ML20149K347
| ML20149K347 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 05/28/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1980-004-3L | |
| Download: ML20149K347 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
154451 Date:
February 12, 1980
Title:
Inadvertent Opening of PORV at Haddam Neck The failure sequence was:
- 1. With the reactor at full
- power, spurious signal to the PORV and its isolation block valve was initiated in Pressurizer Pressure Control Channel 1.
- 2.
Both valves opened and the RCS depressurized to 1992 psig.
- 3.
The PORV and its associated block valve were remote-manually closed within approximately 10 seconds of the start of the transient.
RCS pressure was restored to greater than 2000 psig within 2 minutes, terminating the transient.
Corrective action:
Investigation and testing did not reveal the source of the problem.
The channel and valve controls were placed in the normal operating mode.
Design purpose of failed system or component:
PORVs are designed to prevent challenges to the main safety valves and to assist in control of RCS pressure.
Reactor at full power Spurious signal opens Operator closes I
PORV and block valve block valve Potential Severe Core Damage No No - small-break LOCA mitigation capability prevents core damage No NSIC 154451 -
Actual Occurrence for Inadvertent Opening of PORV at Haddam Neck
Small Reactor Auxiliary High Low Pressure Potential Sequence LOCA Trip Feedwater and Pressure Recirculation Severe No.
Secondary Injection and LPR/HPI Core Heat Removal Cross-Connect Damage No I
Yes 2
Yes 3
No 45 Yes 5
Yes 6
Yes 7
NSIC 154451 -
Sequence of Interest for Inadvertent Opening of PORV at Haddam Neck
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER:
154451 LER NO.:
80-04/3L DATE OF LER:
February 12, 1980 DATE OF EVENT:
February 4, 1980 SYSTEM INVOLVED:
Pressurizer relief system COMPONENT INVOLVED:
PORV and block valve CAUSE:
Spurious actuation signal SEQUENCE OF INTEREST:
Small break LOCA ACTUAL OCCURRENCE:
Inadvertent opening of a PORV and block valve REACTOR NAME:
Haddam Neck DOCKET NUMBER:
50-213 REACTOR TYPE:
PWR DESIGN ELECTRICAL RATING:
580 MWe REACTOR AGE:
12.5 years VENDOR:
Westinghouse ARCHITECT-ENGINEERS:
Stone and Webster OPERATORS:
Connecticut Yankee Atomic Power Co.
LOCATION:
13 miles east of Meriden, Connecticut DURATION:
N/A PLANT OPERATING CONDITION:
Full power TYPE OF FAILURE:
Inadequate performance; inadvertent operation DISCOVERY METHOD:
Operational event COMMENT:
Actuation logic for the PORV and block valve has been modified from a one channel pressure signal to a 2 out of 3 channels to prevent spurious actuations.