ML19275A651
| ML19275A651 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 09/27/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Goodwin C PORTLAND GENERAL ELECTRIC CO. |
| References | |
| NUDOCS 7910180061 | |
| Download: ML19275A651 (1) | |
Text
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UNITED STATES
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WALNUT CREEK, CALIFORNIA 94596 September 27, 1979 Docket No. 50-344 Portland General Electric Company 121 S. W. Salmon Street Portland, Oregon 97204 Attention: Mr. Charles Goodwin Assistant Vice President Gentlemen:
The enclosed Bulletin 79-24 is forwarded to you for action. Written responses are required.
If you desire additional information regarding this matter, please contcct this office.
Sincerely, l${~} ~,d(C ~.
R. H. Engelken Director
Enclosures:
1.
Designated Applicants for Operating Licenses cc w/ enclosures:
C. P. Yundt, PGE F. C. Gaidos, PGE 1184 296 7910180 O b !
Accession t'o. 7908220114 SSINS No:
6820 UflITED STATES NUCLEAR REGULATORY COMMISSIOF 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 September 27, 1979 IE Bulletin No. 79-24 FR0 ZEN LINES Summary:
On January 3, 19) an unusual event occurred at Davis-Besse, Unit 1.
The event involved the freezing of the water in a portion of the hiah pressure coolant injection (HPCI) system recirculation line that is common to both hiah pressure coolant injection pumps. The line was not thawed until January 5,1979, and the event was not reported to NRC until varch 12, 1979.
In addition, over the past five years, there have been several events involving frozen instrument and sampling lines.
Descrintion of Circunstances:
The condition was discovered on January 3,1979, while the reactor was operating at approximately 96 percent power. During a monthly surveillance test of the HPCI numns, there was no flow through the recirculation line from the pump discharae to the Borated Water Storcge Tank (BWST).
Investigation revealed that water in a portion of the line exposed to the outside weather was frozen.
This portion of the line to the BWST is common to both HPCI rumps.
The line has redundant heat tracing (a heated wire to prevent freezing); it is insulated; and it has a low-temperature alarm system to warn of freezing conditio s.
Water in the line froze apparently because of prolonged sub-freezing temperatures and a defect in the insulation. There was no apparent malfunction of the heat tracing or temperature alarm circuits, although the temperature sensing elements are located in an area not exposed to the coldest temperature conditions.
This recirculation line serves two purposes: One is to provide a flow path for surveillance testing, and the other is to provide a minimum flow path to prevent possible damage to the pump in the event it is operated against a closed discharge valve or a reactor coolant systen pressure greater than the maximum discharge pressure of the pump (approximately 1600 psia).
In the initial review of the event on January 3,1979, the licensee concluded that the pumps ware still operable with the recirculation line frozen. Therefore, no immediate action was taken to thaw the frozen section of the line.
On January 5,1979, the line was thawed an was successfully completed.
DUPLICATE DOCUMENT Entire document previously entered into system under:
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