Interaction of the fuel injected in the torus of the International Thermonuclear Experimental Reactor (ITER) with the wall surrounding the plasma is characterized by a large number of physical and chemical processes which lead to the retention of tritium. Understanding of the dynamic behavior of these processes vary with some of the processes being better understood than others. Experimental data from tokamaks with high fuel flow inside the torus is non-existent, thus contributing to this lack of understanding. Conversely, the tritium plant dynamics are much more clearly understood. However, since the tritium retention inside the torus will affect the downstream tritium plant reprocessing systems during reactor operation, tritium plant dynamics in an integrated setting will need to take into account the aforementioned torus tritium retention and dynamics.

The tritium fuel cycle has been recently modeled by integrating modules representing different parts of the fuel cycle. Tritium plant modules have already been developed for use within such an integrated model. With respect to the torus, detailed models of tritium retention for specific physicochemical processes have been developed, but such detailed models are of limited usefulness in an integrated model. Therefore, an appropriate torus module for use within an integrated dynamic fusion fuel cycle tritium model is needed.

In this paper, we develop a simplified model for tritium-related processes taking place inside the torus chamber in order to reduce the computation time required. All the tritium retention processes are identified and simplifications are appropriately applied where needed. For example, a saturation model is applied to the surface layer as validated from experimental data. On the other hand, where uncertainties predominate in the calculations, models with less detail and more generalizations are utilized. Such is the case with respect to codeposition where the fraction of the fueling rate that is codeposited is the main parameter used.

Results are obtained which show the effects of the inclusion of such a simplified torus module in an integrated fuel cycle simulation. For example, the effects on the ISS due to isotopic exchange of tritium with protium or deuterium is examined. The effects from tritium codeposition are also analyzed for a mixture of fueling and conditioning scenarios. Conditioning requirements are proposed using as a basis present day conditioning achievements for a variety of methods. Protium, deuterium, and tritium retention are analyzed in detail for a number of possible operating scenarios.