ML20149K348
| ML20149K348 | |
| 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 1981-003-00 | |
| Download: ML20149K348 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
165900 Date:
April 21, 1981
Title:
Inadvertent Opening of Pressurizer Relief Valve at Haddam Neck The failure sequence was:
- 1. With the reactor at 100% power, pressurizer PORV PR-SOV-570 and its block valve PR-MOV-569 opened spuriously due to a connector coming loose from pressure controller PC 401/3.
- 2.
This resulted in an RCS pressure decrease from 2000 to 1980 psi.
Corrective action:
- 1. The connector was reinstalled.
Actuation logic for the PORV and block valve were modified from a one channel pressure signal to 2 out of 3 channels to prevent spurious actuations.
Design purpose of failed system or component:
The PORV provides overpressure protection for the RCS and prevents challenges to the code safety valves.
Reactor at Pressure controller PC 401/3 Twenty psi RCS 100% power comes loose, resulting in the pressure decrease opening of PORV PR-SOV-570 before event and block valve PR-MOV-569 terminated Potential Severe Core Damage No -
incident ter-minated prior to significant RCS blowdown No No NSIC 165900 - Actual Occurrence for Inadvertent Opening of Pressurizer Relief Valve and Block Valve at Haddam Neck
Small Reactor Auxiliary High Low Pressure LOCA Trip Feedwater and Pressure Recirculation Secondary Injection and LPR/HPI Heat Removal Cross-Connect Potential Severe Core Damage Sequence No.
No 1
Yes 2
Yes 3
No 4
Yes 5
Yes 6
Yes 7
NSIC 165900 -
Sequence of Interest for Inadvertent Opening Valve and Block Valve at Haddam Neck of Pressurizer Relief
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER:
165900 LER NO.:
81-003 DATE OF LER:
April 21, 1981 DATE OF EVENT:
April 3, 1981 SYSTEM INVOLVED:
Pressurizer relief COMPONENT INVOLVED:
PORV and block valve CAUSE:
Loose electrical connector caused spurious signal SEQUENCE OF INTEREST:
Small break LOCA ACTUAL OCCURRENCE:
Small break LOCA REACTOR NAME:
Haddam Neck DOCKET NUMBER:
50-213 REACTOR TYPE:
PWR DESIGN ELECTRICAL RATING:
580 MWe REACTOR AGE:
13.7 years VENDOR:
Westinghouse ARCHITECT-ENGINEERS:
Stone and Webster OPERATORS:
Conn Yankee Atomic Power Co.
LOCATION:
13 miles east of Meriden, Connecticut DURATION:
N/A PLANT OPERATING CONDITION:
100% power TYPE OF FAILURE:
Inadvertent opening DISCOVERY METHOD:
Operational event COMMENT: