Optimisation of operating parameters for plasma facing components detritiation

Abstract

Within the framework of management of waste produced by fusion facility, the presence of high tritium content in large pieces is very specific. This question is very sensitive in the case of maintenance of plasma facing components (PFC). In order to reach several goals (tritium recovery, limitation of tritium content in the waste), several treatment methods have been analysed and thermal detritiation is selected as a reference process. In the case of ITER facility a tritium recovery station based on this technique is foreseen. In order to better understand which parameters have important influence on the efficiency of the treatment (detritiation factor), a recall of the process principle and of the main data concerning tritium behaviour in different materials is done. For example, low tritium diffusion coefficient in Be which is the material of the first layer on some components can limit drastically the process performance. In this paper a recall of the different process parameters is presented. Some important parameters are selected in order to lead a sensitivity study on adequate variation domains. It allows studying several scenarios of treatment and analysing the consequences of them. The main parameters of this study are the level of temperature, the duration of treatment, the renewal rate of the furnace atmosphere, the presence of Be or not. The main response to this sensitivity analysis is the detritiation factor, however some other consequences such as tritiated water flow rate and also tritium concentration in water are evaluated. Then the consequences of change of operating parameters are compared in order to identify what could be the most appropriate operating domain.