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1 FE8 f 519h Jersey Central Power & Light Company Docket No. 50-219 6
Attention:
Mr. R. H. Sims, Vice President Madison Avenue at Punch Bowl Road Morristown, New Jersey 07960 Gentlemen The attached Directorate of Regulatory Operations Bulletin No. 73-1
" Faulty Overcurrent Trip Delay Device in Circuit Breakers for Engineered l ~'
Safety Systems," is sent to you to provide you with information we re-ceived from the Wisconsin Electric Power Company' and the Rochester Cas j
and Electric Corporation concerning the Point Beach and Ginna pressurized water reactor facilities. This information may relate to the design, fabrication and performance of certain equipment at your facilities.
j Action requested on your part is identified in Section B of the Bulletin.
f Sincerely, i
I I
James P. O'Reilly Director
Enclosure:
As Stated Mr. T. J. McCluskey, Station Superintendent cc:
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Attachment I Bulletin 73-1 FAULTY OVERCURRENT TRIP DELAY DEVICE IN CIRCUIT BREAKERS FOR ENGINEERED SAFETY SYSTEMS l
We have received information from two licensees relating to the failure of circuit breakers in engineered safety systems. These circuit breakers, Westinghouse Models DB-25, DB-50 and DB-75, are used extensively at both PWR and BWR facilities. These failures, which could negate operation of engineered safety system components, were attribuced to faulty overcurrent-I trip delay devices. Westinghouse has formulated an on-site testing program j'
to determine if the time delay devices are faulty and is developing a new j
and cap-for the dashpot used in the time delay devices. Similar make and i
model circuit breakers, when used for scram purposes, do not require the overcurrent trip feature and, therefore, are not included in this pro-blem. -Pertinent details relating to this problem are contained in Section A below. Action requested by this Bulletin is contained in Section B.
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-l A.
Description of Circumstancee 1
i Plant A I'
p During the performance of the routine monthly surveillance test of the Safety Injection System, the pump motor tripped as it approached operating speed. A second attempt to start the pump produced'the same result. The cause of the pump trip was at-tributed to malfunction of an overcurrent trip device. This
_ device, which has an adjustable time delay, tripped out the pump motor on starting current because of leakage in the time delay dashpot. Subsequent====4 nation of the dashpot disclosed a crack in the end cap of the air chamber. The crack per-mitted air to leak into the chamber at an excessive rate, 4
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Form AEC.318 (Rev. 9.$3) AECM 0240 l=
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. reducinr tl? time delay from approxinate?y 45 seconds to 5.
second s. Testing of similar model breakers ecuipped with the overcurrent trip delay feature revealed four additional units with low trip delay times caused by cracks in the end caps.
Approxinately 25 circuit breakers of the type described are utilized to energize components of engineered safety feature systems at this facility.
Plant,B A 480 volt AC bus circuit breaker tripped open when the auxiliary buildine supply and exhaust fans were started simultaneously. The cause of the failure was attributed to a cract in the end cap of the cine delay dashpot in the overcurrent trip device. The trip delav unit and the circuit breaker in cuestion are sirilar to the units which failed at Plant A.
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The cracks found in the end caps of the tir+ delay dashpots are con-sidered a connon mode of failure.
E, Action Renuceted of the Licensec It is requested that you deternine whether safety rel'ated (Class It) circuit breakers of the described nake and e.odels v T'irinp overcurrent trip tinc delay features are installed at your facil-itics and provide thin of fice with your findinco.
If the suFject brenhers are installed, please include in vour re-socnse a description and the results of your prorrnn to deternine if you have any faulty overcurrent trip time delav devices installed For and the scheduled conviction date of your corrective actions..
facilities currently under construction, please inferr us of your plans to assurn that the appropriate nodification has been incor-porated in all safety related circuit breakers of the type described that have been or will be installed at your facility. This infor-nation should be provided to this office, in writing, within forty-five days of your receipt of this letter.
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