Transient and accident analyses for justification of technical solutions at nuclear power plants

The general safety requirements for Finnish nuclear power plants are presented in the Government Resolution (395/1991). The most essential safety principle is to consider anticipated operational transients and postulated accidents in the design of nuclear power plants. This principle requires the design of the reactor and its cooling system to be such that the plant can, with a sufficient safety margin, be maintained in a safe state under the aforementioned plant conditions. This also requires that the plant be equipped with reliable safety systems having passive or active operational principles. In addition to anticipated operational transients and postulated accidents, provision shall be made for the possibility of severe accidents. According to section 6 of the Government Resolution (395/1991), the fulfilment of the safety requirements is to be demonstrated by the necessary experimental and analytical methods. In this guide, the requirements for the transient and accident analyses of the nuclear power plant are given