ML20168A576
| ML20168A576 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1977-020-00 | |
| Download: ML20168A576 (4) | |
Text
PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
132979 Date:
August 10, 1977
Title:
Both Diesel Generator Fuel Supply Valves Found Shu~t at Millstone 2 The failure sequence was:
- 1. During a routine inspection with the plant in cold valves on both diesel generators were found shut.
closure was not known.
shutdown, the-fuel supply The cause of valve
- 2. Both fuel supply valves were reopened.
Corrective action;
- 1. The valve manual operators were chain locked in the open position.
Design purpose of failed system or component:
The diesel generators provide on-site emergency power for safety-related loads in the event of fsite power and the-~unit generator are unavailable.
Unavailability of system per W4ASH 140U;
- emergency power:
3 x 10-2 /1)
Unavailability of component per WASH 1400:* diesel generators:
10-2 /D
- Unavailabilities are in units of per demand D-1.
Failure rates are in units of per hour HR-1.
Unit in cold shut-Diesel-generator #1 Diesel-generator #2 down and plant fuel supply valve fuel supply valve inspection in found shut in found shut in progress violation of violation of procedures procedures Potential Severe Core Damage No -
unit in cold shutdown plus of fsite power available
[NO NSIC 132979 -
Actual Occurrence for Both Diesel Generator Fuel Supply Valves Found Shut at Millstone 2
Loss of Off site Power Turbine Generator Runs Back and Assumes House Loads Emer-._
gency Power Auxiliary PORV PORV or Feedwater and Demanded PORV Iso la-Secondary tion Valve Heat Removal Closure IHigh Pressure Inj ection Long Potential Term Severe Core Core Cooling Damage No Sequence No.
2 3
4 5
6 7
8 9
10 11 12 13 NSIC 132979 -
Sequence of Interest for Both Diesel-Generator Fuel Supply Valves Found Shut at Millstone 2
- Not included in mitigation procedures.
CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION NUIMER:
132979-DATE OF LER:
August 10,- 1.977 (Original report date June 14, 1977)
DATE OF EVENT:
May 15, 1977 SYSTEM'- INVOLVED:. on-site emergency.power COýONENT INVOLVED:
diesel-generators CAUSE:
fuel supply valves shut, human error SEQUENCE OF INTEREST:
loss of of fsite power ACTUAL OCCURRENCE:
fuel supply valves discovered to be. shut during an inspection-REACTOR NA11E:
Millstone 2 DOCKET NUMBER:
50-336 REACTOR TYPE:
PWR DESIGN ELECTRICAL RATING:
870 MWe REACTOR AGE:
2.0 yr VENDOR:
.Combustion Engineering ARCHITECT-ENGINEERS:
Bechtel OPERATORS:
Northeast Nuclear Energy Co.
LOCATION:
5 allea SI'tof New London, Comm.
DURATION:
180(a) hours PLANT OPERATING CONDITION:
cold shutdown SAFETY FEATURE TYPE OF FAILURE:
(a) inadequate performnance; (ba) failed to start; (Omade inoperable; (d)
DISCOVERY METHOD:
routine inspection COMIENT:
-