05000029/LER-1985-006, Forwards LER 85-006-00

Forwards LER 85-006-00

ML20137B476
Person / Time
Site:	Yankee Rowe
Issue date:	12/20/1985
From:	St Laurent N YANKEE ATOMIC ELECTRIC CO.
To:	Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
NUDOCS 8601150406
Download: ML20137B476 (1)

LER-2085-006, Forwards LER 85-006-00

Event date:
Report date:
0292085006R00 - NRC Website

text

,

YANKEE ATOMIC ELECTRIC COMPANY Rowe, Massachusetts 01367 Yamass

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December 20, 1985 U.S. Nuclear Regulatory Comission Region I 631 Park Avenue King of Prussia, Pennsylvania 19406 Attention: Dr. Thomas E. Murley, Regional Administrator

Reference:

(a) License No. DPR-3 (Docket 50-29)

(b) YAEC Letter to NRC dated May 8,1980, " Response to IE Bulletin No. 80-04"

Subject:

Licensee Event Report 50-29/85-06, Revision 0 Condensate Pump Trip Circuit Inoperable

Dear Sir:

In accordance with 10 CFR 50.73(a)(2)(ii), the attached Licensee Event Report, is hereby submitted.

Very truly yours,

& s,c.o' [ ' sus *C '

V Normand N. St. Lauren V Plant Superintendent DAR/nm Enclosure cc: [3] NSARC Chairman (YAEC)

[1] Institute of Nuclear Power Operations (INP0) h00YD l

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E esdtC Fere 300 W 8. NUCLE A2 & EOULA704 7 CoasassessoN APPROv53 OMe mio 3:304:0e LICENSEE EVENT REPORT (LER)

DOCA ti Nunset M (2e PAGE G

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On November 20, 1955 with the plant in Mode 6 for refueling, during surveillance testing, the three main condensate pump circuit breakers failed to open on receipt of a simulated Containment Isolation Systen (CIS) "A" trip signal and a coincident Non-Return Valve (NRV) Main Steam Line Low Pressure trip signal. The trip circuit was declared inoperable. A four hour notification was made to the NRC.

The trip circuit failure was caused by an open circuit resulting from stripped threads on the test plug at point 1 on circuit terminal block 906. To ensure this condition does not recur, the test plug configuration was modified with a permanently instelled jumper between the terminals. The circuit was tested satisfactory and declared operable at 2155 hours0.0249 days <br />0.599 hours <br />0.00356 weeks <br />8.199775e-4 months <br /> on November 20, 1985. The open, automatic, trip circuit would not have prevented the pumps from being tripped manually from the Control Rcom. There was no adverse effect to the health and safety of the public as a result of this event.

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NRC Form 384A U $ NUCLE Al E EIULATZY Cowwa$$504 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION AreRovfo ove mo siso-e x i EXPIRES 8/3t/BS F ACILITY NAME til DOCKET NUMGER 12) LER NUMGER tel PAGE13' VEAR 80 7,{( (' ,N Yankee Nuclear Power Station Rowe, Massachusetts 0 l510 lo lo l0 l 2 l 9 8l5 -

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0l0 012 0F 0 l2 TEXT W more spece a recuret ese empeoner MC Form J664 W lin On November 20, 1985, with the plant in Mode 6 for refueling, during surveillance testing, the three main condensate pump circuit breakers failed to open on receipt of a simulated Containment Isolation System (CIS) "A" trip signal and a coincident Non-Return Valve (NRV) Main Steam Line Low Pressure trip signal. The trip circuit was declared inoperable and a four hour ENS notification was made to the NRC.

The surveillance test of this circuit is performed during each refueling outage. The last test was June 6,1984.

The failure of the trip circuit was due to an open circuit caused by stripped threads i on the test plug at point 1 on circuit terminal board 906. To ensure this condition does not recur, the test plug configuration was modified with a permanently installed jumper between the terminals. The circuit was tested satisfactory and declared operable at 2155 hours0.0249 days <br />0.599 hours <br />0.00356 weeks <br />8.199775e-4 months <br /> on November 20, 1985. This is the first reportable occurrence of a test plug / terminal block failure of this type.

The circuit provides early termination of feedwater flow in the event of a steam line break inside the Vapor Container (VC). It operates on coincident NRV closure and CIS (Containment high pressure) trip signals. These two conditions are indicative of a main steam line break (MSLB) in the Vapor Container. If a MSLB had occurred in the VC during the time that the trip circuit was inoperative, the condensate pumps could have been tripped manually by the Control Room Operators (the open, automatic trip circuit would not have prevented the pumps from being tripped manually).

In addition, plant operating procedures require that, in the event of a reactor scram, the Control Room Operators immediately confirm the tripping of the Boiler Feed Pumps, and also that they close the motor operated and the air operated feed line isolation valves, thereby terminating feed flow.

A review of the analyses of potential accidents for which the condensate pump trip circuit provides protection to the plant, specifically, recriticality and containment excess pressure, show that operator immediate actions, in lieu of automatic actions, would be adequate to terminate feedwater flow. Therefore, there was no adverse effect to the health and safety of the public as a result of this event.

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