ML17251A976

LER 88-001-00:on 880205,reactor Trip Occurred.Caused by Higher than Normal Count Rate on Source Range (SR) Nuclear Instrumentation Sys Due to Faulty Connectors at Detectors. SR Detectors replaced.W/880307 Ltr

ML17251A976
Person / Time
Site:	Ginna
Issue date:	03/07/1988
From:	Backus W, Snow B ROCHESTER GAS & ELECTRIC CORP.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
LER-88-001, LER-88-1, NUDOCS 8803140134
Download: ML17251A976 (9)

Text

ACCELERATED DlRIBUTION DEMONSTTION SYSTEM C7 REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:8803140134 DOC.DATE: 88/03/07 NOTARIZED: NO DOCKET g FACIL:50-244 Robert Emmet Ginna Nuclear Plant, Unit 1, Rochester G 05000244 AUTH. NAME AUTHOR AFFILIATION BACKUS,W.H. Rochester Gas & Electric Corp.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 88-001-00:on 880205,higher than normal count rate on source range NIS due to faulty connectors.

W/8 ltr.

DISTRIBUTION CODE: IE22D COPIES RECEIVED:LTR 4 ENCL )

TITLE: 50.73 Licensee Event Report (LER), Inci ent Rpt, etc.

SIZE:

. D

. NOTES:License Exp date in accordance with 10CFR2,2.109(9/19/72). 05000244 S

RECIPIENT ID CODE/NAME COPIES LTTR ENCL ID RECIPIENT CODE/NAME COPIES LTTR ENCL i'

PD1-3 LA 1 1 PD1-3 PD 1 1 STAHLE,C 1 1 INTERNAL: ACRS MICHELSON 1 1 ACRS MOELLER 2 2 AEOD/DOA 1 1 AEOD/DSP/NAS 1 1 AEOD/DSP/ROAB 2 2 AEOD/DSP/TPAB 1 1 ARM/DCTS/DAB 1 1 DEDRO 1 1 NRR/DEST/ADS7E4 1 0 NRR/DEST/CEB8H7 1 1 NRR/DEST/ESB 8D 1 1 NRR/DEST/ICSB7A 1 .1 NRR/DEST/MEB9H3 1 1 NRR/DEST/MTB 1 1 NRR/DEST/PSB8D1 1 1 8E 9H'RR/DEST/RSB 1 1 NRR/DEST/SGB 8D 1 1 NRR/DLPQ/HFB10D 1 1 NRR/DLPQ/QAB10A 1 1 NRR/DOEA/EAB11E 1 1 NRR/DREP/RAB10A 1 1 NRR/DREP/RPB10A 2 2 NRR/J)RIS SIB9A1 1 1 NRR/PMAS/ILRB12 -1 1 REG F 02 1 1 RES TELFORD,J 1 1 D EIB 1 1 RES/DRPS DIR 1 1 RGN1 FILE 01 1 1 EXTERNAL: EG&G GROH,M 5 5 FORD BLDG HOY,A 1 1 H ST LOBBY WARD 1 1 LPDR 1 1 NRC -PDR 1 1 NSIC HARRIS,J 1 1 NSIC MAYS,G 1 1 S

I A

TOTAL NUMBER OF COPIES REQUIRED: LTTR 46 ENCL 45

HAC fr>or SOS Uh, NVCLKAll IllOVLATOIIYCOMMISSION (9021 APPROVED OMS NO.1190 OIO>t EXPIRES ~ 0/Sl/SS LICENSEE EVENT REPORT {LER) f ACILITY NAME (Il DOCKET NVMSEII (11 PA R>E Gi a Nuclear Power 1 0 6 0 0 0 1 OF TITLE lcl Higher Than Normal Count Rate on Source Range NIS Due to Faulty Connectors, EVENT DATE ISI LER NVMS (SI RltORT DATE I OTHER FACILITIKS INVDLVKDIl)

IKOVINT>AL DAY YEAR FACILITYNAMKS DOCKET NVMSER(51 MONTH DAY YEAR YKAR cScl? N UM 9 1 A >>VMSKA MONTH 0 5 0 0 0 SOW(

0 6 0 0 O 0 2 DPKAATINO THIS I(KtOAT IS SVSMITTKD PURSUANT TO 'THK A K OUI AE MENTS Of 10 CF II f! (Corri ooo o> more ot t>>o tot>o>>otl (ill loOOK I~ ) 10.401(ol 20.409(rl 90.724)(11(tr) 72.71( ~ )

~ OrrK II 2O.COS ( ~ ) I I )(0 ~) Ill 90.7141(1( lrl 72.71(4)

LKVEL 110) 1o.oos Io IllI I 1 1 SOM la I (2) 90.724) (1) l>SI OTHE(I /h>>CIIY Io AOotrrt oslo>>oo>tip Tort, NhC from 20.400(o)(1)(10) 90.7 2(o I (2 I I I) 90.71(o)(2l(rt>I) IA) J>MA) 20.c004)(l)(>r) 90,714 IIS II9) 90.71(o)(1) lrtl)IS I SÃ55~4 20.SOS 4) ll) lr) 90.7 14) (2 I I PS) 90.711> I (1 ) 4)

LICKNSKK CONTACT FOR THIS LER I'ISI NAME TELEPHONE NUMSER Wesley H. Backus AREA COPE Technical Assistant to th COMtLKTK ONE LINE fOA EACH COMPONENT FAILURE DESCIIISKO IN THIS" REPORT'(12)

CAVSE SYSTEM COMPONENT MANUFAC EtDRTASLE TO NPRDS g3'9 ': 2 CAUSE SYSTEM COMPONENT TUAER EPORTASL TO NtADS TVRER gc E~S~<gjyocgk'ANUFAC i)%Egg.:c(N~4xgj

~i-'paPi'-'mTS~4Y4 Il~ ) MONTH DAY YEAR SVttLKMKNTALAKPORT EXtECTED EXPECTED SV 9 M I S9 I OH DATE 114I YES ltt yor. comp>>to EXP/CTTD SVF NISSIOIr DATE/ NO ASSTAACT (Llmtt tO (COO>p>cor, Ko.. opp>o>P>>otrly IIIHoo >lottosP>to tytr>rrtttoo I>or>I ll~ I On February 5, 1988 at 1857 EST with the reactor subcritical during a planned shutdown for the Annual Refueling and Maintenance Outage, a reactor trip occurred from Source Range (SR) Hi Flux.

The two reactor trip breakers opened as required and all shutdown and control rods inserted as designed.

The reactor trip was due to the SR instruments indicating higher than normal count rate when re-energized during the controlled shutdown. The root cause of the higher than normal count rate was circuit noise caused by faulty connectors at the detectors, possibly damaged by personnel or objects entering the instrument portso Immediate corrective action was to stabilize the plant, rack out and hold the reactor trip breakers, and borate the Reactor Coolant System to refueling shutdown concentration. Subsequent action was to changeout the two source range detectors.

Action planned to prevent recurrence is to install protective gratings over the instrument ports during outages.

SP03iq0130 SS0307 AOOCK 05000244 PDR eopaa)gg NRC fr>m 7OS (907)

U.S, NUCLEAR REOULATORY COMMISSION NRC fons ESSA (SS5 I LICENSEE EVENT REPORT ILER) TEXT CONTINUATION APPROVEO OMS NO. 315OWI04 EXPIRES'ISIISf fACILITYNAME III OOCKET NUMSER IEI LER NUMSER I ~ I CCQVCNTIAL II 'CVISXIN NVMCCR " NVM CW R.E. Gonna Nuclear Power Plant TEXT TII'mom cfcfc Ic tryakeC NPP ~ NIIC JemI SIEIASI llll o s o o o 244 88 0 1 0 0 0 2 OF 0 7 PRE-EVENT PLANT CONDITIONS Unit shutdown was in progress per Operating Procedure 0-2. 1 (Normal Shutdown To Hot Shutdown) for the Annual Refueling and Maintenance Outage.

DESCRIPTION OF EVENT A. EVENT:

On February 5, 1988 at 1857 EST with the reactor subcritical during a planned shutdown, a reactor trip occurred from Source Range (SR) Hi Flux when the SR Nuclear Instrumentation System (NIS), upon re-energizing at the normal setpoint of 5 x 10 11 amps on the Intermediate Ranges (IR) NIS, indicated higher than normal count rate.

The Control Room operators performed the actions'f Emergency Operating Procedures E-0 (Reactor Trip or Safety In)ection), and ES-O.l (Reactor Trip Response),

and stabilized the plant.

The Control Room operators, per procedure ER-NIS.1 (SR Malfunction), held open the reactor trip breakers, continued boration to refueling shutdown and notified the Instrument and Control Department to investigate.

B. INOPERABLE STRUCTURES f COMPONENTS P OR SYSTEMS THAT CONTRIBUTED TO THE EVENT:

None NRC CORM SCCA IS43l

U.S. NUCLEAII IIEOULATOIITCOMMISSION NIIC Senw ESSA I 045 I LICENSEE EVENT REPORT {LER) TEXT CONTINUATION APPROVEO OMS NO. SISOWI04 EX ~ IR E 5 SIS I IS 5 SACILITY NAME III OOCKET NUMSEII ITI LER NUMSER lSI PACE ISI 55QVSIITIAL REVISION NUM 5 II MVM R. E. Ginna Nuclear Power Plant 0 5 0 0 0 2 4 4 8 8 0 1 0 0 0 3 oF 0 TEXT (JI'ROW ~ N ISSMISC M55 SIMSSRSI NIIC Ann SSLS Sl (ITI C. DATES AND APPROXIMATE TIMES FOR MAJOR OCCURRENCES:

o February 5, 1988, 1857 EST: Event date and time o February 5, 1988, 1857 EST: Discovery date'nd time o February 5, 1988, 1914 EST: Reactor trip breakers racked out and held o February 6, 1988, 0120 EST: Source Range NIS N-31 and N-32 declared inoperable o February 6, 1988, 0221 EST: Reactor Coolant System Boron Concentration at refueling shutdown concentration (2004 ppm) o 'ebruary 7, 1988, 1147 EST: Source Range NIS N-32 declared operable o February 8, 1988, 1118 EST: Source Range NIS N-31 declared operable D. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED:

None E. METHOD OF DISCOVERY:

The event was immediately apparent due to alarms and indications in the Control Room.

NRC SOIIM SSSA IS4$ I

U.E. NUCLEAR REOULAEORY COMMIEEION NRC Perm 1EEA (04$ l LICENSEE EVENT REPORT {LERI TEXT CONTINUATION APPROVEO OME NO. 1150&IIM ER ~ IREE EI1IIES SACILIEY NAME III OOCKEY NUMEER 11I LER NUMEER I ~ I ~ AOE I1I SEQUENTIAL REVISION

~~PS NUMINE ll NVM ER R.E. Ginna Nuclear Power Plant o 5 o o o 24 48 8 0 01 0 0 40F 0 7 EEXE llS IRONS PASSED PP PSESPNE SSS SSMEbnat HIIC Ann ~'Pl I 171 F. OPERATOR ACTION:

0 After the reactor trip the Control Room operators performed the actions of Emergency Operating Procedures E-O (Reactor Trip or Safety Injection),

and ES-0.1 (Reactor Trip Response) and stabilized the plant.

Subsequently the Control Room operators performed the actions of equipment restoration procedure ER-NIS. 1 (SR Malfunction) and held the reactor trip breakers racked out, continued RCS boration to refueling shutdown concentration and notified the Instrument and Control (I&C) Department of the SR malfunction.

III. CAUSE OF VlENT A. IMMEDIATE CAUSE:

The reactor trip occurred due to SR NZS Hi Flux (i.e. SR count rate greater than or equal to 10 counts per second (cps) ) .

B. INTERMEDIATE CAUSE:

The SR Hi Flux reactor trip was received because the SR NIS was indicating higher than normal count rate when they re-energized automatically as the IR NIS decreased below 5 x 10 11 amps.

C. ROOT CAUSE:

The root cause of the higher than normal count rate on the SR NZS was due to noise caused by faulty connectors at the detectors. Zt is believed that these connectors could have been damaged by persons or objects entering the instrument port holes during work in the reactor cavity.

NRC SORM 1EEA I0 43 I

I I ~

NRC Sebum SSSA U.S. NUCLEAR RSOULATORY COMMISSION 10431 LICENSEE EVENT REPORT ILER) TEXT CONTINUATION ASSROVSO OMb NO. SISOWI04 SXSIRSS SISIISS SACILITY NAMS 111 LSR NUMSSR ISI

,Ivr SloUSNTtAL RSV I%ION NUM fs NUM TR

~~

R.E. Gonna Nuclear Power Plant 0 S 0 0 0 2 4 4 8 0 0 1 0 0 5 oF 07 Vga SIT nsso H ooo oAWonol H11C Fons JRSA'ol 1171 ANALYSIS OF EVENT This event is reportable in accordance with 10 CFR 50.73, Licensee Event Report System, item (a) (2) (iv) which requires reporting of, <<any event or condition that resulted in manual or automatic actuation of any Engineered Safety Feature (ESF), including the Reactor Protection System (RPS),<< in that the Source Range Hi Flux reactor trip was an automatic actuation of the RPS.

The Source Range instrumentation system also had a Technical Specification (TS) operability action statement associated with it. This action statement from TS table 3.5.1, action statement 4 states, "with the number of operable channels one less than the minimum operable channel requirement (i.e. 2 source range instruments), suspend all operations involving positive reactivity changes. If the channel is not restored to operable status within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />, open the reactor trip breakers within the next hour."

The plant operators racked out and held the reactor trip breakers soon after the reactor trip and only negative reactivity changes were made thereafter.

An assessment was performed considering both the safety consequences and implications of this event with the following results and conclusions:

There were no operational or safety consequences attributed to the SR Hi, Flux reactor trip because:

o The two reactor trip breakers opened as required.

o All withdrawn control and shutdown rods inserted as designed.

o The unit was already shutdown with the reactor sub-critical so there were no power, temperature, or pressure transients related to the reactor trip.

NRC SORM SOOA 10431

A~

P U.S. NUCLEAR RTOVLATORY COMMITNON NRC FP//// 0FCA 100' LICENSEE EVENT REPORT (LER) TEXT CONTINUATION APPROVEO OMS NO 0150WI04 f XPIRK$ 8/lI/SS FACILITY NAMC 111 OOCRKT NUMITR Ill LTR NUMICR III A 1 V /T /0 //

YTAR 'A,'% 0 U T/I T/AL NVMPTR NUM ~ R R.E. Ginna Nuclear Power Plant 0 5 0 0 0 8 8 001 00 06 oF 0 7 TSCl'X/RP/P RaeoP 4 terakeC ~ ~HIICAn/I ~'Pl 1111 Implications of the event were the loss of accurate core

'neutron flux monitoring for shutdown considerations. A review of these implications was made with the following results:

o Nuclear data accumulated, following the controlled shutdown indicates that the actual neutron fluence at the SR detector locations was well below the trip setpoint of 10 cps.

o The failure of the SR NIS's was in the conservative direction (i.e. the indicated count rate was higher than the actual count rate).

o With the controlled shutdown negative reactivity was added continuously using Boric Acid addition as reactor power was decreased. This Boric Acid addition was continued after the reactor was subcritical thus assuring more than adequate core shutdown margin at all times.

o After the reactor trip the reactor trip breakers were racked out and held, assuring no inadvertent positive reactivity insertion due to control rods.

Based on the above margin was more it than can be concluded that core shutdown adequate at all times during the SR NIS malfunction assuring the public's health and safety.

V CORRECTIVE ACTION A. ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT NORMAL STATUS:

o Source Range detectors for N-31 and N-32 SR channels were replaced with new detectors. With these new detectors the SR channels were cali-brated and tested satisfactorily.

NIIC I'ORM 0FF*

104ll

U.S. NUCLEAR RSOULATORY COMMISSION NRC Perm SSSA ISSS I LICENSEE EVENT REPORT ILER) TEXT CONTINUATION APPROYSO OMS NO. $ 150WI04 SRPIRSS SISI/SS PACILITY NAMS III OOCKST NUMSSR l1) LSR NUMSSR lSI PAOS ISI SSOUCNTIAL P ~ OSYISrON HUM %1 rrUM SA R.E. Gonna Nuclear Power Plant 0 5 0 0 0 2 4 4 8 8 0 0 1 0 0 7oF 0 7 TSXT IP more ~ N reerrOeC rroo eerAlorNP HRC Amr SHIA'ol IITI o Subsequent investigation revealed that the N-31 SR detector connector was broken at the detector.

This connector was replaced and tested satis-factorily.

o Subsequent investigation revealed that the N-32 SR detector connector was dirty. This connector was cleaned and tested satisfactorily.

B. ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:

o Ginna Station Work Request Trouble Report No. 88-1331 was initiated to design, manufacture and install heavy gauge tubing or armored grating over the NIS instrument ports to protect against people and tools from falling into the instrument ports during outages.

ADDITIONAL INFORMATION A. FAILED COMPONENTS:

o The faulty components were: Amphenol Connectors, part number 52975-1051.

B~ PREVIOUS LERs ON SIMILAR EVENTS:

A similar LER event historical search was conducted with the following results: No documentation of similar LER events at Ginna Station could be identified.

C. SPECIAL COMMENTS:

The industry was notified of this event through Nuclear Network on February 24, 1988.

HRC PORM SOSA I5SS I

ROCMESTER GAS AND ELECTRIC CORPORATION ~ 89 EAST AVENUE, ROCMESTER, N.Y. I 4649 Tf cl'~~Pal'oiA coDE: ~II 5 6 2 March 7, 1988 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Sub j ect: LER Range 88-001, Higher Than Normal Count Rate On Source NIS Due To Faulty Connectors, Causes Reactor Trip During Source Range Re-energization.

R.E. Ginna Nuclear Power Plant Docket No. 50-244 In accordance with 10 CFR 50.73, Licensee Event Report System, item (a) (2) (iv) which requires a report of, "any event or condition that resulted in manual or automatic actuation of any Engineered Safety Feature (ESF), including the Reactor Protection System (RPS)," the attached Licensee Event Report LER 88-001 is hereby submitted.

This event has in no way affected the public's health and safety.

Bruce A. Snow Superintendent of Nuclear Production xce U.S. Nuclear Regulatory Commission Region I Z 475 Allendale Road ~l King of Prussia, PA 19406 f

Ginna USNRC Resident Inspector