ML20168A746
| ML20168A746 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1974-LTR-01 | |
| Download: ML20168A746 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSTC Accession Number:
89252 Date:
February 17, 1974
Title:
Three Related Abnormal Occurrences with Diesel Generator at Zion 2 The failure sequence was:
- 1. Two auxiliary feed pumps were out of service.
- 2. During testing of the diesel generator associated with the operable auxiliary feed pump, the diesel generator tripped on overspeed while starting.
- 3. Once the diesel was started, its output breaker would not close on the associated safety-related bus because of a relay failure.
Corrective action:
- 1. The synchro-speed setter was readjusted to its correct setting, which permitted the diesel to start without tripping out on overspeed.
- 2. A foreign object (screw and two washers) was removed from the failed relay and the relay was returned to service.
Design purpose of failed system or component:
- 1. The diesel generators provide emergency electric power to safety related loads in the event of loss of offsite power.
- 2. The failed relay permits generator output breaker closure once the generator is up to frequency.
Unavailability of system per WASH 1400:
- Emergency Electric Power:
1 x 10-2 /D Unavailability of component per WASH 1400:
- Diesel Generator:
3 x 10-2 /D Relay, failure to energize:
1 X 10" /D Unavailabilities are in units of per demand D-1.
Failure rates are in units of per hour li-1C
Testing with ANW Pumps 2A Diesel Generator 2B Offsite Power Reactor at and 2B Fails to Start and Available 25% Power Inoperable Load Due to Over-speed Trip and Failure of an Output Breaker to Close Potential Severe Core Damage No No -
ANW not required
-No -
ANW not required NSIC 89252 -
Actual Occurrence for Failure of Diesel Generator to Start and Load When Two ANW Pumps Were Out of Service at Zion 2
Loss of Turbine Emer-Auxiliary PORV PORV or High Long Offsite Generator gency Feedwater and Demanded PORV Isola-Pressure Term Power Runs Back Power Secondary tion Valve Injection Core and Assumes Heat Removal Closure Cooling House Loads Potential Severe Core Damage No Sequence No.
2 3
4 5
6 7
8 9
10 11 12 13 NSIC 89252 -
Sequence of Interest for Failure of Diesel Generator to Start and Load When Two AFW Pumps Were Out of Service at Zion 2
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER: 89252 DATE OF LER:
February 27, 1974 DATE OF EVENT:
February 17, 1974 SYSTEM INVOLVED: Emergency electric power and auxiliary feedwater COMPONENT INVOLVED:
Diesel generator, diesel generator output breaker, and AFW pumps CAUSE:
The diesel generator fai4 led to start due to incorrect synchro-speed setting, an output breaker relay failed to close because of a foreign object lodged in SEQUENCE OF INTEREST:
loss of offsite power the relay, and two AFW pumps were ACTUAL OCCURRENCE:
Failure of diesel-generator to start and load when 2 AFW pumps were out-of-service.
REACTOR NAME:
Zion 2 DOCKET NUMBER:
50-304 REACTOR TYPE:
PWR DESIGN ELECTRICAL RATING:
1040 Mwe REACTOR AGE:
.15 yr VENDOR:
Westinghouse ARCHITECT-ENGINEERS:
Sargent & Lundy OPERATORS:
Commonwealth Edison Co.
LOCATION:
40:imiles-north of Chicago, Ill.
DURATION:
6.75 hours8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br /> PLANT OPERATING CONDITION:
25% power SAFETY FEATURE TYPE OF FAILURE:
(a) inadequate performance;(
failed to siart; made inoperable; (d) __________
DISCOVERY METHOD:
during testing COMMENT:
-