ML20012C513

LER 86-029-02:on 860718,19,21 & 870508,loss of Reactor Protection Sys Power Occurred Due to Spurious Tripping of Alternate Feed EPA Breakers.Caused by Low Output Voltage of Alternate Feed Transformer.Output adjusted.W/900316 Ltr

ML20012C513
Person / Time
Site:	Shoreham File:Long Island Lighting Company icon.png
Issue date:	03/16/1990
From:	Notaro J, Schnaars G LONG ISLAND LIGHTING CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-86-029, LER-86-29, PM-90-046, PM-90-46, NUDOCS 9003220106
Download: ML20012C513 (5)

Text

I, l

+_ , .

,4DMF.*'MM S1f$6#4PAb44'4M M ' r l [,#{g f LONG'18 LAND LIGHTING COMPANY

. beuemmy weg$ bHOFtEH AM NUCLE AR POWL R ST ATION

• P.O. DOM 628 e WADING RIVE H, NEW YORK 11792 TE L. (616) 929 8300 March 16, 1990 PM 90-046 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555

Dear Sir:

In accordance with 10CFR50.73,. enclosed are Shorehara Nuclear Power

-Station's Licensee Event Reports, LER 86-029 Rev 2 and LER 88-015 Rev 1. 1 Sincerely yours, ,

,g Jack A. Notaro Plant Manager JN/RP/jp Enclosure cc: Thomas T. Martin, Regional Administrator Institute of Huolear Power Operations, Records Center American Nuclear Insurers SR2.A21.0200 phf j@h , ,

3,g2 S

F C-8082.P e ,

.sRCPDHlfl3es U.S. EUCL112 s t;ULs,T LXY COMMIEEeON APrHoytD OMO NO. 3 tW 0104 16N Entlhts 4/J0/92 ESTIMAf tD BuftDth PER ht$PONSE 10 COMPLY WTH THi$

fo',fM t lT'i ?JcTn'o','Nflf *no"I N NT ,'M A TYTIM' t ?t cMM LICENSEE EVENT REPORT (LER)

ULATORY MMI ION H NGT ND bbb AN M.'otiO AM?tT.Tf=20'!#!,'C%!""

F ACILITY NA4 6 H) DOCEL T NUMOtR m FAGE I3i c:hnrnh,m Nein,r tw.nr es% Tw * , OI51010l013I? D 1 l0Fl o la itTLt 144 ESP Actuations Due to EPA breaker Trips While RPS Power was being Supplied by the M rnrnwn vnna mennennwr tVENT DAf t (Si LIR NUMetR tel RIPORT DAf f th OTMin f ACILITits INv0LvtD its 8 ActuT. N Auts DOCKlf NvMtitMist MONTH DAY YEAR veAR " QM k"'

,, $$ MONTH DAY vtAR 015101010 1 1 I

~ ~

O!? 1l8 8 6 M6 0l 9 lo nl9 0l 3 d6 4! 0 01510f01011I  !

n,,,,,,,, Tuis AtPoRT is sueMiTTE D PuR$uANT TO THe R60uiREMENTs or io C,R g ICA.<a en. ., m.,. er ea. #ed...e, tiu a

]

Mat = 4 a .o = n .. .on iaH , n Ti.i l to aos imtil eo.ast.Hu sonuinan. 133nei no, n o.imm . . .. ,m n ,an..,

n inin _ _ _ g,g, _7,.,gg ;

w .o.l.immi .. n.. i o u ,, n,. inn. nu ..o 20 4066.H1Havi 60.T 34.la Hul 60 T34.l(2HeniHel 20 4051.H1Hvi to.T 34.H3 Hud to F3i.H2Hal LICENSEE CONT ACT FOR THis Lim Hal NAMg T&t $ PHONE NWM0t H AHL A COOT George D. Schnaars, Operational Compliance Engineer 51 116 9 2l41-lAl'41 010 COMPLif t ONE LINE FOR ( ACH COMPONENT F AsLunt DESCRiet0 IN TMit REPORT H35 HEPORiA e CAust SysTIM CouPONENT "$'g AC-stPoR L

yg pnDi A's CAust Sv 8T E M COMPONENy MA C-y pp i l I I i l l I I I i i l l I I I I I l 1 I I I I l l l SuPPLEM8NT AL REPORT IXPECTED ties MONTH DAY viAR SUSMrs$lON v t$ let p.s temos.t. IRPECTIO Svenet$510N DA TEI NO l l l a 1 R :.C T u , . ,e , w . . . . .- . .,,,...., ,. n ,,, <. ,, ,..,.n.. .., n .,

On five separate occasions while RPS power was being supplied.from the Alternate Feed Transformer (1071-T-001), a loss of RPS power

>>ccurred due to the spurious tripping of the Alternate Feed EPA breakers. The events occurred on the following dates: 7/18/86 at 1406, 7/19/86 at 0554, 7/19/86 at 0821, 7/21/86 at 1404 and on 5/8/87 at 0636. The first three occurred when "A" RPS was on the c2 l

alternate feed and the last two occurred when "B" RPS was on the alternate feed. On each loss of power a half reactor trip occurred along with a half NSSSS isolation, RWCU isolation and RBSVS/CRAC initiation. The plant was in Operational Condition 4 (Cold Shutdown) for all five events with the mode switch in Shutdown and all rods inserted in the core. After each trip, operators took the appropriate actions necessary to restore the affected systems to normal. A temporary procedure was implemented to monitor the system (RPS) when RPS power was being supplied by the alternate feed transformer. No abnormalities were observed during this period. A spare EPA breaker was bench tested to determine if the breaker was the cause of the trips. The voltage regulator output voltage was also checked. This supplemental report is being submitted to outline c2 the results of the investigation and corrective action.

t l

N. c eeem 3eis to ann

U.S.NuCLEA' R$1pLATORY COMMste ON

, enc 90mm attA PPROWD Out & WM

EMPIRil #J30/92 LICENSEE EVENT REP 5RT (LER) 'Sgt,D,otuas",M"o0'$8"l',,'%cM',' To',"J"4 TEXT CONTINUATION S ,5*,,',",'o'416T,?d Mf',0!'e',"f,'.'# u '",' $dn P A,L HWO RL u lion H O 60 0 D IC OF MANACE ML NT AND 9UDGE T, W A&HINGTOh, DC 20603.

.f.

F ACILITV foam 4 HI DOCE&T NuMein 121 ggR Nunes&R tes PAGE (31.

1. l'n a f Shoreham Nuclear pwer Station Unit-1 015jolojol3l212 81 6 0l2l9 -

01 2 0l2 of 0l4 *l Tnn, w e e , . m a .,a ennew,e unc w mw nn ,

PLANT AND SYSTEM IDENTIFICAT.10H j General Electric'- Boiling Water Reactor Energy' Industry Identification System (EIIS) codes are identified i in the text as [xx).

.lDEHTIFICATION_OE.,_THE_ EVENT Five unplanned automatic actuations of' ESF systems [ Half RPS, half Nuclear Steam Supply Shutoff System isolation (NSSSS), Reactor Water Cleanup isolation (RWCU), and a Reactor Building Standby Ventilation System (RBSYS) / Control Room Air' Conditioning (CRAC) System-  ;

initiation) due to loss of RPS power resulting from spurious tripping of the Alternate Feed EPA breakers.

Event.Date: 7/18/86

<2 Report Date: 3/16/90 CONDITIONS ERIOR TO THE EVENT Operational Condition 4 (Cold Shutdown) (all five events)

Mode Switch - Shutdown (all five events)

RPV Pressure = 0 psig (all five events) RPV Temperature a between 99 degrees F and 108 l

L degrees F for all five events L ' DESCRIPTION _QE;THE EVENT On five separate occasions while RPS power was being supplied from L

the Alternate Feed Transformer (1071-T-001), a loss of RPS power I

occurred due to-the spurious tri:..ing of the Alternate Feed EPA breakers. The events occurred on the following dates: 7/18/86 at 1400, 7/19/86 at 0554, 7/19/86 at 0821', 7/21/86 at-1404 and 5/8/87 at 0636. The first three occurred when "A" RPSRPS was on the alternate was on the feed and the fourth and fifth occurred when "B"

alternate feed. On each loss of power a half reactor trip occurred along with a half NSSSS isolation, a RWCU isolation and an l RBSVS/CRAC initiation. The first incident was thought to have been l

caused by maintenance workers in the area of the EPA breakers who i may have accidentally bumped the breakers. However, after the l

l l'

(IC Feasm 3e6A (tH691

y ,- gCgon.=A u u uCa.. m v6. von,co .. ,,, ,, ,, ,, ,, ,

. EXPIIts 4/30/92 a

LICENSEE EVENT REPORT (LER)- ,,lgf#o',f3M"o 'j;f"h,'

.oc "iV ,T",J"n'! - i TEXT CONTINUATION c "",h",'o'J'S^2ds"f',M'e',"^,'j3R;' M&i PAP (H O Mt u 110N J l'3 to [O IC ~

. OF MANAGEMENT AND 9uDGEY,WA$HINGTON, DC 20603.

. ACl44TY 8sAML Hi DOCsLLT NV.eSLR (2) Lt A NUMSER (4) PA06 (34 l

v5*a "$7,P. "'1*.72 E Shoreham Nuclear power Station Unit 1 ,

015 lo 1010 l 31212 816 -

0 l2 h -

012 Ol 3 0F oIa l mim ., w. ,- cu, .;nn ,

l L

1 uccond trip (and after it was determined that no one was in the I vicinity of the EPA breakeru), operators attempted to restore the "A" RPS MG set to operation. It was tagged out of service for the purpose of Instrument and Controls (I&C) surveillance testing.

Before normal "A" RPS power could be restored, the third trip occurred. After the third trip,'the I&C section was requested to check the operation of the EPA breakers lo ensure that they were functioning properly. Technicians found the voltage trip setpoint to be at the high side of the acceptable band and lowered it to try l and correct the problem. At this time the problem seemed to have been corrected. The fourth trip occurred when the "B" RPS MG set L

I was tagged out of service for surveillance testing. After the fourth trip, the problem was believed to be with something other than the EPA breakers. The Operating Engineer directed the Control Room to not use the alternate feed power supply until the root cause could be identified and corrected. Temporary Procedure TP 23.312.02,-Testing of RPS Alternate Supply EPA Breakers, was performed to determine why spurious EPA breaker trips were occurring when an RPS bus was being supplied from the alternate feed transformer. The results of this test indicated that no voltage or current fluctuations were occurring. A spare EPA breaker was bench tested to determine if the breakers were the source of the problem.

However, no failures were observed during these tests. Since a cause for the EPA breaker trips could not be determined and since the investigation had not discovered any problems, the alternate feed supply was allowed to be used again. The fifth trip occurred when the "B" RPS power was being fed from the alternate feed 4 ~1 transformer due to the "B" RPS MG Set being tagged out of service for preventive maintenance. After the fifth trip of an EPA breaker the voltage regulator (installed between the-alternate feed transformer and the EPA) was inspected and found to be working in accordance with the vendor manual. However, the output of the voltage regulator was only 119.7 V. Its output was then adjusted to 121.5 V. TP 23.312.02 was again performed between 7/28/87 and 10/9/87 to determine if the voltage regulator was working properly.

During this period, no voltage fluctuations were observed. Since the adjustment of the alternate feed transformer voltage regulator output, no further trips of its associated EPA breakers have occurred.

After each trip, operators took the appropriate actions necessary to restore the affected systems to normal. In each case, Plant Management was notified of the event and the NRC was notified per 10CFR50.72.

J OCIC Fe,ei antA uM93

,. A u... .veum wm, co . .o. , , , , , , , , , , , , , , , ,

EXPIR48 4/30/02 LICENSEE EVENT REPORT (LER) L'ls"^'Mo*M80/cWo"'!!?vi'/ o*M'J/ ,"o's'J!

TEXT CONTINUATlON FN"*J,",'o',';! MM*d 't"f'.M','c'n,'!31 'u"' OED'f!

P A,(RWO MED TION H J t'3 00 Dei! O IC OF MANAGE ME F f AND euDGE T, W A$H4NQlON, QC 20 03.

FACILifY NAuttil 00 CELT Numeun(21 LIR NUMSER 461 Pact (31 viaa "Otl:P. 3*30 Shoreham Nuclear power Station Unit 1 o l5 l0 l0 l0 l 3l2 l 2 8l6 0l2l9 -

0l2 0l4 OF 0 l4 fixT a . w M-.,hac w .n w .n ni ,

CAUSE OF THE EVENT The cause.of these events was the low output voltage of-the alternate feed transformer (1071-T-001). The output voltage was e2 119.7 V which was too close to the upper limit of the EPA breaker undervoltage trip (118.9 V).

ANALYSIS _OF THE EYEHT These events resulted in unplanned automatic actuations of ESF systems (1/2 RPS, 1/2 NSSSS, RBSYS/CRAC and RWCU) and is reportable per 10CFR50.73(a)(2)(iv). There is minimal safety significance to the events. All systems operated as designed. Operators carried out all required actions. Had this event occurred under a more severe set of circumstances (5% power), the safety significance would still be minimal.

CORRECTIVE ACTIQHS

1. The output of the voltage regulator was adjusted from 119.7 to 121.5 V. This latter value is approximately midway between the-EPA undervoltage and overvoltage setpoints.

l l 2. . Station' Procedure SP 44.611.02, RPS " EPA" Breaker Calibration l and Functional Test, was revised to reqaire that the output voltage of the voltage regulator be verified and recorded.

L 3.- Preventive Maintenance activity, 1C71-410E/E-001-4010, was e2 '

written to require periodic cleaning and inspection of the voltage regulator.

4. Surge arrestors were installed on the high side of the RPS alternate supply transformer. These devices will prevent most voltage spikes from passing through to the EPAs.

ADDITIONAL _INFORMATION i a. Manuf.ncturer and_model.numher_of_ failed _ component _Lal I

None

b. LEB_ numbers _sf_nreylons_similar_ey.ents87-011 (2 89-001 1

i tac f.an 3esa (640

,