ML20042G452

LER 90-015-00:on 900407,discovered That Relay Contact Which Actuates Reactor Trip Breaker Shunt Trip Not Adequately Functionally Tested.Caused by Failure to Examine Circuit in Detail When Test developed.W/900507 Ltr

ML20042G452
Person / Time
Site:	Calvert Cliffs
Issue date:	05/07/1990
From:	Denton R, Muth D BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-015, LER-90-15, NUDOCS 9005140250
Download: ML20042G452 (7)

Text

_

, BALTIMORE l

. GAS AND ELECTRIC CHARLES CENTER e P.O. BOX 1475

• BALTIMORE. MARYLAND 21203 1475 F1. E. DE NTON MANAufM I CalvlRf CLitf 8 NUCl( AR j POWl9 PLANT DIPARTMrNT i

, May 7, 1990 U. S. Nuclear Regulatory Commission Docket No. 50 317 Document Control Desk License No. DPR 53 Washington, D. C. 20555

Dear Sirs:

The attached LER 90 15, Revision 0, is Deing sent to you as required under 10 CFR 50.73.

Should you have any questions regarding this report, we would be pleased to discuss them with you, cry truly yours, R. . Denton DWM/1r cc: Thomas T. Martin Director, Office of Management Information and Program Control Messrs: G. C. Creel C. H. Cruse J. R. Lemons L. B. Russell R. P. Heibel p yace'l l Y

/ I \

9003140230 900507 gDR ADOCK0500g7

i pohw sob u t NuCL E:.m LI .vv tomy CoMMissipN A>>novtp Dv6 No 3 600104 i CGt 8 4'30 I?

ItfiMittD DCDIN 3 83 ht SPONSI 10 C05 PLY Ctu tung 1 EN"i. ,, OcWJ L*ds 'no"l,ffs'!,'vaYl ,7,ll #eU"i

' i UCENSEE EVENT REPORT (LER) " "

02?A'! Co',t,t,01,L"O'5"4',f i"!A"f,# '"

I"'M10o"itiu "MSa',' fdf;aRu%ft"

DOCEti NuMDL R Q) P'M i3i e ACILif V NAME n1 Calurt C11 Ifs. Unit 1 0 l6 l 0 l0 l 0 l1 l 1l 7 1l0Fl016 18144 441 Inadeaunte functionni Test of Reactor Circuit Breaker Shunt Trip Relay Contact tvtNT DATI tti Lta hpMet h een klPont DAf f 171 OTHt h 8 ACILITI-18 INVOLYlO 10, pockst NvM6teusi MONTM DAY vt &8t vtan  %,7,j

%  ;'4 $8,'Q voNTH car vtan face 6ste haMas Ca l ve r t Cliffn, Unit 2 016 l 010 l 0 l 3 l1 jg

~ ~

0l 4 0l 1 9 0 ul 0 0l 1 l$ 0l 0 0l$ 0l7 9l0 m .,, ., r*. w .,, nu 0 15t 0 1 0 1 0 i l l

,,,,,,,,,,, tais a:Pont is sueMittto PunsvaNT to tut niovialMtNt os se Cea 6 <C,.

• D' * $ n acam n aiei.i no ni.inni.i ,a tiw n asa,nnu a wanu a ni.nsa.i n tn.i

. . .. n,,

no, O i Oi0 _

innoi

.n. an _ =>, ,7,,M,.;;,,7j,

. . noi x u n.nin,, o ni. inn.e.in i ..,

peoswnnw so.n unensi u tsanan innai H 4esi.nlIM 90.784 4tnM M 784.nf usi LICtNSit CDNT ACT FOR THIS LEM (191 es 1Mt it LEPHONt hvM0tm

• • t. cool

_th W. Mut h, Compliance Engineer 31011 216 1 01-Il 1 51012 COMPti18 ONE LINI FOR E ACM COMPONINT 8 AltUnt DE SChitt0 IN THI$ htPORT 1191 0 "' gaggg gy g,g y gnyppggq9 C PDRfA E ,

Caull SYtitM COMPONINT t0 8 8 I l l 1 1 1 I l I l l l 1 I l l ? I l l l I l l I l l l SUPPLtMENT AL plPORY IkPtCYtO ltel MONTH Day stam SuDYtS810N

%IS 00 s.n temPae e ikPLC180 CV06015SION Oe til NO l l l ani .e,<t-,,,em ..,. .. +w ,. . - - m.,nei on April 7, 1990. with Unit 1 in MODE 5 and Unit 2 defueled, it was found that the relay contact which actuates the Reactor Trip Breaker (RTB) (EIIS JC 72) shunt trip for Unit I was not being adequately functionally tested.

This condition was caused by inadequate issue discovery in that the circuit was not examined in sufficient detail when the test of the contact was developed, Surveillance Test Procedure 0 6-1 has been revised to test the RTB shunt trip relay contact without the presence of the parallel current path via the red local breaker position indication light.

The circuitry will be modified to remove the parallel current path when the RTB opens.

We have instituted a Performance Improvement Plan item requiring the review of STPs for technical adequacy relative to the Technical Specifications. The goal of this review is to assure that STPs are consistent with Technical Specification requirements. This review will also identify the design basis of the equipment associated with each STP. The circumstances relative to this event will be factored into the decision regarding the level of detail of this review, 1

N ..m

gjgo- . *

u. .uco.. .t ut_1o. , c-,oh y,,,m,,,,,,,,,,,,

$ ZPillB 4?3092 UCENSEE EVENT EEPORT (LER) L','$n',%',fRiNd'5?fu,'%*f'lI'l .T." '"% l

. TEXT CONTINUATION *?7;'e",'!#,"MMi UN'.O'e'0,'!# 'u"/ MM i M",'A,'e"JM.EEN*~',

Of MAN A04 MENT AND SUDGE T n Oil?'h?.*d%Wiil?

A$MINGTON, DC 70603.

9 AC6ketv HAM 411 Dockti NUMDtR Ut um wguggh (91 PA06 (31

• • • a " W!.G" *%*e# ,

On 1 ve r t C11fis. Unft 1 0 l6 [0 l0 l0 l3 l 1l 7 o]o -

ol1l $ -

0l0 ob M o l6 sext tu aw, amo e own. m enn nonc swa ma mm I, DISCUSSION On April 7,1990, with Unit 1 in MODE 5 and Unit 2 defueled, it was found that the relay contact which actuates the Reactor Trip Breaker (RTB) (EIIS JC 72) shunt trip for Unit I was not being adequately functionally tested.

This is a violation of Technical Specification Surveillance Requirement 4.3.1.1.1 and therefore reportable under 10 CFR 50.73 (a)(2)(1)(B).

The RTBs can be tripped by either of two redundant devices: an under voltage (U/V) relay (EIIS JC 27) or a shunt trip coil (TC) relay (Ells JC 59) (see Figure 1). The Reactor Protection System (RPS) utilizes a "K" relay to actuate these devices. The K relay has a normally closed contact which opens to trip the U/V relay. The same K relay also has a normally open contact which closes to trip the TC relay. An amber Control Room (CR) mimic display light (EIIS JC.1L) is associated with each of the two trip relays. Red and green local breaker position indication lights are also included in the circuit. The red light indicates if the RTB is closed'arcJ the green light indicates if the RTB is open.

Figure 2 is a simplified diagram of the RPS shunt trip relay section of the circuit. With the RTS closed, current flows through the red local breaker position indication light and the TC relay. The current is sufficiently decreased at the 1200 ohm resistor associated with the red breaker position indication light to prevent the TC relay from tripping the RTB. The resistance associated with the amber Control Room (CR) mimic display light is sufficiently great to essentially prevent current flow through the amber light.

Upon receipt of an RPS signal, the normally open K relay contact closes, essentially shorting out the circuit and deenergizing the red breaker position indication light. Sufficient current flows through the TC relay to trip the RTB. Once the RTB opens, the TC relay protection contact opens. The current is then directed through the amber light, causing it to energize. This indication in the CR was used to verify that the shunt trip relay was activated.

This configuration, however, is not adequate to demonstrate operability of the RTB shunt trip relay contact. Should the normally open K relay contact fail to close, the RTB could trip as a result of the unde rvoltage relay (see Figure 1), thus opening the TC relay protection contact. The amber light could be energized via the red light, which would not energize since the current through the circuit, while suf ficient to power the amber light, is too low to

, energize the red light. The amber light would thus remain lit until the TC relay protection contact was reset.

l 1

This condition was found during perfornance of monthly Surveillance Test Procedure (STP) M 210 A/B 1, "RPS Functional Test," which governs the test verifying operability of the K relay. The STP relies on the amber CR mimic NGC Fenn 3e6A 4491

,onM ae.A US NuCnt m klevt tony consM,eston

,,,q py, I x,C tl Cf3092 UCENSEE EVENT CEPORT (LER) '5,'sh"?,4$fRJQ0'$o*l',,'

, .!f'l'T.,7,70"2

. TEXT CONTINUATION E"".'i,A';'.t'"faiMW'.ML'c'n"','.'# t,"'

0'REN C,f",'A,'i%"M,'".".itW.A'.!.E?C?"J.*#2 O MakAGlWINT AND DVDC it W A6HtNGTON. DC 70bO3 Mil?

,actLeTV HAMS Hp Dock ti NUnset n (21 4til NUMSilt 461 ,A04 06 n aa " $t?.; ',", W.T; cnivert c l i f f r. , Unit 1 o]6lojol0l3l1l7 g jo -

o [ tl5 - o jo ol3 o' 016 nri v =-. . w. u ,w we % 3.u u n,,

display light to prove closure of the normally open K relay contact. An alert technician noted a discrepancy in that the amber CR mimic display light associated with one RTB went out when the normally open K relay contact was reset. The CR mimic display amber lights associated with all other RTBs stayed on. Upon review, it was found that this was due to a burned out red local breaker position indication light. Further investigation led to the discovery of the testing inadequacy described above. An NCR was initiated to document this problem.

Technical Specification 4.3.1.1.1 requires that the RPS logic matrix relays be demonstrated operabic prior to restart and monthly thereafter. The pre start functional test is governed by STP 061, "RPS Startup Test."

The RTB shunt trip relay section of this STp is identical to the one governed by STP M 210 A/B 1. A revision was made to this procedure to require that the red local breaker position indication light associated with each TC ,

relay be removed prior to performance of the test. This ensured that the normally open K relay contacts were adequately tested. This revised STP was successfully performed on April 8, 1990.

11. CAUSE OF CONDITION This condition was caused by inadequate issue ditcovery in that ti.e circuit was not examined in sufficient detail when the test of the contact was developed.

The amber CR mimic display light was assumed to provide sufficient indication that the normally open K relay contact was closed. The parallel current path via the red local breaker position indication light was difficult to detect and had not been accounted for. This methodology was incorporated into STPs M 210 A/B 1(2) and 0 61(2). The RPS logic matrix relays were part of the original design of the plant. The test methodology had remained essentially unchanged since that time.

III. ANAINSIS OF CONDITION l

The U/V and TC relays utilize contacts from the same K relay. The U/V contacts were found to have functioned satisfactorily, indicating that the K relay was functional. It is highly unlikely that the TC contacts would have failed independently. As stated above, the Unit I normally open K relay contacts all performed satisfactorily when tested using revised methodology. Records indicate that none have been previously replaced due to failure. It could therefore be concluded that the contacts had performed adequately even though the STP did not provide conclusive verification.

Nnc e 3 A miei

l

g. .

u. Noci ... .ouso.,e . ,

,,,,,,,,,,,,,,x,

.:,i: now LICENSEE EVENT REPORT (LER) ",'s..',%',fM*,PJo0'!7a'"l's,' ,*f'l'.' TJ."2"'!

. TEXT CONTINUATION R**.'.",'o' ';!6'E"ni M 3E0f'.M!,'c'O,'j2 u'"' OMf"fA P Art .WO .I t e0N 84 JC I bD L 0 1 OF MANAGtMt W1 AND DVDGET, W A$MINGTON. DC 20h03 8&Cl411V hAMt tti POCEt t NVa.66. tai ti. NUMet. (41 PA06 (31

• • • a " W .;'^6 "OJ.T2 cnivert Cliffs. Unit 1 0 l6 l0 [o l0 l3 l1l7 9l 0 -

0l1l5 -

0l 0 0 l4 0F 0l6 virica . m ,w ace asne. inn A review of records since 1983 found no instances of RTB failure during the performance of STPs M 210 A/B 1(2) or 0 6-1(2). It is therefore concluded that this condition did not represent a threat to the health and safety of the public or the environment. ,

IV. CORRECTIVE ACTIONS Immediate Corrective Actions:

1. As stated above, STP 061 has been revised to test the RTB shunt trip relay contact without the presence of the parallel current path via the red local breaker position indication light.

Long Term Corrective Actions:

2. The circuitry will be :4odified to remove the parallel current path when the RTB opens. Should this modification not be complete prior to the next scheduled performance cf STP M 210 A/B 1(2) or 062, these STPs will be revised as in (1) above.

3. Wo have instituted a Performance Improvement Plan item requiring the review of STPs for technical adequacy relative to the Technical Specifications. The goal of this review is to assure that STPs are consistent with Technical Specification requirements. This review will also identify the design basis of the equipment associated with each STP, The circumstances relative to this event will be factored into the decision regarding the level of detail of this review.

V. ADDITIONAI, INFORMATION Similar events in which inadequate surveillance testing resulted in a condition prohibited by Technical Specifications were reported in LERs 317/89 013, 317/89 017, 318/89 022, 317/89 024, 317/90 01, 317/90 07, 317/90 08, and 317/90 10.

Nce-3Aem

g,, .

u vca . uuto.Y .

p,,. 8x,,u . . w UCENSEE EVENT REPORT (LER) $#t'!,%',f s;[",P,"o0'#Po",j!,.!M." ,T n?"4  :

, TEXT CONTINUATION *#,'",1,',';!6.'"",l*,i3f"f',Mt'c'"','!# 'v",' 0MNf!

0?"it,'i%".'nE:"ra,'3",A'!2?'.NGTON, 07 MANAGtMth? Ah'D $uDGE14% A&M DC 70b03.5 t AC.kl1Y h4Mt til 00Ckti WUM9th (21 4th WUnstth (6) P&Of tai "aa " 0:.;; . i

"'a*J:

cnivert cliffr., Unit 1 o l6 lo lo lo l 31117 i 910 -

o lt l 5 -

ol0 ol5 or o l6 ,

TimT (# move spese 4 savioW, asas ochgeww 44C Form W yi(173 4 a n w ,

,lill

=

c" l

w~ >

I

(

• W

• I[

l i T '. 5 t

I; l i ) < >

l b.

t g ya* q, l* -

l!:

=+,-n U i 11 l

e @ z E

11 e, l E '

NAC Perm astA (648.

4,. A u.. .ucam. oa,oo co . o., ,,,,,,,,,,,,,,,,,, f

. e x,iai. . ow  :

LICENSEE EVENT REPORT (LER) !So'i^.'!,io*.,Tsf,El"o0'."lOl's,' .!f%Y .7," Jet ,

, TEXT CONTINUATION R"*,'.7A"!""" ni3E"f',"!!'C,77.'!3!,P'".'OM!n! v PAPimwD K mtf TID 4 JC (3 0 4 .

OF MAe:ActwtNT AND puDQtt.WASHINGTDN.DC 20h03 P-S ACitit? HAM 6 Hi DUChli NutIDER Lil Eth NMik ft) tatt tal ea6 es vlah 66 ke,I p q pa'YI Calvert Cliffs, Unit 1 0 l6 ]O j o l0 l3 l 1l 7 9l0 -

0l1l5 -

0l0 0 l6 0F 0 l6 Yart w == = w. .mm.w.c s.vn JERA W H7) e i

Wlll1 \,1ll/

l  :

.. . . 3

/\ ...- , ,

/ \ .

N '

'l g .

lll.l

p. .

I i

l-i I

i

> S E > z I

a s.

C Penn astA IS89) ]

~. 1

- - . .