Experimental activities will be supported with mass transport modeling of the experimental setups. Mass transport models of H-isotopes will be developed at two different scales. Firstly, system level models will be used for large systems over long time scales. This approach will be used for modelling the complete CLIPER loop which allows computing key parameters such as sensor signals, mass losses and H-isotope retention. System level models are based on certain simplifications that allow modelling large systems in small amounts of time. Nonetheless, this method is not expected to be accurate enough for capturing the specifics of the mass transport in the extractor prototypes (both membrane-based and free-surface configurations). For this reason, 3D Finite Volume Methods (FVM) and Finite Element Methods (FEM) will be employed as well for high accuracy at small spatial scales. This second kind of models will include the detailed fluid dynamics of the PbLi flow and the evolution of the H-isotopes in both extractor prototypes described in O1.
- O3.1 – Experimental campaign design The design of the experiments will be assisted by the predictions made by numerical models. Indeed, models can be a useful tool to determine if the outcome signals (extraction fluxes and deuterium partial pressures) are expected to be in range of the allowable detectors under a set of particular conditions. If the constraints of the PbLi loop make it possible, the models should replicate the same controllable conditions in both extraction systems (free-surface and membrane-based) across a range of characteristics like mass flow rate, deuterium concentration at the inlet, temperature, etc. One specific point of the PbLi is that, when exposed to neutrons in a real fusion environment, may contain activated products mainly coming from the chemical interaction (corrosion, erosion) with pipes and components of the system. Together with tritium, it is a source of activated material. The presence of certain products could lead to tritium retention by chemical trapping; others can be deposited in cold parts of the circuit, causing blocking and, if it is in the extractor membrane, it will diminish its capabilities. Neutronics and activation calculations will be used for evaluate how the operation in CLIPPER can contaminate the PbLi affecting the H-extraction. In addition, at the FPP end of life, activated components will be classified according to the principle of Low Level Waste (LLW). Specifically, a target for tritium extraction will be given to fulfill this LLW principle for PbLi within 100 years from the shutdown of an FPP.
- O3.2 – Model validation with results The results of the experiments will be used to confirm or dismiss the hypotheses made during the creation of the models in the design phase, and hence to partially/fully validate or reject them. Moreover, the accurate measurement and registration of a set of operational variables will allow adjusting the models by means of already defined features or code development. Therefore, the predictive capability of the selected tools can be improved for the further design of new components and experiments.
