ML20024E837

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Forwards Oyster Creek Vital AC Sys Automatic Transfer Switches,Coordination Study Re Adequacy of Protective Devices (Ref SEP Topic VI-7.C.1,App K)
ML20024E837
Person / Time
Site: Oyster Creek
Issue date: 09/01/1983
From: Fiedler P
GENERAL PUBLIC UTILITIES CORP.
To: Crutchfield D
Office of Nuclear Reactor Regulation
Shared Package
ML20024E838 List:
References
TASK-06-07.C1, TASK-6-7.C1, TASK-RR NUDOCS 8309070125
Download: ML20024E837 (2)


Text

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GPU Nuclear

_ NggIgf 100 Interpace Parkway Parsippany, New Jersey 07054 201 263-6500 TELEX 136-482 Wr;;ar's Direct Dial Number:

September 1, 1983 Mr. Dennis M. Crutchfield, Chief Operatirg Reactors Branch #5 4 Division of Licensing U.S. Nuclear Regulatory Comission  !

Washirgton, D. C. 20555 Dear Mr. Crutchfield;

Subject:

Oyster Creek Nuclear Generatirg Station Docket No. 50-219 SEP Topic No. VI-7.C.1, Appendix K -

Electrical Instrumentation and Control Rereview At Oyster Creek Nuclear Generatirg Station there are five (5) automatic bus transfers (ABT) and two (2) auto-contact transfers (ACT) in the vital AC distribution system. Durirg the integrated assessment of the subject SEP topic, the NIC staff recommended that these ABT/ ACTS be removed or the circuits be otherwise modified to ensure that faulted loads will not be transferred.

By letter dated May 28, 1982, GPU Nuclear proposed to perform a coordinated load and circuit breaker analysis to assure proper coordinated protection of the circuits to and from the existing ABT/ ACTS. The attached report (Oyster Creek Vital AC System Autmatic Bus Transfer Switches, Coordination Study) summarizes our recent study of the protective devices.

The study reviews each ABT/ACT circuit individually for its effect on the electrical irdependence of the vital AC distribution system. The evaluation is based on the adequacy of protective devices and their coordination for a fault downstream of the ABT/ACT.

The results of the evaluation establish that each protective device is adequately applied and even though a fault could be transferred by an ABT/ACT from one power train to another, the protective devices will prevent the loss I of redundant safety loads. A fault anywhere on a circuit to or from an ABT/ACT, thus will not cause the loss of power to the redundant safety loads.

Additionally, the results of our probabilistic risk anclysis (PRA) indicate that the automatic transfer switches in the vital AC distribution system do not contribute in any significant way to the failure probability of any key mitigation system and, consequently, to the core melt frequency.

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GPU Nuclear is a part of the General Public Utilities System

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  • It is, therefore, concluded that removal of the ABT/ ACTS or modification of the circuit is not considered necessary.

Very truly yours, P

Vice President and Director Oyster Creek 1r cc: Aministrator Region I U. S. Nuclear Regulatory Comnission 631 Park Avenue Kirg of Prussia, Pa. 19406 NIC Resident Inspector Oyster Creek Nuclear Generatirs Station Forked River, NJ 08731 4

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