Defense-in-depth concept for nuclear power plant normal plant control systems using probability analysis

The author describes some of the problems facing a designer and the solutions adopted to satisfy a probability approach to normal controls system design. This approach is intended to improve the overall plant reliability and minimize the probability of reactor trip. Of prime importance is knowledge of the reliability data of nuclear plant components and components failure rates. This can be achieved by a systematic analysis of field experience gained in operational power plants. The main importance of the proposed method lies in its ability to identify areas of relative weakness of a normal control system, which when rectified would provide an optimum design, and to improve the availability of nuclear power plants