ML20149K349
| ML20149K349 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 05/28/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1980-069-00 | |
| Download: ML20149K349 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
163478 Date:
July 10, 1980
Title:
HPCI and RCIC Fail to Inject Following Scram at Hatch I The failure sequence was:
- 1. At 99.4% power, an erroneous reactor high water level signal initi-ated tripping of the feedwater pumps and the turbine/generator, which subsequently resulted in a reactor scram.
- 2.
The reactor water level dropped to the low-low level set point.
- 3.
The feedwater pump started but tripped since the MSIVs were closed.
- 4.
On low low level the HPCI system received an auto-initiation signal but failed to inject water into the reactor due to automatic isolation of the HPCI turbine caused by the initial high steam pressure to the HPCI turbine.
- 5.
RCIC was manually initiated during the event, but failed to start and remained inoperable throughout the event.
- 6.
About 5 min after the event began, the operators cleared the HPCI steam supply isolation trip and HPCI auto-initiated successfully and injected water into the core.
Corrective action:
- 1. The HPCI isolation, due to steam line high pressure differential, was caused by the turbine speed controller being out of calibration.
The system was recalibrated and HPCI tested satisfactorily.
- 2.
The RCIC failure, determined to be due to a faulty limit switch and/or relay, was corrected by replacement of both components.
The system was then tested satisfactorily.
- 3.
Calibration surveillance and test procedures were being revised to include cold quickstarts of both HPCI and RCIC.
Design purpose of failed system or component:
RCIC provides RCS makeup following reactor trip or loss of feedwater.
HPCI provides cooling to the core given a small break LOCA.
Reactor at full power Reactor level HPCI initiates RCIC initiated Operator clears and feedwater trip, drops to low but trips manually but HPCI trip and turbine trip, and water level immediately on failed to start HPCI success-reactor trip follow-high steam AP due to a faulty fully injects ing erroneous high due to an out-switch or relay level signal of-calibration turbine speed controller Potential Severe Core Damage No No -
ADS/
LPCI/CS operable No No No NSIC 163478 -
Actual Occurrence of HPCI and RCIC Failure to Inject Following Scram at Hatch 1
Loss of Reactor Standby RClC/HPCI Automatic LPCI or Long Feedwater Scram Liquid
Response
Depressurization CS Response j Term Flow Control Adequate System Operates Adequate Core Initiated Cooling Potential Severe
.Core Damage Sequence No.
No 1
Yes No 2
3 4
Yes Yes Yes S
6 No 7
Yes Yes Yes 8
9 10 NSIC 163478 -
Sequence of Interest forRCIC and HPCI Failure to Inject Following Scram at Hatch 1
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER:
163478 LER NO.:
80-069 DATE OF LER:
July 10, 1980 DATE OF EVENT:
June 26, 1980 SYSTEM INVOLVED:
HPCI and RCIC systems COMPONENT INVOLVED:
HPCI speed controller; RCIC trip switch and relay CAUSE:
Failed components, improper calibrating procedures SEQUENCE OF INTEREST:
Loss of feedwater ACTUAL OCCURRENCE:
HPCI and RCIC fail to inject following scram REACTOR NAME:
Hatch 1 DOCKET NUMBER:
50-321 REACTOR TYPE:
BWR DESIGN ELECTRICAL RATING:
777 MWe REACTOR AGE:
5.8 years VENDOR:
General Electric ARCHITECT-ENGINEERS:
Bechtel OPERATORS:
Georgia Power Co.
LOCATION:
11 miles north of Baxley, Georgia DURATION:
N/A PLANT OPERATING CONDITION:
Power not specified prior to scram TYPE OF FAILURE:
Failed to start DISCOVERY METHOD:
Operational event COMMENT: