 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 purge 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.
Investigation by the licensee indicated that the valves may have been improperly positioned 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 period.
The valve misalignment had no actual impact on the public health.
However, in the event of a design basis accident wherein fuel damage and release of primary coolant inside the containment are postulated, the open valves would provide a significant path for a radioactive release from the containment.
The initial design purpose for the bypass system was to provide a long term hydrogen contro basisaccident.hcapabilityforthecontainmentatmospherefollowingadesign It was intended that after approximately 30 days following an accident, when containment pressure and activity levels dropped sufficiently to permit venting, this system would be manually valved to vent the containment atmosphere, through high efficiency and charcoal filters, to the exhaust stack.
Thus the components in the bypass line beyond the two manual isolation valves were not designed for the severe service they would be exposed to with the valves open during the initial pressure surge of the design 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 leakage, an extremely hazardous operation.
The principal cause for this event was inadequacy of the procedures addressing proper use and positioning of the!
valve line-up checklist, which is 1/ Current NRC requirements call hydrogen buildup.
Palisades has i Entire document previously entered into system under:
ANO No. of pages:
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