An integrated methodology to predict the likelihood of spurious actuation of AC circuits due to fires in commercial nuclear power plants

Research efforts by the nuclear power industry and, most recently, its regulatory agency, the U.S. Nuclear Regulatory Commission (USNRC), have provided information useful for risk-informed analysis of the effects of spurious actuation (“hot shorting”) of alternating current (AC) electrical circuits at nuclear power plants. The results from these efforts have been integrated into a methodology to predict the likelihood of spurious actuation of AC circuits due to fires in commercial nuclear power plants.

► Three separate models for fire-induced AC circuit electrical “failure” have been integrated.
► The “Cable Failure” model predicts both the time and probability of thermally induced failure.
► The “Hot Short Probability” model estimates the likelihood of inadvertent equipment actuation.
► The “Hot Short Duration” model predicts the probability of double or triple hot short concurrence.
► The integrated model is demonstrated via an example application.