ML17229A616

LER 98-001-00:on 980104,inadvertent RPS Actuation Occurred Due to Personnel Error.Caused by Procedural Inadequacies & Inadequate self-checking by Licensed Utility Personnel. Placards Have Been Placed in CRs.W/980203 Ltr

ML17229A616
Person / Time
Site:	Saint Lucie
Issue date:	02/03/1998
From:	Frehafer K, Stall J FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-98-018, L-98-18, LER-98-001, LER-98-1, NUDOCS 9802110012
Download: ML17229A616 (7)

Text

CATEGORY 1~REGULARLY INFORMATION DISTRIBUTIOF%YSTEM (RIDS)p)*ACCESSION NBR:9802110012 DOC.DATE: 98/02/03 NOTARIZED:

NO FACIL:50-335 St.Lucie Plant, Unit 1, Florida Power&Light Co.AUTH.NAME AUTHOR AFFILIATION FREiIXFER,K.W.

Florida Power&Light Co.-STALL,J.A.

Florida Power&Light Co.RECIP.NAME RECIPIENT AFFILIATION DOCKET¹05000335

SUBJECT:

LER 98-001-00:on 980104,inadvertent RPS actuation occurred due to personnel error.Caused by procedural inadequacies

&, inadequate self-checking by.licensed utility personnel.

Placards have been placed in CRs.W/980203 ltr.DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE: TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.NOTES: 'C RECIPIENT ID CODE/NAME PD2-3 PD INTERNAL: ACRS AEOD/S PD/RRAB NRR/DE/ECGB NRR/DE/EMEB NRR/DRCH/HICB NRR/DRCH/HQMB NRR/DSSA/SPLB RES/DET/EIB EXTERNAL: L ST LOBBY WARD NOAC POORE,W.NRC PDR COPIES LTTR ENCL 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 RECIPIENT ID CODE/NAME WIENS,L.Cg NRR DE EELB NRR/DRCH/HHFB NRR/DRCH/HOLB NRR/DRPM/PECB NRR/DSSA/SRXB RGN2 FILE Ol LITCO BRYCE,J H NOAC QUEENER,DS NUDOCS FULL TXT COPIES LTTR ENCL 1 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 NOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE.TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DISTRIBUTION LIST>>OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR ORGANIZATION, CONTACT THE DOCUMENT CONTROI DESK (DCD)ON EXTENSION 415-2083 FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 25 ENCL 25 Florida Power&Light Company, 6351 S.Ocean Drive, Jensen Beach, FL 34957 February 3, 1998 L-98-018 10 CFR 50.73 U.S.Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C.20555 Re: St.Lucie Unit 1 Docket No.50-335 Reportable Event: 98-001 Date of Event: January 4, 1998 Inadvertent RPS Actuation Due to Personnel Error The attached Licensee Event Report is being submitted pursuant to the requirements of 10 CFR 50.73.Very truly yours, J.A.Stall Vice President St.Lucie Plant JAS/KWF Attachment cc: Regional Administrator, USNRC, Region II Senior Resident Inspector, USNRC, St.Lucie Plant'ir802ii0012

'rr80203 PDR ADQCK 05000335 8 PDR llllllllllllllllllllllllll llllllllllll an FPL Group company NRC FORM 366 (4.9e)U.S.NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)(See reverse for required number of digits/characters for each biock)APPROVED SV OMB No.S(60<0(O4 EXARES 04/30/S S ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS MANDATOR INFORMATION COLLECTION REOUEST: 60.0 HRS.REPORTED LESSON LEARNED ARE INCORPORATED INTO THE UCENSING PROCESS AND FE BACK TO INDUSTRY.FORWARD COMMENTS REGARDING BURDEN ESTIMAT TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (TW F33(US.NUCLEAR REGIAATORY COMMISSION, WASHINGTON, DC 20666ENO I AND TO THE PAPERWORK REDUCTION PROJECT (3(600104I, OFRCE 0 MANAGEMENT AND BUDGET, WASHINGTON, DC 20603.FACIUTY NAME UI ST LUCIE UNIT 1 TITLE (4I Inadvertent RPS Actuation Due to Personnel Error DOCKET NINVIB(R (2(05000335 PAGE (SI 1 OF4 DAY YEAR 4 98 YEAR SEOUENTIAL REVISION MONTH NUMBER NUMBER 98,-001-0 OAY YEAR 3 98 FACIUTY NAME FACIUTY NAME DOCKET NUMBER 05000 DOCKETNUMBER 05000 OPERATINQ MODE (9)POWER LEVEL l10)20.2201 (b)20.2203 (a)(2)6)20.2203{a)

(2)(iii)20.2203 (a)(2)(iv)20.2203(a) l2)(v)20.2203(a)

(3)(ii)50.36(c)(1)50.36(c)(2)50.73(a)l2){i)50.73(a)(2)(iii)50.73(a){2){v)50.73(a)(2)(vii) 50.73{0)l2)(viii)73.71 OTHER Specify In Abstract below or in NRC Form 366A NAME K.W.Frehafer, Licensing Engineer TELEPHONE NUMBER Src(vde Arta Codel (561)468-4284 CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE TO NPRDS CAUSE SYSTEM COMPONENT MANUFACTURER To NPRDS JC N/A N/A N/A YES{It yes, complete EXPECTED SUBMISSION DATE).X No EXPECTED SUBMISSION DATE (15)MONTH OAY YEAR ABSTRACT (Umit to 1400 spaces, l.e., approximately 15 single-spaced tYpewritten lines)(16)On January 4, 1998, Unit 1 was at zero percent power, in Mode 3, with pressurizer pressure less than 1750 psig.A reactor plant heatup to normal operating temperature and pressure following refueling was in progress.The reactor trip breakers were closed and all reactor control element assemblies were fully inserted.The operators were directed to remove the zero power mode bypass keys for each channel of the reactor protection system once the fourth reactor coolant pump was started.The reactor trip breakers opened immediately after the reactor protection system'C'hannel zero power mode bypass was unbypassed.

This event was caused by procedural inadequacies and inadequate self-checking by licensed utility personnel.

The procedure did not address plant conditions necessary to ensure the reactor protection system thermal marginflow pressure trip setpoint was below actual system pressure when the zero power mode bypass keys were operated.During the event, plant conditions would have set the thermal margin/low pressure trip setpoint at 1887 psia, and actual reactor coolant system pressure was approximately 1740 psia when the reactor protection system zero power mode bypass was unbypassed.

Additionally, the operator continued with the unbypassing of the zero power mode bypass and did not give the crew time to review the validity of the alarms and ensure all conditions were satisfactory prior to completing the procedure.

Corrective actions included procedural enhancements, counseling the operator, and crew briefings on the event.NRC FORM 366{4.9S)

NRC FORM 366A I4.9S)LICENSEE EVENT REPORT (LER)TEXT CONTINUATION U.S.NUCLEAR REGULATORY COMMISSIO ST.LUCIE UNIT 1 05000335 YEAR SEQUENTIAL REVISION 98-001-0 2 OF 4 TEXT/if more spece is required, use eddidonel copies of NRC Form 36@A/I17]On January 4, 1998, Unit 1 was at zero percent power, in Mode 3, with pressurizer pressure less than 1750 psig.A reactor plant heatup to normal operating temperature and pressure following refueling was in progress in accordance with Normal Operating Procedure NOP-1-0030121,"Reactor Plant Heatup-Cold to Hot Standby." Reactor Coolant System (RCS)temperature was approximately 510'F and pressure was approximately 1700 psia.Reactor Trip Circuit Breakers (TCBs)[EIIS:JC:BKR]

were closed and all reactor Control Element Assemblies (CEAs)[EIIS:AA]were fully inserted.The fourth Reactor Coolant Pump (RCP)[EIIS:AB:P], 1A1, was successfully started in accordance with step 6.5.12 of the heatup procedure.

Step 6.5.13 directs an operator to remove the Zero Power Mode Bypass (ZPMB)[EIIS:JC:33]

keys for each channel of the Reactor Protection System (RPS)[EIIS:JC]once the fourth RCP is started.At 1050, the reactor operator turned the ZPMB key from bypass to off for RPS channel'A'nd the Thermal Margin/Low Pressure (TM/LP)trip locked in.The reactor operator continued ,with the procedure and turned the ZPMB key from bypass to off for RPS channels'B','C', and'D'n sequence.It was then noted that the TCBs had opened, and it was confirmed via the Sequence of Events Recorder (SOER)[EIIS:IQ]that the TCBs had opened immediately after RPS channel'C'as unbypassed.

The operators immediately returned the ZPMB keys back to the bypass position.This event was caused by procedural inadequacies in procedure NOP 1-0030121,"Reactor Plant Heatup-Cold to Hot Standby." Inadequate self-checking by licensed utility personnel contributed to this event.Procedure NOP 1-0030121,"Reactor Plant Heatup-Cold to Hot Standby," step 6.5.13, directs the operators to place the ZPMB key from bypass to off after the fourth RCP is started.However, the procedure did not address all trip functions potentially bypassed by the ZPMB key.The ZPMB switch is a key operated switch, one for each RPS channel.The ZPMB allows the RPS low flow and TM/LP trips to be bypassed for subcritical testing of control element drive mechanisms; This RPS bypass is automatically removed when reactor power level increases above one percent power.The low flow trip is provided to protect the core against Departure from Nucleate Boiling (DNB)in the event of a coolant flow decrease.The low flow trip is a function of measured differential.

pressure across the steam generators and the number of operating RCPs.NRC FORM 366A (4-9S) y1 NRC FORM 366A I4.96)LICENSEE EVENT REPORT (LER)TEXT CONTINUATION U.S.NUCLEAR REGULATORY COMMISSIO ST.LUCIE UNIT 1 05000335 YEAR SEQUENTIAL REVISION 98-001-0 3 OF 4 TEXT llf more speceis required, use edditionel copies of fVRC Form 3MAI I17I CAUSE OF THE EVENT cont'd The TIVI/LP trip is provided for two purposes.The low pressurizer pressure portion of the trip functions to trip the reactor in the event of a loss of coolant accident.The thermal margin portion of the trip, in conjunction.

with the low reactor coolant flow trip, is designed to prevent the reactor core safety limit on DNB from being violated during anticipated operational occurrences.

The TM/LP trip setpoint is either a calculated pressure value based on RCS temperature, power and flow, or a minimum biased pressure value of 1887 psia.During the event, four RCPs were operating (ensuring that a low flow trip would not be present), but existing plant conditions set the TM/LP trip setpoint at the minimum biased pressure value of 1887 psia, The ZPMB keys were placed from bypass to off while RCS pressure was approximately 1740 psia, which resulted in the TM/LP trip and opening the reactor TCBs.Additionally, personnel error by the operator and operating crew resulted in not investigating the cause of the TM/LP alarms when they were received as the RPS channel ZPMB keys were sequentially placed from bypass to off.The operator continued with the procedure and did not give the crew time to review the validity of the alarms and ensure all conditions were satisfactory prior to completing the procedure.

The TCBs opened when the third RPS channel ZPMB key was placed from bypass to off, which completed the coincidence requirements for the TM/LP reactor trip.St.Lucie Plant management expectations for licensed operator response to unexpected control room alarms are that the licensed operator acknowledging the alarm announce the alarm to control room personnel as"unexpected," that control room activities stop to permit investigation of the alarm, and that actions are taken in accordance with plant alarm response procedures to determine the cause of the alarm.Such activities did not occur during this event.This event is reportable as a valid actuation of the RPS per 10 CFR 50.73(a)(2)(iv).

Since removing the bypass from the ZPMB restored the capability of the TM/LP trip circuitry to respond to an RCS low pressure condition, this event is considered a valid RPS actuation based on actual plant conditions.

It was reported to the NRC as a four hour ENS notification at 1708 hours0.0198 days <br />0.474 hours <br />0.00282 weeks <br />6.49894e-4 months <br /> on January 5, 1998.The reactor was shutdown in Hot Standby prior to the event.Although the TCBs were opened by a valid RPS signal, the reactor trip signal did not result in any physical change to core reactivity because the CEAs were fully inserted prior to the trip signal.Therefore, this event had no impact to the health and safety of the public.NRC FOAM 388A I4.96)

NRC FORM 366A I4-9SI LICENSEE EVENT REPORT (LER)TEXT CONTINUATION U.S.NUCLEAR REGULATORY COMMISSIO ST.LUCIE UNIT 1 05000335 YEAR SEQUENTIAL REVISION 98-001-0 4 OF 4 TEXT (If more speceis required, use eddilionel copies of ftVRC Rearm 366A j I17)2.Procedure changes to NOP 1-0030121 and NOP 2-0030121,"Reactor Plant Heatup-Cold to Hot Standby," were initiated to ensure that after the fourth RCP is started, the ZPMB bypass keys remain in bypass until pressure is greater than 1900 psia and no trips are present.i The operator was counseled, and the operator conducted briefings for each operating crew to describe the event in detail, including the seriousness of the event, the use of self checking, and the need for involvement from the operating crew when alarms are received.3.Placards have been placed in the control rooms that require either of the following conditions be met prior to placing the ZPMB keys from bypass to off: a)the reactor TCBS open, or b)the unit at normal operating temperature and pressure.None None NRC FORM 386A I4.95)