Heavy Liquid Metal Thermal Hydraulic Progress in the MYRTE Project

In Europe, the Horizon 2020 MYRTE project which ran from 2015 till 2019 aimed to perform the necessary research in order to demonstrate the feasibility of transmutation of high-level waste at industrial scale through the development of the MYRRHA research facility. Within MYRRHA as a large research facility, the demonstration of the technological performance of transmutation will be combined with the use for the production of radio-isotopes and as a material testing for nuclear fission and fusion applications. Part of this project addressed the main outstanding technical issues in thermal hydraulics by numerical simulations and experimental validation in the field of fuel assembly and pool thermal hydraulics. This paper presents the main progress which has been achieved. The main topics to be addressed are liquid metal heat transfer, fuel assembly thermal-hydraulics, pool thermal-hydraulics, and system thermal-hydraulics. With respect to liquid metal heat transfer, new reference data, both experimental and numerical DNS and LES data have been generated. Starting from the most promising RANS turbulent heat transfer modelling routes which can simultaneously deal with different flow regimes (natural, mixed, and forced convection), these routes have been evaluated against these data where needed further developed. Considering fuel assemblies, abnormal conditions like flow induced vibrations, resulting fretting, and formation of blockages has been studied. Again, experiments and numerical simulations go hand in hand. Finally, with respect to pool thermal-hydraulics, the purpose is to develop and validate sufficiently accurate methods to model the coolant behavior in the MYRRHA pool using various modelling approaches ranging from system thermal hydraulics codes to CFD and multi-scale codes. Significant progress has been made in all these fields which will be presented.