ML20168A557
| ML20168A557 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1979-059-00 | |
| Download: ML20168A557 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number: 150499 Date: July 28, 1979
Title:
RCIC and HPOI Isolate Following a Reactor Scram at Hatch 2 The failure sequence was:
- 3. The operators reset and manually started both systems.
Corrective action:
- 1. One AIP switch was out of specs and it was reset.
- 2. An investigation was initiated to discern the cause of the out-of-spec condition.
Design purpose of failed system ur component:
- 1. HPCI is designed to maintain water level control given a small Loca.
- 2. ROIC is designed to maintain water level control given a loss of feed-water flow.
- 3. The AIP switches are designed to send an isolation signal given a steamline pipe break in the HPCI or RCIC system.
Unavailability of system per WASH 1400:
- HPCI: 8.8 x* 10-2 /D given Loca RCIC: 8.0 x 10 2 /D given Loca Unavailability of component per WASH 1400:
- pressure switches: 10-4 /D Unavailabilities are in units of per demand D
.Failure rates are in units of per hour HR-1.
Reactor tripped as HPCI & RCIC JOperator resets intended during MSIV isolate on high HPCI/RCIC &
fast closure test A~P signal m anually initiates jthen Potential Severe Core Damage No No Feedwater system, available as was the AD~S, LPCI/CS system No NSIC 150499 -
Actual Occurrence of RCIC and HPCI Isolate Following a Reactor Scram at Hatch 2
Potential Severe Core Damage Sequence No.
No Yes No 2
3
&t Yes Yes 6
Yes7 NSIC 150499 -Sequence of Interest for ROTC and HPCI Isolate Following a Reactor Scram at Hatch 2
'Success requires the operator to reset HPCI and/or RCIC.
2Loss of feedwater is presumed.
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS N4SIC ACCESSION NUMBER:
150499 DATE. OF LER:
July 6, 1979 DATE OF EVENT:
June 28, 1979 SYSTEM INVOLVED: HPCI, RCIC COMPONENT INVOLVED: AP switches CAUSE:
unknown as of reporting date SEQUENCE OF INTEREST:
loss of feedwater flow ACTUAL OCCURRENCE: RCIC and HPCI isolate followingas reactor scram at Hatch 2 REACTOR NAMýE: Hatch 2 DOCKET NUMBER:
50-366 REACTOR TYPE:
BWR DESIGN ELECTRICAL RATING:
784 Nwe REACTOR AGE:
1.0 yr VENDOR: General Electric ARCHITECT-ENGINEERS: Southern Services/Bechtel OPERATORS:
Georgia Power LOCATION:
11 miles N of Baxley, Georgia DURATION:
36 0(a) hours PLANT OPERATING CONDITION:
0% power SAFETY FEATURE TYPE OF FAILURE:
(a) inadequate performance; (b) failed to start; (5made inopera ble; (d) ____________
DISCOVERY METHOD:
operational test COMMENT: -