ML17342B094

LER 87-033-00:on 871225,during Controlled Shutdown,Reactor Tripped When Source Range High Neutron Flux Trip Unblocked & Detector Went Out of Svc W/O Bypassing Trip Signal.Caused by Inadequate Procedure.Procedures changed.W/880122 Ltr

ML17342B094
Person / Time
Site:	Turkey Point
Issue date:	01/22/1988
From:	Hart R, Woody C FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
L-88-35, LER-87-033, LER-87-33, NUDOCS 8802010153
Download: ML17342B094 (5)

Text

REQULAT~icY INFORMATION DISTRIBUTIO

.-YSTEN (RIDS)ACCESS/ON NBR: 8802010153 DOC.DATE: 88/01/22 NOTARIZED:

NO FACIL: 50-250 Turkey Point Planti Unit 3i Florida Power and Light C AUTH.NANE AUTHOR AFFILIATION HART'.D.Florida Power 5 Light Co.REC'IP.MANE RECIPIENT AFFILIATION DOCKET 0 05000250

SUBJECT:

LER 87-033-00:

on 871225.during control led shutdown.reactor tripped when source range high neutron flux trip unblocked 5 detector out of svc w/o bypassing trip signal.Caused by-inadequate

'procedure.

Procedures changed: M/8880122ltr.

, DISTRIBUTION CODE: IE22D COPIES RECEIVED: LTR)ENCL J SIZE: TITLE: 50.73 Licensee Event Report (LER)i Incident Rpti etc.NOTES: REC IP IENT ID CODE/NAME PD2-2 LA Nc DONALD.D INTERNAL: ACRS NICHELSON AEOD/DOA AEOD/DSP/ROAB ARN/DCTS/DAB NRR/DEST/ADS NRR/DEST/ELB NRR/DEST/NEB NRR/DEST/PSB NRR/DEST/SQB NRR/DLPG/GAB NRR/DREP/RAB NRR B RES/DE/EI8 RQN2 FILE 01 EXTERNAL: EG8cQ QROHs N H ST LOBBY NARD NRC PDR NSIC NAYSi G COPIES LTTR ENCL 1 1 1 1 1 1 1 2 2 1 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 5 5 1 1 1 1 RECIPIENT ID CODE/NANE PD2-2 PD ACRS MOELLER AEOD/DSP/NAS AEOD/DSP/TPAB DEDRO NRR/DEST/CEB NRR/DEST/I CSB NRR/DEST/MTB NRR/DEST/RSB NRR/DLPG/HFB NRR/DOEA/EAB NRR/DREP/RPB NRR/P NAS/ILRB RES TELFORDi J RES/DRPS DIR FORD BLDG HOYLE A LPDR NSIC HARRIS>J COPIES LTTR ENCL 1 1 2 2 1 1 i.1 1 1 1 1 1 1 1 1 1 1 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 TOTAL NUMBER OF COPIES REQUIRED: LTTR 4b ENCL 45 NAC Form r04 r 59 LICENSEE EVENT REPORT{LERI U.S.NUCLEAR AEQULATORY COMMISSION APpRDYED QMA NO, 2)504)oe EXPIRES: SISI/55 FACILITY NAME (I I DOCKET NVMSEA 12)0 5 0 0 0 PA 4 Sl 1 OF Reactor Trip During Controlled Shutdown When Source Range High Neutron Flux Trip EVENT DATE I I MONTH OAY YEAR YEAR LER NVMSER (5)SEQVENTIAL NUMEER REvrerQN NVMEEII REPORT DATE (7I YEAR MON IH OAY O'7 ER FACILITIKS I VOLVE (SI FACILITY NAMES DOC)(ET NUMSERISI 0 5 0 0 0 1 2 25 8 7 87 0 3 3 0 0 0 1 2 2 8 8 0 5 0 0 0 OPERATINQ MODE (9)POWER LEVEL II 0)20.402(o)20.405(~Il1 Ill)20.e05 I~I(1)IEI 20AOE I~I (I I (iil I 20A05 I e I (I)I I r I 20,e05(~I (11 Iv)20.e05(~)50.14(el(1)

$0.$4(c)(1)50.71(e l(2)(ll 50.71(e)l2l(EI 50.71(e)C(l(ill)

LICENSEE CON'TACT FOA THIS LER (12I 50.72(e I (2)(iv)S0.71(el(2)(v)50.71(e)(2)(rr(l 50.7 1(e I (2)(rill)IA)50.71(el(2)(viE)

(~I S0.71(e I (1)(e I THIS REPORT IS SVSMITTEO PURSUANT 7 0 THE REQUIREMENTS OF 10 CFR (): ICntce ont or iriort of tnt loliowinpl 111 72.7)1 I 71.71(cl OTHER ISotcify in AONrtct Oeiow end in Pert, NAC Form 266AI NAME Randall D.Hart, Licensing Engineer AREA CODE TKLEPHONE NUMBER COMPLETE ONE LINE FOR EACH COMPONENT FAILURE OESCRI~ED IN THIS REPOAT IIS)CAUSE SYSTEM COMPONENT MANVFAC TVRER EPORTABLE TO NPRDS eopk%+p cor<cu~wH6i6)

CAUSE SYSTEM COMPONENT MANVFAC.TURER EPORTASLE TO NPADS X I G JX W 120 Y 4'N.""~&SUPPLEMKNTAL REPORT EXPECTED I(El MONTH DAY YEAR YES III yrL comoltre EXPECTED SUSMISSION OAT'El x.o EXPFCTKD SUSMISSION DATE (15)ASSTAACT ILimir to lt00 rptctr, lt., tpprorimtttiy liftrtn rinprt tptct typtwnrttn lintel (14)On December 25, 1987, Unit 3 experienced a subcritical reactor trip.Unit 3 was in the process of a controlled shutdown due to pressurizer pressure control problems.The unit was taken off the line and the operators proceeded to fully insert the control rods.When the indication on both intermediate range detectors decreased to below 10 E-10 amps, the source range detectors (N-31 and N-32)energized.and began indicating in counts per second (cps).N-31 had been taken out of service for a previous failure and the instrument fuses in the drawer had been removed, but the level trip bypass switch had been left in normal position.This places the channel in the tripped condition and locks in the input to the reactor, trip logic.Therefore, when the source range detectors reenergized, the reactor trip logic for a source range high flux reactor trip at shutdown was fulfilled.

The reactor trip occurred as designed and the unit was stabilized in mode 3 (hot standby).A contributing factor was that the off normal operating procedure did not address the failure of a source range detector in mode 1 (power operation).

Appropriate procedure changes will be made and a post trip review was performed to assure proper operation of safety related equipment.

Upon completion of the post trip review and appropriate maintenance, the unit was returned to service on December 27, 1987.NAC Form 144 (9 SSI 80g010153 000250 PDR ADOCK 0 PDR 8

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NRC SO/III 3BEA (SA3l LICENSEE NT REPORT{LER)TEXT CONTINU N U.S.NUCLEAR REGULATORY COMMISSION APPRQVEQ QMB//Q 3150&(0<EXPIRES: 9/31/EB SACILITY NAME ((l DOCKET NUMBER (ll YEAR LER NUMBER (5)SEOUENTIAL I/UM E R rOr'<rz.II E V IS IO II NUMOOA PAGE (3I Turkey Point Unit 3 TIKT/PAKoo deco 8~oso os(bno/N/TC%%d//II~9/((Tl 0 5 0 0 0 OF ANALYSIS OF EVENT: At the time of the event, Unit 3 was in mode 3 with control rod banks A, B, C, and D inserted and shutdown bank A partially inserted.When the reactor trip signal was generated, the reactor trip breakers opened and shutdown banks A and B inserted into the core as designed.A post trip review was performed to assess the proper operation of safety-related equipment.

The post trip review established that the transient behavior of pertinent plant parameters for the reactor coolant system and steam generators responded as expected for a reactor trip of this kind.Based on the above, the health and safety of the public were not affected.CORRECTIVE ACTIONS: 1)The vendor of the source range detectors is currently working on a modification to replace the solid state circuitry for the high voltage cutout circuitry.

Upon receipt of the modification package and appropriate materials the problem will be repaired.2)Operating surveillance procedure (OSP)3-0SP-059.1, Source Range Nuclear Instrumentation Analog Operational'est, was performed to verify operability of N-31 prior to restart of Unit 3.3)Pressure control valve (PCV)PCV-3-'455A was repaired, satisfactorily tested and placed back in service.4)Off normal operating procedure (ONOP)3-0NOP-059.3, Nuclear Instrumentation Malfunction, will be replaced by separate procedures that will address each portion of the nuclear instrumentation system (NIS).Each procedure will provide guidance to the operators on what actions to take when a NIS channel malfunctions in each mode.5)Upon completion of the post trip review and scheduled maintenance activities, the unit was placed on the line at 0535 on December 27, 1987.6)This event will be reviewed by the Training Department to determine if additional training is warranted.

ADDITIONAL DETAILS: The source range detectors are Westinghouse model WL-23706 proportional counters.'CV-3-4S5A is a Copes-Vulcan Model D-100-160-2 1/2'inch valve.Similar Occurrences:

LERs 250-84-040, 2SO"84-021, 251-84-014, 251-84-023, and 250-87-022 reported events where a subcritical reactor trip occurred due to source range high flux reactor trip signal but they did not have the same root cause as this LER.MAC SORM 3OOA (943(~U.S GPQ:(985 0 Blo 538/455 P.O.14000, JUNO BEACH, FL 33408.0420 JANUARY 2 2 1988 L-88-35 10 CFR 50.73 U.S.Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C.20555 Gentlemen:

Re: Turkey Point Unit 3 Docket No.50-250 Reportable Event: 87-33 Date of Event: December 25, 1987 Reactor Trip During Controlled Shutdown When Source Range High Neutron Flux Trip Unblocked and a Detector Out of Service Without B assin the Tri The attached Licensee Event Report (LER)is being submitted pursuant to the requirements of 10 CFR 50.73 to provide notification of the subject event.Very truly yours, (Qr~c-.>i C.0.Woo Executi Vice President COW/SDF/gp Attachment cc: Dr.J.Nelson Grace, Regional Administrator, Region II, USNRC Senior Resident Inspector, USNRC, Turkey Point Plant S DF/0 18~LER an FPL Group company