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 DOCKET 0 FACIL: 50-250 Turkey Point Planti Unit 3i Florida Power and Light C 05000250 AUTH. NANE AUTHOR AFFILIATION HART'. D. Florida Power 5 Light Co.

REC'IP. MANE RECIPIENT AFFILIATION

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

NOTES:

REC IP IENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NANE LTTR ENCL PD2-2 LA 1 1 PD2-2 PD 1 1 Nc DONALD. D 1 INTERNAL: ACRS NICHELSON 1 1 ACRS MOELLER 2 2 AEOD/DOA 1 1 AEOD/DSP/NAS 1 1 AEOD/DSP/ROAB 2 2 AEOD/DSP/TPAB i. 1 ARN/DCTS/DAB 1 1 DEDRO 1 1 NRR/DEST/ADS 0 NRR/DEST/CEB 1 1 NRR/DEST/ELB 1 1 NRR/DEST/ I CSB 1 NRR/DEST/NEB 1 1 NRR/DEST/MTB 1 1 NRR/DEST/PSB 1 1 NRR/DEST/RSB 1 NRR/DEST/SQB 1 1 NRR/DLPG/HFB 1 NRR/DLPG/GAB 1 NRR/DOEA/EAB 1 1 NRR/DREP/RAB 1 1 NRR/DREP/RPB 2 2 NRR B 1 1 NRR/P NAS/ ILRB 1 1 1 RES TELFORDi J 1 1 RES/DE/EI8 1 1 RES/DRPS DIR 1 1 RQN2 FILE 01 1 1 EXTERNAL: EG8cQ QROHs N 5 5 FORD BLDG HOYLE A 1 1 H ST LOBBY NARD 1 1 LPDR 1 1 NRC PDR NSIC HARRIS> J 1 1 NSIC NAYSi G 1 1 TOTAL NUMBER OF COPIES REQUIRED: LTTR 4b ENCL 45

NAC Form r04 U.S. NUCLEAR AEQULATORY COMMISSION r 59 APpRDYED QMA NO, 2)504)oe EXPIRES: SISI/55 LICENSEE EVENT REPORT {LERI DOCKET NVMSEA 12) PA 4 Sl FACILITY NAME (I I 0 5 0 0 0 1 OF Reactor Trip During Controlled Shutdown When Source Range High Neutron Flux Trip EVENT DATE I I LER NVMSER (5) REPORT DATE (7I O'7 ER FACILITIKS I VOLVE (SI SEQVENTIAL REvrerQN FACILITYNAMES DOC)(ET NUMSERISI MONTH OAY YEAR YEAR NUMEER NVMEEII MON IH OAY YEAR 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 THIS REPORT IS SVSMITTEO PURSUANT 7 0 THE REQUIREMENTS OF 10 CFR (): ICntce ont or iriort of tnt loliowinpl 111 OPERATINQ MODE (9) 20.402(o) 20.e05( ~) 50.72(e I (2)(iv) 72.7)1 I 20.405( ~ Il1 Ill) 50.14(el(1) S0.71(el(2) (v) 71.71(cl POWER LEVEL 50.71(e)(2)(rr(l OTHER ISotcify in AONrtct II0) 20.e05 I~ I(1) IEI $ 0.$ 4(c)(1)

Oeiow end in Pert, NAC Form 20AOE I ~ I (I I (iilI 50.71(e l(2)(ll 50.7 1(e I (2)(rill)IA) 266AI 20A05 Ie I (I) I I r I 50.71(e) l2l(EI 50.71(el(2)(viE) ( ~ I 20,e05( ~ I (11 Iv) 50.71(e)C(l(ill) S0.71(e I (1)(e I LICENSEE CON'TACT FOA THIS LER (12I NAME TKLEPHONE NUMBER AREA CODE Randall D. Hart, Licensing Engineer COMPLETE ONE LINE FOR EACH COMPONENT FAILURE OESCRI ~ ED IN THIS REPOAT IIS)

MANVFAC EPORTABLE MANVFAC. EPORTASLE CAUSE SYSTEM COMPONENT TVRER TO NPRDS eopk%+p cor<cu~wH6i6)

CAUSE SYSTEM COMPONENT TURER TO NPADS X I G JX W 120 Y 4'N.""~&

SUPPLEMKNTAL REPORT EXPECTED I(El MONTH DAY YEAR EXPFCTKD SUSMISSION DATE (15)

YES IIIyrL comoltre EXPECTED SUSMISSION OAT'El x .o 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.

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U.S. NUCLEAR REGULATORY COMMISSION NRC SO/III 3BEA (SA3l LICENSEE NT REPORT {LER) TEXT CONTINU N APPRQVEQ QMB //Q 3150&(0<

EXPIRES: 9/31/EB DOCKET NUMBER (ll LER NUMBER (5) PAGE (3I SACILITY NAME ((l YEAR SEOUENTIAL rOr'< IIE V IS IO II I/UM E R rz. NUMOOA TIKT/PAKoo deco 8 ~

Turkey Point Unit oso os(bno/ N/TC %%d//II 3

~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 ~ U.S GPQ:(985 0 Blo 538/455 (943(

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