ML18004B878

LER 87-035-00:on 870617,reactor Coolant Pump C Tripped, Resulting in Reactor Trip Due to Low Flow in Reactor Coolant Loop C.Caused by Physical Contact W/Bus Encl.Program to Check & Drain Steam Supply Lines initiated.W/870713 Ltr

ML18004B878
Person / Time
Site:	Harris
Issue date:	07/13/1987
From:	Hudson O, Watson R CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
HO-870462-(O), LER-87-035, LER-87-35, NUDOCS 8707200448
Download: ML18004B878 (8)

Text

ULA Y INFORMATION DISTR TI SYSTEM <RIDS)

ACCESSION NBR: 8707200448 DOC. DATE: 87/07/13 NOTARIZED: NO DOCKET FACIL: 50-400 Shearon Harris Nuclear Power Planti Unit li Carolina 05000400 AUTH. NAME AUTHOR AFFILIATION HUDSON'. N. Carolina Power Sc Light Co.

WATSON'. A. Carolina Power 5 Light Co.

RECIP. NAME RECIPIENT AFFILIATION

SUBJECT:

LER 87-035-00: on 870617'eactor coolant pump C trippedI resulting in reactor trip due to low flow, in reactor coolant loop C. Caused bg physical contact w/bus encl. Program to check 8c drain steam supply lines initiated. W/870713 itr.

DISTRIBUTION CODE: IE22D "COPIEB RECEIVED: LTR I ENCL i BIZE:

TITLE: 50. 73 Licensee Event Report (LER)i Incident Rpti etc.

NOTES: Application for permit renewal filed. 05000400 RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-,1 LA 1 1 PD2-1 PD 1 1 BUCKLEYIB 1 1 INTERNAL: ACRS MICHELSON 1 ACRS MOELLER AEOD/DOA'EOD/DSP/TPAB 1 1 AEOD/DSP/ROAB 2 2 1 1 DEDRO 1 NRR/DEST/ADE 0 NRR/DEST/CEB NRR/DEST/ I CSB 1

1 1,

1 1

NRR/DEST/ADS NRR/DEST/ELB NRR/DEST/MEB 1,1 1

1 0

1 NRR/DEST/MTB 1 NRR/DEST/PSB 1 NRR/DEST/RSB 1 1 NRR/DEST/SGB 1 NRR/DLPG/HFB 1 1 NRR/DLPG/GAB 1 1 NRR/DOEA/EAB 1 1 NRR/DREP/RAB 1 1 NRR/DREP/RPB l S/ILRB 1 1 NRR/PMAS/PTSB 1 1 G 02 1 1 RES DEPY GI ,1 1 RES TELFORDi J 1 1 RES/DE/EIB 1 RGN2 F ILE 01 1 EXTERNAL: EGSG GROHI M 5 5 H ST LOBBY WARD 1 1 LPDR 1 1 NRC PDR 1 1 NSIC HARRIS> J 1 1 NSIC MAYSI G 1 TOTAL NUMBER OF COPIES REQUIRED: LTTR 44 ENCL '2

'RC Form 388 UA. NUCLEAR REGULATORY COMMISSION (84)3)

APPROVED OMB NO. 31504104 EXPIRES: 8/31/SS I.ICENSEE EVENT REPORT (LER)

FACILITYNAME (1) DOCKET NUMBER (2) PA E 3 Shearon Harris Nuclear Power Plant Unit 1 0 5 0 0 0 1 OF TITLE (4)

Reactor Trip Reactor Coolant Low Flow due to Reactor Coolant Pump Trip EVENT DATE D)) LER NUMBER IS) REPORT DATE (7) OTHER FACILITIES INVOLVED (81 MONTH DAY YEAR YEAR SEOVENTIAL gent REVISION MONTH OAY YEAR FACILITYNAMES DOCKET NUMBER(S)

NVMSER NUMBER 0 5 0 0 0 0 1 7 7 7 3 5 0 0 0 7 1 3 8 7 0 5 0 0 0 OPERATING THIS REPORT IS SUBMITTED PURSUANT T0 THE REOVIREMENTS OF 10 CFR (): IChech one or more of the follow/nfl (11)

MODE (8) 20A02(tr1 73.7 'I (8) 20A05(c) 50.73(e) (2) (Iv)

POWER 20A05(e) (I ) B) 50.38(c) (1) 50.73(e) (2)(v) 73.71(c)

LEVEL (10) 20.405(el(11(iil 50.38(c) (2) 50 73(e) (2) (vill OTHER (Specify In Abstrect trelow encl In Text HRC Form W405(el(1) (iiil 50.73(e) (2) (i) 50.73(el(2)(viii) (Al 3SSA/

20.405(e) (I) Bv) 50.73(e) (2) (ii) 50.73(e) (2) (viii)(8) 20A05(el(11(v) 50.73(e)(2) (IB) 50.73(e I (2)(x)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER AREA CODE

0. N. Hudson Senior En ineer Re ulator Com liance 9 1 36 -2 63 CAUSE SYSTEM COMPONENT COMPLETE ONE LINE FOR EACH COMPONENT FAILURE OESCRISEO IN THIS REPORT (13)

MANUFAC.

TVRER TO NPROS gPso. P@g~ CAUSE SYSTEM COMPONENT

'ANVFAC.

TVRER EPORTABLE:4 TO NPROS P 'x SUPPLEMENTAL REPORT EXPECTED (141 MONTH OAY YEAR EXPECTED SUBMISSION DATE (15)

YES flfyes, complete EXPECTED SIIEEIISSIOII DATE) NO ABSTRACT (Limit to 1400 soccer, l.e., epproxlmetely flftren slnple.spree typewritten Ilnml (18)

On June'17, 1987, the Shearon Harris Nuclear Power Plant was operating at 100X reactor power. At 0908, Reactor Coolant Pump "C" tripped which resulted in a reactor trip due to low 'flow in reactor coolant loop "C". Later investigation revealed that physical contact with the bus enclosure caused the trip of auxiliary bus 1C due to the actuation of the Phase "."." bus differential relay, which actuated the bus lockout relay and de-energized auxiliary bus 1C.

Plant shutdown response was normal except that the turbine-driven Auxiliary Feedwater (AFW) Pump started and then tripped'on overspeed. The motor-driven AFW pumps started normally.

8707200448 870713 PDR ADOCI(I 05000400 8 PDR NRC Form 388 (883)

NRC Form SSBA U.S. NUCLEAR REOULATORY COMMISSION (943)

LICE EE EVENT REPORT ILERj TEXT CON INUA APPROVEO OMB NO. 3)50-0(04 EXPIRES: 8/31/88 FACILITY NAME (1) OOCKET NUMBER (2) LER NUMBER (5) PAOE (3)

YEAR SEOUENTIAL r~~'I REVISION Ngj+ NUMBER 'A ) NUMBER 0 OF Shearon Harris Unit 1 5 0 0 0 TEXT /S IIR>>s <<ec>> /1 rsdUSmf, Uso ////Oon>>/HRC err/I 3/)849/ (IT)

DESCRIPTION OF EVENT On June 17, 1987, the Shearon Harris Nuclear Power Plant was operating at 100K reactor power. At 0908, Reactor Coolant Pump (RCP) 'C'ripped. This resulted in a reactor trip due to low flow in reactor coolant loop 'O'. Plant shutdown response was normal except that the turbine-driven Auxiliary Feedwater Pump (AFW) started and then tripped on electrical overspeed. The motor-driven AFW pumps started normally.

CAUSE Immediate investigation of the trip showed that auxiliary Bus 1C tripped due to the actuation of the phase 'A'us differential relay, which actuated the bus lockout (86) relay and de-energized auxiliary Bus 1C by opening circuit breaker 109. The, result was the loss of RCP 'C'nd a loop low flow trip; There were no other observable circuit breaker trip flags on the RCP circuit breaker or circuit breaker 109. Bus and RCP motor leads were checked for grounding and no deficiencies were noted. The phase A differential relay was taken to the shop for testing.and found to be in calibration and proper operating condition. Inspection of RCP 'C'nd components in containment did not reveal any problems.

The investigation uncovered no equipment failures; thus, events which could have caused spurious actuation of the relays were investigated next. The investigators searched for and contacted personnel who had been in that area around 0900. It was determined that at about the time of the trip, a work crew of three individuals and a security officer were maneuvering a cart in front of the bus enclosure. The workers involved were construction personnel completing penetration seals. The cart was loaded with several pails of heavy penetration insulating material. The work creM had to maneuver the cart through a door and over a six-inch high drainage curb on the floor adjacent to the bus enclosure. The barrier is removable, but it is bolted to the floor and heavily caulked.

While moving the cart over the barrier, the cart steering handle and one of the workers must have been within a few inches of the bus enclosure. The workers did not recall any contact with the bus enclosure', however, interviews with the workers verified the fact that the plant trip occurred just after the cart front wheels passed over the barrier. The workers stated that they had heard some noise as they were moving the cart. The workers, however, were not familiar with the plant and plant operation; they did not understand that the noise they heard was actuation of relays which resulted in the plant trip.

'NRC'FORM'SSSA *U.S.OPO:1988.0.824 538/455

($43)

RC Form 388A US. NUCLEAR REGULATORY COMMISSION (983).

L/C SEE E NT REPORT (LER) TEXT CO INUA N APPROI/ED OMB NO. 3150-0104 EX PIR ES: 8/31/88 FACILITY NAME 11) DOCKET NUMBER (2) LER NUMBER (6) PACE (3)

YEAR gSi:

$ EOVENTIAL NUMBER

~/ REVSION

'r%'UMBER Shearon Harris, Unit 1 0 5 0 0 0 4 0 0 7 035 0 0 03 QF 0 4 TEXT %mac gwce 1I nocked, usr ~//RC  %%dnn 38848) (IT)

CAUSE (continued)

Upon examination, the investigators noticed a small fresh "ding" on the enclosure near the phase differential relay, and they collected a few paint chips. Since it appeared that the bus enclosure may have been bumped, the.

investigators tested and verified that a moderate blow to the auxiliary Bus- 1C enclosure in the vicinity of the phase, differential relay would cause one of the relays to actuate. Contact with other utilities indicates that at least one other plant site has experienced impact sensitivity with the same model relay.

As a result of: (1) the workers moving the heavy load in the immediate vicinity of the bus enclosure, (2) the workers having heard the plant trip as they were moving the load, (3) the fresh "ding" on the enclosure, and (4) verification that contact with the bus enclosure could trip the relay, it was concluded that one of the workers or the cart inadvertently contacted the auxiliary bus enclosure and caused the trip.

At the time of this event, the turbine-driven AFW pump was not declared operable pending the closeout of an AFW check valve modification on the AFW line to the Steam Generator. The affected line was in the process'of being returned to service and the pump should have responded properly to the start signal. The steam supply line had been drained by the plant Operators earlier in the shift. After the trip, the lines were drained again and considerable moisture was found. After draining the lines, .the AFW pump was successfully started three times and test started under full flow conditions. It was determined that the water accumulation in the steam supply lines was the probable cause of the turbine overspeed. The steam supply line is normally depressurized but accumulates moisture due to leakage past the isolation valves. Prior to this event, the moisture was being manually drained approximately every four hours. A plant modification (PCR-1235) to install drain traps was pending installation. After the event, an escalated program was initiated to check and drain the steam supply lines.

ANALYSIS This event is reportable in accordance with 10CFR 50.73(a)(2)(iv) due to the automatic reactor trip and the actuation of the reactor protection system, and the Auxiliary Feedwate'r System.

The loss of flow fromingle RCS loop is'an event analyzed in the FSAR. An automatic trip is required to protect the fuel from damage by maintaining DNBR greater'han 1.30. Since the reactor trip was successfully initiated by the loop flow indicators, no adverse consequences occurred. There was no impact on plant safety as a result of this event. All systems, with the exception of the turbine-driven AFW Pump, functioned as required, by design.

NRCWORM 088A *U.S.GPO:1988.O824 538/455 BF83)

~

NRC Form 366A US. NUCLEAR REGULATORY COMMISSION

($ 83)

LIC SEE EVENT REPORT (LER) TEXT CONTINUA N APPROVED OMB NO. 3(50-0(04 EXPIRES: 8/31/88 FACIUTY NAME (ll DOCKET NUMBER (2l LER NUMBER (6) PACE (3)

SEQUENTIAL rI REVISION YEAR :j~g

.ikC NUMBER

.P NVMBER Shearon Harris, Unit o so oo400 8 7 035 0 0 0 40F 04 TEXT /~~ EPooo /F ~, INB ~///IC 1

PEN 368A3/(In CORRECTIVE ACTIONS The following corrective actions to prevent recurrence of this event have been taken or are planned:

1. A program has been initiated to check and drain the steam supply lines as necessary. At least until PCR"1235 is'installed (Item 2 below), the lines will be checked approximately once per hour. If the lines drain more than 2-3 minutes, the frequency will be increased. Any reduction in frequency must be, documented and approved by plant management.

2. Complete plant modification PCR-1235 to install drain traps on the steam supply lines to the, turbine-driven AFW pump.

3 ~ Identify locations of similar relays throughout the plant, and paint the floor area around them to heighten personnel awareness when they are'n these locations.-

'NRC FORM 366A *U.S.GPO:1988-0 62i.538/455 8/83)

0 0 ~

CA&.L Carolina Power S Light Company HARRIS NUCLEAR PROJECT P.O. Box 165 New Hill, NC 27562 JUL f5 198T File Number'SHF/10-13510C Letter Number.'HO-870462 (0)

U.S. Nuclear Regulatory Commission ATTN: NRC Document Control Desk Washington, DC 20555 SHEARON HARRIS NUCLEAR POWER PLANT UNIT 1 DOCKET NO. 50-400

-LICENSE NO. NPF-63 LICENSEE EVENT REPORT 87-035-00 Gentlemen.'n accordance with Title 10 to the Code of Federal Regulations, the enclosed Licensee Event Report is submitted. This report fulfills the requirement for a written report within thirty (30) days of a reportable occurrence and is in accordance with the format set forth in NUREG-1022, September, 1983.

Very truly yours, R. A. Watson Vice President Harris Nuclear Project RAW:skm Enclosure cc: Dr. J. Nelson Grace (NRC RII)

Mr. B. Buckley (NRR)

~

Mr. G. Maxwell (NRC SHNPP)

~ ~ 0

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