ML20168A569

Final ASP Analysis - Millstone 1 (LER 245-71-099)

ML20168A569
Person / Time
Site:	Millstone
Issue date:	06/16/2020
From:	Christopher Hunter NRC/RES/DRA/PRB
To:
Littlejohn J (301) 415-0428
References
LER 1971-099-00
Download: ML20168A569 (5)

Text

essure Transient and Blowdown at Millstone Point 1 sequence was:

unction in the turbine pressure control system (not specified) caused sure transient which resulted in a reactor trip on high neutron flux.

rbine was manually tripped. This caused the turbine bypass valve to s expected.

bypass valve failed to close so the operator manually closed the MSIVs.

owdown continued through an open relief valve until the reactor pressure d 263 psig when it reseated. The valve's main disk was wire drawn and eroded.

(See attached page) action:

lief valve was ground,rebuilt, and tested prior to being reinstalled.

rbine control problem was thought to be with. the linkage however this ng investigated.

ose of failed system or component:

valves provide for reactor pressure control ity of system per WASH 1400:* Relief valve failure to reset: 1-10-'/D ity of component per WASH 1400:*

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

core.

______________ to lift__________I________________

No No, EGGS avail-able No No, ECCS avail-able No No, ECCS avail-able No 96 - Actual Occurrence of a Pressure Transient and Blowd iat Millstone Point 1

No 1 Yes 2 No 3 Yes 4 Yes 5 Yes 6 NSIC 66996 - Sequence of Interest for Pressure Transient and Blowdown at Millstone Point 1 1

Millstone Point 1 utilizes ICj and FWCI instead of RCIC and HPCI.

2 Stuck open relief valve.

N NUMBER: 66996 October 22, 1971

October 10, 1971 ED: Turbine control system, pressure relief OLVED: Relief valve sion and wire drawn seat NTEREST: Loss of Coolant Accident (small)

ENCE: Pressure transient and blowdown at Millstone Point 1 Millstone Point 1

50-245 BWR ICAL RATING: 660 MWe 1 yr INEERS: Ebasco orth East Nuclear Energy Company 5 miles SW of New London, Conn.

A NG CONDITION: 680MWe E TYPE OF FAILURE: (a) inadequate performance; (b) failed to start; (c) made inoperable;O failed to close.

HOD: Operational event