Modelling and Safety Assessment of Programmable Platform Based Information and Control Systems Considering Hidden Physical and Design Faults

Abstract

The information and control system (I&CS) of Nuclear Power Plant (NPP) is considered as a set of three independent hardware channels including on-line testing system. NPP I&C system’s design on programmable platforms is rigidly tied to the V-model of the life cycle. Functional safety and availability during its life cycle are assessed using Markov models. Markov models are used to assess availability function and proof test period. The basic single-fragment model MICS01 contains an absorbing state in case of hidden faults and allows to evaluate risks of “hidden” unavailability. The MICS02 model simulates “migration” of states with undetected failures into states with detected faults. The results of Markov modeling (models MICS01 and MICS02) are compared to evaluate proof test period taking into account requirements for SIL3 level and limiting values of hidden fault probabilities.