ML20168A577
| ML20168A577 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1971-LTR-00 | |
| Download: ML20168A577 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
74242 Date:
December 31, 1971
Title:
High Coolant Level at Nine Mile Point The failure sequence was:
- 1. Surveillance testing of the reactor protection system high/low water sensors was being conducted.
The sensor support was accidently bumped causing a turbine trip and an anticipatory reactor trip.
- 2. Following the trip the reactor water level began to decrease rapidly, causing the feedwater system to respond by overfeeding, as it should, in the automatic mode.
3.After 20 seconds the operator took manual control since in his opinion the feedwater flow was high.
- 4. The manual transfer of control was slow and some water spilled into the main steaialifie.
Corrective action:
Since the autonatic response of the expected system response to the feedwater system was correct, a review of transients was given,, to the operating staff.
Design purpose of failed system or component:
The feedwater system is part of the steam cycle and provides makeup water to the nuclear boiler.
Unavilailiy ofsysem er WSH 400 Unavailability of systoemt per WASH 1400:-
Unavailabilities are in units of per demand D-1.
Failure rates are in units of per hour HR-1.
A TurBine/Reactor Trip The Feedwater System The Operator Incorrectly Took Occurred During Surveil-Overfeed The Reactor Conrol of the Feedwater System lance Testing of the High!
to Compensate for and Caused Water to Flow Into Low Level Scram Sensors the Shrinking Water the Steam Lines Level Potential Severe Core Damge MSLB initiator No No NSIC 74242 - Actual Occurrence of High Coolant Level at Nine Mile Point
Excessive Coolant Reactor Scram Reactor Vessel or Reactor Coolant Overflows Steam Line Break Long Term Potential Inventory Turbine Isolate Into Steam Lines, Is Dis-Due to Turbine Core Severe charged Through Relief Missiles, etc.
Cooling Core Valves, Which Stick Open Success Damage Small LOCA Initiator No Yes MSLB No No Yes No Yes NSIC 74242 -
Sequence of Interest for High Coolant Level at Nine Mile Point
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER:
74242 DATE OF LER:
January 20, 1972 DATE OF EVENT:
December 31, 1971 SYSTEM4 INVOLVED:
Feedwater COMPONENT INVOLVED:
Controls CAUSE:
Operator Error SEQUENCE OF INTEREST:
Excessive Coolant Inventory Transient ACTUAL OCCURRENCE:
High Coolant Level REACTOR NAME:
Nine Mile Point DOCKET NUMBER:
50-220 REACTOR TYPE:
BWR DESIGN ELECTRICAL RATING:
620 MWe REACTOR ACE:
2.4 yr VENDOR:
General Electric ARCHITECT-ENGINEERS:
Utility OPERATORS:
Niagara Mohawk Power Company LOCATION: 8 miles NE of Oswego, NY DURATION:
N/A PLANT OPERATING CONDITION:
Greater than 45% of rated load SAFETY FEATURE TYPE OF FAILURE:
(a) inadequate perform ce; (b) failed to start; (c) made inoperable; (0~Lnirec pat epoe DISCOVERY METHOD:
operational transient COMMENT: