ML20168A455
| ML20168A455 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1977-110-00 | |
| Download: ML20168A455 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
133706 Date:
December 11, 1977
Title:
Co ntrol of Both Auxiliary Feed Pump Turbines Lost at Davis-Besse 1 The failure sequence was:
- 1. During testing, control over both auxiliary feedwater pump turbines was lost, rendering the pumps inoperable.
- 2. Control of the turbine for pump 1-1 was lost due to mechanical binding in the governor.
- 3.
Control of the turbine for pump 1-2 was lost due to blown control power supply fuses for the speed changer motor.
Corrective action;
- 1. On pump 1-1, the roll pin which was binding was repositioned, cleaned, and lubricated.
- 2. On pump 1-2, the blown fuses were replaced, as were two relays suspected of sticking and causing the blown fuses.
Design purpose of failed system or component:
- 1. The auxiliary feedwater pumps provide RCS heat removal when the main feed system is unavailable.
Unavailability of system per WASH 1400:
- Auxiliary feedwater:
3.3 x 10-5 /1)
Unavailability of component per WASH 1400:
- Pumps, failure to start 1 x 10-3 /D Unavailabilities are in units of per demand D-1.
Failure rates are in units of per hour HR 1 '.
Reactor in hot Auxiliary feedwater Auxiliary feedwater Auxiliary feedwater standby during pump 1-1 operable pump 1-2 operable pump required "Reactor/Turbine Trip Test" Potential Severe Core Damage No No No No Yes No NSIC 133706 -
Actual Occurrence for Control of Both Auxiliary Feed Pump Turbines'Lost at Davis-Besse 1
Potential Severe Core Damage Sequence No.
No 1
2 3
4 5
6 7
8 9
10 11 12 13 at Davis-Besse 1 NSIC 133706 -
Sequence of Interest for Control of Both Auxiliary Feed Pump Turbines Lost
- not included in mitigation procedures
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUMBER:
133706 DATE OF LER:
January 3, 1978 DATE OF EVENT:
December 11, 1977 SYSTEM INVOLVED: Auxiliary feedwater COMPONENT INVOLVED:
Auxiliary feedwater pump turbines CAUSE:
Mechanical binding, blown fuses SEQUENCE OF INTEREST:
Loss of feedwater ACTUAL OCCURRENCE:
Auxiliary feedwater pumps inoperable during testing.
REACTOR NAME:
Davis-Besse 1 DOCKET NUMBER:
50-346.
REACTOR TYPE:
PWR DESIGN ELECTRICAL RATING:
906 MWe REACTOR AGE:
0.6 yr VENDOR:
Babcock & Wilcox ARCHITECT-ENGINEERS:
Bechtel OPERATORS:
Toledo Edison LOCATION:
- 21. iWles east 6E.Toledo, Ohio DURATION:
360(a) hours PLANT OPERATING CONDITION:
hot standby SAFETY FEATURE TYPE OF FAILURE:
(a) inadequate performance; (b) failed to start; Qin%
ade inoperable; (d) __________
DISCOVERY METHOD:
During testing COMMENT:
-