ML19275A648
| ML19275A648 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| Issue date: | 09/27/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Crane P PACIFIC GAS & ELECTRIC CO. |
| References | |
| NUDOCS 7910180057 | |
| Download: ML19275A648 (1) | |
Text
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'o UNITED STATES l(.
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'o NUCLEAR REGULATORY COMMISSION 3.k'^/d, /. ;,E nEGION V 0, ' ',k j,
,7 1990 N. CALIFORNI A DOULEVAHD
%, ~ b SulTE 202, V/ALNUT CREEK PLAZA V/ALNUT CREEK, CALIFORNIA 94596 September 27, 1979 Docket flo. 50-133 Pacific Gas and E'iectric Company 77 Beale Street San Francisco, California 94106 Attention: Mr. Philip A. Crane, Jr.
Assistant General Counsel 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 contact this office.
Sincerely, IYMS$. -~--
R. H. Engelken Director
Enclosures:
1.
IE Bulletin flo. 79-24 2.
Designated Applicants for Operating Licenses cc w/ enclosures:
W. Barr, PG&E W. Raymond, PG&E E. Weeks, PGSE, Humboldt Bay 1184 290
}910180 O E~7
Accession No. 7908220114 SSINS No:
6820 UNITED STATES NUCLtAR REGULATORY COMMISSION
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OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 September 27, 1979 IE Bulletin No. 79-24 FROZEN LINES Summary:
On January 3,1979, 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 comon 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 March 12, 1979.
In addition, over the past five years, there have been several events involving frozen instrument and sampling lines.
Description 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 numps, there was no flow through the recirculation line from the pump discharge to the Borated Water Storage Tank (BWST).
Investigation revealed that water in a portion of the line exoosed to the outside weather was frozen.
This portion of the line to the BWST is common to both HpCI pumps. The line has redundant heat tracing (a heated wire to prevent freezing); it is insulated; and it has a low-temperature alarm systen to warn of freezing conditions.
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 alarn 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 minimun flow path to prevent possible damage to the pump in the event it is operated against a closed dischar e valve or a reactor coalant systen pressure greater than the maximum discharge pressure of the pump (approximately 1600 psic).
In the initial review of the event on January 3, 1979, the licensee concluded that the pumps were still operable with the recirculation line frczen. Therefore, no inmediate action was taken to thaw the frozen section of the line.
On
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January 5,1979, the line was thawed a ' "
was successfully completed.
DUPLICATE DOCUMENT Entire document previously 1184 2e)1 enteree into system uncer:
xNo 7. b..H, A1aW. p No. of pages: