ML20168A739
| ML20168A739 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1973-005-00 | |
| Download: ML20168A739 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
82198 Date:
July 13, 1973
Title:
Failure to Transfer Auxiliary Power to Startup Transformer at Turkey Point 3 The failure sequence was:
- 1. With the reactor at 87% power, calibration of steam line pressure transmitters was in progress.
- 2. Inadvertant safety-injection resulted from coincident trips of two channels of No. 3C steam line high differential pressure.
(One channel was in test and another channel received a transient signal to trip.)
- 3. Following initiation, the reactor tripped and all safety features operated satisfactorily.
- 4. Automatic transfer from the auxiliary transformer to the startup transformer did not occur due to an unconnected wire in the automatic transfer circuitry.
- 5. The operator manually closed the startup transformer breakers to the safety-related buses.
Corrective action:
- 1. The unconnected wire in the automatic transfer circuitry was properly connected and the completed circuit was tested.
Design purpose of failed system or component:
The failed circuit provided for automatic transfer of the safety-related buses to the offsite power source in the event of a loss of power from the unit generator.
Unavailability of system per WASH 1400:
- offaite power:
10 3/D following trip Unavailability of component per WASH 1400:
- Unavailabilities are in units of per demand D-1.
Failure rates are in units of per hour HR-1.
Reactor at 87%
Inadvertent Reactor trip, Failure to transfer Diesel generators power and cali-safeguards turbine trip safety-related loads start and assume bration of steam initiation from auxiliary safety-related line pressure during testing transformer to loads transmitters in startup transformer progress Pol Se~
Coi Dat No I
No
-No ten tial 7ere re nage turbine driven AFW pumps available -
may require manual opening of motor operated valves NSIC 82198 -
Actual Occurrence for Failure to Transfer Auxiliary Power to Startup Transformers at Turkey Point 3
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 Sequence No.
2 3
4 5
6 7
8 9
10 11 12 13 NSIC 82198 -
Sequence of Interest for Failure to Transfer Auxiliary Power to Startup Transformers (effective loss of offsite power)
- Success-requires manual-transfer to-the--startup-transformer.
"*Not included in mitigation procedures.
at Turkey Point 3
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER:
82198 DATE OF LER:
July 13, 1973 DATE OF EVENT:
July 4, 1973 SYSTEM INVOLVED:
plant electrical system COMPONENT INVOLVED:
auxiliary to startup transformer transfer circuitry CAUSE:
unconnected wire SEQUENCE OF INTEREST:
loss of offsite power ACTUAL OCCURRENCE:
imadvertant reactor and turbine trip and safeguards initiation during testing REACTOR NAME:
Turkey Point 3 DOCKET NUMBER:
50-250 REACTOR TYPE:
PWR DESIGN ELECTRICAL RATING:
693 MWe REACTOR AGE:
.7 yr VENDOR:
Westinghouse ARCHITECT-ENGINEERS:
Bechtel OPERATORS:
Florida Power and Light Company LOCATION:
25 mi. south of Miami, Florida DURATION:
N/A PLANT OPERATING CONDITION:
87% power SAFETY FEATURE TYPE OF FAILURE:
(a) inadequate performance; (b) failed to start; (c) made inoperable; (9 fa11le to trnngfpr DISCOVERY METHOD:
operational event COMMENT:
--