ML19275A331
| ML19275A331 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 09/27/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Crouse R TOLEDO EDISON CO. |
| References | |
| NUDOCS 7910040062 | |
| Download: ML19275A331 (1) | |
Text
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UNITED STATES E
NUCLEAR HEGULATORY COMMISSION 3,,
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REGION 111 3
0, 795 ROOSEVELT ROAD
,e" GLEN E LLYN. lLLINplS 60137 3r Docket No. 50-346 Toledo Edison Company AITN:
Mr. Richard P. Crouse Vice President Energy Supply Edison Plaza 300 Madison Avenue Toledo, OH 43652 Gentlemen:
The enclosed IE Bulletin No. 79-24 is forwarded to you for action. Written res;- nses are required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, Q __. % g
(/Jame's'G.K ler Director
Enclosures:
1.
Designated Applicants for Operating Licenses cc w/ enc 1:
Mr. T. Murray, Station Superintendent Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PD" a2
TIC Harold W. Kohn, Power Siting Commission lielen W. Evans, State of
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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 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 high pressure cooiant injection (HPCI) system recirculation line that is common to both high pressure coolant injection pumps.
The lir; was not thawed until January 5, 1979, and the event was not reported to NRC until March 12, 1979.
In addition, over the ptst 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 the 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 Storage Tank (BWST).
Investigation revealed that water in s portion of the line exposed to the outside weather was frozen.
This portion of the line to the BWST is common to bott 'IPCI pumps. 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 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 temperr.tJre 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 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
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zwas successfully completed.
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