ML19332D633

LER 89-011-00:on 891027,outboard Nuclear Steam Supply Shutoff Sys Isolation Valves Isolated.Caused by Personnel Error Due to Lack of Attention to Detail by Technicians. Event Discussed at All Hands meeting.W/891127 Ltr

ML19332D633
Person / Time
Site:	Limerick
Issue date:	11/27/1989
From:	Endriss C, Mccormick M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-011-02, LER-89-11-2, NUDOCS 8912050061
Download: ML19332D633 (7)

Text

e 10 CPR 50.73 )

1 PHILADELPHIA ELECTRIC COMPANY l LIMERICK GENER ATING ST ATION S AN ATOG A. PENNSYLV ANI A 19464 (Ill) 3271200 mat. 2000 q c2. J. m e c o m u 6 c u. J... p.t. l 6 2 . . . /.' C'. .".'.",".* *. . . .. Noyember 27, 1989 l Docket No. 50-353  :

License No. NPP-85 t U.S. Nuclear Regulatory Commission l Attn Document Control Desk Washington,.DC 20555 .

l

SUBJECT:

Licensee Event Report t Limerick Generating Station - Unit 2 This LER reports an actuation of the Nuclear Steam Supply Shutoff System, an automatic Engineered Safety Feature due to a i personnel error.rosulting from a lack of attention to detail, e

Reference:

Docket No. 50-353

• Report Number 2-89-011 -.

Revision Number: 00 Event Date: October 27, 1989

• Report Date: November 27, 1989 i Facility: Limerick Generating Station P.O. Box A, Sanatoga, PA 19464 ,

This-LER is being submitted pursuant to the requirements of 10 CPR 50.73(a)(2)(iv).

• i Very truly yours,

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WGS:ch cca W. T. Russell, Administrator, Region I, USNRC T. J. Kenny, USNRC Senior Resident Inspector, LGS

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On October 27, 1989, at 0611 hours0.00707 days <br />0.17 hours <br />0.00101 weeks <br />2.324855e-4 months <br />, the Unit 2 Nuclear Steam Supply Shutoff System (NSSSS) outboard containment isolation valve logic was de-energized. This resulted in an isolation of the outboard NSSSS isolation valves which is an actuation of an l Engineered Safety Feature. The de-energization occurred during l the performance of a surveillance test when Instrument and Control (I&C) personnel inadvertantly grounded and blew the

outboard valve logic power supply fuse in an Auxiliary Equipment

l. Room (AER) panel. A test lead became disconnected from a voltmeter and created a short to ground. The power supply fuse was replaced and the valve isolations were reset by 0735 hours0.00851 days <br />0.204 hours <br />0.00122 weeks <br />2.796675e-4 months <br />.

All isolations and systems actuated as designed. The consequences of this event were minimized due to prompt operator actions. The cause of this event is personnel error due to a lack of attention to detail by two I&C technicians performing the test. The I&C personnel involved with this event were counseled to stress the importance of a higher level of attention to detail while performing work tasks. This event has been discussed at an I&C all-hands meeting and a test lead retaining device is

currently undergoing trial use. A task force has been developed to thoroughly investigate, identify, and address the root causes of this and similar events, gc,,... u.

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010 0l 2 or 0 l6 m, w m . ~ - ~.c o nu u nn i Unit'2 Conditions Prior to the Event:

I Operating Condition: 1 (Power Oparation)  !

Power Levelt 67%  ;

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. Description of the Event:

OniOctober 27, 1989, at 0611' hours, the Unit 2 Nuclear Steam '

Supply Shutoff System-(NSSSS) (EIIS:JM) outboard valve isolation logic was de-energized. This NSSSS isolation logic de-energization occurred during the performance of Surveillance  :

. Test ST-2-042-659-2, "NSSSS - Reactor Vessel Water Level - Levels l'and~2;' Division II A, Channel C Functional Test," when ,

L Instrument and Control (I&C) personnel inadvertantly grounded and i l blew the outboard valve logic power supply fuse (EIIS FU),

'B21-F15D,.in the Auxiliary Equipment Room (AER) panel (EIIStPL) 20C623. This caused de-energitation'of the NSSSS logic and e resulted in an isolation (i.e. valve initially open then closed) '

of the outboard valves, an Engineered Safety Feature (ESP), in the following NSSSS Groups:

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o' Residual Heat Removal (RHR) Heat Exchanger (HTX) Vacuum '

Breaker Lines (EIIS BO) .

o Reactor Water Cleanup (EIISICE) o Primary Containment Exhaust to Reactor Enclosure Equipment

. Compartment Exhaust and Nitrogen Block Valves '

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l o' Primary Containment Instrument Gas Process Lines (PCIG)  ;

(EIIS:LK) o Drywell Chilled Water (DWCW) (EIIS KM) and Reactor Enclosure Cooling Water (RECW) (EIIS:CC) to the Recirculation Pumps o Drywell Sump, Suppression Pool Cleanup (EIIS:CG) and PCIG Traversing Incore Probe Supply (TIPS) (EIIS:IG) Purge Supply. ,

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0l0 0l3 or 0l6 The following NSSSS outboard groups received an isolation signal, however no valve movement occurred since the associated valves were already closed due to plant conditions prior to the event.

o Main Steam and Reactor Sampling i

o RHR Shutdown Cooling .

o RHR HTX sample line and drains to Radwaste o Primary Containment Purge Supply and Exhaust (EIIStVA)

At 0611 hours0.00707 days <br />0.17 hours <br />0.00101 weeks <br />2.324855e-4 months <br />, Licensed Main Control-Room (MCR) operators received isolation indication in the MCR for isolations of the above listed NSSSS groups and immediately took actions to restore DWCW, RECW, and PCIG.

MCR operators restored DWCW and RECW at 0613 hours0.00709 days <br />0.17 hours <br />0.00101 weeks <br />2.332465e-4 months <br /> and PCIG at 0620 hours0.00718 days <br />0.172 hours <br />0.00103 weeks <br />2.3591e-4 months <br /> using NSSSS isolation bypass switches in accordance ,

with the Event procedure E-2BY160, " Loss of 2B RPS and UPS Power," Off Normal procedure ON-113, " Loss of RECW," and General  !

Plant Procedure GP-8, " Primary and Secondary Containment Isolation Verification and Reset." MCR operators recognized the cause of the isolations to be a blown fuse and instructed the I&C personnel, performing the NSSSS surveillance test in the AER, to ,

stop testing. The blown fuse was then replaced by the IGC

i. technicians. MCR operators then reset and restored the remaining l isolations by 0735 hours0.00851 days <br />0.204 hours <br />0.00122 weeks <br />2.796675e-4 months <br /> using GP-8. All NSSSS isolations l previously mentioned above were reset, restored and placed into ,

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l service within-one hour and twenty four minutes.

A four hour notification was made to the NRC on October 27, 1989, L at 0919 hours0.0106 days <br />0.255 hours <br />0.00152 weeks <br />3.496795e-4 months <br /> in accordance with the requirements of 10 CPR 50.72 l (b)(2)(ii), since this event resulted in the spurious automatic actuation of an ESF. Accordingly, this report is being submitted in accordance with the requirements of 10 CFR 50.73 (a)(2)(iv).

l Consequences of the Event:

The consequences of this event were minimal. There was no release of' radioactive material to the environment as a result of this event. These NSSSS isolation valves functioned as designed under the loss of logic power condition created by the failed power supply fuse. The isolations were bypassed or reset and the g.;p.. ..

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0l0 01 4 or nl6 TEXT t# pure amosv a 8peam9W. ens. eWWeems' MC for8m W .* 1171 systems were restored quickly enough by operators in accordance with plant procedures to prevent any adverse impact on plant systems.

Immediate and follow up actions to this type of event (i.e., Loss of Logic Power) are provided in procedures E-2BY160, ON-113, and GP-8. Licensed operators receive requalification training to review and perform operator responses to transients of this type.

This training provides practice on immediate operator actions and minimizes the length of time certain systems are isolated reducing the impact on the plant. Therefore, as a result of adequate procedural guidance, training, and prompt operator actions, the event duration was limited and no adverse plant i conditions developed.

Additionally, if the fault introduced during the performance of the surveillance test had resulted in this logic system being inoperable, the redundant NSSSS isolation logic channel would have been available in the event that an isolation of the NSSSS system were required.

Cause nf the Event:

The cause of this event is personnel error due to a lack of attention to detail by two I&C technicians performing ST-2-042-659-2. While in the AER panel, these technicians did L not ensure the test leads were adequately connected into the l digital voltmeter at the time measurements were to be taken. As l a result of this lack of attention to detail, one of the test leads connected to the voltmeter became disconnected, dropped downwards within the AER panel and created a short to ground.

This short to ground caused the logic power supply fuse, B21-F15D, to blow initiating the NSSSS outboard containment valve ,

isolations.

The test leads used during the testing was a contributing cause to this event. The test leads did not have insulated connectors nor a retaining device at the point of connection t.o the voltmeter. As a result, one of the I&C technicians was able to dislodge the test lead and this uninsulated lead was able to contact a grounded point in the panel.

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On October 27, 1989, at 0611 hours0.00707 days <br />0.17 hours <br />0.00101 weeks <br />2.324855e-4 months <br />, MCR licensed operators evaluated the annunciators which alarmed due to the spurious NSSSS valve isolations and determintd that the NSSSS valve isolations were not due to actual reactor or primary containment transients warranting isolation of these systems. In accordance with procedures E-2BY160, ON-113, and GP-8, DWCW.and RECW isolations were bypassed at 0613 hours0.00709 days <br />0.17 hours <br />0.00101 weeks <br />2.332465e-4 months <br /> and the PCIG isolations were bypassed at 0620 hours0.00718 days <br />0.172 hours <br />0.00103 weeks <br />2.3591e-4 months <br />. MCR operators recognized the cause of the isolations to be a blown fuse and the I&C technicians were immediately instructed to halt further performance of ST-2-042-659-2 and replace the logic power supply fuse. MCR operators reset and restored the remaining isolations by 0735 hours0.00851 days <br />0.204 hours <br />0.00122 weeks <br />2.796675e-4 months <br /> per GP-8 returning the plant to pre-transient conditions.

Actions Taken to Prevent Recurrence:

The I&C personnel involved with this event were counseled to stress the importance of a higher level of attention to detail while performing work tasks. The event has been discussed at an I&C-All Hands Meeting with emphasis placed on the need for attention to detail. Additionally, this discussion conveyed the continuous need to use proper techniques during troubleshooting tasks and the importance of using precautions to prevent exposed metal surfaces on test leads and tools from shorting to ground.

A lead retaining device that can be attached to digital voltmeters.to prevent stressing of lead connections was developed and is currently undergoing trial use. A task force has been developed to review this and similar events within the AER. This task force will thoroughly investigate, identify, and address the root causes of these events and evaluate previous corrective actions to determine whether the actions were effective or not.

This review and evaluation is expected to be completed by December 31, 1989.

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0]O 0]6 or 0 l r, l raxw- .-,. ..e, n,ni, Previous Similar Occurrences: .

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LERs 1-84-021, 1-84-030, 1-85-011, 1-85-012, 1-85-049, 1-85-074 l 1-86-045, 1-87-021 1-87-038 and 1-89-006 also reported NSSSS '

isolation due to a blown fuse as a result of personnel error.

._ The review and evaluation will determine whether the corrective  !

actions in these previous events were effective or not in preventing future recurrences of those types of events.

Tracking Codes: (A) Personnel Error E

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