Validation of European computer codes used for fusion safety analysis

The development of safety files for fusion plants rely on several calculations and safety codes used for computing various situations and events. Within the future safety files, several safety related simulation codes are used for demonstrating the safe behaviour of the concerned machine and the limited impact on the population and environment in various situations from the normal operation up to the largest credible accident. These codes are ranging from neutronics calculation and dose assessment to the modelling of accident sequences and thermo hydraulics analysis in normal, incidental and accidental situations. An important aspect for the safety analysis process is the validation of the models and the reliability of the calculation results. This necessitates simulating in actual facilities physico-chemical situations related to the specific validation needs of the concerned codes. Several of these computer codes were already applied for long time in the fission industry and have been validated for this purpose. Fusion, however, requires the development of specific codes or the extension of existing ones to deal with all fusion specific conditions. These newly developed or extended computer codes have to be validated by conducting representative experiments or by cross checking various codes based on different modelling approaches . The paper reviews the most important computer codes applied for fusion plants and ITER safety analysis together with the validation efforts carried out in the various European Member States. Experimental data and facilities used for this purpose will also be presented. Finally, the paper addresses the still remaining gaps in the code validation and provides guidance on needs for further code development