ML20168A713
| ML20168A713 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1971-002-00 | |
| Download: ML20168A713 (4) | |
Text
PRECURSOR DESCRIPTION AnD DATA NSIC Accession Number:
65757 Date:
June 30, 1971
Title:
Failure of Containment Sump Isolation Valves at Point Beach 1 (Semi-Annual Operations Report for January-June, 1971)
The failure sequence was:
- 1. During a reactor heatup, the control room operator attempted to open both containment sump isolation valves.
- 2. Both valves failed to open due to air-binding in their hydraulic operating mechanisms.
In addition, both hydraulic units were found to be installed 90% from their upright positions.
Corrective action:
The valve hydraulic mechanisms were re-oriented and the suction piping re-routed to take suction from the bottom of the oil sumps.
Design purpose of failed system or component:
The valves isolate the containment sump from the low pressure in~jection/
recirculation system during normal operation. After the RWST Is emptied following a LOCA, these valves are opened to provide suction flow to the low pressure recirculation system.
Unavailability of system per WASH 1400:
Low pressure recirculation:
1.3 x 10-2 /D Unavailability of component per WASH 1400: *Valves, motor operated, failure to operate:
1 x 10-3 /D Valves, air-fluid operated, failure to operate:
3 x 10-4 /D Unavailabilities are in units of per demand D-1.
Failure rates are In units of per hour HR-1.
Reactor in Operator Successfully Heatup j
Opens Containment Sump Isolation Valves During Testing Potential Severe Core Damage No I
WTh No event existed which required the use of these valves NSIC 65757 -
Actual Occurrence for Failure of Containment Sump Isolation Valves at Point Beach I
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 65757 -
Sequence of Interest for Failure of Containment Sump Isolation Valves at Point Beach 1 a
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER:
63757 DATE OF LER: June 30, 1971 DATE OF EVENT: April 16, 1971 SYSTEM INVOLVED:
Low pressure recirculation COMPONENT INVOLVED: Containment sump isolation valves CAUSE: Valves failed closed due to air-bound hydraulic operators SEQUENCE OF INTEREST: LOCA ACTUAL OCCURRENCE: Sump Isolation valves failed closed during testing REACTOR NAM~E:
Point Beach 1 DOCKET NUMBER: 50-266 REACTOR TYPE:
PWR DESIGN ELECTRICAL RATING: 497 MWe REACTOR AGE:
.45 yr VENDOR: Westinghouse ARCHITECT-ENGINEERS:
Bechtel OPERATORS: Wisconsin Electric Power Co.
LOCATION:
.15.mi:lea,iorthief ilanitowoc, Wisc.
DURATION:
360(a) hours PLANT OPERATING CONDITION:
Reactor heatup SAFETY FEATURE TYPE OF FAILURE:
(a) inadequate performance; (b) failed to start; (c) made Inoperable; M9 failed to open DISCOVERY METHOD: Testing COMMENT: