L-92-321, Revised Special Rept:On 920630,DG 1A Declared Out of Svc in Order to Perform Preventive Maint on Air Start Sys.On 920701 DG Tripped Due to High Water Jacket Temp.Temp Switch TS-59-003A Replaced W/New Switch
| ML17227A663 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 12/14/1992 |
| From: | Sager D FLORIDA POWER & LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| L-92-321, NUDOCS 9212180119 | |
| Download: ML17227A663 (4) | |
Text
DOCKET 05000335 NOTES:
LET%'N NXRSIX'54P' ACCESSION NBR:9212180119 DOC.DATE: 92/12/14 NOTARIZED: NO FACIL850-335 St. Lucie Plant, Unit 1, Florida Power
& Light Co.
AUTH.NAME AUTHOR AFFILIATION SAGER,D.A.
Florida Power
& Light Co.
RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
SUBJECT:
Revised special rept:on 920630,DG 1 A declared out of svc in order to perform preventive maint on air start sys.On.920701 DG tripped due to high water jacket temp. Temp switch TS-59-003A replaced w/new switch.
DISTRIBUTION CODE:
IE22D COPIES RECEIVED:LTR
( ENCL )
SIZE:
3 TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.
RECIPIENT ID CODE/NAME PD2-2 LA NORRIS P J INTERNAL: ACNW AEOD/DOA AEOD/ROAB/DSP NRR/DLPQ/LHFB10 NRR/DOEA/OEAB NRR/DST/SELB 8D NRR/ ST/S LB8D1 2
REG FI 02 GN2 FILE 01 EXTERNAL: EG&G BRYCEPJ.H NRC PDR NSIC POORE,W.
COPIES LTTR ENCL 1
1 1
1 2
2 1
1 2
2 1
1 1
1 1
1 1
1 1
1 1
1 2
2 1
1 1
1 RECIPIENT ID CODE/NAME PD2-2 PD ACRS AEOD/DSP/TPAB NRR/DET/EMEB 7E NRR/DLPQ/LPEB10 NRR/DREP/PRPB11 NRR/DST/SICB8H3 NRR/DST/SRXB 8E RES/DSIR/EIB L ST LOBBY WARD NSIC MURPHYPG.A NUDOCS FULL TXT COPIES LTTR ENCL 1
1 2
2 1
1 1
1 1
1 2
2 1
1 1
1 1
1 1
1 1
1 1
1 D
D D
NOTE TO ALL"RIDS" RECIPIENTS:
PLEASE IIELP 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 NEED!
D S"
I TOTAL NUMBER OF COPIES REQUIRED:
LTTR 31 ENCL 31
P.O. Box 128, Ft. Pierce, FL 34954-0128 December 14, 1992 L-92-321 10 CFR 50.36 U. S. Nuclear Regulatory Commission Attn:
Document Control Desk Washington, D.
C.
20555 Re:
St. Lucie Unit 1 Docket No. 50-335 Special Report Revision Date of Event:
June 30, 1992 Emer enc Diesel Generator Failure The attached Special. Report aevision is being submitted pursuant to the requirements of St.
Lucie Technical Specifications.
This report provides. notification of one non-valid failure of the 1A Diesel Generator.
The original report submitted under L-92-217 dated July 27,
- 1992, did not contain the current surveillance interval.
Should there be any question on this information, please contact us
~
Very truly yours, 4'.
A.
er Vice r'ident, St.
Lu e Plant DAS/JWH/kw Attachment cc: Stewart D. Ebneter, Regional Administrator, USNRC Region II Senior Resident Inspector, USNRC, St. Lucie Plant DAS/PSL iNF823-92 1700g:.
92121B0119 921214 PDR ADOCK 05000335 S
1A DIESEL GENER T R
TITLE 1A Diesel Generator non-valid failure due to faulty water jacket temperature switches.
PSL Unit ¹1 Event Date: 30 June 1992 II.
PSL Unit ¹1 was at 100% power III.
EVENT SEQU ENCE On June 30, 1992 at 2315, the 1A Diesel Generator was declared out of service in order to perform preventative maintenance on the air start system.
Following successful completion of preventative maintenance, the Diesel Generator was started at 1118 on July 1, 1992.
However, the Diesel tripped at 1200 due to high water jacket temperature.
The Diesel Generator High Water Jacket Temperature Switches, TS-59-002A (1A1 Engine/1 6 Cylinder) and TS-59-003A (1A2 Engine/12 cylinder) are set at 205 Degrees Fahrenheit. Local indication of water jacket temperature however, peaked at 180 Degrees Fahrenheit.
At 1208, a local start was performed for troubleshooting purposes, but the Diesel tripped immediately on high water jacket temperature.
It was determined by local observation of the trip relay flags that the Diesel was tripped in both cases by TS-59-002A.
The Diesel Generator High Water Jacket Temperature switches were both removed to verify their trip setpoints.
It was discovered during inspection that a mounting screw within TS-59-002A had come loose and was subsequently replaced.
Both switches were verified to have the correct trip setpoint of 205 Degrees Fahrenheit and were then reinstalled.
The 1A Diesel Generator was restarted locally at 2136 and loaded to 3400 KW for a one hour surveillance run.
This surveillance run was successfully completed at 2315.
However, there was still reasonable doubt that the Diesel Generator failure was due to the loose mounting screws on TS-59-002A. Thus, the Diesel Generator remained out of service to perform meggering of the trip wiring in order to preclude the existence of any electrical grounds or faults. Allwiring was verified free of grounds and the 1A Diesel was restarted at 1733 on July 2. However, at 1821 the Diesel again tripped on high water jacket temperature.
The operator on the scene verified local water jacket temperature to be 183 Degrees Fahrenheit, well below the required setpoint.
This trip, however, was attributed to TS-59-003A.
At this point, both TS-59-002A and TS-59-003A were removed for inspection.
No observable damage was noted in TS-59-002A, however a new switch was calibrated and installed.
Upon disassembly of TS-59-003A, the setpoint spring nut was found to be loose.
TS-59-003A was subsequently-repaired and the setpoint spring nut was reattached.
The 1A Diesel Generator was restarted on July 3 at 0243 and successfully completed a two hour surveillance run. The 1A Diesel Generator was declared back in service at 0445 on July 3.
IV.
AUSE OF EVENT The cause of the event was equipment failure of the 1A Diesel Generator cooling water jacket temperature switches. This problem was evaluated to be a non-valid failure per Regulatory 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 4.16 KVAC buses.
Additionally, actual water jacket temperature never exceeded 183 Deg F.
Thus, the unsuccessful runs were attributed to spurious operation of a trip that is bypassed in the emergency operating mode.
V.
ORB ECTIVE ACTION
- 1. TS-59-003A was replaced with a new switch.
- 2. TS-59-002A was repaired, recalibrated, and reinstalled.
- 3. The remaining temperature switches on the 1B, 2A and 2B Diesel Generators were determined to be of a different model type than what had failed on the 1A Diesel Generator.
The Unit 2 Diesel Generators and temperature switches are supplied by a vendor different from Unit 1. The 1A Diesel Generator temperature switches are different from the 1B Diesel Generator because the originally supplied temperature switches were obsolete and replaced with a new model during the previous refueling outage.
- 4. This was determined to be the first failure of this model of temperature switch at St. Lucie Plant.
Vl.
UPPORTIN INF MATI N
- 1. The most recent valid failure of the 1A Diesel Generator was on July 5, 1991.
This was the only valid failure in the previous 100 valid tests.
- 2. The 1A Diesel Generator was out of service for approximately 53 1/2 hours
- 3. Based on this non-valid failure, the 1A Diesel Generator surveillance schedule remained at once every 31 days as per plant Technical Specifications.