ML20168A467
| ML20168A467 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1978-021-00 | |
| Download: ML20168A467 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
137305 Date:
April 7, 1978
Title:
Auxiliary Feedwater System Failure at Farley 1 The 1.
2.
3.
4.
5.
failure sequence was:
A low-low water level condition occurred in one steam generator and resulted in a reactor trip.
Both motor-driven auxiliary feedwater pumps started.
A low-low water level condition occurred in the second steam generator.
The turbine driven auxiliary feedwater pump failed to start.
The recirculation bypass valves were found open on all auxiliary feedwater pumps, rendering the operating motor-driven pumps ineffective.
Corrective action:
Isolation valves were closed restoring system to operable status.
Design purpose of failed system or component:
Prevent core damage upon loss of normal feedwater.
Unavailability of system per WASH 1400:*
3.5 x 10-5 /D Unavailability pf component per WASH 1400:*
Unavatlabilities are in units of per demand D71.
Failure rates are in units of per hour HR 1
Low-Low Reactor 1 of 2 motor Water level Turbine Operator water level trip driven aux in second driven aux inteizventin in I. steam feedpumps stean generator feed pump successful generator operable (1) T.maintained operable (2)
Potential Severe Core Damage No No No No Yes ATWS NSIC 137305, -
Actual Occurrence for Auxiliary Feedwater SysteraLýFailures (I & 2).
valves were later found open (resulting in flow reduction) (2) opened a closed turbine valve.
(1) Be-circ bypass trip/throttle
of Reactor Auxiliary FORV PORV or High Long Term Potential Sequence Trip Feedwater and Demanded PORV Isola-Pressure Core Severe No.
ater Secondary tion Valve Injec tion Cooling Core Heat Removal Closure Damage No 1
No 2
Yes 3
Yes 4
No 5
No 6
Ye s 7
Yes 8
-Yes 81 Yes 13 NSIC 137305 -Sequence of Interest for Auxiliary Feedwater System Failures at Farley 1
- mat included in mitigation sequence
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER:
137305 DATE OF LER:
April 7, 1978 DATE OF EVENT:
March 25, 1978 SYSTEM INVOLVED:
Auxiliary feedwater COMPONENT INVOLVED:
Valves CAUSE:
Human error -
valves left open SEQUENCE OF INTEREST:
Loss of normal feedwater ACTUAL OCCURRENCE:
Low-low water level in one Steam generator REACTOR NAME:
Farley 1 DOCKET NUMBER:
50-348 REACTOR TYPE:
PWR DESIGN ELECTRICAL RATING:
829 MWe REACTOR AGE:
- 0. 6 yr VENDOR:
Westinghouse ARCHITECT-ENGINEERS:
Bechtel OPERATORS:
Alabama Power Co.
LOCATION:
Z4 mile& SE.,of. Dothanx, Ala.
DURATION:
360(a) hours PLAN'T OPERATING CONDITION: 0% Power SAFETY FEATURE TYPE OF FAILURE:
(a) inadequate performance; (b,) failed to start; 0 made inoperable; (d) _______
DISCOVERY METHOD:
operational event COMMENT:
-