ML19275A315
| ML19275A315 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities, Zion  |
| Issue date: | 09/27/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Brian Lee COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 7910040034 | |
| Download: ML19275A315 (1) | |
Text
T1C UNITED STATES
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NUCLEAR REGULATORY COMMISSION g
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799 ROOSEVELT ROAD
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GLEN ELLYN. ILLINOIS 60137 SEP P 71979 Docket Nos. 50-10, 50-237, 50-249, 50-254, 50-265, 50-295, and 50-304 Commonwealth Edison Company ATTN:
Mr. Byron Lee, Jr.
Vice President Post Office Box 767 Chicago, IL 60690 Gentlemen:
The enclosed IE Bulletin No. 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, O.. O gs-k w damesG.KepIl$r Director
Enclosures:
1.
Designated Applicants for Operating Licenses cc w/ encl:
Mr. B. B. Stephenson, Site Director, NRR/ DOR Station Superintendent PDR Mr. N. Kalivianakis, Local PDR Station Superintendent NSIC Mr. N. Wandke, Station TIC Superintendent Anthony Roisman, Esq., Attorney Central Files Mr. Dean Hansell, Office Director, NRR/DPM of Assistant Attorney General
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h 1101 292 0y G
7910040,g,
t Accession No. 7908220114 SSINS No:
6820 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 September 27, 1979 IE Bulletin No. 79-24 FR0Z2N LINES 2nanary:
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 high pressure coolant injection (HPCI) system remirculation line that is common t' both high 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 Circumstances:
The condition was discovered on January 3,1979, while ti e reactor was operating at approximately 96 percent power.
During a monthly surveillance test of the HPCI pumps, there was no flow through the recirculation line from the pump discharge to the Borated Water Storagt 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 pumps. The line has redundant he.1 tracing (a heated wire to prevent freezing); it is insulated; and it has a low-temperature alarm system 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 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 pr Jole damage to the pump in the event it is operated against a closed discharge valve or a reactor coolant system pressure greater than the maximum discharge pressure of the pump (approximately 1600 psig).
In the initial review of the event on January 3, 1979, the licensee concluded that the pumps were 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 and the surveillance test of the pumps
~ '
was successfully completed.
DUPLICATE DOCUMENT Entire document previously entered
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