ML20168A568
| ML20168A568 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1973-001-00 | |
| Download: ML20168A568 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
78418 Date:
February 2, 1973
Title:
Failure of Charging Pump Valves to Open After an Ice Storm at Maine Yankee The failure sequence was:
- 1. During ECCS valve surveillance testing, the suction valve from the RWST to charging pump 14A failed to open due to ice on the valve stem, a result of an ice storm earlier in the day.
- 2. The suction valve from the RWST to charging pump 14B failed to open completely, also because of ice on the valve stem.
Corrective action:
The ice was removed from the valve stems and protective covers fabricated for the valves.
Design purpose of failed system or component:
The charging pump suction valves admit water from the RWST to the charging pumps during safeguards actuation, when pump suction flow is automatically switched from the volume control tank to the RWST.
Unavailability of system per WASH 1400:
- High Pressure Injection System (Two of Three Pumps Required on Surry):
1.2 x 10-2 Unavailability of component per WASH 1400:
- Motor O~erated Valve, failure to operate:
1 x 10 ID Unavailabilities are in units of per demand D-1.
Failure rates are in units of per hour HR-1
Reactor at 60%
Charging Pump l4A Charging Pump 14B Power and Suction Valve Fails Suction Valve Fails Testing After to Open Due to to Fully Open Due an Ice Storm Icing on Valve Stem to Icing on Valve Stem Potential Severe Core Damage No -
Actual Occurrence for Failure of Charging Pump Valves to Open After an Ice Storm at Maine Yankee
Small Reactor Auxiliary High Low Pressure LOCA Trip Feedwater arnd Pressure Recirculation Secondary Injection and LPR/HPI Heat Removal Cross-Connect Potential Severe Core Damage Sequence No.
1 2
3 4
5 6
7 NSIC 78418 -
Sequence of Interest for Failure of Charging Pump Valves to Open
- After an Ice Storm at Maine Yankee
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER:
78418 DATE OF LER:
February 7, 1973 DATE OF EVENT:
February 2, 1973 SYSTEM INVOLVED:
High Pressure Injection System COMPONENT INVOLVED:
Charging pump suction valves.
CAUSE:
Ice on valve stems SEQUENCE OF INTEREST: small LOCA ACTUAL OCCURRENCE: valve failure to open during testing REACTOR NAME:
Maine Yankee DOCKET NUMBER:
50-309 REACTOR TYPE:
PWR DESIGN ELECTRICAL RATING:
825 MWe REACTOR AGE:
.3 yr VENDOR:
Combustion Engineering ARCHITECT-ENGINEERS:
Stone and Webster OPERATORS:
Maine Yankee Atomic Power Co.
LOCATION:
10 miles north of-Bath, Maine DURATION: 360(a) hours PLANT OPERATING CONDITION:
at 60% power SAFETY FEATURE TYPE OF FAILURE:
(a) inadequate performance; (b) failed to start; (0
made inoperable; (d) ___________
DISCOVERY METHOD:
during testing COMMENT:
-