ML17228A938

LER 94-008-00:on 941104,inadvertent Cis Caused by Failure of B Instrument Inverter Concurrent W/Channel D Cis in Tripped Condition.Operations Restored Power to B Train Safeguards Instrumentation & Reset CIS.W/941130 Ltr

ML17228A938
Person / Time
Site:	Saint Lucie
Issue date:	11/30/1994
From:	Harmon J, Sager D FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-94-302, LER-94-008, LER-94-8, NUDOCS 9412050215
Download: ML17228A938 (7)

Text

WWJ.MLS.J. X

{ACCELERATED RIDS PROCI'.SSliG) i REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBRe 9412050215 DOC DATE 94/1 1/30 e ~ NOTARIZEDe NO DOCKET FACIL:50-335 St. Lucie Plant, Unit 1, Florida Power & Light Co. 05000335 AUTH. NAME AUTHOR AFFILIATION HARMON,J.W. Florida Power & Light Co.

SAGER,D.A. Florida Power & Light Co.

RECXP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 94-008-00:on 941104,inadvertent. CIS caused by failure of B instrument inverter concurrent w/channel D CIS in tripped condition. Operations restored power to B train Safeguards Instrumentation & reset CIS.W/941130 ltr.

DISTRIBUTION CODE: IE22T COPXES RECEIVED:LTR ENCL SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

NOTES:

RECXPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-2 PD 1 1 NORRIS,J 1 1 INTERNAL: ACRS 1 1 3P'OD/-ROAB/DSP 2 2 AEOD/SPD/RRAB 1 1 fFILE CENTER+ 02 1 1 NRR/DE/EELB 1 1 NRR/DE/EMEB 1 1 NRR/DORS/OEAB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRSS/PRPB 2 2 NRR/DSSA/SPLB 1 1 NRR/DSSA/SRXB 1 1 NRR/PMAS/IRCB-E 1 1 RES/DS IR/EIB 1 1 RGN2 FILE Ol 1 1 EXTERNAL: L ST LOBBY WARD 1 1 LITCO BRYCE,J H 2 2 NOAC MURPHY,G.A 1 1 NOAC POORE,W. 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1 YOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP US TO RFDUCE KVASTE! CONTAC'I THE DOCt:i'lEYTCO<'TROL DESk. ROOWI Pl-37 (EXT. 504. OS3 ) TO F LI NIINATE 5'OI.'R SAXIL F ROTI DISTR IIIU I'IOY. LIS'I'S FOR DOCI.'WIL4'I'S )'OL'OX" I'LI! D!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 27 ENCL 27

Florida Power 8 Light Com, P.O. Box t28, Fort Pierce, FL34954.0128 November 30, 1994 L-94-302 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: 94-008 Date of Event: November 4, 1994 Inadvertent Containment Isolation Signal Caused b Failure of Instrument Inverter The attached Licensee Event Report is being submitted pursuant to the requirements of 10 CFR 50.73 to provide notification of the subject event.

Very truly yours, D. A. ger Vice r sident St. Lucie Plant DAS/msd Attachment cc: Stewart D. Ebneter, Regional Administrator, USNRC Region Senior Resident Inspector, USNRC, St'. Lucie Plant II

/<i'QG 94220~

PDR ADOCK S 05000335 F'DR an FPL Group company

NRC FORH 366 U.S. NUCLEAR REGULATORY COMHISSION APPROVEO BY OHB NO. 3150-0104 (5-92> EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPONSE TO COMPLY WITH I XCENSEE EVZNT REPORT (LER) THIS INFORMATION COLLECTION REQUEST: 5D.O MRS.

FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO TME INFORHATION AND RECORDS MANAGEMENT BRANCH x'.

(HNBB 7714), U.ST NUCLEAR REGULATORY COHMISSION, (See reverse for required number of digits/characters for each block) WASHINGTON, DC 20555-0001 AND TO THE PAPERWORK REDUCTION PROJECT (3140-0104), OFFICE OF HANAGEMENT AND BUDGET WASHINGTON DC 20503.

FACILITY NAHE (1) DOCKET NUMBER (2) PAGE (3)

St. Lucie Unit 1 05000335 1 OF 4 TITLE <4) Inadvertent Containment Xsolation Signal (CXS) caused by failure of the B v rc EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8)

SEQUENTIAL REVI SIOH FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NUMBER HONTH DAY YEAR Unit 2 05000389 04 94 94 --008-- 0 11 30 94 FACILITY NAME N/A DOCKET NUMBER OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREHENTS OF 10 CFR 5: (Check one or more) (11)

MODE (9) 20.402(b) 20.405(c) 50.73(a)(2)(iv) 73.71(b>

POWER 20.405(a)(1)(i) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c)

LEVEL (10) 20.405(a)(1)(ii) 50.36(c)(2) 50.73(a)(2)(vii) OTHER 20.405(a)<1)(iii) 50.73(a)(2)(i) 50.73(a)(2)(viii)(A) (Specify in 20.405(a)(1)(iv) 50.73(a)(2)(ii) 50.73(a)(2)(viii)(B) Abstract and in Text, below 20.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x) NRC Form 366A)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUHBER (Include Area Code)

Zohn N. Harmon, Shift Technical Advisor {407) 465-3550 x3151 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT ('13)

REPORTABLE REPORTABLE CAUSE SYSTEH COMPONENT MANUFACTURER CAUSE SYSTEH COHPONENT MANUFACTURER TO NPRDS TO NPRDS EF XbMWTER S250 RADIATION IL DETECIOR V115 SUPPLEMENTAL REPORT EXPECTED ('I4) EXPECTED MONTH DAY YEAR YES SUBHISSION (If yes, complete EXPECTED SUBHISSION DATE) ~

X NO DATE (15)

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

The D channel of Containment Isolation Signal(CIS) had been placed in trip on 9/12/94 per Technical Specification 3.3.2.1. On 11/4/94 St. Lucie Unit 1 was in Node 6 during a scheduled refueling outage. At 0615 an invalid/inadvertent Engineered Safety Features Actuation Signal (ESFAS) occurred on the CIS.

The B Xnstrument Inverter tripped which deenexgized the B channel of CIS.

The CIS is a deenergize to actuate ESFAS signal. This resulted in two ESFAS channels (MB and MD) being in the tripped state which made up the rectuired two of four logic for a CIS Actuation.

The cause of the event was CIS channel D being in the tripped state during Mode 6 concurrent with failure of the B Instrument Inverter. The root cause of the Instrument Xnverter failure was a failure of the oscillator board.

Corrective actions were: Operations restored power to the B train Safeguards Instxumentation and reset the CIS. Electrical Maintenance and Technical Staff confirmed that the CIS components properly actuated. Cperations placed channel D of CIS in bypass as allowed by the Technical Specifz.cations in Mode

6. EM replaced the oscillator board and returned the Instrument Inverter to sexvice. le replaced the failed channel D radiation detector and returned the radiation detector to sexvice.

NRC FORM 366 ( -92)

HRC FORH 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS.

r ICZmSEE ZVZmr REPORT (LER) FORWARD COMMENTS REGARDING BURDEH ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH TEXT CONTINUATION (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-ODD1 AND TO THE PAPERWORK REDUCTION PROJECT (3140-0104), OFFICE OF MANAGEMENT AND BUDGET WASHINGTON DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

SEQUEHTIAL REVISION YEAR St. Lucie Unit 1 NUMBER NUMBER 05000335 94 --008-- 0 2 OF 4 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

The channel D Containment Isolation Signal (CIS)(EIIS:JM) radiation monitor (EIIS:IL) was inoperable and awaiting parts for repair due to a radiation detector failure. Therefore, the channel D radiate.on detection portion of CIS had been placed in trip on 9/12/94 per Technical Specification 3.3.2.1.

On 11/4/94, St. Lucie Unit 1 was in Node 6 during a scheduled refueling outage. At 061S an invalid/inadvertent Engineered Safety Features Actuation (ESFAS)(EXIS:JE) occurred on the CXS. The CIS is a deenergize to actuate ESFAS signal. The B Instrument Inverter (EIXS:EF) tripped which deenerqized the B channel of CXS. This resulted in two channels (MB and MD) being 3.n the tripped state which made up the required two of four logic for a CIS Actuation.

The CIS components actuated as required. To reset the CXS, the Instrument Inverter had to be reenergized. The Operations crew reenergized the B Instrument Inverter utilizing the Maintenance Bypass bus then CIS channel B was reset. The 1B Emergency Diesel Generator (EDG)(EIIS:EK) was secured at 0642. Both Unit 1 and Unit 2 Control Room Ventilation (EIIS:VI) systems went on recirculation as required.

It was initially reported that the 1B EDG had started after restoration of power to the B Instrument Inverter. Review of the Emergency Response Data Acquisition Display (ERDAD) Computer showed that the 1B EDG had m fact started as required on the CIS signal. Additionally the conditions of the event were recreated and it was confirmed that the CIS components actuated properly. A contributing factor to this reporting error is that the EDG start is not captured on the sequence of events recorder (only the EDG output breaker position is recorded) . Since offsite power was unaffected by this event, by design, the EDG output breaker did not close.

The cause of the event was CIS channel D being in the tripped state during Mode 6 concurrent with failure of the B Instrument Inverter. The root cause of the Instrument Inverter failure was the failure of the oscillator board.

The root cause of the 9/12/94 CIS channel D radiation detector failure is undetermined at this time. The CIS radiation channel had been in the tripped condition due to unavailability of replacement parts for the radiation detector.

NRC- FORM 66A (5-92)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEH PER RESPONSE TO COMPLY WITH THIS IHFORMATION COLLECTION REQUEST: 50.0 HRS.

FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO LXCENSZZ ZVENT REPORT (LZR) THE INFORMATION AHD RECORDS MANAGEMENT BRANCH TEXT CONTlNUATlON (MNBB 7714) i U S NUCLEAR REGULATORY COMMI SSION i WASHIHGTON, DC 20555-0001 AND TO THE PAPERWORK REDUCTION PROJECT (3'150-0104), OFFICE OF MANAGEMEHT AHD BUDGET WASHIHGTON OC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

SEQUENTIAL REVISION St. Lucie Unit 1 YEAR NUMBER NUMBER 05000335 94 --008-- 3OF4 TEXT (If more space is required, use additional copies of HRC Form 366A) (17)

This event is reportable as an actuation of the Engineered Safety Features (ESFAS) under 10CFR50.73 (a) (2) (iv) . The A and B train CIS components actuated to their proper CIS position. The plant was in Mode 6 during a refueling outage with both the B train High Pressure Safety Injection pump and B train charging pump capable of taking suction from the Refuelinq Water Tank for Reactor Coolant makeup. Reactor Coolant makeup was not required as a result of this event. The CIS actuation did not interrupt shutdown cooling. Therefore, the health and safety of the public were not affected.

1) Operations placed the B Instrument Inverter on the maintenance bypass bus and restored power to the B train instrumentation.

2) Operations reset the CIS.

3) Electrical Maintenance and Technical Staff confirmed that the CIS components properly actuated.

4) Operations placed the CIS radiation channel D in bypass, as allowed by the Technical Specifications in mode 6.

5) Operations will revise OP 1-0030127 "Reactor Plant Cooldown - Hot Standby to Cold Shutdown" to include a step to place any CIS channel in the tripped condition into Bypass after entry into Mode 6.

6) Electrical Maintenance determined that a failed oscillator board was the root cause for the Instrument Inverter failure. EM replaced the oscillator board and returned the Instrument Inverter to service.

7) Instrument and Control replaced the failed CIS channel D radiation detector and ratemeter.

8) Operations will revise Administrative Procedure 00110120 "Conduct of Operations" to require the performance of the applicable Emergency Operating Procedure (EOP) 99 table to verify proper actuation of all ESFAS components during a spurious invalid actuation prior to restoration.

NRC FORM 366A (5 92)

NRC FORH 366A U.S. NUCLEAR REGULATORY COHHISSION APPROVED BY OHB NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORHATION COLLECTION REQUEST: 50.0 HRS.

FORWARD COMMENTS REGARDING BURDEH ESTIMATE TO LICENSEE EVENT REPORT {LER) THE INFORMATION AND RECORDS MANAGEHENT BRANCH TEXT CONTINUATION (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001 AND TO THE PAPERWORi(

REDUCTION PROJECT (3150-0104), OFFICE OF MANAGEMENT AND BUDGET WASHINGTON DC 20503.

FACILITY NAME (1) DOCKET NUHBER (2) LER NUMBER (6) PAGE (3)

SEQUENTIAL REVISION YEAR St. Lucie Unit 1 NUHBER NUMBER 4OF4 05000335 --OOS-- 0 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

Instrument Inverter Oscillator board Manufacturer: Solid State Controls Model: SV12075/TS750NB-A/TS750MB Radiation detector and ratemeter Manufacturer: Uictoreen Inc Model: 857-3 IZR 335-90-004 "Inadvertent Partial Actuation of "A" train Containment Isolation and Containment Spray Systems due to equipment malfunction" LER 335-90-003 "Spurious Containment Isolation Signal resulting from Radiation monitor spikes due to external Grid disturbance" LER 389-84-009 "Inadvertent Containment Isolation Signal"