ML20161A167
| ML20161A167 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 06/09/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1981-011-00 | |
| Download: ML20161A167 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
169587 Date:
November 4, 1981
Title:
Safety Injection Path to RCS Obstructed at Turkey Point 4 The failure sequence was:
- 1.
At the beginning of a refueling outage and while conducting a routine periodic test during partial draining of the RCS, the flow path to the RCS associated with the boron injection tank (BIT) was found obstructed.
- 2.
The apparent cause of the obstruction was reduced temperature resulting from missing insulation in the vicinity of a 4-in. tee at the inlet to the BIT.
- 3.
As a result of the obstruction, the safety injection flow path from all high head safety injection pumps to the RCS cold legs were blocked.
A flow path to the hot legs was verified to be operable by establishing flow.
Corrective action:
- 1.
The flow path was reestablished by alternating pump operation and raising the thermostat setting for the related heat tracing.
Design purpose of failed system or component:
The safety injection system provides high-pressure replacement water to the RCS during a LOCA and steam line break.
This system also provides boron injection for steam break return to power considerations.
Potential Severe Core Damage No -
no requirement for safety injection No NSIC 169587 - Actual Occurrence for Safety Injection Path to RCS Obstructed at Turkey Point 4
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 I
Yes Yes 2
3 4
No Yes Yes Yes 5
6 7
NSIC 169587 -
Sequence of Interest for Safety Injection Path to RCS Obstructed at Turkey Point 4
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER:
169587 LER NO.:
81-011 DATE OF LER:
November 4, 1981 DATE OF EVENT:
October 21, 1981 SYSTEM INVOLVED:
Safety injection COMPONENT INVOLVED:
4-in. piping tee CAUSE:
Boric acid solidification blocked tee SEQUENCE OF INTEREST:
LOCA ACTUAL OCCURRENCE:
Unavailability of high head safety injection paths REACTOR NAME:
Turkey Point 4 DOCKET NUMBER:
50-251 REACTOR TYPE:
PWR DESIGN ELECTRICAL RATING:
693 MWe REACTOR AGE:
8.4 years VENDOR:
Westinghouse ARCHITECT-ENGINEERS:
Bechtel OPERATORS:
Florida Power & Light LOCATION:
25 miles south of Miami, Florida DURATION:
360 h (estimated)
PLANT OPERATING CONDITION:
Entering refueling shutdown TYPE OF FAILURE:
Made inoperable DISCOVERY METHOD:
Testing COMMENT: