Application of the radio species transport model to the JSI water activation loop

The development of analysis tools to calculate the activation of flowing water under irradiation is essential for fusion technology and for the ITER project. The Radio-Species Transport Model (RSTM) method is a simulation methodology developed by Fusion for Energy based on the Ansys Fluent® user-defined scalar (UDS) approach. It predicts the activation of a flowing fluid in domains where neutron fields and flow regimes require the coupling of activation and fluid dynamic effects. RSTM was successfully applied to ITER First Wall (FW) studies and benchmarked against experiments at the Frascati Neutron Generator (FNG). This research focuses on the application of the RSTM to the KATANA closed water activation loop at the JSI TRIGA Mark II fission reactor, as part of the EUROfusion Preparation of ITER Operation (PrIO) programme. Future work will compare these results with experimental data and other predictive tools including ActiFlow, GammaFlow (by UKAEA) and FLUNED (by UNED). In the next phase of operation, the KATANA facility aims to tackle experiments more relevant to ITER conditions. For this reason, Fusion for Energy is applying RSTM to design an alternative irradiation head that resembles the cooling circuit of an ITER First Wall panel, this being one of the main components where the water undergoes activation. This study shows the results of the RSTM tool for the current configuration of the JSI KATANA water activation loop. Conclusions are drawn on the relevance of the alternative ITER-relevant irradiation head for the next phase of the JSI water activation loop.