ML17227A588

LER 92-006-00:on 920810,manual Reactor Trip Occurred Due to Fire in 2C Condensate Pump Motor Electrical Lead Box.Caused by Procedural Deficiency.Fire Extinguished & Unit Stabilized in Mode 3.W/920904 Ltr

ML17227A588
Person / Time
Site:	Saint Lucie
Issue date:	09/10/1992
From:	Sager D, Wachtel P FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-92-252, LER-92-006-01, LER-92-6-1, NUDOCS 9209150402
Download: ML17227A588 (7)

Text

ACCELERATED DTRIBUTION DEMON'RATION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEN (R IDS)

ACCESSION NBR: 9209150402 DQC. DATE: 9'2/09/10 NOTARIZED: NO DOCKET 0 FACIL: 50-389 St. Lucie Plant> Unit 2> Florida Poeer 5 Light Co.- 05000389 AUTH. NAME AUTHOR AFF ILI ATION WACHTEL> P. K. Florida Power 5 Light Co.

SAGERi D. A. Florida Power h Light Co.

R EC IP. NAME RECIPIENT AFF ILIAT ION

SUBJECT:

LER 92-006-00: on 920810> manual reactor trip occurred due to fire in 2C condensate pump motor electr ical lead box. Caused bg procedural deficiency. Fir e extinguished 8c unit stabilized in Mode 3. W/920904 ltr.

DX STR I BUT ION CODE: I E22T CQP I ES RECEIVED: LTR l ENCL SI ZE:

TITLE: 50. 73/50. 9 Licensee Event Rcport (LER) i Incident Rpti etc.

NOTES:

REC IP XENT COPIES RECIPIENT COP I ES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-2 LA PD2-2 PD NORRIS> J 1,1 1 1 INTERNAL'CNW 2 2 ACRS 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEQD/ROAB/DSP 2 2 NRR/DET/EMEB 7E 1 '

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PLEASE HE' US TO REDUCE V'ASTE! CONTACT THE DOCUMENT CO)NTROL DESK.

ROOM PI-S i {EXT. 504-20(5) TO ELliMINATEYOUR iNAME FROiM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT-CONVERSXON REGUIRED TOTAL NUMBER 'OF. COP XES REQUIRED: LTTR 31 -

ENCL 31

P.O. Pcs 12k, FI, Piorcc, FL 3R95R-0128 September 4, 1992 L-92-252 10 CFR 50.73 U. S. Nuclear Regulatory. Commission Attn: Document Control Desk Washington, D. C. 20555 Re: St. Lucie Unit 2 Docket No. 50-389 Reportable Event: 92-006 Date of Event: August 10, 1992 Manual Reactor Trip Due to a Fire in the 2C Condensate Pump Motor Electrical Lead Box Caused b Procedural Deficienc 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.

Vice L 'l ger r sident DAS/JWH/kw Attachment cc: Stewart D. Ebneter, Regional Administrator, USNRC Region II Senior Resident Inspector, USNRC, St. Lucie Plant DAS/PSL 75773-92 j4Ul.li:..8 5'2091 50402 9~09<4 PDR ADOCK 05005389 PDR an FpI. Gt>>p <<n'p .n~

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LICENSEE EVENT REPORT (LER) ISCSSST:504 IITS fCNIAAITI~NTSINONTNNO55405CN CSTTNATS lOTIO lf INOCSOS 1005 ISSONTS TWIT NCNT 505ANCN 400A 15$ , NOCIC Nl IS CMJLTTSTT 50MSSNCIC WANNNOTOI.OO50%5, N05 TO TNS ffPCNWOIN ISOVCTCSI fNON Cl 01 50050AC CffICC Of IIANACSISNTAIO OAICCT IIASINOtOK OC IONIA FACILITYNAME (1) DOCKET NUMBER (2) PAGE 3 St. Lucie Unit 2 050003891 0 4

'~ (4) Manual Reactor Trip Due to a Fire in the 2C Condensate Pump Motor Electrical Lead Box Caused by Procedural Deficiency EVENT DATE (5) , LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8)

AL R FACILITYNAMES DOCKET NUMBER(S)

DAY YEAR YEAR S DAY YEAR N/A 0 8 109292 0 0 6 0 0 0 9 1 0 9 2 N/A 05000 THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR:

OPERATING Check one or more of the followin (11)

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

POWER 20 405(a)(1)(l) 50.73(a)(2)(v) 73.71(c)

LEVEL 50.36(c)(1)

(10),0 7 3 20.405(a)(1 )(ii) 50.36(c)(2) 50.73(a)(2)(vii) OTHER (Specify in Abstract 20.405(a)(1 )(iii) 50.73(a)(2)(i) 50.73(a)(2)(viii)(A) below and in Text 20.405(a)(1)(iv) 50.73(a)(2)(viii)(B) NRC Form 366A) 50.73(a)(2)(ii) 20.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x)

LICENSEE CONTACT FOR THIS LER 12 NAME TELEP ONE NUMBER AREA CODE Patricia K. Wachtel, Shift Technical Advisor 465 -3550 4 0 7 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 13 MANUFAC- REPORTABLE MANUFAC- REPORTABLE CAUSF SYSTEM COMPONENT TURER TO NPRDS CAUSE SYSTEM COMPONENT IURER TO NPRDS I I I SUPPLEMENTAL REPORT EXPECTED 14 EXPECTED MONTH DAY YEAR SUBMISSION YES (ifyes, complete EXPECTED SUBMISSION DATE) X NO DATE (15)

ABSTRACT (Limit to 1400 spaces.i.e. approximately fifteen single-space typewritten lines) (1 6)

Qn August 10, 1992, St. Lucie Unit 2 was in Mode 1, operating at 73% power. At 2023 hours0.0234 days <br />0.562 hours <br />0.00334 weeks <br />7.697515e-4 months <br />, a non-licensed utility operator reported to the control room that there was a fire in the 2C Condensate Pump motor electrical lead box. The fire team was dispatched to extinguish the fire and the reactor was manually tripped at the direction of the Assistant Nuclear Plant Supervisor. were performed, all safety functions were met, and the unit was stabilized in Mode 3, Hot Standby.

The fire in the 2C Condensate Pump motor electrical lead box was the result of one of the energized motor leads becoming disconnected from its feeder cable. The cause of the motor lead becoming disconnected was due to the lead having beenbent at a sharp angle where it entered the barrel of the lug, a situation that was created due to the short length of the motor leads. The root cause of this event has been attributed to lack of procedural guidance on minimum bend requirements for cable routing and terminations.

Corrective actions taken as a result of this event include: extinguishing the fire and stabilizing the unit in Mode 3, inspecting the motor leads on the 2A and 2B Condensate Pumps to ensure proper installation, revising Electrical maintenance and non-utility contractor procedures to discuss the minimum bend requirements, and the Training Deparlment will review this event for use in maintenance staff training.

/

FPL Facsimile of NRC Form 366 (6-89)

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YEAR EQUENTIAL REVISIO St. Lucie Unit 2 NUMBER NUMBER 0500038992 0 0 6 0 0 0 2 0 4 TEXT (ffmore space'is required, use additional NRC Form 366A's) (17)

On August 10, 1992, St. Lucie Unit 2 was in Mode 1 and operating at 73% power to facilitate repairs to the 282 intake water traveling screen. At 2022 hours0.0234 days <br />0.562 hours <br />0.00334 weeks <br />7.69371e-4 months <br />, the control room received the 'A'4.16 KV auxiliary transformer (EIIS:EA) ground annunciator. The Auxiliary Transformer-Off Normal Operation procedure was entered and the Nuclear Watch Engineer (NWE) was dispatched to investigate the ground. At 2023, a non-licensed utility operator reported to the control room that there was a fire in the 2C Condensate Pump (EIIS:SD) motor electrical lead box and that the pump should be secured.

The fire team, along with the NWE, was sent to the condensate pit. The Assistant Nuclear Plant ~

Supervisor directed the licensed-utility operators to manually trip the reactor and turbine and secure the 2A Main Feedwater Pump (EIIS:SJ) and the 2C Condensate Pump. Emergency Operating Procedure (EOP)-1, was performed and all safety functions were met.

The trip was an uncomplicated reactor trip with all safety functions being met. During the post trip recovery, Auxiliary Feedwater Actuation Signals-1 and 2 (AFAS) (EIIS:BA) occurred normally on both the 2A and 28 Steam Generators (EIIS:AB) after level decreased in each generator to the AFAS setpoint. The three Auxiliary Feedwater Pumps (EIIS:BA) auto-initiated and supplied water to each steam generator until main feedwater was restored. EOP-2, -

was completed with two sets of satisfactory safety function status checks, AFAS was reset, and the unit was stabilized in Mode 3, Hot Standby.

The fire in the 2C Condensate Pump motor electrical lead box was caused by a motor lead which had become disconnected from its feeder cable. The resulting arcing and high currents caused the fire and burnt two holes in the termination box cover. The cause of the motor lead becoming disconnected has been attributed to the lead having been bent at a sharp angle where it entered the barrel of the lug. The as-found connections on the two remaining motor leads resembled ninety degree terminations with the motor lead cable making the ninety degree angle with the barrel of the lug. The combination of thermal cycling, resonant motor vibration, cable tensioning, and the bending of the cable provided sufficient stress to cause the motor lead to fail, thereby disconnecting the motor lead. The three motor leads on the 2C Condensate Pump motor were found to be shorter than the leads on the 2A Condensate Pump and the desired straight in-line connection with the appropriate feeder cables could not be obtained. Additionally, the connection configuration on the 2A Condensate Pump motor used a 'bus'echnique to connect the motor and feeder cables, which minimized the cable bending requirements. The 28 Condensate Pump motor was inspected and found to be configured similar to the 2C pump motor. The terminations on the 28 pump motor were reterminated to a connection configuration similar to that on the 2A Condensate Pump motor.

A review of utility and non-utility maintenance procedures indicated there was no guidance for the minimum requirements for cable routing and terminations for motor leads. Therefore, the root cause FPL Facsimile of NRC Form 366 (6-89)

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FPL Fscslmrs or U.S. NUCLEAR REGULATORY COMMrSSION AfflKNto0SNIAT,SINAIII NRC Form 366 t efetN loee I (689)

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FACILITYNAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

EQUENTIAL REVISIO NUMBER NUMBER St. Lucie Unit 2 0 500 0389 9 2 0 0 6 0 0 0 3 0 4 TEXT (I/more spaceis reriuired, use additional NRC Form 366A's) (17) of this event has been attributed to inadequate procedural guidance on minimum bend requirements for cable routing and terminations. The 2C Condensate Pump motor leads were last reassembled by non-utility contractor personnel with utility maintenance supervision during the Spring, 1992 refueling outage.

This event is reportable to the NRC under 10CFR50.73(a)(2)(iv) as any event or condition. that results in a manual or automatic actuation of any engineered safety feature, including the reactor protection system. The Assistant Nuclear-Plant Supervisor directed the licensed-utility operators to manually trip the reactor and turbine to prevent further damage to plant equipment. The trip was an uncomplicated reactor trip, the plant response was observed to be normal for the given conditions, and all systems functioned as designed, with the exception of the 2C Condensate Pump.

The plant response to this event is bounded by Section 15.2.5.1.1 of the St. Lucie Unit 2 FUSAR which assumes a loss of feedwater by means of a feedwater pipe rupture. The actual plant response was more conservative than described in the analysis for the following reasons:

1. The plant was not at full power when the event occurred.

2. Auxiliary feedwater flow was initiated by the AFAS signal in approximately 210 seconds as opposed to the 420 seconds considered in the accident analysis.

3. Neither steam generator had water level go below 53% wide range. Therefore, the capability of the steam generators to act as a primary heat sink was not in jeopardy.

4. The reactor trip was manually initiated prior to exceeding any protective setpoints.

5. A redundant train of main feedwater was available to supply both Steam Generators.

This event was replicated on the St. Lucie Plant simulator by the Training Department. The Technical Staff compared the data from the simulator with the transient data obtained during the reactor trip. No unexpected differences were noted during the review.

The fire was confined to the 2C Condensate Pump motor lead box and did not pose a danger to any other plant equipment. Therefore, the health and safety of the public were not endangered at any time during this event.

1. Operations personnel extinguished the fire in the 2C Condensate Pump motor electrical lead box and stabilized the unit in Mode 3, Hot Standby.

2. The motor leads on the 2A and 28 Condensate Pumps'lectrical motor lead boxes were inspected to ensure proper installation. The 28 pump motor terminations were reterminated using a 'bus'echnique connection configuration.

FPL Facsimile of NRC Form 366 (6-69)

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'EAR EQUENTIAL REVISIO St. Lucie Unit 2 NUMBER NUMBER 0 5 0 0 03 89 9 2 0 0 6 0 0 0 4 0 4 tEXT (Ifmore space is required, use additional NRC Form 366A's) (17)

3. Utility and non-utility maintenance procedures will be revised to address the minimum bend requirements. This will'ensure that all motor leads on both Unit 1 and Unit 2 will be inspected for minimum bend requirements during normal maintenance overhauls.

4. Protection and Controls personnel verified the proper operation of protective relays for the 2C Condensate Pump motor.

5. Transmission and Distribution personnel inspected the 2A 41 60 VAC transformer which supplied power to the 2C Condensate Pump. The inspection revealed the transformer was free of damage from this event.

6. The 2C Condensate Pump motor has been refurbished and provided with longer motor leads.

7. The Training Department will evaluate this event for use in maintenance staff training.

No component or material failures were the direct cause of this event.

This is the first event in which a Condensate Pump motor fire resulted in a reactor trip.

FPL Facsimile of NRC Form 366 (6-89)