ML19275A316
| ML19275A316 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood, LaSalle  |
| Issue date: | 09/27/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Brian Lee COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 7910040037 | |
| Download: ML19275A316 (1) | |
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UNITED STATES
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NUCLEAFi REGULATORY COMMISSION 3,
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.r REGION 111 O[
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o GLEN ELLYN. ILLINOIS So137 SEP 2 71979 Docket Nos. 50-456, 50-457, 50-454, 50-455, 50-373 and 50-374 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 information.
If you desire additional information regarding this matter, please contact this office.
Sincerely,
)L A_
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ames G. Keppler Director
Enclosure:
IE Bulletin No. 79-24 cc w/ enc 1:
Mr. L. J. Burke, Site Director, NRR/ DOR Project Superintendent PDR Mr. T. E. Quaka, Quality Local PDR Assurance Supervisor NSIC Mr. R. H. Holyoak, TIC Stt'lon Superintendent Anthony Roisman, Esq., o L.rney M_. Gunner Sorensen, Site Mr. Dean Hansell, Offu Project Superintendent of Assistant Attorney Central Files General Director, NRR/DPM 1101 294 3910040037 o
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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 FR0 ZEN 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 peessure coolant injection (HPCI) system recirculation line that is common to 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 sar.pling 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 a portion of the line exposed to the outside weather was frozen.
This portion of tFe 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 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 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 concleded 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
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January 5,1979, the line was thawed a was successfully completed.
DUPLICATE DOCUMENT Entire document previously entered into system under:
I ANO 790 62 2. C H L/-
g 1101 295 no-or vases:
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