United States Nuclear Regulatory Commission - Protecting People and the Environment

Test Results (NUREG/CR-7100, Final Report)

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Publication Information

Manuscript Completed: December 2011
Date Published: April 2012

Prepared by
S.P. Nowlen, J.W. Brown, T.J. Olivier, F.J. Wyant

Sandia National Laboratories
Risk and Reliability Analysis Department 6761
P.O. Box 5800
Albuquerque, NM 87185-0748

G. Taylor, NRC Project Manager

NRC Job Code N6579

Office of Nuclear Regulatory Research

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Abstract

This report presents the results of a series of fire tests performed to assess cable failure modes and effects behavior for direct current (dc)-powered control circuits. The project, known as the Direct Current Electrical Shorting in Response to Exposure Fire (DESIREE-Fire) test project, was sponsored by the U.S. Nuclear Regulatory Commission Office of Nuclear Regulatory Research. The tests were performed by and at Sandia National Laboratories in Albuquerque, NM. The program was conducted with the collaboration of the Electric Power Research Institute (EPRI) and its member utilities. EPRI representatives participated in all phases of program planning, execution, data analysis, and data reporting by providing both peer review and in-kind material support.

The test program involved a series of both small- and intermediate-scale fire tests. Each test exposed one or more electrical control cables commonly used in the existing fleet of U.S. nuclear power plants (NPPs) to fire exposure conditions. Each test cable was connected to one of several circuit simulator units designed to mimic the behavior of typical NPP components. The simulated dc-powered control circuits included motor-operated valves, solenoid-operated valves of various sizes, and a medium voltage circuit breaker unit. Cable electrical performance is monitored throughout each test to determine both the timing and mode of circuit faulting behavior. This report focused on a factual reporting of the test program and test data. Insights regarding dc-powered control circuit cable failure modes and effects are to be addressed separately via a Phenomena Identification and Ranking Table (PIRT) exercises to qualitatively rank fire-induced electrical circuit phenomena and an expert elicitation to provide quantitative numerical estimates to the likelihood of various fire-induced circuit failure configurations. One PIRT panel focused on electrical behavior and the second on implications for probabilistic risk assessment.

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