ML20168A469
| ML20168A469 | |
| Person / Time | |
|---|---|
| Site: | FitzPatrick  |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1975-024-00 | |
| Download: ML20168A469 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
100415 Date: March 5, 1975
Title:
All Drywell High Pressure Switches Found Isolated at Fitzpatrick The failure sequence was:
During routine surveillance testing,.an instrumentation technician discovered the rack isolation valves for drywell high pressure instruments in both trains closed.
Further investigation revealed the associated root valves at the drywell penetrations were also closed.
It is presumed the valves were left closed since August 1974 when the valves were supposed to be reopened following the completion of surveillance testing.
Corrective action:
- 1. The valves were immediately opened and locked to prevent reoccurrence of this event.
- 2. The root valves and other isolation valves are being added to appropriate operational and maintenance check lists.
Design purpose of failed system or component:
The high drywell pressure switches send initiation on signals to the RPS & ECOS Initiation Systems, Unavailability of system per WASH 1400:*-
Unavailability of component per WASH 1400:*
3 x 10- 3 /D general human error Unavailabilities are in units of per demand D-1.
Failure rates are in units of per hour HR'1
Plant operating at steady state power Routine surveillance testing underway Tech, discovers all drywell high pressure switches valved out JPoten Severe Core Damage 1
No No -
system not demanded; reactor water level switches operable A 0 system not demanded; reactor water level switches operable NSIC 100415 -
Actual Occurrence of All High Pressure Switches Found Isolated at FitzPatrick
Loss of Reactor RCIC/HPCI Automatic LPCI or Ln Feedwater Subcritical
Response
Depressurization CS Response Tr F-low Adequate System Operates Adequate Cr Potential Severe Core Damage Sequence No.
No 1
Yes 2
No Yes Yes Yes Yes 3
4 5
7 NSIC 100415 -
Sequence of Interest for All Drywell Pressure Switches Found Isolated at Fitzpatrick
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER: 100415 DATE OF LER:
March 5, 1975 DATE OF EVENT:
February 25, 1975 SYSTEM INVOLVED: reactor protection, emergency core cooling system COMPONENT INVOLVED: drywell high pressure switch CAUSE:
human error SEQUENCE OF INTEREST:
loss of feedwater ACTUAL OCCURRENCE:
all drywell high pressure switches found isolated at Fitzpatrick REACTOR NAME:
Fitzpatrick DOCKET NUMBER:
50-333 REACTOR TYPE:
BWR DESIGN ELECTRICAL RATING:
821 NWe REACTOR AGE:
.3 yr VENDOR:
General Electric ARCHITECT-ENGINEERS:
Stone & Webster OPERATORS:
Power Authority of the state of New York LOCATION: 8 miles NE of Oswego, NY DURATION:
5110 hours0.0591 days <br />1.419 hours <br />0.00845 weeks <br />0.00194 months <br /> PLA~NT OPERATING CONDITION: steady state operating conditions SAFETY FEATURE TYPE OF FAILURE:
(a) inadequate performance; (b) failed to start; 1-0)ade inoperable; (d) _____________
DISCOVERY METHOD:
surveillance testing COMMENT:
The switches were inoperable for more than 6 months.