ML19275A637
| ML19275A637 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 09/27/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Pilant J NEBRASKA PUBLIC POWER DISTRICT |
| References | |
| NUDOCS 7910180043 | |
| Download: ML19275A637 (1) | |
Text
CENTRAL FILES PDR:HQ R
UNITED STATES
[** af coq'o, NUCLEAR REGULATORY COMMISSION IISIC
@ 'O t' ^
REGION IV I
611 RY AN PLAZA DRIVE, SulTE 1000 E I
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o ARLINGTON, TEX AS 76012 S A 8 "/j j 7 'g; ;qh t
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~; p September 27, 1979 Docket No.
50-298 Nebraska Public Power District ATTN:
J. M. Pilant, Director Licensing & Quality Assurance Post Office Box 499 Columbus, Nebraska 68601 Gentlemen:
The enclosed IE 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,
/
-we s
Karl V. Seyfrit Director *
Enclosures:
1.
Designated Applicants for Operating Licenses 3.
List of IE Bulletins Issued in Last Six Months cc:
L. C. Lessor, Superintendent Cooper Nuclear Station Post Office Bex 98 Brownville, Nebrash 68321 1184 246 Ob t910l80
Accession No. 7908220114 SSINS No:
6820 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 IE Bulletin No. 79-24 Date: September 27, 1979 Page 1 of 2 FR0 ZEN LINES Eummary:
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 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 h"RC until March 12, 1979.
In addition, over the past live 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 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 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 ucirculation line serves two purposes: One is to provide a flow path fm surveillance testing, and the other is to provide a minimum flow path to
,,revent 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 no immediate action was taken to thaw t January 5, 1979, the line was thawed an was successfully completed.
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