05000339/LER-1980-029-01, /01T-0:on 800624,during Mode 3 Operation,Power Operated Relief Valve PCV-2456 Opened Inadvertently & Failed to Reclose.Caused by Cocked Bearing in Valve Actuator. Upstream MOV-2535 Closed to Terminate Relief Flow

/01T-0:on 800624,during Mode 3 Operation,Power Operated Relief Valve PCV-2456 Opened Inadvertently & Failed to Reclose.Caused by Cocked Bearing in Valve Actuator. Upstream MOV-2535 Closed to Terminate Relief Flow

ML19318D126
Person / Time
Site:	North Anna
Issue date:	07/02/1980
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19318D121	List: 05000339/LER-1980-029, Forwards LER 80-029/01T-0 05000339/LER-1980-029-01, /01T-0:on 800624,during Mode 3 Operation,Power Operated Relief Valve PCV-2456 Opened Inadvertently & Failed to Reclose.Caused by Cocked Bearing in Valve Actuator. Upstream MOV-2535 Closed to Terminate Relief Flow
References
LER-80-029-01T, LER-80-29-1T, NUDOCS 8007070379
Download: ML19318D126 (2)

LER-1980-029, /01T-0:on 800624,during Mode 3 Operation,Power Operated Relief Valve PCV-2456 Opened Inadvertently & Failed to Reclose.Caused by Cocked Bearing in Valve Actuator. Upstream MOV-2535 Closed to Terminate Relief Flow

Event date:
Report date:
3391980029R01 - NRC Website

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U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT CONTROL BLOCK / / / / / / / (1)

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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/V/A/N/A/S/2/ (2)

/0/0/0/0/0/0/0/0/0/0/0/ (3)

/1/1/1/1/1 (4)

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LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT

/L/ (6)

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E DOCKET NUMBER EVENT DATE REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10)

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In Mode 3, the Power Operated Relief valve PCV-2456 opened inadvertently and

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failed to reclose being placed in service following corrective maintenance.

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Pressure relief was minimized by closing the upstream isolation valve MOV-2535./

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The health and safety of the general public was not affected. The event is

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being reported pursuant to a May 7, 1980 NRC letter requiring reports of

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failures of relief valves to close (item II.K.3.3 position (a)).

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SYSTEM

CAUSE

CAUSE COMP.

VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE

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/C/J/ (11) /D/ (12) LZf_ (13) /V/A/L/V/0/P/ (14) M/ (15)

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SCQUENTIAL OCCURRENCE REPORT REVISION LER/R0 EVENT YEAR REP 02T NO.

CODE TYPE NO.

(17) REPORT NUMBER

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ACTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP. COMPONENT TAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER MANUFACTURER

/A/ (18) /G/ (19) /Z/ (20) /Z/ (21) /0/0/0/0/ (22) g/ (23) /N/ (24) /N/ (25) [M/1/2/0/ (26; CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27)

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The inadvertert opening was caused by a cocked bearing in the valve acturator. /

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With the bearing cocked, the valve actuator lost its spring closing force.

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The upstream MOV-2535 was closer *. to terminate relief flow. Further instruc-

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tions will be identified for maintenance of the valve.

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FACILITY METHOD OF STATUS

% POWER OTHER STATUS

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/B/ (28)

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NA

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/ OPERATOR OBERSEVATION/

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RELEASED OF RELEASE AMOUNT OF ACTIVITY (35)

LOCATION OF RELEASE (36) l

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[ZL (33)

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l PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION (39)

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PERSONNEL INJURIES NUMBER DESCRIPTION (41)

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LOSS OF OR DAMAGE TO FACILITY (43)

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PUBLICITY ISSUED DESCRIPTION (45)

NRC USE ONLY

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800 # 0 NAME OF PREPARER W. R. CARTWRIGHT PHONE (703) 894-5151

Virginia Electric and Power Company North Anna Power Station, Unit #2

Attachment:

Page 1 if 1 Docket No. 50-339 Report No. LER 80-29/01T-0

Description of Event

Power Operated Relief Valve PCV-2456 inadvertently opened and failed to reclose following return to service.

Corrective maintenance had been performed to repair the valve actvator diaphram. The valve actuator was disassembled and reassembled by procedure with the upstream relief lin; isolation valve MOV 2535 closed. The valve spring adjustment was made and the valve was stroked with MOV-2535 closed. With PCV-2456 closed, MOV-2535 was opened in order to return the power operated relief valve to service. This resulted in the inadvertent opening of PCV-2456.

Probable Consequences of Occurrence The consequences of the event were limited by immediate operator action to close MOV-2535 thus terminating relief flow. The health and safety of the general public was not affected by this occurrence.

Cause of Event

A ball bearing race on the valve actuator forms a firm bearing surface for contact with the spring adjustment screw. The ball bearing race became cocked during reinstallation of the actuator. Adjustment of the actuator closing force was made by use of the spring adjustment screw; however with the ball bearing race cocked and unfirm entrapment of the main actuator spring resulted. As a final check to the maintenance, the valve was satisfactorily stroked with MOV-2535 closed and a minimum of relief line pressure present. With PCV-2456 closed, MOV-2535 was opened to return the relief valve to service. PCV-2456 inadvertently opened due to insufficient spring closing force. The event is attrib-utable to an inadquate procedure and is not believed to be a generic Conce rn.

Immediata Corrective Action MOV-2535 was closed immediately thus terminating relief line flow.

Scheduled Corrective Action The valve actuator was examined and the cocked bearing was observed.

The valve was properly reassemblied and stroked. At this time, further maintenance is being performed to insure the valve will meet its required stroke time.

Actions Taken to Prevent Recurrence A more detailed procedure will be developed for the Power Operated Relief Valves.

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