Tritium and dust source term inventory evaluation issues in the European DEMO reactor concepts

Abstract

Fusion reactors represent a future evolution of the nuclear technology improving the world-wide energy portfolio. The experimental fusion reactor under construction (ITER) and the planned industrial fusion reactors (DEMO) are large and complex facilities. For their operation it is necessary to ensure safety limiting of radiological and mobilizable source terms inventory, such as tritium and radioactive dust.The source term inventories shall be assumed in the establishment of operational and safety requirements for DEMO, as well as performing safety analyses for commercial fusion devices. In the last few years a methodology for evaluation of tritium and dust source term inventory has been proposed in the framework of the EUROFusion project. The basis of the methodology is a semi-empirical approach to scale the radioactive inventory limits implemented in ITER. The source term amounts derived for DEMO will supply a guidance for safe operation of future fusion reactors. The development of methodology has to be completed and refined because of the lack of validation versus adequate experimental data and rules for extension to different scenarios.The aim of this work is assessment of the developed methodology for evaluation of the source terms inventory versus JET operating limits for tritium and versus the dust control strategy adopted in ITER for the dust. The updating of the methodology for the dust and T inventory was carried out in line with the current DEMO design. The new values of the in-VV source terms were achieved. These values are recommended to be used for the safety assessment of the fusion reactor. Calculated DST and TST inventories’ values show a reasonable agreement with scaled ITER or assessed JET limits.