ML20168A575

Final ASP Analysis - Millstone 2 (LER 336-76-049)

ML20168A575
Person / Time
Site:	Millstone
Issue date:	06/16/2020
From:	Christopher Hunter NRC/RES/DRA/PRB
To:
Littlejohn J (301) 415-0428
References
LER 1976-049-00
Download: ML20168A575 (4)

Text

ffsite Power Lost at Millstone 2 e sequence was:

a hurricane, severe salt contamination caused several switchyard es, resulting in a loss of offsite power and a reactor trip from ower.

esel generators, which had been running prior to the trip, provided to safety related loads.

e action; yard equipment and insulators were washed down, damaged circuit ere repaired, and the offsite transmission lines returned to service.

rpose of failed system or component:

e power provides the preferred source of power to safety related the unit generator is not available.

ility of system per WASH 1409:

• off-site power: 2 x lO-5Ihr ility of component per WASHi 1400:*

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

and loss of offaite Damage power and conse-quent reactor trip No No - steam driven AFW pump available for RX cooling No No No - steam driven AFW pump available for Rx cooling No 117944 - Actual Occurrence for Offsite Power Lost at Millstone 2

I 2

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9 10 11 12 13 IC 117944 - Sequence of Interest for Offsite Power Lost at Millstone 2 e of HPI after AFW failure not included in mitigation procedures.

diesel generators running but not loaded

CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS CESSION NULMBER: 117944 LER: September 3, 1976 EVENT: August 10, 1976 NVOLVED: offsite power T INVOLVED: switchyard insulators and equipment severe salt spray wetting during hurricane OF INTEREST: loss of off site power CCURRENCE: reactor trip with loss of offsite power and diesel generators previously started and running NAMtE. M~illstone 2 NUMBER: 50-336 TYPE: PWR ELECTRICAL RATING: 830 MWe AGE: .8 yr Combustion Engineering CT-ENGINEERS: Bechtel RS: Northeast Nuclear Energy Co.

N: 5 miles SW of.New London, Conn.

N: N/A PERATING CONDITION: 100% powet FEATURE TYPE OF FAILURE: (a) inadequate performance; (b) failed to start; r(Omade inoperable; (d)__________

RY MET1EOD: during operation

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