ML20168A707

Final ASP Analysis - Pilgrim (LER 293-78-035)

ML20168A707
Person / Time
Site:	Pilgrim
Issue date:	06/16/2020
From:	Christopher Hunter NRC/RES/DRA/PRB
To:
Littlejohn J (301) 415-0428
References
LER 1978-035-00
Download: ML20168A707 (5)

Text

Loss of Offsite Power at Pilgrim 1 ilure sequence was:

reactor was operating at 100% full power when lightning struck offsite stribution lines. This caused a ground fault in the high speed relays.

s resulted in a loss of offsite power.

reactor scrammed automatically.

e diesels started and loaded.

e RCIC/HPCI were manually started to maintain a proper water level.

fety/relief valve 203-C was opened once for pressure control.

ive action:

fsite power was returned to the startup transformers within 1/2 hour.

purpose of failed system or component:

The transmission lines connect Pilgrim 1 with-the New England Grid.

ability of system per WASH 1400:

• loss of offaite power 2.0 x 10-5 /hr ability of component per WASH 1400: *-

navailabilities are in units of per demand D-1. Failure rates are in f per hour HR-1 .

No No - see note 1 No - see note 2 No - see notes 1 & 2 No - see note 3 No - see notes 1 & 3 No - see notes 2 & 3 No - see notes 1, 2, & 3 ATWS 140140 - Actual Occurrence for the Loss of Offsite Power at Pilgrim 1

No. of Valves Set Pressure (PSIG) ef valves 3 1090 to 1240 ety valves 2 1240 HPCI and the RCIC autoactuate at either low-low reactor water inven-y or high dry well pressure. See note 1.

HPCI and RCIC are capable of initiation without an a.c. power source.

safety and relief valves also have this capability. The battery systems capable of 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> operation without recharge. .Since offsite power was tored within -11hour, a potential core damage situation did not exist.

er Sra Startad ScSrica byd the Initiates CSorer Core

{ Manually Driven In j Cooling Damage No 1 Yes 2 No 3 Yes 4 Yes 5 No 6 Yes 7 Yes 8 No 9 Yes 10 No 11 Yes 12 Yes 13 Yes 14 Yes 15 NSIC 140140 - Sequence of Interest for the Loss of Of fsite Power at Pilgrim 1

CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS CESSION NUMBER: 140140 LER: August 8, 1978 EVENT: August 6, 1978 INVOLVED: electric power NT INVOLVED: grounding relays lightning striking offsite transmission line caused high speed relay opera-tion for line to ground faults.

OF INTEREST: loss of offsite power OCCURRENCE: loss of offsite power NAME: Pilgrim 1 NUMBER: 50-293 TYPE: BWR ELECTRICAL RATING: 655 MWe ACE: 6.2 yr GE CT-ENGINEERS: Bechtel S: Boston Edison

4 miles .SE of Plymouth, Mass.

N/A ERATING CONDITION: 100% power FEATURE TYPE OF FAILURE: (a) inadequate performance; (b) failed to start;

~made inoperable; (d)____________

Y METHOD: "xt az t