ML20168A718
| ML20168A718 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1975-031-00 | |
| Download: ML20168A718 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
105540 Date:
August 17, 1975
Title:
Low Flow Feedwater Line Severed at 6"1 to 4"1 Reducer at Quad Cities The failure sequence was:
- 1. The reactor was increasing power after startup.
- 2. A transfer was being made from the low flow feed regulating valve to the main feed regulating valve.
- 3. With both main and low feed regulating valves partially opened, a feedwater vibration alarm was received in the control room.
- 4. The operator manually scrammed the reactor because the low flow lime --
ad signs that it was starting to sever.
- 6. A-pproximately 11,500 gallons of water was spilled; of this 65% was reactor coolant and the remaining 35% was service water.
- 7. It is believed the failure resulted from vibration of the feedwater regulating station during the transfer.
- 8. RCIC was used to maintain water level control.
Corrective action:
1.
2.
3.
A new 4 x 6 reducer fabricated from more ductile steel was installed.
Snubbers were installed to reduce pipe movement.
One of the main feedwater valves was replaced with a "drag valve" to provide more control over a wide spectrum of flow conditions.
Design purpose of failed system or component:
The feedwater system provides feedwater to the reactor.
Unavailability of system per WASH 1400:*
Unavailability of component per WASH 1400:
- Pipe >3" 1 x 10-1 /hr.
Unavailabilities are in units of per demand D2 Failure rates are in units of per hour HR-'.
Reactor increasing power Operator manually Operator isolates RCIC used to during startup and vibra-scrams the reactor feedwater regu-maintain water tions from feedwater and trips feedwater lating station level control regulating station induce PUMP pipe break in 6x4 reducer in the low flow feedwater line Potential Severe Core Danage No No -
HPCI, ADS/LPCI/CS and other feedpump available No -
ECCS available No -
power conversion system available NSIC 105540 -
Actual Occurrence of Low Flow Feedwater Line Severed at 6x4 Reducer at Quad Cities 2
Loss of Coolant Accident reactor IIPci/RCIC Maintained
Response
Subcritical Adequate ADS/ LPC I Long Potential CS Term Severe
Response
Core Core Adequate Cooling Damage No Yes No Yes "es Yes Seýquence No.
2 3
4 5
6 NSIC 105540 -
Sequence of Interest 'for Low Flow Feedwater Line Severed at 6x4 Reducer at Quad Cities 2
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER:
105540 DATE OF LER:
August 27, 1975 DATE OF EVENT:
August 17, 1975 SYSTEM INVOLVED:
Peedwater COMPONENT INVOLVED:
Piping CAUSE:
Pipe rupture SEQUENCE OF INTEREST:
Loss of Coolant Accident ACTUAL OCCURRENCE:
Low Flow Feedwater Line Severed at 6" to 4" Reducer REACTOR NAME:
Quad Cities 2 DOCKET NUMBER:
50-265 REACTOR TYPE:
BWR DESIGN ELECTRICAL RATING:
789 MWe REACTOR AGE:
3.3 yr VENDOR:
General Electric ARCHITECT-ENGINEERS:
Sargent & Lundy OPERATORS:
Commonwealth Edison LOCATION:
20 miles.NE o~f M~oline, Ill.
DURATION:
N/A PLANT OPERATING CONDITION:
Power accension SAFETY FEATURE TYPE OF FAILURE:
(a) inadequate performance; (b) failed to start; (c) made inoperable;Q 0
everdd.
DISCOVERY METHOD:
Operational Event COMMENT: