ML17228A852

Special Rept:On 940823 & 25,RAB Exhaust Sys WRGM RM-26-90 Declared Out of Svc.Caused by Intermittment Communication Due to Power Supply Regulator Failure.Chemistry Procedure C-93 Implemented & Portable Monitor Installed

ML17228A852
Person / Time
Site:	Saint Lucie
Issue date:	09/09/1994
From:	Sager D FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-94-232, NUDOCS 9409210165
Download: ML17228A852 (3)

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REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9409210165 DOC.DATE: 94/09/09 NOTARIZED- NO DOCKET FACIL:50-389 St. Lucie Plant, Unit 2, Florida Power & Light Co. 05000389 AUTH. NAME AUTHOR AFFILIATION SAGER,D.A. Florida Power & Light Co. P RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Special rept:on 940823 & 25,RAB exhaust sys WRGM RM-26-90 declared out of svc.Caused by intermittment communication due to power supply regulator failure. Chemistry Procedure C-93 implemented & portable monitor installed.

DISTRIBUTION CODE: IE22D COPIES RECEIVED:LTR ENCL SIZE:

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

NOTES RECIPIENT 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 AEOD/ROAB/,DS P 2 2 AEOD/SPD/RRAB 1 1 ILE CENTER 0~2 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/DSIR/EIB 1 1 RGN2 FILE 01 1 1 EXTERNAL: EG&G BRYCE,J.H

=D 2 2 L ST LOBBY WARD 1 1 NOAC MURPHY,G.A 1 1 NOAC POORE,W. 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1 U

NOTE TO ALL"RIDS" RECIPI EYTS:

PLEASE HELP US TO REDUCE 'O'ASTE! COYTACTTHE DOCl'ifEiTCOiTROL DESK, ROOXf PI-37 (EXT. 504-2083 ) TO ELIXIINATEYOUR i'AifE PROif DISTRIBUTION LIS I S I'OR DOCL'NfEi'I'S YOU DOi "I'I,"I'.D!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 27 ENCL 27

P.O. Box 128, Fl. Pierce, FL 34954 0128 September 9, 1994 L-94-232 10 CFR 50.4 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Gentlemen:

Re: St. Lucie Unit 2 Docket No. 50-389 Special Report Date of Event: August 23, 1994 Reactor Auxiliar Buildin Exhaust S stem Wide Ran e Gas Monitor Out of Service for Greater than 72 Hours The attached Special Report is being submitted pursuant to the requirements of St. Lucie Technical Specifications 3.3.3.1. and 6.9.2. This report provides notification of the failure of the Reactor Auxiliary Building Exhaust System Wide Range Gas Monitor (WRGM).

Very truly yours, n C D. A. Sager Vice President St. Lucie Plant DAS/JWH/kw cc: Stewart D. Ebneter, Regional Administrator, Region Senior Resident Inspector, USNRC, St. Lucie Plant II, USNRC DAS/PSL 81200-94 q4Qc/OP 0'-~ O5OOO~8" qZO92 QQQCK PDt PQI an FPL Group campanv

SPECIAL REPORT TITLE Reactor Auxiliary Building Exhaust System Wide Range Gas Monitor out of service for greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

INITIALCONDITIONS St. Lucie Unit 2 was at.100% power.

EVENT SEQUENCE On August 23, 1994, at 2107 hours0.0244 days <br />0.585 hours <br />0.00348 weeks <br />8.017135e-4 months <br />, the Reactor Auxiliary Building Exhaust System Wide Range Gas Monitor (WRGM), RM-26-90, was declared out of service due to loss of communication. The WRGM is comprised of three detectors which monitor radioactive gases from normal operating levels up to calculated accident concentrations. Utility Instrument &, Control (I&C) technicians found that the communication failure was intermittent. The suspect components that could have caused the failure were replaced. A system functional check was performed, and the system was declared back in service on August 24 at 1425 hours0.0165 days <br />0.396 hours <br />0.00236 weeks <br />5.422125e-4 months <br />. On August 25, the WRGM failed again due to loss of communication and was declared out of service. On August 2S, as per the Technical Specification 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Limiting Condition of Operation, a plant approved alternate sampling method was installed to, provide monitoring of the effluent flow stream.

CAUSE OF THE EVENT Suspect WRGM components were replaced. Subsequent troubleshooting determined the root cause for the intermittent communication was most likely due to a power supply regulator failure.

CORRECTIVE ACTIONS

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1) The plant approved alternate sampling method, Chemistry Procedure C-93, was implem'ented. The "A" Emergency Core Cooling System WRGM's middle and high range gas channels were connected to the Reactor Auxiliary Building Exhaust System flow stream to provide monitoring capabilities.

2) Subsequently, a portable monitor was installed to provide dedicated monitoring of the Reactor Auxiliary Building Exhaust System flow stream.

3) The portable monitor will remain in operation until the Reactor Auxiliary Building Exhaust System WRGM's reliability has been verified. The Reactor Auxiliary Building Exhaust System WRGM will be returned to service before October 1, 1994.

4) A representative from the monitoring system's manufacturer was brought onsite to provide plant maintenance personnel with technical assistance.

5) The suspect power supply is being sent to an independent facility to have a root cause failure analysis performed.