Technical emergency measures in Swiss nuclear power plants - pressurized water reactors

Three pressurized water reactors are at present in operation on the sites of Goesgen and Beznau in Switzerland. The development and introduction of emergency measures in Switzerland was characterized mainly by the exploitation of international experience and the conclusions drawn from major accidents, or near-accidents, as well as the systematic analysis of accident sequences exceeding the design basis within the framework of plant-specific probabilistic safety analyses. In the mid-eighties, evaluation resulted in a program of measures against major accidents supervised by the authorities. One of the requirements contained in the program was the establishment of a complete plant-specific PSA (initiating events in the plant plus all overriding in-plant events and level-1, level-2, and outage PSA external events). The most important technical plant requirements to be met by emergency measures were laid down in HSK Guideline R-103: - Requirements for protection of the primary containment. - Requirements for protection of the plant personnel. - Rules of procedure. - Accident instrumentation. PSA serves as a tool for optimizing emergency measures. On the basis of a realistic plant-specific PSA model, information can be generated about the effects of emergency measures. The status of the emergency measures put into effect and the structure of the emergency regulations are shown for Swiss plants in a comparison with the requirements laid down in HSK Guideline R-103. (orig.)