05000339/LER-1981-019-03, /03L-0:on 810214,at 100% Power,Auxiliary Feedwater Overspeed Trip Valve Tripped Twice,Rendering Feedwater Pump Inoperable.Caused by Improper Alignment of Linkage Parts.Parts Machined & Pump Returned to Svc

/03L-0:on 810214,at 100% Power,Auxiliary Feedwater Overspeed Trip Valve Tripped Twice,Rendering Feedwater Pump Inoperable.Caused by Improper Alignment of Linkage Parts.Parts Machined & Pump Returned to Svc

ML19345G243
Person / Time
Site:	North Anna
Issue date:	03/13/1981
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19345G242	List: 05000339/LER-1981-019, Forwards LER 81-019/03L-0 05000339/LER-1981-019-03, /03L-0:on 810214,at 100% Power,Auxiliary Feedwater Overspeed Trip Valve Tripped Twice,Rendering Feedwater Pump Inoperable.Caused by Improper Alignment of Linkage Parts.Parts Machined & Pump Returned to Svc
References
LER-81-019-03L-01, LER-81-19-3L-1, NUDOCS 8103170437
Download: ML19345G243 (3)

LER-1981-019, /03L-0:on 810214,at 100% Power,Auxiliary Feedwater Overspeed Trip Valve Tripped Twice,Rendering Feedwater Pump Inoperable.Caused by Improper Alignment of Linkage Parts.Parts Machined & Pump Returned to Svc

Event date:
Report date:
3391981019R03 - NRC Website

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O LICENSEE EVENT REPORT i

CONTROL BLOCK / / / / / / / (1)

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT

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

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On February 14, 1981, with Unit 2 at 100 percent power, the auxiliary feedwater/

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pump turbine overspeed trip valve tripped twice. Closure of the valve rendered /

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the turbine driven auxiliary feedwater pump inoperable. Both events are re-

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portable pursuant to T.S. 6.9.1.9.b.

Two redundant full size motor driven

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auxiliary feedwater pumps were operable. The action statement of the LCO was /

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met.

The public health and safety were not affected.

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SYSTEM

CAUSE

CAUSE COMP.

VALVE CODE CODE-SUBCODE COMPONENT CODE SUBCODE SUBCODE

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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 LB/ (18) LA/ (19) /_Z/ (20) LZ/ (21) /0/0/0/0/ (22) LY/ (23) LN/ (24) /A_/ (25) /T/1/4/7/ (26)

CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27)

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Improper alignment of the overspeed trip device linkage parts due to wear

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caused the unexpected trips. The parts were machined to obtain proper clear- /

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ances, the overspeed trip tested, and the pump returned to service after test- /

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ing.

New parts are on order and will be installed at a later date.

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FACILITY METHOD OF STATUS

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OPERATOR OBSERVATION

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ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY (35)

LOCATION OF RELEASE (36)

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PERSONNEL EXPOSURES NUMBER TYPE

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PUBLICITY ISSUED DESCRIPTION (45)

NRC USE ONLY

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NAME OF PREPARER-W. R. CARTWRIGHT PHONE (703) 894-5151 8103170437

Virginia Electric and Power Company North Anna Power Station, Unit #2 Attachment: Page 1 of 2 Docket No. 50-339 Report No. LER 80-019/03L-0

Description of Event

On February 14, 1981, with Unit 2 at 100 percent power, the auxiliary feedwater ptap turbine overspeed trip valve tripped twice. Closure of the valve rendered the turbine auxiliary feedwater pump inoperable.

This event is reportable pursuant to T.S. 6.9.1.9.b.

Probable Consequences of Occurrence Two redundant full size motor driven auxiliary feedwater pumps were operable. The turbine driven auxiliary feedwater pump was tested and returned to operable status 18 hours2.083333e-4 days <br />0.005 hours <br />2.97619e-5 weeks <br />6.849e-6 months <br /> after the first event (the second event occurred 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> after the firrt event). The action statement of the LCO was met.

The public health eafety were not affected.

Cause of Event

Improper alignment of turbine overspeed trip device to trip v21ve linkage (tappet nut to head lever alignment incorrect) caused the trips.

Imptcper alignment was caused by worn parts.

Immediate Corrective Action

The first time the valve closed the overspeed trip was reset, tripped to verify that it was functional, and reset. A security check verified that no one was in the turbine driven auxiliary feedwater pump house when the trip occurred. When the valve tripped again 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and 10 minutes after the first event, the turbine driven auxiliary feedwater pump was declared. inoperable. The existing parts were machined to obtain proper linkage clearances and reinstalled. The overspeed setpoint was checked after maintenance was complete and the pump was returned to operable status after being tested in accordance with T.S. and IWP requirements.

Scheduled Corrective Action i

New parts to replace the worn linkage parts are on order and will be installed at a later date. The linkage will be checked yearly as recommended by the manufacturer.

l Actions Taken to Prevent Recurrence Since August 1980, the Unit 1 turbine driven auxiliary feedwater pump has had three overspeed trips unexpectedly and the Unit 2 turbine driven auxiliary feedwater pump has had four unexpected trips. An on going investigation is being conducted to determine actions which should be taken to prevent recurrence, if any.

On February 11, 1981, three days before the events, an investigation of the overspeed' trip device by the Safety Engineering Staff revealed the improper alignment problem. The Safety Engineering Staff documented

, their concern about - the problem and recommendations in a' memorandum to the Maintenance Department on February 11, 1981;: unfortunately, before L

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Attachment: Page 2 of 2 the Maintenance Department was able to take action the alignment problem caused the events described above.

Generic Implications An identical problem was found on the Unit 1 overspeed trip device.

' The probles is not considered generic because the manufacturer recommends checking overspeed trip device linkages and clearances once yearly for wear in their current maintenance manuals.

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