Publications Details
Cable failure modes and effects risk analysis perspectives
One effect noted during the March 1975 fire at the Browns Ferry plant is that fire-induced cable damage caused a range of unanticipated circuit faults including spurious reactor status signals and the apparent spurious operation of plant systems and components. Current USNRC regulations require that licensees conduct a post-fire safe shutdown analysis that includes consideration of such circuit effects. Post-fire circuit analysis continues to be an area of both technical challenge and regulatory focus. This paper discusses risk perspectives related to post-fire circuit analysis. An opening background discussion outlines the issues, concerns, and technical challenges. The paper then focuses on current risk insights and perspectives relevant to the circuit analysis problem. This includes a discussion of the available experimental data on cable failure modes and effects, a discussion of fire events that illustrate potential fire-induced circuit faults, and a discussion of risk analysis approaches currently being developed and implemented.