ML20006E424

LER 90-006-00:on 900117,control Room General Area Radiation Monitor Spiked High,Resulting in Switching Ventilation Sys to Emergency Mode of Operation.Caused by Damaged Pins on Channel Backplate & Modules.Pins repaired.W/900215 Ltr

ML20006E424
Person / Time
Site:	Salem
Issue date:	02/15/1990
From:	Miller L, Pollack M Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-006, NUDOCS 9002230113
Download: ML20006E424 (4)

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'g' g - ' Public Sorvios Electric and Gas Company P.O. Box 236 Hancocks Bridge, New' Jersey 08038.' J

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SAL.UM GENERATING, STATION E LICENSE NO. DPR-75'  :

~ DOCKET.NO.;50-311' UNIT;NO. 2 LICENSEE EVENT REPORT 90-006-00 c

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'b- ,This Licensee Event Report is being submitted pursuant to.the ,

i requirements;of the Code of Federal-Regulations 10CFR 1

. _50.73 (a) (2) (iv) . . This-report'is' required within' thirty (30)' days m' of discovery.-

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. -,,.. ,,,,- n el l l 5 l On January 17, 1990, during normal plant operation, the control Room general area Radiation Monitoring System (RMS) (Ibl monitor (2R1A) spiked high. This resulted in the automatic switching of the Control l Room ventilation from normal operation to its accident mode of l operation-(100% recirculation). The switching of the Control Room i ventilation system to its emergency mode of operation is an Engineered i Safety' Feature (ESF). The root cause of this event has been attributed to design / equipment concerns. Investigations identified

' damaged pins on the channel backplane and modules. The damaged backplane and module pins were repaired and the channel setpoints reset. Upon successful completion of a channel functional test, the channel was. declared operable. As indicated in LER 311/89-025-00, Engineering has investigated the concerns with the power supply to the Unit 2 RMS channels. It is anticipated that several system design modifications will eliminate the spurious ESF actuation signals. One of these design modifications is the installation of an uninterruptable power supply (UPS). The plans for completion of these I modifications are included in the current PSE&G Living Engineering Plan for the RMS system.

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LICENSEE: EVENT: REPORT'(LER)-TEXT, CONTINUATION

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58alen Generating: Station ..: DOCKET NUMBER LER: NUMBER- PAGE Unit 2 5000311 90-006-00 2 of 3

' PLANT AND SYSTEM' IDENTIFICATION:

Wentinghouse- sPressurized Water Reactor- 'i

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l Energy Industry Identification System-(EIIS) codes are identified in; the text as (xxl j) l

' IDENTIFICATION'OF OCCURRENCE: I

,o Engineered? Safety Feature = Actuation _ Automatic" Switching ofxthe Contro1~ Room Ventilation;to the~ Emergency Mode of Operation Due to '

Equipment Design Concerns.

' Event Date: 1/17/90 ,

Report Date: 2/15/90 This report was initiated by Incident Report No.90-048.

JCONDITIONS PRIOR TO OCCURRENCE:

q  : M o d e -1~ Reactor Power _100% - Unit Load 1160 MWe ,

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L DESCRIPTION OF OCCURRENC3:

On January 17, 1990, during normal plant operation,;the Control' Room general area Radiation Monitoring System'(RMS) (ILl: monitor- (2R1A) 4 spiked'high. This resulted in the-automatic switching of the control;

' Room. ventilation from normal operation to its accident mode of operation i (1004 . recirculation) . - ,

The switch'.ng of the Control-Room ventilation system to its emergency. T!

mode of operation is an Engineered Safety Feature (ESF). Therefore,

• L on January 17, 1990 at 2330 hours0.027 days <br />0.647 hours <br />0.00385 weeks <br />8.86565e-4 months <br />,'the Nuclear Regulatory' Commission was: notified of- the automatic switching in 'accordance with Code' of .!~

. Federal: Regulations 10CFR 50.72(b) (2) (ii) .

APPARENT CAUSE'OF OCCURRENCE:

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l L" The root cause of this event has been attributed to design / equipment L . concerns. Investigations identified damaged pins on the channel L 'backplane and modules.

.This-event is similar to a prior event as' identified in LER '

311/89-025-00. This other event was also attributed to the same -

equipment design concern although the previous failure was attributed

.to an electrical spike, f-

[; Prior.LERs,-involving Victoreen radiation monitoring equipment (e.g., ~

[ 311/89-002-00, which involved a Containment Ventilation Isolation ESF L

actuation) have' indicated that the Victoreen design is susceptible to L. ' voltage spikes.

e TheE2RIA detector is a Victoreen 857-20, GM tube.

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apg LICENSEE EVENT REPORT-(LER)-TEX 4 CONTINUATION-l Salem Generating-Station .

DOCKET NUMBER LER NUMBER PAGE

. Unit 2 5000311- 90-006-00 3 of'3 d

&NALYSIS~OF OCCURRENCE: 1 The-2R1A Control Room general area radiation monitor monitors the ambient gamma radiation levels in the Unit 2 Control Room. Generally, the Control Room' dose rate would increase due to ventilation of radioactive materials. Therefore, the Control Room. intake duct is. ,

' isolated-and the ventilation air is put in' full recirculation through.

HEPA'and' Charcoal filters. This design is in accordance with-the <

L UpdatedLFinal-Safety Analysis (UFSAR) which requires protection of

? Control Room personnel during a loss-of-coolant' accident (LOCA), by  :

limiting dose-to 5 rem to the whole body, or its equivalent to any ~

i part;of-the body.

'The'2RlB Control Room intake ~ duct radiation monitor is used'to corroborate the 2R1A channel readings. It too has the same automatic ,

isolation function. During this event, no increase of_ activity was '

noted.

As indicated previously, the automatic switching of the Control Room i ventilation 1to.its accident mode of operation was not caused by high radiation .h.vels, but by an equipment design concern. Therefore, the.

healthLand safety of the public was not affected by this event. -

However, since the uwitching to the accident mode of operation is-considered an ESF actuation, this event is reportable in accordance

.with Code :of Federal Regulations 10CFR 50.73 (a) (2) (iv) .

' CORRECTIVE ACTION:

l The damaged backplane and module pins were repaired and the channel.

setpoints reset. Upon successful completion of a channel functional

. test, the~ channel was declared operable.

As indicated in LER 311/89-025-00, Engineering has-investigated the L - concerns with the-power supply to the Unit 2 RMS channels. It is l anticipated that several system design modifications will' eliminate- 1 l

.the spurious ESF actuation signals. -One of these design modifications is the. installation of an uninterruptable power supply'(UPS) which is

!. scheduled to be installed by June 1990. The plans for completion of L These-modifications are included in the PSE&G Living Engineering Plan forithe RMS system. ,

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SORC Mtg.90-014 m

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