ML19327B494

LER 89-004-00:on 890926,Group Iia Primary Containment Isolation Actuated Closing of RWCU Sys Isolation Valve & Tripping RWCU Pump 3B.Caused by Personnel Error.Isolation Logic Reset & Individual counselled.W/891025 Ltr

ML19327B494
Person / Time
Site:	Peach Bottom
Issue date:	10/25/1989
From:	Cribbe T, Danni Smith PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-004-03, LER-89-4-3, NUDOCS 8910310311
Download: ML19327B494 (4)

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! D. M. Smith i Ykt Prnkk nt v October 25, 1989 l- ,

Docket No. 50-278 j i

, Document Control Desk

! U. S. Nuclear Regulatory Commission ,

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SUBJECT:

Licensee Event Report .

Peach Bottom Atomic Power Station - Unit 3  :

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! This LER concerns an Engineered Safety Feature (ESF) actuation as a result l of not following plant approved procedures, j

Reference:

Docket No. 50-278  ;

Report Number: 3-89-004 l Revision Number: 00 i Event Date: 09/26/89 l Report Date: 10/25/89 l Facility: Peach Bottom Atomic Powcr Station  :

RD 1, Box 208A, Delta, PA 17314

} This LER is being submitted pursuant to the requirements of 10 CFR .

50.73(a)(2)(iv).

Sincerely, i l

i cc: T. P. Johnson, USNRC Senior Resident inspector .

W. T. Russell, USNRC, Region 1 l

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At 0902 am, on September 26, 1989, with Unit 3 in Cold Shutdown, a Group IIA Primary Containment Isolation actuated, resulting in automatic closure of the Reactor Water Cleanup (RWCU) System (inboard)isolationvalveandtrippingofthe"3B"RWCUpump.

The root cause of the event was improper action resulting from a personnel error. A non-licensed utility maintenance planner opened a RWCU Low Pressure side Instrument Drain Valve. Opening the Instrument Drain Valve simulated a high flow condition in the RWCU suction piping and the isolation occurred as designed. At 0932 am the isolation logic was reset and the RWCU System was returned to service.

No safety consequences occurred as a result of this event. Had this event occurred at power, the temporary isolation of the RWCU System would have no significant impact on continued power operations or reactor water chemistry.

The individual involved in the event was counselled. This event and its consequences were discussed with appropriate Maintenance, Instrument and Control, and Plant Supervisory personnel. There were no previous similar events.

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This report is required per 10 CFR 50.73(a)(2)(iv) because an event occurred which l resultedinanautomaticactuationofanEngineeredSafetyFeature(ESF).

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Unit Status at Time of the Event j 1

Unit 3 was shutdown with the Reactor Mode Switch (E!!S HS) in the shutdown position.

l 83B" Reactor Water Cleanup (RWCU) (EIISICE) pump (EIIStP) was operating.

The RWCU pump Differential Pressure Indicator (DPI) (EIIS DPI) was indicating down scale with the RWCU System in operation.  ;

Description of the Event On September 26, 1989 at 9:02 am a Group !!A Inboard Primary Containment Isolation  !

(PCI) (E!!S JM) occurred as a result of opening the Low Pressure side Instrument Drain Valve (LPIDV) (EIIS V) of the RWCU Differential Pressure Indicator Switch ,

(DPIS)(EIIS:PDIS). A Group IIA inboard PCI results in tripping the RWCU pumps and l 1solatingtheRWCUSystembyclosingtheinboardRWCUsuctionvalve(M0-3-12-15) .

I (E!!S V) i l The RWCU DPI was indicating down scale with the RWCU System in operation. It was l l

thought that the sensing line may be clogged. In an attempt to determine if blockage j existed in the instrument lines a non-licensed utility maintenance planner ,

individually opened the High Pressure side Instrument Drain Valve (HPIDV) and LPIDV -

to the RWCU DPIS. Drain flow was noticed from each side of the DPIS. Opening the  ;

LPIDV simulated a high flow condition in the RWCU suction piping (EIIS:FSP) and a Group IIA inboard PCI occurred as designed. Control Room Annunciators alerted the  :

Control Room Operators of the Group IIA inboard PCI. Subsequent investi >

determined the cause of the isolation. At 0932 am the isolation logic (gationE!!d:#) was  :

reset and the RWCU System was returned to service.

i Cause of the Event .

The proximate cause of this event was failure to follow Plant approved work control procedures. The root cause of this event was an inappropriate action based on an  ;

incorrect perception that formal troubleshooting controls did not have to be  !

followec'. This incorrect perception was based on the following conditions: a) the '

RWCU DPI read down scale, and b) the HPIDV and LPIDV had tygon tubing connected to them leading to the floor drain (E!!S:DRN). Based on the long term shutdown of Unit i 3, with most systems having been out of service and the Instrument Drain Valves (IDV) l having tygon tubing set up for the function the maintenance planner wanted to l perform, he opened the valves to check for blockage in the instrument lines.  ;

One additional error was made which may have prevented this event. The maintsnance planner failed to communicate with Control Room personnel, as required by plant procedures, his prospective actions prior to opening a valve. During the post incident investigation, the individual stated he realized he was not permitted to manipulate valves or controls.

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olo 013 o' oit l Analysis of the Event l No safety consequences occurred as a result of this event.

f The equipment properly responded to this event. The isolation of the dump flow path '

andtheresultantincreaseofReactorPressureVessel(RPV)(E!!S:RPV)waterlevel l increased the margin of safety with respect to adequate covering of the core  ;

(Ells:AC). The regulation of reactor temperature utilizing the Residual Heat Removal  ;

(E!!S:BO) and Reactor Recirculation System (Ells:AD) was unaffected by the isolation of the RWCU System. l If this event occurred during power operations, there would be no actual or adverse  !

consequences whether the RWCU System was aligned for normal operation or discharge to  !

radwaste (E!!S WD). During normal operation, the RWCU System removes water from the RPV for purification and returns water to the vessel via the feedwater (Ells:SJ) inlet resulting in no net inventory change. During the discharge to radwaste mode of operation, up to approximately 7.0E4 lbs/hr of water may be withdrawn from the RPV.

t If the isolation had occurred under these circumstances, the change in RPV mass outflow would be insignificant, and is well within the capability of the feedwater control system to maintain RPV water level.

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During this event, the purification function of the RWCU System was unavailable for r 30 minutes. The RWCU System could have been quickly returned to service, had this  !

event occurred during power operation, and the effect on primary coolant chemistry would have been minimal. ~

Corrective Actions -

The Group IIA inboard PCI was reset, and the "3B" RWCU pump was returned to service.  ;

The individual involved in the incident was counselled. ,

This event and its consequences were discussed with appropriate Maintenance. l Instrument and Control, and Plant Supervisory personnel. The purpose of these discussions were to insure appropriate troubleshooting procedures are used, and '

stress the importance of realizing actions in the plant may have significant ,

consequences including jeopardizinq personnel safety and challenging plant safety  ;

systems. -

t Previous Similar Events .

There were no previous LERs identified that resulted in an inboard Group IIA PCI as a result of failing to follow procedures.

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