A Pfd-based 1D model for dynamic and transient tritium transfers between ITER HCLL TBM auxiliary systems

ITER fuel demands and tritium availability scenarios will determine the pathway to future fusion reactors. Because tritium is not a resource available from natural sources and its emission from the facility should be minimized, to keep the material balance in the entire plant and to control its inventory and safety is an essential issue toward the DEMO reactor. Predictive modeling tools are one of the major values to confirm the tritium breeding self-sufficiency, control and safe management in fuel cycle. Tritium Process Flow Diagrams (PFD) are demanded in order to quantify tritium transfers between breeding module and auxiliary systems for the TBM ITER inner breeding cycle. A 1-dimensional process flow diagram model for dynamic and transient tritium transfers between ITER HCLL TBM and auxiliary systems is proposed. The model is implemented by the use of TMAP7 tool, an ITER QA validated tool for tritium transport analyses. Although being 1-D, the physical reliability on tritium transport assessments is the main characteristic of the model; in particular, the dynamic coupling of primary coolant chemistry (oxidations and/or H2 swamping) and EUROFER surface reactions. The model assumes an especial treatment of the surface processes which involve ionic exchange of the different species (H2, HT, T2, HTO, H2O). From a set of parametric representative conditions for nominal HCLL TBM systems design thermal-hydraulic inputs, an optimum choice of primary coolant chemistry parameters is proposed and argued in terms of processing systems design characteristics.