ML20199E916

Final Significant Const Deficiency Rept Re Overspeed Trip on Emergency Diesel Generator Mfg by Colt Industries.Initially Reported on 860213.All Colt-Pielstick PC-2 Engines Will Be Modified by 860415

ML20199E916
Person / Time
Site:	Hope Creek
Issue date:	03/07/1986
From:	Corbin McNeil Public Service Enterprise Group
To:	Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
NUDOCS 8603270485
Download: ML20199E916 (3)

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Pubbc Service Electne and Gas Company Corbin A. McNeill. Jr. Pubhc Service Electoc and Ga s Company P O Bov 23tiHancocks Ondge. NJ 08038 609 33+#00

%ce Ptes dent Nrev March 7, 1986 Dr. Thomas E. Murley, Administrator U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region I 631 Park Avenue King of Prussia, Pennsylvania 19406

Dear Dr. Murley:

SIGNIFICANT CONSTRUCTION DEFICIENCY DIESEL AIR START SYSTEM HOPE CREEK GENERATING STATION On February 13, 1986, a verbal report was made to Region I, Office of Inspection and Enforcement representative, Mr. M.

Connor, advising of a potentially significant construction deficiency concerning an overspeed trip on our Emergency Diesel Generators. The following final report is provided in accordance with 10CFR50.55(e).

Description of the Deficiency Colt Industries, manufacturer of our Emergency Diesel Generators has determined that the Diesel Air Start System, which actuates I the governor rack boost is not vented from the rack boost promptly I

after start signal is terminated. This causes the boost to restrain the governor and create a potential overspeed coridition. An l overspeed trip had been reported to Colt Industries by Public l Service of New Hampshire, Seabrook Nuclear Plant, Unit 18. Inves-tigation of the problem at Seabrook Station revealed that the source of air pressure for the rack boost cylinder was staying on (at a high pressure) for up to 15 seconds beyond the time that the air start process was otherwise terminated. This condition is caused by improper venting of the rack boost cylinder. It was always thought that the air pressure in these headers was vented out through the engine, and/or the air start distributor assembly.

It has been determined that this is not always the case.

A k4 S

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Dr. T. E. Murley 2 3-7-86 Safety Analysis The Emergency ~ Diesel Generators are safety related and supply power to engineered safeguard equipment and other safety related equipment required for safe shutdown of the plant if offsite power is not available. Had this problem gone undetected and uncorrected, there was the potential for loss of one or more of the four standby Diesel Generator sets. We, therefore, consider this condition to be reportable in accordance with 10CFR50.55(e).

Corrective Action To prevent any further occurrences, or the possibility of same, Colt Industries is recommending that all Colt-Pielstick PC-2 engines in nuclear service be modified to positively vent the air from the rack boost cylinder, and its associated shuttle valves, by making the source of that air supply from the pilot air lines that control the main air start admission valves.

The pilot air lines are controlled by solenoid valves that receive the start signal from the control system. These are three way valves which positively vent the pilot signal to atmosphere when the control system senses that the engine is started.

Testing conducted at Seabrook Station on the unit that had experienced the problem demonstrated the positive action of this change in air source for the rack boost cylinder.

Startup Deviation Report No. KT-1457 has been generated to complete Colt's recommended modifications to our Emergency Diesel Generators. The completion date will be April 15, 1986.

Sincerely, N\

C Office of Inspection and Enforcement Division of Reactor Construction Inspection Washington, D. C. 20555 NRC Resident Inspector - Hope Creek P. O. Box 241 Hancocks Bridge, NJ 08038 w

O Dr. T. E. Murley 3 3-7-86 C Records Center Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlanta, GA 30339

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