ML18096A588

LER 92-003-01:on 920123 & 0224,ESF Actuations Signals Received & Control Room Ventilation Automatically Switched from Normal to Accident Mode of Operation.Caused by Design Inadequacy.Channel Controller cleaned.W/920319 Ltr

ML18096A588
Person / Time
Site:	Salem
Issue date:	03/19/1992
From:	Pollack M, Vondra C Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-92-003, LER-92-3, NUDOCS 9203300262
Download: ML18096A588 (6)

Text

Puhlic Service Electric and Gas Company P.O. Box 236 Hancocks Bridge. New Jersey 08038

~alem Generating Station March 19, 1992 U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Dear Sir:

SALEM GENERATING STATION LICENSE NO. DPR-75 DOCKET NO. 50-311 UNIT NO. 2 LICENSEE EVENT REPORT 92-003-01; SUPPLEMENT This Supplemental Licensee Event Report is being submitted pursuant to the requirements of lOCFR 50.73. It addresses a subsequent event which is similar in causal factors and circumstances of occurrence.

MJP:pc Distribution 9 ~03300~6~

920319

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NRC FORM JM ls.Ml *

• LICENSEE EVENT REPORT (LER)

U.S. NUCL(AR RlGULAtOMV COMMISSIOl'll

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I I I This LER addresses 4 Engineered Safely Feature !ESF) actudtions. 011 1/23/92 at 1622 hours0.0188 days <br />0.451 hours <br />0.00268 weeks <br />6.17171e-4 months <br />, 1701 hour*s and 1720 hours0.0199 days <br />0.478 hours <br />0.00284 weeks <br />6.5446e-4 months <br />, Salem Units 1 crnd 2 Control Room Ventilation automatically switched from the normal to the accident mode of operation. On 2/24/92, a fourth event occurred. No positive indication in either Control Room showed which Radiation Monitoring System (RMS) channel caused the ESF actuations. Subseque11t i n v e s l i g d t i o n d "° t. .-:' r* ni i n f: d t. h "' t t h .-:.* 1 / 2 1 I q 2 *~ v *~ n t s wt> r t:.' t Ii e 1 t" s u I t '

• f 2R1B channt-1 equipn1.-:-nt failun:>. Th,* l/23/92 ~RlB d1.irrn1.*l t.1il1ir.:*is) were the l't'SUlt of two (;!) bent. pins on th~ control ,*in~uit1y ~;c<1Ln*

module resulting in poor c:ontiJ<:t wit.ti t:h*.~ c~hannel bdckpli111.-*. 'l'h*~ pins were repair*ed. Tht: Mainll'J1o1111*.~*-Tf.*~ li':'<~hnici.in w.i~; t1lil .. tn 1***1*1ndu1*t, lht: 1/~3/92 t:Vt.'llt":l h'I m.111i1>1,].11 ID!\ ,,f !ht" Sl.'cll.11 m11d1ilt*. H11tl; th.-* 1R1R

<Hld 2RlB rMs chan:iels ~fr.- lrlSP*~<<tc:d; how~v~1. d S p t ) ( ' i f i , * \'ill1:;** nf tlw

~/24/97. l:'Vt-*nt could not t;,~ i',J,,*nt ifii':'d '.-;t'V*.>r,11 :-!RIA 1*h.11111el ,_.1,. ct.r i1.*.ll r.umpCJl'l*.~lllS Wt'l"t" 1*:~µl:1c:**d ti.1~;t*d 1>11 pd!:t t':'Xpt~r it*l\t't:. ll~*on cnm~*l***t i1>1. ,,f repctir*s. th*! 2RlB ,_.h.11;11vl w.i~: Sll*'Ct*ssfully ,*.dibr.11 ... d .ind r.*t11111***l !11

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LICENSEE EVENT REPORT (LER) TEXT CONTINUATION

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Salem Generating Station DOCKET NUMBER LER NUMBER PAGE u~_tt _;2 5000311 92-003-01 2 of 5 J?_1--_f\_N'f_ AND .SYSTEM. IDENTIFICATION:

Westinghouse - Pressurized Water Reactor Energy Industry Identification System (EIIS) codes are identified in the text as lxxl I_PE:NTIF_ICATION _OF OCCURRENCE:

Engineered Safety Feature signal actuations; Control Room Ventilation switched to emergency operating mode This LER Supplement addresses a fourth Engineered Safety Feature (ESF) actuation, due to an electrical spike, associated with the Radiation Monitoring System (RMS) IILI 2R1B channel (Control Room Air Intake Monitor). The first three ()) actuations occurred on January 23, 1992 and the fourth occurred on February 24, 1992.

Event ~~te(s) 1/23 1 92 and 2/24/92 Report Date: J/19/92 This report was initiated by Incident R~port Nos. 97.-0~4. 92-0S5. and 92-129.

CONDITIONS PRIOR TO OCCURRENCE:

Unit 2: 1/23/92 - Defueled; 6 1 b Refueling Outage in Proqr~ss 2/24/92 - Mode 6 Unit 1: 1/23/92 - Hode 2 I Startup); Unit in Hod~ 2 due to Circulating Water INNI conc~rns 2/24/92 - Mode 1 100% Reactor Power, Unit Load - 1155 MWe DESCRIPTION OF OCCURRENCE:

On ~anuary 23. 1992 at 1622 hours0.0188 days <br />0.451 hours <br />0.00268 weeks <br />6.17171e-4 months <br />. Salem Unit 1 and Unit 2 Control Room Vt-ntilrition automatic,1lly switched from tht* normal to the accident mod~ (*f operdti*>n (101)\ recirclll<it ion). NG pusit.ivt>

indication in either Control Roorn show~d which RMS channel c-;111s~d tht~

event.

The ac!.uct~_ion siqnal could have bef'n ca11st-d by t!it.ht>r t.hl"' IJr1it. 2 Control R()CJm Air Intake RMS Cha11nel (~RlBl, or* tht~ Unit l Control Room Air Intake RMS Chann~l llRlBl. Since tht-> Cerni rol R<>om indic.-tt ion r1f the initiatin*J sjgnal was from 'I'rilin "H" ;rnd not 'l'rnin "A". thf' llnit l and 2 Control Room Gener ..tl Ar~il Monqor*s (1 (:~lR1Al whi\*h <l1~~**, prnvide an actuation 5i~1nal. could nnt ha. initi.itt*d tl1t> sinn.\1.

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Salem Generating Station

• LICENSEE EVENT REPORT (LER) TEXT CONTINUATION DOCKET NUMBER

• I.ER NUMBER PAGE Unit 2 5000 '311 9 2 *- 0 0 1 -* 0 1 3 of 5 I:JESCRIPTION OF OCCURRENCE: (cont'd)

At approximately 1700 huurs. t.he lRlB jumpt":"r w.1s installed <rnd the Control Room ve11tilation isDlilt.ion siqn<tl i11dic,1tiun WrlS r*,,.set. t\t this time, a second Contr*1l Rl>om V***nt i L1t.iun a11f Pmat ic switch .... v.~nt occurred_ Known reL1t.P.d m.1:intenanct* ( i .*~ .. ve11t i lat iun dampf.*r tf~sting) was in p1nqn~ss at the time of this ~v.:*nt. dlld w.ts likely to have caus.:-:d this event.. It. WrtS 1ater d ...*tt~rmi11r>d that H.tintt-n.ince had nut initidted th.:* test actu.1t.ion.

At 1720 hours0.0199 days <br />0.478 hours <br />0.00284 weeks <br />6.5446e-4 months <br />. aft<::-r* resetri111,1 the C'ontr*ol R,1nm ventil.:ttion isol.1tion s i r.J n a 1 i n d i ca t i on , r1 t_ h i t d Con t. r o 1 R o. 'm Ve n t. i l ;i t. i n n a u t om" t i c s w i t c: h event occurred. After this eve11t, it w<ts dete1*mi11..-d that thf' 2R1R RMS c h a n n .:- l wa s t h '°' c a u s ,~ o f a 1 1 t h r e e ( ) l £-: S F <H: t u a t i o n e v .~ 11 t s . T t. wa s removed from service and the chcu1n~l ,\la1*m feature w.1s pL1ct~d 111 "block".

Following repair* of the 2R1B RMS chc:u1rH:>l conttPl circuitr*y sc.tldr module backplane pi rn.' and succl:'.'ss tu l f unc ti on._i l t.:-stirn;1. tlw 1*hrt11nel was returned to setvic~.

On Febru;,ry J~. 199:-', ci f<)llrth ch,u111.;>l fail 1 1t~~ OC<.'*jrn**d . .-111.1in resulting in dn F.SF aC"tu..ition. Tbis evt:-nt w.is sirnil.11 tl) tht:> first ESF actu<ltion on Jan1:a1*y 21, l9g2. A'Jrii11 C<>rit*rul f.',.-.. _,rn p1_'r:-:1*nn"i t*,_o1i1d not de t e nn in e whet he t t h P 1 F< 1 R or* t he ~ R 1 R ch rt n 11 ~ 1 c ;i us t~ d r l 1,,.

actuation. No work was on-q\li11q i.n t-ithP.r Unit 1 or- llnit ~ Cnn1 r11l Room rack areas which ,:ould hnve cont.ributt'd tl' th,. c.111s ... of this event.

The swit1*hinq of t_t~e c,n1trol Roum V"°'nti1.1t.iori systen* tu tth- .:-:nt-:"T<J*Jnc:y mode of opex*ation is an F.nqin****r*~d Safety Featurt-> (F,SF). '1'hetr!f<1rt*,

the Nuclear Requlatory Commission INRC) w~s nulifi,...d of the ESF a c c u a t i on s i n a r. co n.i an c t w i t h t he Cod t o f F ... d t":' r a 1 Re q u L1 t i or 1~; 1 0 CF R 50.72!b) (2) ( i i ' .

APPARENT CAPSF. OF (W("!TRRF.tffF.

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LICENSEE EVENT REPORT (LER) TEXT CONTINUATION

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Salem Generating Station DOCKET NUMBER LER NUMBER PAGE lJ~iL ~------ _________ . -- _ _ 5000311 92-003-01 4 of 5

~g-~_~RE~-- CAUSE OF OCCURRENCE - 1/23/92 ESF EVENT: (cont'd) channel failures resulting in ESF actuations in other LERs. Unit 2 LER 311/91-002-00 addresses a 2R1A channel failure occurrinQ on January 23, 1991 and Unit 2 LER 311/91-013-00 addresses a 2R12B channel failure occurrino on September 10, 1991.

Prior to installation of channel modules, the module pins are inspected by the technician. FollowinQ installation. channel calibration or functional testinQ is performed (as appropriate). The design of the Victoreen channels will not provide direct positive identification of pin problems unless sufficient circuit continuity is established. If sufficient pin contact is not established, due to one or more bent/damaged pins, eventual loss of circuit continuity may occur over time due to component vibration.

~_l'gA.REN'I'_C_AUSE OF OCCURREN:E - 2/24/92 ESF EVENT:

The cause of the fourth ESF actuation is attributed to equipment failure.

Investigation of the cause of the ESF actuation involved both the lRlB and the 2Rl8 RMS channels since it could not be determined which channel caused the event. Investigation included attempts to reproduce channel failure/spikinQ and inspection of circuits, pins and connectors. The event could not be reproduced nor were any failed components identified (for either channel) which would have caused this event.

As a preventive measure (bas~d on past ~xperience with Victoreen channel failures), several alarm and failure circuit components (e.g.,

capacitors, diodes, resistors . . . . etc.) were replaceJ on the 2R1B channel. These components have contributed to channel failures/spikinQ on other Victoreen channels in the past.

ANALYSIS OF OCCURRENCE:

The 2R1B channel continuously monitors the air from the HV.AC" i11t<1k~

duct into the Unit. 2 Control Room. This monitor utilizes a Victor* .. l"n scintillrstion dete<_*tor. When th~ alarm Sl"tpoint is r*t'!ach~d. the monitor actuat.*?s an alarm .rnd initiates closure *_)f the tiuct intakf'

~alve tu pr-event. cr.int.<tmin.tted air from ~ntP.rin<;J the Control Room (both Salem Units).

The :?.RlA ch~nn~l (Cor1tr<>l Room Go:*n ... r<il Art*il H1,r1itor) - is used .is t.h..-

corroboratinr.1 channel '" pnivid.,. indication nr .1id1ori1** <tct ivity in th .. cont.rl.! rqom. Tlii!; r*ti.u1nrl t1.*1s tti .. s.tm .. .-111t1>mlr*. It w.1s in 111,-* l*l*H"**ss <>f t11~iriq 1*ppl;11°*'*d

.:1!1 p1~r pr*t*vious LF.1-'. 1*011mitm*~11I~; .is:;c,._*i.it .. d 1o1ith Vic*t111 ...... n RMS 1*h.111nt*l F. ~ f-' it I" I. U *I f. i I.> 11 ~ V ~ r I t S

• As disc:u~u..-:d -ihuvt*, t.h** 2P1fi ch.1nn**I 1":s1o* ,,.*111.1t i* 11s wt*r** tt,,.. r**sult 1 ut equipm!:!nt frtilun~; tt1~rt*fnr**, tt .... ht.. dth i111d !l11lt*ty c*f ll1t* p11t.li1:

• Salem G~nerating Station

• LICENSEE EVENT REPORT DOCKET (l,ER)

NUMBF.R

• TEXT CONTINUATION LER NUMBF.R PAGE t!;i~t 2 5000311 92-003-01 5 of c;

~-~_LYSIS OF OCCURRENCE: (cont'd) was not affected. However, since Control Room ventilation system switching to the accident mode of operation is an ESF actuation, this event is reportable to the Nucle.1r RequlatoTy l.ommission in accordance with Code of Federal Re9ulations lOrFR ">0.73(al 12) (ivl.

CORRECTIVE ACTION:

Following the January 23. 1992 ESF actuations, the 2R1B RMS channel t controller. scalar and backplant> pins were cleaned and the bent scalar pins were straightened. Upon completion of repairs, the channel was successfully cal ibrat.ed and ret.ur 1ed to service.

The lRlR channel was ret:urned to seTvic:e upon completion of inspection and testing after th~ February 24, 1992 RSF event.

Following ceplacement of 2R1B RMS ~h~nnel ~lectric~l circuit components (subsequent to the Ft:>bruary 24. 1qg:;> F.SF t:>vent l <tnd

• successful calibrdtion, tho=> channel WdS ret1nnP.d to servi<:".:.-.

System EnCJineoering has initiated a review, of thest> 2R1B RMS C'hannel ESF actuations, to determine if additiondl testing, munitorinq or component replacement is war*ranted.

As indicated in LER 311/91-013-00, EnginPerinq hds investiqatPd concerns with the Unit 2 RMS channels. Several system desigr1 modifications aTe being implemPnted to ~limindte spurious ESF actuation signals. Thf:'se modificat*ions include r*eplctcement of st:lected RMS chdnno:>ls. The schedule for replitcement is based nn th*?

RMS channel's failure histor*y. The remdining C"hanno:>1s dre being

~valuated for simildr r~plac~~ents.

M.J P: fl('

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