ML20043D374

Safety Evaluation Accepting Use of Fiber Optic Cables as Isolation Media Between safety-related Sys & SPDS

ML20043D374
Person / Time
Site:	Farley
Issue date:	05/30/1990
From:	Office of Nuclear Reactor Regulation
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ML20043D358	List: ML20043D374
References
NUDOCS 9006070436
Download: ML20043D374 (1)

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ENCLOSURE 3 SUPPLEMENTAL SAFETY EVALUATION REPORT BY THE OFFICE OF NUCLEAR REACTOR REGULATION SAFETY PARAMETER DISPLAY SYSTEM ISOLATION DEVICES JOSEPH M. FARLEY NUCLEAR PLANT, UNITS 1 AND 2 DOCKET N05. 50-348 AND 50-364 1.

INTRODUCTION In order to satisfy the NRC requirements concernin Display System (SPDS) Alabama Power Company (APC)g the Safety Parameter

, the licensee for the Joseph M. Farley Nuclear Plant, Units 1 and 2 (Farley), submitted a Safety Analysis Report (SAR) by letter dated. November 30,1983(Reference 1).

I Based on an analysis of the SAR and additional responses to requests for informati*.1, a Safety Evaluation Report (SER--Reference 2) was issued by the staff on June 12, 1985.

In the SER, the staff approved the isolators used at Farley with the exception of the isolation devices used between the core exit temperature monitoring system and the SPDS. These isolation devices had not been procured at the time that the SER was written.

The licensee committed to address the adequacy of these isolators for this application, including testing for maximum credible faults applied to the isolators in the transverse mode. The qualification of the isolators to be used in the core exit temperature monitoring system is a confirmatory item in Section I!!.E of the SER.

II. DISCUSSION AND EVALUATION By letter dated March 31,1986(Reference 3),thelicenseeforwardedthe details of the temperature monitoring system design. The desi the thermocouples to feed Class IE isolators, which, in turn, gn calls for input to a ClassIEInadequateCoreCoolingSystem(ICCS) processor. The ICCS processor is powered from a power source belonging to the same train as the processor. The interface between the Class IE ICCS processor and the non-Class 1E SPDS is achieved using a fiber-optic cable.

The staff has accepted the use of fiber-optic crbles as the isolation media between safety-related systems and the SPDS.

Fiber-optic cables have the following properties which qualify them as ideal isolators:

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