ML20168A706

Final ASP Analysis - Pilgrim (LER 293-78-003)

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 Potential at 24% power mission lines lost due to load and load Severe Core weather 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.

to No -at less than 50% power BWR's can survive an ATWS 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 Potential Sequence Powier Sca Loartad SBcSrica Rod Are S Initias tesCre Severe No.

Powier Scam Sartad SBcSrica byd the CTer Initiates Core jManually Driven In .Cooling Damage No 1 Yes 2 No 3 Yes 4

'Yes 5 No 6 Yes 7 to Yes 8 No 9 Yes 10 No 11 Yes 12 Yes 13 Yes 14 Yes 15 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:-