ML20041B105

LER 82-002/03L-0:on 820114,at 99% Power,Lockout Relay 86B1, Containment Radiation High Signal,Failed to Actuate on Demand by Plant Radiation Monitoring Sys.Caused by Burnt Coil on Lockout Relay.Coil Replaced & Tested Satisfactorily

ML20041B105
Person / Time
Site:	Fort Calhoun
Issue date:	01/28/1982
From:	Mueller R OMAHA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20041B093	List: ML20041B092 ML20041B105
References
LER-82-002-03L, LER-82-2-3L, NUDOCS 8202230277
Download: ML20041B105 (4)

Text

NRC FORM 36G U. S. NUCLEAR REGULATORY COMMISSION

.(747) *. O LICENSEE EVEf4T REPORT CONTROL BLOCK: l l l l l l l (PLEASE PRINT On TYPE ALL REQUIRED INFORMATION) 1 6

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7 3 t>J 68 EVENT DATE 74 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h

[TTI] l During power operations at approximately 99% power, lockout relay 86Bl/CRHS (Contain- l gja; j ment Radiation High Signal) failed to actuate on demand by the plant radiation l l n ) ., ; l monitoring system. This resulted in the failure of one of the Engineered Safety l jo;3; ; Feature channels to operate. However, during the inci.. ant all redundant CRHS lockout l lO ls l l relays (86/./CRHS, 86Al/CRHS and 86B/CRHS) functioned as designed and initiated ap- l 10171 l propriate safeguards equipment as required. [

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SYSTEM CAUSE CAUSE COMP. VALVE FCOE CODE SUSCUDE COMPONENT CODE SUBCODE SUBCODE l0l9) 8 lS l Fl@ W@ l A l@ lR lE lL l A lY lX l@ y@ W @

9 10 12 13 18 20 7 11 19 SEQUENTIAL OCCURRENCE REPORT REVISION LE R RO E REPORT NO. CODE TYPE N O.

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43 44 47 CAUSE DESCRIPTION AND CCRRECTIVE ACTIONS h 1 O lThe coil of the 86B1/CRHS lockout relay was noticed to have been burnt and thereby I Iilil l"open-circuited". The coil was immediate1v reolaced ner Maintonnnce Order #13MO. I IiI71 1In addition, the relay coil latching mechanism was cleaned, lubricated and checked forl Ii1:1i lproper alignment. The relay was subsequentic satisfactorily tested for onerability l I1 14Il via surveillance test ST-RM-2 (F.2) and returned to service. l

, 8 3 80 STA S "6 pCWER OTHE R STATUS IS O RY DISCOVERY DESCRIPTION li 151 LEj@_ l 0 l 919 l@l NA l [B_j@l Operator Observation l ACTIVITY COr TENT RELEASED OF RELEASE AMOUNT OF ACTIVITY LOCATION OF RELEASE NA NA I Ii 108 L1J 7 9

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NAME OF PREPARER PHONE:

LER No.82-002 Omaha Public. Power District Fort Calhoun Station Unit No. 1

. Docket No. 05000285 Attachment No. 1 Safety Analysis The Fort Calhoun Station Unit No. 1 Engineered Safety Features are designed such that no single failure can prevent Engineered Safeguards equipment from performing designed safety functions. During the failure of the 86Bl/CRHS lockout relay, the redundant channel "A" relay - 86A/

CRHS, and the derived signal lockout relay - 86Al/CRHS, as well as the primary channel "B" lockout relay - 86B/CRHS, were all operable and fully capable of performing the necessary functions to safely mitigate an accident.

The CRHS lockout relays are tested each month per Surveillance Test ST-RM-2 and prior to all gas releases. Since these relays are tested on a regular basis, with relatively few resultant relay failures, further maintenance and/or testing of these relays is not warranted at this

, time.

I

. .. 2 LER No.82-002

- Omaha Public Power District

-Fort-Calhoun Station Unit No. 1 Docket No. 05000285 Attachment No. 2 Corrective Action During the failure of the 86Bl/CRHS lockout relay, the operators immediately-reviewed the engineered safeguards CRHS (Containment Radiation High Signal) and VIAS (Ventilation Isolation Actuation Signal) circuitry

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and associated equipment to ensure it was in its " conservative" or accident-position. Maintenance Order No. 13650 was written to changen

- theLburnt relay coil and perform other- slight maintenarce, such as:

cleaning and lubricating the rollers and brass bushing of the 86Bl/CRHS lockout relay coil trip mechanisms and ensuring proper alignment.of the coil trip mechanism. The relay was returned to service after several satisfactory test operations.

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LER No.82-002

Omaha Public Power District Fort. Calhoun Station Unit No.1 Docket No. 05000285' Attachment No. 3 Failure Data This is the fifth failure involving CRHS lockout relays at the Fort Calhoun Station Unit No.1. The previous failures being reported per LER's81-008, 79-022,78-004 and 77-026. However, additional Engineered Safeguards lockout relay failures are reported 'per LER's80-022, 78-035,

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78-015,77-022 and Abnormal Occurrences 74B-1, 74-18 and 75-3.

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