Insights from applications of the RSTM tool for coupled CFD-activation fluid simulation

Abstract

Accurate prediction of the activation of fluids flowing under irradiation is important for the timely development of fusion technology. One of the major current issues is the cooling water of ITER, which becomes activated by plasma neutrons during nuclear operations, thus raising a number of radiological implications such as radiation effects on sensitive equipment, compliance with radiological protection zoning, and compliance with radioactivity limits in regulations of pressure equipment and effluents. Further significant applications are the activation of other service fluids in ITER and of the LiPb in both ITER and DEMO breeding blanket modules.To avoid systematic uncertainties, simulation of the activation of fluids flowing in arbitrarily complex 3D geometry, flow regimes and neutron fields requires full coupling of activation with fluid-dynamics physics models. No such tools were available until recently: the Radio-Species Transport Model (RSTM), based on the well-established ANSYS Fluent® UDS methodology, is one conceived and developed at F4E. Here we review the methodology and capabilities of the RSTM, as well as earlier development, validation, benchmarking and application activities. We then report currently ongoing further applications and benchmarking being performed in collaboration with specific tasks of the EUROFusion programme Preparation for ITER Operation. Computations, results and comparison with other methodologies for several cases of interest are presented and discussed.