ML20010H858

LER 81-008/03L-0:on 810813,86B/CRHS (Containment Radiation High Signal) Lockout Relay Failed to Actuate When RM-062 Was Placed in Alarm,Resulting in Failure of 86B1/CRHS Relay to Actuate.Caused by Dirt in Relay Latching Mechanism

ML20010H858
Person / Time
Site:	Fort Calhoun
Issue date:	08/27/1981
From:	Mueller R OMAHA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20010H854	List: ML20010H853 ML20010H858
References
LER-81-008-03L, LER-81-8-3L, NUDOCS 8109290361
Download: ML20010H858 (4)

Text

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' 4 t4 tf C,0CK ET N UMB E a d W EVENT O ' TE 74 75 REPOHT D ATE EVET DE3CRIP TlON AND PROS A8LE CONSEQUENCES h l o 121 [Rith lh.e_ reactor operating at appgrox. 95% cower. engine.ered saf.eguards_e.quipment re- 1

. [n ;;; Qating to RM-062 was tested for proper operation prior to a gas release. Subsequently,j l o j ., ; lthe 86B/CRHS (Containme-t Radiation High Signal) lockout relay failed to actuate when j

[o;3; ;RM-062 was placed in " alarm". This also resulted in a failure of the derived signal l

o gg ; g lockout 86Bl/CRHS relay to actuate. The redundant channels relay, 86A/CRHS and 86Al/ l 1ol3l lCRHS were operable and did actuate at the time of the 86B/CRHS failure. l

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!3 ; o j lThe relay latching mechanism was found to be bound due to dirs 2se. The coil 1 13 l3j l latching mechanism was c.eaned and lubricated. Subsequently, the relay was tested j i, i ;, i lseveral times and proved to be operating satisfactorily in all cases. I I

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. LER 81-008 Omaha Public Power District Fort Calhoua Station Unit No. 1 Docket No. 05000285 ATTACHMENT NO. 1 cafety Analysis The Fort Calhoun Station Unit No. 1 Engineered Safeguard Features are designed such that no single failure can prevent Engineered Safe-guard equipment from performing designed safety functions. During the time of the failure of the 86B/CRHS lockout relay, the redundant channel 86A/CRHS lockout relay (and its associated derived signal relay, 86Al/CHRS) was operabic and fully capable of performing the necessary functions to safely mitigate an accident.

The 86A/CRHS and 8/B/CRHS lockout relays are tested each month per Surveillance Test ST-RM-2 and prior to all contaittent gas releases.

3 Since these relays are tested on a regular basis, with few resultant i

relay failures, further maintenance and/or testing of these relays is not warrantsl at this time.

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. LER 81-008 Omaha Public Power District Fort Calhoun Station Unit No. 1 Docket No. 05000285 ATTAC10 TENT NO. 2 Corrective Action Upon testing the Radiation Monitor RM-062'"high alarm trip" and the .

corresponding 86B/CRHS lockout relay, the relay failed to trip-properly.

The operators immediately placed the Ventilation Isolation Actuation System (VIAS) actuation circuitry into f.ts accident 4 position. M.0.

1. 11182 was written to investigate the problem. Corrective action in-volved the cleaning and lubricating of the rollers and brass bushings of the 86B/CRHS coil trip mechanism. The relay was then retested several times a I operated satisfactorily each time.

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LER 81-008 Omaha Public Power District Fort Calhoun Station Ur.it No. 1 Decket No. 05000285 ATTACllMENT NO. 3 Failure Data This is the third failure involving CRilS lockout relays at the Fort

. Calhoun Station Unit No. 1. The first and second failures correspond to LER's78-015 and 79-022, respectively, i