ML20084R563

ROs 50-249/75-18,17 & 16:on 750304,LPCI Valve 3-1501-5A Experienced Thermal Trip After Going Closed.Cause Unknown. Valve Returned to Open Position

ML20084R563
Person / Time
Site:	Dresden
Issue date:	04/03/1975
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
229-75, RO-50-249-75-16, RO-50-249-75-17, RO-50-249-75-18, NUDOCS 8306150192
Download: ML20084R563 (2)

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6. . ' Chicago. Illinois 60690 BBS LTR. #229-75 Dresden Nuclear Pceer Station R. R. #1 Morris, Illinois 60450 April 3, 1975

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Mr. James G. Keppler, Regional Director I; '

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Directorate of Regulatory Operations-Region III ~

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U. S. Nuclear Regulatory Coznission ' " '- '

799 Roosevcit Road '

. Glen Ellyn, Illinois 60437 ,

SUBJECT:

REPORT OF UNUSUAL EVCIP PFR SECTION 6.6,0 OF THE TECHNICAL SPECIFICATIONS THERMAL TRIP OF LFCI VALVE 3-1501-SA"

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Reference:

1. Regulatory Guide 1.16 Rev. 1 Appendix A -

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2. P,& ID Drawing M360 ,/ , 1? r[p/ ,Il'g\^

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Incident Reports 50-249/1975-18,17,and16. ". - p 3  ;.

Report Date: April 3, 1975 \

Occurrence Date March 4, 1975 x .

Facility: Dresden Nuclear. Power Station, Morris, Illinoin CONDITID'IS PRIOR TO OCCURREOU Pribr to thermal trip of LPCI valve 3-1501-5A the unit was in the "run" mode with thomal power at 1250 megawatts. Electrical load at the time of the occurrance was 410 megawatts.

DESCRIITION OF OCCURRENCE On March 4, 1975 at about 0230 hours0.00266 days <br />0.0639 hours <br />3.80291e-4 weeks <br />8.7515e-5 months <br /> LPCI valve 3-1501-5A cxperienced a themal trip after going closed. Tho trip occurred while LPCI ourveillance testing uaa in progress. Following the trips attempts were made to open the valve without

( success for two minutes. After a two minuto period, the themal overload automatically reset and the valve opened without a thomal trip. -

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! DESIG'iATION OF APPARENT CAUSE OP OCCURRF2.'CE On investigation it was detemined that the valve motor for the }-1501-5A valve was drawing about 3 5 mpa during nor.nl operation. The notor full load current is rated at 2.9. m.pa.

rated at Ituasfurtherdicoveredthatthe)h8fis 15 ft. lbo, torque which is the same as the motor for the 8306150'192 750403 PDR ADOCK 05000249 .

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S PDR-CO SEN.T REGION

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.- . - Mr. Jtees'G. Keppler April 3, 1975

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0 3.-1402 4 & B valvo of the core spray system. The 3-1402-4A & B valves are presently under investigation due to a similiar failure of the valve motors.

(Incident Reports 50-249/1975-18,17,and16). ,

ANAIXSIS OF OCCURREI'CE The failure of the 3-1501-5A valve to close did not place the safety of the plant or public in jeopardy. The 3-1501-5A valve is nomally in the open position during operation. Failure of the valve to close would not have hampered the design function of the LPCI syste:n.

CORRB7tIVE ACTKW, No in::sediate correative action was required because the valve was returned to the open. position, which is the safe position. Additional corrective action required that all the 3-1501-5 valves be placed in the open position while opera-ting. Also, two new 15 ft. lbs motors have been ordered to replace motors on the >1402-4A and 4B valves of core spray which er.hibit the same type of failures. Following the delivery of the motors a test vill be cado with the new motors to determine the cause of the problem. During the 1975 refueling outage which is scheduled for April 30, 1975 the 3-1402-4A valve will be disassembled and inspected. The results of this inspection will also help in determining the cause of the problem.

FAILURE DATA This is the first time a failure has been noted of this type on the 3-1501-5A i valve. However, the Core Spray valves 3-1402-4A and B are presently under investi6ation for a similar problem.

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. B. S ephenson Superintendent -

BBS:TEL:smp File /hRC 9

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