ML20168A567
| ML20168A567 | |
| Person / Time | |
|---|---|
| Site: | University of Utah |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1972-014-00 | |
| Download: ML20168A567 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
75074 Date:
August 17, 1972
Title:
Loss of Load and Iodine Release at La Crosse The failure sequence was:
- 1. One of the two paralleled 69/161 kv transformers in the switch yard adjacent to the plant was taken out of service to repair an oil leak.
- 2. Upon completion of the repairs oil was being added to the transformer at a rate which caused operation of the "sudden pressure relay".
This relay had not been disabled prior to repair as specified in the proceedures.
- 3. The relay protecting the turbine generator also tripped for unknown reasons.
- 4. House loads were transferred from the unit auxillary to the reserve trans-former resulting in a complete loss of generator load.
- 5. The diesel generator started and assumed safety related loads.
Corrective actiun:
Maintenance personnel were instructed on the function of the "Sudden pressure" relay function and details were incorporated into the transformer maintenance proceedures to prevent inadvertant operations of protective devices.
Design purpose of failed system or component:
Offsite power provides power to house loads when the generator is down.
Unavailability of system per WASH 1400:
LOOP:
2 x lO-5 /hr 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
Maintenance Was Being The Operator Failed To The Turbine Generator The Diesel Started And Performed On An Oil Disable The Sudden Relay Tripped For Un-Assumed Safety Loads Thercwitcyr Breaker TnPes rippeda Asd The knwRess Circuwitcyr Breaker TnPes repRela Asd THe knwRess Added Oil Resulting IInALOOP_______________________
Potential Severe Core Damage No No, offsite power was restored within 20 minutes, IC 'is sufficient No No NSIC 75074 -
Actual Occurrence of Loss of Load and Iodine Release at LaCrosse
LOss of Reactor Diesel Reactor Made Sub-RCIC/UPCI ADS/LPC-I Long Ptnil Sqec Offsite Scram Start and critical by the Initiates CS Term Severe No.
Manually Driven In lCooling Damage No1 Yes2 No 3
Yes 4
Yes 5
N G 6
Yes 7
Yes 8
No 9
Yes 100 No 11 Y es 12 Yes 13 Yes 14 Yu+/-s 15 NSIC 75074 -
Sequence of Interest for Loss of Load and Iodine Release at LaCrosse
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMf3ER:
75074 DATE OF LER:
September 13, 1972 DATE OF EVENT: August 17, 1972 SYSTEM INVOLVED:
Offsite power COMPONENT INVOLVED:
Relays CAUSE: Operator Error SEQUENCE OF INTEREST:
Loss of Offsite Power ACTUAL OCCURRENCE:
Loss of Load and Iodine Release REACTOR NAME:
La Crosse DOCKET NUMfBER:
407 REACTOR TYPE:
BWR DESIGN ELECTRICAL RATING:
50 MWe REACTOR AGE:
5.1 yr VENDOR: Allis Chalmers ARCHITECT-ENGINEERS:
Sargent and Lundy OPERATORS:
Dairyland Power Corporation LOCATION:
19 miles S of La Crosse.
DURATION:
N/A PLANT OPERATING CONDITION: Just scrammed from power SAFETY FEATURE TYPE OF FAILURE:
(a) inadequate perfo ce; (b) failed to start; (c) made inoperableo; 0,d init-intng Pvpnt DISCOVERY METHOD: Operational Event COMMENT: