Modelling the loss and recovery of electric power

General analytical models are developed to quantify the frequencies and durations of transients involving loss of off-site power or total loss of alternating current. Such transients are often important initiating events in probabilistic safety studies of nuclear power plants. Recursive equations are developed for the frequencies of production loss events when there is one or more standby systems available and a grace period to start a reserve unit. The methodology is illustrated with numerical applications.