05000285/LER-1980-032-03, /03L-0:on 801210,primary Heat Tracing Circuits Associated W/Piping Between Boric Acid Pump Discharge & MCV-268 Found Inoperable.Caused by Blown Power Supply Fuses. Fuses Replaced

/03L-0:on 801210,primary Heat Tracing Circuits Associated W/Piping Between Boric Acid Pump Discharge & MCV-268 Found Inoperable.Caused by Blown Power Supply Fuses. Fuses Replaced

ML19351F383
Person / Time
Site:	Fort Calhoun
Issue date:	12/17/1980
From:	Mueller B OMAHA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19351F348	List: 05000285/LER-1980-032, Forwards LER 80-032/03L-0 05000285/LER-1980-032-03, /03L-0:on 801210,primary Heat Tracing Circuits Associated W/Piping Between Boric Acid Pump Discharge & MCV-268 Found Inoperable.Caused by Blown Power Supply Fuses. Fuses Replaced
References
LER-80-032-03L, LER-80-32-3L, NUDOCS 8101120348
Download: ML19351F383 (4)

LER-1980-032, /03L-0:on 801210,primary Heat Tracing Circuits Associated W/Piping Between Boric Acid Pump Discharge & MCV-268 Found Inoperable.Caused by Blown Power Supply Fuses. Fuses Replaced

Event date:
Report date:
2851980032R03 - NRC Website

text

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8 60 61 DOCKET NUM6; R 68 69 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBA8LE CONSEO JENCES h lo l2l l On 12/10/80, while operating at approximately 75% power, the primary heat tracing l

10 l a I i circuits associated with the piping located between the Boric Acid Pump (Cil-4A) dis-l l o 14 l l charge and one of the isolation valves (IICV-268) to the charging pump suction l

log3; l header were found to be inoperable. During the time of the failure, the secondary l

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LER No.80-032 Omaha Public Power District Fort Calhoun Station Unit No.1 Docket No. 05000285 ATTACHMENT N0. 1

Safety Analysis

During the time in which the piping extending from the Boric Acid Pump (CH-4A) discharge to the isolation valve of one of the two charging pump suction headers, HCV-268, was declared inoperable, at least two redundant flow paths were still operable and capable of supplying re-quired borated water to the reator if necessary. Several alternate and redundant flow paths consisted of 1) the charging pumps taking suction from the Boric Acid tanks via gravity feed, 2) the charging pumps taking suction from the SIRWT (Safety Injection Refueling Water Tank), and 3) the safety injection pumps taking suction from the SIRWT and lastly the flow path from the redundant Boric Acid pump CH-48 to the charging pump suction.

The lowest temperature recorded on the piping was above the temp-erature at which the required concentration of Boric Aicd would have solidified. This temperature was held for only a minimal time as the entire system returned to normal temperature within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> of repair.

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LER No.80-032 Omaha Public Power District Fort Calhoun Station Unit No. 1 Docket No. 05000285 ATTACHMENT NO. 2

Corrective Action

Upon discovery of de-energized primary heat tracing circuits per-taining to the piping in question, the blown fuses were replaced and the system was returned to normal temperature within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

At the time of the heat tracing circuit failures, circuits P-69, P-28, P-33, S-33, and P-48 were found to be drawing higher-than-normal amperage.

It is postulated that the excessive current draw was due to wet pipe insulation coupled with SCR potentiometers operating slightly out of adjustment. All applicable heat tracing circuits were re-adjusted to attain desired current ead verify proper operability. The heat tracing system will contir.ue to be visually monitored by the Operations staff in order to more closely moni".or the operability of the system.

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LER No.80-032 4

i Omaha Public Power District Fort Calhoun Station Unit No.1 j

Docket No. 05000285 i

ATTACHMENT N0. 3 j

Failure Data l

This is the first failure of this type at the Fort Calhoun Station.

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