ML20168A706
| ML20168A706 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 06/16/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1978-003-00 | |
| Download: ML20168A706 (4) | |
Text
B-46 2
.PRECURSOR DESCRIPTION AND DATA NSIC Accession Number:
135932 Date:
February 6, 1978
Title:
All Offsite Transmission Lines Lost at Pilgrim 1 The failure sequence was:
The reactor was operating at 24% power when high winds and ice caused all the transmission lines to fail.
This event, caused the reactor to trip.
Corrective action:
The insulators were washed with fresh water and the reactor was returned to service. A plant design change was issued to resolve the flashover problem on standoff insulators.
Design purpose of failed system or component:
The transmission lines connect Pilgrim 1 with the New England Grid.
These lines provide power to the reactor when the station isn't generating.
Unavailability of system per WASH 1400:
- loss of offaite power 2 x 10-5/hr Unavailability of component per WASH 1400:*
Unavailabilities are in units of per demand D-1.
Failure rates are in units of per hour HR-1.
Reactor operating All off site trans-Reactor scra Diesel str at 24% power mission lines lost due to load and load weather Potential Severe Core Damage No Yes -when fully loaded the batteries last 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
It required 1,39 hours4.513889e-4 days <br />0.0108 hours <br />6.448413e-5 weeks <br />1.48395e-5 months <br /> to return offsite power.
No -at less than 50% power BWR's can survive an ATWS to Yes -
see comment on sequence /#2.
No NSIC 135932 -
Actual Occurrence of the Loss of All Transmission Lines at Pilgrim 1 1
It is presumed the diesels started and loaded properly.
Loss of Reactor Diesel Reactor Made Sub-RCIC/HPCI ADS/LPCI ILong Powier Sca Loartad SBcSrica Rod Are Initias S
tes Cre Powier Scam Sartad SBcSrica byd the Initiates CTer jManually Driven In
.Cooling Potential Severe Core Damage Sequence No.
No Yes No Yes
'Yes No Yes Yes No Yes No Yes Yes Yes Yes 1
2 3
4 5
6 7
8 9
10 11 12 13 14 15 to NSIC 135932 -
Sequence of Interest of the Loss of All Transmission Lines at Pilgrim 1
B-46 5 CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS NSIC ACCESSION4 NUMBER:
135932 DATE OF LER:
February 23, 1978 DATE OF EVENT: February 6, 1978 SYSTEM INVOLVED:
electric power COMPDONENT INVOLVED:
offsite transmission lines CAUSE:
insulator flashover due to inclement weather SEQUENCE OF INTEREST:
loss of offsite power ACTUAL OCCURRENCE:
loss of offsite power REACTOR NAME: Pilgrim 1 DOCKET NUMBER:
50-293 REACTOR TYPE:
BWR DESIGN ELECTRICAL RATING:
655 NWe REACTOR AGE:
5.7 yr VENDOR:
GE ARCH ITECT-ENGINEERS: Bechtel OPERATORS: Boston Edison LOCATION:
Four miles SE of Plymouth, Mass.
DURATION:
N/A PLANT OPERATING CONDITION:
25% full power SAFETY FEATURE TYPE OF FAILURE:
(a) inadequate performance; (b) failed to start; Omade inoperable; (d)____________
DISCOVERY METHOD:
operational event COMMENT:-