ML17223A353

LER 89-005-00:on 890913,turbine & Reactor Trip Occurred Due to Opening of Breaker CB-3 Inside Reactor Protection Sys Cabinet.Caused by Inadequate Work Order Work Description. Sensitive Sys Procedures Reviewed & revised.W/891013 Ltr

ML17223A353
Person / Time
Site:	Saint Lucie, 05000355
Issue date:	10/13/1989
From:	Holifield C, Sager D FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-89-373, LER-89-005-03, LER-89-5-3, NUDOCS 8910180338
Download: ML17223A353 (6)

Text

gc g<~~TZD ACCESSION NBR:8910180338 0,

Dl S~BU'2 ON DE M ON STRATI 0. i REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

DOC.DATE: 89/10/13 FACIL:50-335 St. Lucie Plant, Unit 1, Florida Power & Light Co.

AUTH. NAME AUTHOR AFFILIATXON 0

NOTARIZED: NO SYSTEM DOCKET 05000335 HOLIFIELD,C.D. Florida Power & Light Co.

SAGER,D.A. Florida Power & Light Co.

RECIP.NAME 'ECIPIENT AFFILIATXON I

SUBJECT:

LER 89-005-00:on 890913,reactor pre-maintenance review.

trip due to inadequate W/8 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR I ENCL / SIZE:

TITLE: '50.73/50.9 Licensee Event Report (LER), 1ncident Rpt, etc.

NOTES RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL 1'

PD2-2 LA 1 1 PD2-2 PD NORRIS,J 1 1 INTERNAL: ACRS MICHELSON 1 1 ACRS MOELLER 2 2 ACRS WYLIE 1 1 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DS P 2 2 DEDRO 1 1 NRR/DEST/ESB 8D 1 1 NRR/DEST/ICSB 7 1 1 NRR/DEST/MEB 9H 1 1 NRR/DEST/MTB 9H 1 1' NRR/DEST/PSB 8D 1 1 NRR/DEST/RSB 8E 1 NRR/DEST/SGB 8D 1 1 NRR/DLPQ/HFB 10 1 1 NRR/DLPQ/PEB 10 1 1 NRR/DOEA/EAB 11 1 1 NRR/DREP/RPB 10 2 2 NUDOCS-ABSTRACT 1 1 1 1 RES/DSIR/EIB 1 1 FILE 01 1 1' EXTERNAL EG&G WILLIAMSi S 4 4 L ST LOBBY WARD 1 LPDR 1 1 NRC PDR 1 1 NSIC MAYS,G 1 1 NSIC MURPHY,G.A 1 1 NUDOCS FULL TXT 1 1 NCTE XO ALL RIDS" RECXPIEtGS'ZEASE HELP US 'IO REDOCE RASTE! CX)NXACr 'IHE DQCUMEÃl CXNIBOL DESK, RXH Pl-37 (EXT. 20079) XO ELXMXNATE RKR NAME FBCN DXSTRXBVZXGN LTBTB PGR DOCUMENTS YOU DONiT NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 38 ENCL 38

P.O.~ Bux14000, Juno Beach, FL 33408 0420

~

APL, OCTOSER 1 3 3969 L-89-373 10 CFR 50.73 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Gentlemen:

Re: St. Lucie Unit 1 Docket No. 50-335 Reportable Event: 89-05 Date of Event:. September 13, 1989 Reactor Trip Due To Inade ate Pre-Maintenance Review The attached Licensee Event Report is being submitted pursuant to the requirements of 10 CFR 50.73 to provide notification of the subject event.

Very. truly yours, OtA'8 u D. A. er Vice sident St. Lucre Plant DAS/JRH/gmp Attachment cc: Stewart D. Ebneter, Regional Administrator, Region Senior Resident Inspector, USNRC, St. Lucie Plant II, USNRC

NRC Sorts 345 U S. NUCLKAR REOULATORY COI/Ntl(SSION (943 I APPROVED OMS NO. 3)500104 LICENSEE EVENT REPORT (LER) EXPIRES: 5/31/55 FACILITY NAME III DOCKf7 NUMSEA (2) PA ST. LUCIE, UNIT 1 0 5 0 0 0 335 1 OFO 4 REACTOR TRIP DUE TO INADEQUATE PRE"MAINTENANCE REVIEW EVENT OATf (SI LER NVMSER (SI REPORT OATK (7), OTHKR FACILITlfS INVOI.VEO I ~ I MONTH DAY YEAR YKAR NVMNEII i

SSOVS NTIAL c. sf VISION MONTH

>Z? NVMNNII OAY YEAR FACILITYNAMES DOCKET NVMSEAISI N A 0 5 0 0 0 9 3 8 9 8 9 0 0 5 0 0 013'9 THIS REPORT IS SUSMITTEO PVASUANT T 0 THE REOUIREMENTS OF 10 CFR g: (Cnrce Onr or more Ol tnr /ot/Or/inc/ (11(

0 5 0 0 0 OPERATINO MODE (5) 20.402(4) 20.405( ~ ) X 50.73(e l(2) l>>l 73.71(II I POISE R 20.405 (~ )(I ) (I) 50.35(cl(l) 50.73(el(1)(rl 73.71(cl LEYEL 0 9 20.405( ~ l(ll(N) 50.35(cl(2) 50.73(el(2((rN) OTHER /Spec/lyin AO/trect Orlorr end ln Test, /IRC Fons 20.405 4 I (I)(I 5 I 50.73(e) (2)(I) 50.73( ~ ) (2) (rill)(Al 366AI 20.405(el(1 l(lr) 50.73(el(2) INI 50.73( ~ I(2)(r(NI(S) 20,405(el(ll(rl 50.73 (4 I (2)(NI) 50.73( ~ )l1)lel LICENSEE CONTACT FOR THIS LER (12I NAME TELEPHONE NVMSER AREA CODE CHARLES D. HOLIFIELD, SHIPT TECHNICAL ADVISOR COMPLETE ONK LINE fOR EACH COMPONENT FAILURE DESCAISED IN THIS AEPOAT (13) 4 074 65 -35 50 CAUSE SYSTEM COMPONENT MANVFAC MANVFAC. EPORTASL TVRER CAVSE SYSTEM COMPONENT TVAER TO NPADS

'ccrc io. "e, 'n'ePr3 ay~.. $ 0?k4>> re SVPPLf MENTAL REPORT EXPfCTED (141 MONTH OAY YEAR EXPECTED SUSMISS/ON YES illyrt, complete fXpfCTfO SVdet/SSIOI/ DA Tf/ NO DATE O5)

AssTAAcT /Lt'mi t to I coo /peen. I ~, rpprori metric /tr>>rn I'no>> corer typrrmt>>n /inn/ IISI ABSTRACT On September 13, 1989, at 1409, while in Mode 1 at 98% power, Unit 1 tripped on Loss of Load. Prior to the trip, there were two Nuclear Plant Work Orders (NPWO) being worked concurrently on the Reactor Plant Protection System (RPS). One of the NPWO's involved removing TCB-1 for maintenance while the other NPWO was for replacing a "C" channel power supply in the RPS cabinet. In order to replace the power supply, breaker CB-3 inside the RPS cabinet was opened. When this was done, TCB-7 and TCB-3 opened,and with TCB-1 already open, a turbine and reactor trip occurred.

The root caus'e of the reactor trip was determined 'to be an inadequate NPWO work description, inadequate communications to Operations by I&C and the pr'ocedure for Unit Reliability"Sensitive Systems did not clearly show that its use.was required.

Corrective, actions: review/revise Sensitive Systems Procedures, writ'e standard work descriptions to be attached, to NPWO's for RPS power supply replacements, add caution statements to I&C procedures to check the TCB's position and expedite plant changes to replace RPS power supplies.

NAC Form 344 (94)3 I

H(IC FerrR BASSA U.S, HUCLEASI (IEGULATOSIY COMM(SS(O

(((4S I LICENSEE ENT REPORT (LER) TEXT CONTINU ON AFFAOVEO OME HO S(50&(OS EXF(AES: I/1(rN(

FACILITY HAME (11 DOCKET HUMSESI (E(

LER HUMSEA (dl ~ AGE (S(

YEAR ssovsrssrAL RSVrSIOrs HvMSSR RVMSSR TEXT ST. LUCIE, UNIT illmore Hrsse is rer(rrsed, o>> ~ 1 HRC %%drm XC4'sl (IT) o 5 o o o 335 8 9 0 5 0 0 2 OF 0 4 DESCRIPTION OF THE EVENT On September 13, 1989, Unit 1 was -in Mode 1 at a reduced power level of 98% to control turbine backpressure which had been increasing due to high injection temperature.

At 0508 reactor control breaker (EIIS:BKR), TCB"1, was placed out of service for maintenance in accordance with Electrical Maintenance procedure l-EMP-63.01.'his quarterly PM was performed using a Nuclear Plant Work Order (NPWO) which was approved by the ANPS, At 0921 I&C started the monthly functional test of the Reactor Protection System (RPS) (EIIS:JC) in accordance with I&C Procedure 1-1400050. This PM was performed using a NPWO which was approved by the ANPS.

While performing the RPS, monthly functional test, an RPS channel "C" Core Protection Calculator (CPC-2) power supply voltage was found to be outside of allowable limits. Since this indicated a power supply failure, the 1&C technician left the RPS monthly procedure in order to repair the failed power supply.

Because of the power supply (EIISIRJX) failure in CPC Channel "C",

the trip bistables for Hi Power, SUR, TM/LP, LPD, and Loss of Load (1, 2, 7, 8 & 10) were placed in bypass in accordance with Technical Specification 3.3.1.1 by using tne RPS channel bypass keys. This switch manipulation was logged in the operator's chronological log and the valve, switch deviation log.

The repair to the faulted power supply was performed using a NPWO which was approved by the ANPS. The explanation of the work to be done, which was given to the ANPS, was that the remaining "C" channel bistables were to be placed in bypass, the RPS "C" channel was to be powered down and the faulted power supply replaced. There was no indication in the work description or the explanation given to the ANPS that any TCB's would be opened. In order to deen'ergize the 120 VAC in the work area, the I&C Supervisor supervising the work opened CB/C and CB-3. He did this knowing that two TCB's would open, but he assumed the other TCB's were shut and there would not be a problem.

srRC FORM SddA (043(

NRC!oem SSSA V.S, NUCLEAR REQULATORY COMMISSIOI (044 I LICENSEE ENT REPORT {LER) TEXT CONTINU ON APPROVEO OMb NO, 4150&IOE EXPIRES: SISI/%

PACILITY NAME uI POCKET NVSISER (ll LER NVMSER ISI PACE (1)

TE*A SEQUENTIAL AEVI5EQN N VMS E A NUMEEA ST. LUCIE, UNIT 1 o 5 o,,o o 335 89 0 5 0 0 3oF0 TEXT Ilfmoce EPEE II ccqvnd. ccw cddSNcMI HRC %%dcm NI'cl ((7(

Prior to opening CB"3, he informed the control room operators.

However, he did not tell them that the K3 relay would deenergize and that the two TCB's would open. Since CB-3 is a breaker located inside the RPS cabinet that the operators don't normally operate, they did not realize that the TCB's would open With CB-3 open, the K3 relay deenergized causing TCB-7 and TCB-3 if CB-3 was opened.

to open. Under normal conditions ,opening TCB-7 and TCB-3 would not cause a trip since there is a redundant power supply via TCB-1 and TCB-2. However, with TCB-1 removed and TCB-7/TCB-3 opened, power to half of the CEDM coils was interrupted. The deenergized CEA bus caused the turbine to trip which caused the Loss of Load Trip. This caused the . remaining CEDM coils to deenergize and a full reactor trip to occur.

The'perators then performed the actions of 1-EOP-1, Standard Post Trip Actions, and 1-EOP>>2, Reactor Trip Recovery.

4 4 CAUSE OF THE EVENT The root causes of this event were:

1. The work description given in the Job Planning Section of the NPWO did not tell the ANPS specifically what work was to be done.

2. The 1&C Supervisor did not adequately explain the work to be performed.

3. As the Unit Reliability-Sensitive Systems procedure is presently written, 'here is no reference to breaker operation by non-operations personnel.

ANALYSIS'F THE EVENT The plant response during this trip wa's observed to be normal; all systems functioned as designed.

~ This event has been deemed reportable as per the requirements of 10 CFR 50.73 (a) (2) (iv), any event or conditions that results in an automatic actuation of the Reactor Protection System.

The event is 'similar to that described in Section 15.2.7.2 of the Unit 1 FUSAR, which assumes a turbine trip without a direct reactor trip. However, since the turbine trip was preceded by a reactor trip in this event, the 'actual plant response was more conservative than, that described in the analysis.

Thus, the health and safety of the public was not threatened during the, event ..

NAC PQAM SEEA (9441

U.S. NUCLEASI REOULATORY NRC smm SeeA COMMISSIO'ppRovEo 104SI LICENSEE NT REPORT {LER) TEXT CONTINU ON oMs No slso&104 EXPIRES: S/Sllà PACILITY NAME III OOCKET NUMSER ill LER NUMSER I~ I PACE IS)

YEAR s,, SEOUENTS*L AEVI/ION N VMe I Il NVMee A ST.'UCIEs UNIT TEXT N neve spsss is nquvrd, uss

/

~ 1 HIIC. %%dnn SSSl'sl I IT) 0 5 0 0 0 8 9 0 5 OO 4 OF 0 4

.CORRECTIVE ACTIONS

1) Operations will revise the Duties and Responsibilities of Operators - on'hift procedure to include guidance concerning sensitive systems or a reference to the Sensitive, Systems Procedure. Operations Supervisor will write a night order regarding the use of the Sensitive Systems Procedure.

2) Technical Staff will coordinate a review of the Sensitive System Procedure with Operations and Maintenance and recommend improvements in implementation of this process.

3) I&C will write standard work descriptions to be attached to Nuclear Plant Work Orders related to replacement of RPS power supplies. The .work description will include warnings, notes and detailed steps to perform the work. I&C will add a caution statement in I&C procedures to verify that TCB-1 through TCB-9 are shut prior to performing any RPS test.

4) I&C will counsel the I&C Supervisor

- on the importance of communicating to the ANPS in complete detail any manipulation to a sensitive system prior to initiating it.

5) Engineering will expedite plant changes for RPS power supply replacements.

ADDITIONAL INFORMATION COMPONENT IDENTIFICATION:

This event was not caused by component failure.

ssssC PORM eeeA ISIS I