ML17228A589

Special Rept:On 940504,non-valid Failure of EDG 1A Occurred Due to Spurious Actuation of High Water Jacket Temp Switch (Designated TS-59-003A).Subj Switch Replaced W/New Model 9025G & EDG 1A Declared Back in Svc on 940505

ML17228A589
Person / Time
Site:	Saint Lucie
Issue date:	06/02/1994
From:	Sager D FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-94-136, NUDOCS 9406130069
Download: ML17228A589 (4)

Text

ACCELERATE DOCUMENT DISTRI@3TION SYSTEM REGULATORY INFORMATION DISTRXBUTION SYSTEM (RIDS)

ACCESSION NBR:9406130069 DOC.DATE: 94/06/02 ,NOTARIZED: NO DOCKET FACIL:50-335 St. Lucie Plant, Unit 1, Florida Power & Light Co. 05000335 AUTH. NAME AUTHOR AFFILIATION SAGER,D.A. Florida Power & Light Co.

RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Special rept:on 940504,non-valid failure of EDG 1A occurred D due to spurious actuation of high water jacket temp switch (designated TS-59-003A).Subj swatch replaced w/new model 9025G & EDG 1A declared back in svc on 940505.

DISTRIBUTION CODE: IE22D COPIES RECEIVED:LTR f ENCL SIZE:

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

NOTES:

RECIPIENT COPIES RECXPXENT COPXES D ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-2 PD 1 1 NORRIS,J 1 1 D

INTERNAL: ACRS 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DS P 2 2 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 EG~3 02 1 1 RES/DSIR/EXB 1 1 GN2 FILE 01 1 1 EXTERNAL: EG&G BRYCE,J.H 2 2 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHYiG A ~ 1 1 NSXC POORE,W. 1 1 NUDOCS FULL TXT 1 1 D

D NOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 504-2065) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEEDI TOTAL NUMBER OF COPIES REQUIRED: LTTR 27 ENCL 27

Zune 2, 1994 FPL L-94-136 10 CFR 50.36 U. S. Nuclear Regulatory Ccmnission Attn: Document Control Desk Washington, D. C. 20555 Re: St. Lucie Unit 1 Docket No. 50-335 Special Report Date of Event: 'May 4, 1994 attached Special Report is being submitted pursuant to the The requirements of St. Lucre Technical Specifications. 'his report provides notification of one non-valid failure of the 1A Diesel Generator.

Should there be any question on this information, please contact us.

Very truly yours, D. A. ger Vice r sident St. u 'e Plant DAS/JNH/kw Attachment cc: Stewart D. Ebneter, Regional Administrator, USNRC Region II Senior Resident Inspector, USNRC, St. Lucie Plant DAS/PSL N1132-94 940613006'P 'rr40602 PDR ADOCK 05000335 8 PDR an FPL Group company

NRC SPECIAL REPORT DIE EL GENERAT R NON-VALID FAILURE SPECIAL REPORT I. TITLE 1A Emergency Diesel Generator non-valid failure due to a spurious actuation of a high water jacket temperature switch.

II. INITIALCONDITIONS St. Lucie Unit 1 and Unit 2 were at 100% power.

III. EVENT SEQUENCE On 5/4/94, the 1A Emergency Diesel Generator (EDG) was started to perform a surveillance in accordance with Technical Specifications Table 4.8-1. Surveillance testing of the 1A EDG is required every 31 days. The 1A EDG surveillance began at 1228. The 1A EDG automatically tripped at 1305 on high water jacket temperature.

An operator was recording the EDG parameters at the time of the trip and the water temperatures were below the 205 degrees Fahrenheit design trip setpoint of the temperature switch (designated TS-59-003A). The temperature switch was replaced, the surveillance was successfully performed and the 1A EDG was declared back in service at 0245 on 5/5/94. The 1A EDG was out of service for approximately 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> to replace the temperature switch.

IV. CAUSE OF THE EVENT The 1A EDG tripped due to a non-valid water jacket high temperature caused by a setpoint drift of the temperature switch. At the time of the trip the recorded water temperature was 172 degrees Fahrenheit as read from installed thermometers in the water piping (the accuracy of the thermometers was verified).

NRC SPECIAL REPORT DIE EL ENERATOR NON-VALID FAILURE SPECIAL REPORT V. CORRECTIVE ACTIONS

1) TS-59-003A (model 9025B) was replaced with the new model 9025G temperature switch. The temperature switch manufacturer (Square D) has replaced the model 9025B switch with the 9025G switch because it is less susceptible to setpoint drift and repeatability problems.

2) The 1A Emergency Diesel Generator was dedared back in service at 0245 on 5/5/94 following the successful completion of the surveillance run.

3) The Instrumentation and Control Department performed a detailed inspection and root cause analysis on the temperature switch.

4) Nuclear Plant Work Orders (NPWO's) have been generated to replace temperature switches of this model number (9025B).

Vl. SUPPORTING INFORMATION

- This problem was evaluated to be a non-valid failure per Reg. Guide 1.108 C.2.e.2 because the high water jacket temperature shutdown is overridden during the presence of a Safety Injection Actuation Signal and an undervoltage condition on the safety related 4.16KV AC buses. Additionally, actual water jacket temperature never exceeded 172 degrees Fahrenheit. Thus, the unsuccessful run was attributed to the spurious operation of a trip that is bypassed in the emergency operating mode.

- The 1A EDG was out of service for approximately 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> until the switch replacement could be completed and a successful surveillance test performed

- The surveillance schedule required because of this non-valid failure remains at 31 days. The last valid failure of the 1A EDG was on 7/5/91 and remains the single valid failure since 6/1 2/90 (EDG run counts started at this time when Reg.

Guide 1.108 was implemented into the St. Lucie Unit 1 Technical Specifications).

The current number of valid tests for the 1A EDG is now 56.