Modelling and simulation of general purpose cold traps

The control of tritium in present and future fusion plants is important for the viability of fusion as a power source. This theoretical study simulates a generic cold trap model which describes the thermal and control principles governing the behaviour of general cold trap assemblies. The model can also be applied to gas separation or purification in chemical processing, archeometry sample processing and process industrial applications, typically in the range of 80-200 K. It applies to any trap configuration and is used to simulate the dynamic behaviour, the thermal and mass transfer processes and the control parameters in order to optimise the performance. In the special case of hydrogen isotope separation (including tritium), as in fusion applications, the model is used for (a) gaining an in-depth knowledge of the packed bed control system and operation under tritium gas, (b) minimising any unnecessary testing and stressing of the cold trap. The results of the calculations show that the controller and cold trap parameters, like the heater power input, gas mixture and coolant mass flow rate, are specific to the given cold trap configuration and dimensions. (author)