ML19254C999
| ML19254C999 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 09/27/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Stampley N MISSISSIPPI POWER & LIGHT CO. |
| References | |
| NUDOCS 7910190267 | |
| Download: ML19254C999 (2) | |
Text
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UNITED STATES 8
NUCLEAR REGULATORY COMMISSION 3
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$4 - [*E REGION 11 o, K' 101 MARIETTA ST N.W., SUITE 3100 ATLANTA, G EORGI A 30303
.....,o SEP 2 71979 In Reply Refer To:
RII:JPO
~50-416
(' 50-417 q _
Mississippi Power and Light Company Attn:
N.
L. Stampley Vice President of Production P. O. Box 1640 Jackson, Mississippi 39205 Gentlemen:
The enclosed Bulletin 79-24 is forwarded to you for information.
If you desire additional information regarding this matter, please contact this office.
Sincerely, shibs
. O'Reilly Di
. tor
Enclosure:
IE Bulletin No. 79-2.,
e 7910190 2 6 7 ek
SEP 2 71979 Mississippi Power and Light Company -
cc w/ encl:
C. K. McCoy Plant Manager Post Office Box 756 Port Gibson, Mississippi 39150
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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 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 NRC until :tarch 12, 1979.
In addition, over the past five years, there have been several event.s involving frozen instrument and sampling lines.
Description f 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 frem the pump discharge to tha Borated Water Storage Tank (BWST).
Investigation revealed that water in a portion of the line exposed to the outside weather w;s frozen.
This portion of the line to the BW~ is common to both HPCI pumps.
The line has redundant heat t racing (a heate d wire to prevent freezing); it is insulated; and it has a low-temperature alarm system to warn of freezing conditions.
Water in the line frwe 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, cnd 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 1.ressure 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 recirculatina 1 4 ~- " - - -
no immediate action was taken to thaw tl January 5, 1979, the line was thawed an<
was successfully completed.
g Entire document previously entered into system under:
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