ML20168A454
| ML20168A454 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1977-098-00 | |
| Download: ML20168A454 (4) | |
Text
Accession Number: 132927 December 16, 1977
- Both 13.8 kV Buses De-energized at Davis-Besse 1 ailure sequence was:
Immediately following a reactor/turbine trip, the operator opened the main generator breakers and attempted a manual transfer to the two station start-up transformers. The applicable emergency procedure incorrectly called for manually tripping the turbine generator output breaker after trip, which did not allow for auto transfer to the startup transformer.
The diesel generators started and DG 2 supplied power to the Dl bus.
Diesel generator DG 1 tripped on overspeed due to the improper setting of the governor high speed limit switch.
Normal off-site power was returned within 11 seconds on the "B" bus and 25 seconds on the "A" bus.
ctive action-applicable emergency procedure was revised to preclude manual tripping he turbine generator breakers after a turbine trip.
n purpose of failed system or component:
ilability of system per WASH 1400: *Loss of offaite power: 2 x 10-5 /hr ilability of component per WASH 1400: -
Unavailabilities are in units of per demand D-1 . Failure rates are in of per hour HR-1 .
in Hot Reactor Operator Follows Diesel Generator 1 Trip Diesel Generator 2 Starts Normal Offaite Power Potential Inme- Incorrect Procedures and on Overspeed Due to an and Provides Power to Returned on "A" Bus Severe Pol- Manually Opens Main Improperly Set Governor Dl Bus in 25 Seconds and Core Generator.Breakers to High Speed Limit Switch "B" Bus in 11 Damage Turbine Manually Transfer Station Seconds Loads to the Startup Trans former No
[ ~Pose ib le - turbine driven AFW could be utilized if closed motor-operated valves could be man-ually opened C 132927 - Actial Occurrence for Both 13.8 kv Buses De-Energized at Davis-Besse 1
2 3
4 5
6 7
8 9
10 11 12 13 32927 - Sequence of Interest for Both 13.8 kv Buses De-Energized at Davis-Besse 1 ncluded in operating procedures.
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS ESSION NUMtBER: 132927 LER: December 16, 1977 EVENT: November 29, 1977 NVOLVED: Electric Power T INVOLVED: Diesel Generator perator incorrectly attempted manual transfer to startup transformers, ncorrect setting of diesel generator governor high speed limit switch.
OF INTEREST: Loss of off site power CCURRENCE: Operator error induced loss of offaite power with subsequent diesel generator overspeed trip.
AME: Davis-Besse 1 MBER: 50-346 YPE: PWR LECTRICAL RATING: 906 Mwe AGE: .30 yr Babcock & Wilcox. Co.
-ENGINEERS: Bechtel
- Toledo Edison Co.
21 miles east of Toledo, Ohio N/A RATING CONDITION: immediately following trip ATURE TYPE OF FAILURE: (aý inadequate performance; 0()failed to start; Ec~ade ino perable; (d) ____________
METHOD: operational event