Simulation based reliability evaluation of AC power supply system of Indian Nuclear Power Plant

Purpose - The purpose of this paper is to demonstrate the potential of simulation approach for performance evaluation in a complex environment with a case of application from Indian Nuclear Power Plant. Design/methodology/approach - In this work, stochastic simulation approach is applied to availability evaluation of AC Power supply system of Indian Nuclear Power Plant (INPP). In the presently followed test, maintenance policies on diesel generators and circuit breakers are considered to exactly model the practical scenario. System success logic incorporates the functional dependencies and dynamics in the sequence of operations and maintenance policies. In each iteration (random experiment), from simulated random behaviour of the system, uptime and down time are calculated based on system success logic. After sufficient number of iterations, unavailability and other required reliability measures are estimated from the results. Findings - The subsystems of AC Power Supply System of NPP are having multi-states due to surveillance tests and scheduled maintenance activities. In addition, the operation of DG involves starting and running (till its mission time) which is a sequential (or conditional) event. Furthermore, the redundancies and dependencies are adding to the complexity. Originality/value - This paper emphasizes the importance of realistic reliability modelling in complex operational scenario with Monte-Carlo simulation approach. Simulation procedure for evaluating the availability/reliability of repairable complex engineering systems having stand-by tested components is presented. The same simulation model finds application in importance measures calculation, technical specification optimization and uncertainty quantification.