Safety classification of mechanical components for fusion application

The safety classification of Structures, Systems and Components (SSCs) used in nuclear power plants provided in various IAEA guides and other international standards is mostly aimed at the fission applications. For fusion the main safety functions are related to the confinement of radioactive materials and the limitation of personnel radiation exposure and not with heat removal or reactivity control. Similarly, various plant states and events with their severity levels specific to a fusion plant are different. Ranking SSCs according to their significance to safety helps to determine the design, quality and manufacturing requirements to be applied to individual SSCs. Classification is a top down process that begins with a basic understanding of the plant design, its safety analysis and how the main safety functions will be achieved. On the basis of the classification, a complete set of engineering rules must be specified which then dictate the codes and standards that are used by the designers. Guidelines for identification and classification of SSCs that are important to safety for Fusion applications have been provided considering the current practice and highlight the differences in the approaches used to identify and classify SSCs that are important to safety.