ML20168A471
| ML20168A471 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1978-045-00 | |
| Download: ML20168A471 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
145209 Date-December 20, 1978
Title:
Both Power Operated Relief Valves (PORVs) Open During Troubleshooting at Fort Calhoun 1 The failure sequence was:
- 1. During a heatup from cold shutdown, one of the two PORV channels failed to respond to system pressure changes.
- 2. A technician, while troubleshooting the problem, pulled recorder fuses.
- 3. This caused both PORVs to open.
- 4. The operator closed both PORV isolation valves.
Corrective action:
- 1. Since the PORVs were being used for NDT overpressure protection, additional administrative controls were established to ensure an overpressure condition could not occur.
- 2. System modifications to prevent reoccurrence were being considered.
Design purpose of failed system or component:
- 1. During normal operation, the PORVs provide relief protection for the RCS and prevent lifting the pressurizer safety valves during pressure transients.
Unavailability of system per WASH 1400:*
Unavailability of component per WASH 1400:
relief valve, imadvertant opening:
1 x 105'/hr Unavailabilities are in units of per demand D-.
Failure rates are in units of per hour HR-1.
Reactor Heating PORV Pressure Technician Pulls Both PORVs Fail Operator Closes Up from Cold Channel Fails Recorder Fuses Open Due to Both PORV Shutdown to Respond During Trouble-Pulled Recorder Isolation Valves shooting of PORV Fuses Pressure Channel Potential Severe Core Damage No I.___No-reactor in cold shutdown L
[N40
[ NO No NSIC 145209 -
Actual Occurrence for Both Power Operated Relief Valves Open During Troubleshooting at Fort Calhoun 1
Small Reactor Auxiliary High Low Pressure LOCA Trip Feedwater and Pressure Recirculation Secondary Injection and LPR/HPI Heat Removal Cross-Connect Potential Severe Core Damage Sequence No.
2 3
4 5
6 7
NSIC 145209 -
Sequence of Interest for Both Power Operated Relief Valves Open During Troubleshooting at Fort Calhoun 1 initiating evemt requires operator failure to close PORV isolation valves.
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER: 145209 DATE OF LER:
January 2, 1979 DATE OF EVENT:
December 20, 1978 SYSTEM INVOLVED:
reactor coolant COMPONENT INVOLVED:
power operated relief valves CAUSE:
Technician error in pulling recorder fuses during troubleshooting resulted in both PORVs failing open, human error SEQUENCE OF INTEREST:
two stuck open PORVs ACTUAL OCCURRENCE:
two stuck open PORVs during cold shutdown REACTOR NAME:
Fort Calhoun 1 DOCKET NUMBER:
50-285 REACTOR TYPE:
PtWR DESIGN ELECTRICAL RATING:
457 MWe REACTOR AGE:
5.5 yr VENDOR:
CE ARCHITECT-ENGINEERS:
Gibbs & Hill, Inc.
OPERATORS:
Omaha Public Power District LOCATION:
19 -miles north of Omnaha,.Nebraska DURATION:
N/A PLANT OPERATING CONDITION: Cold shutdown SAFETY FEATURE TYPE OF FAILURE:
(a) inadequate performance; (b) failed to start; (c) made inoperable; 0 failed open DISCOVERY METHOD:
During operation COMMENT:
-