ANALYSIS OF OPERATIONAL CHARACTERISTICS OF A SMALL MODULAR REACTOR WITH ACCIDENT TOLERANT FUEL

The topic of the paper is focused on numerical simulations of nuclear reactors, the preparation of macroscopic nuclear data using a deterministic approach, and the analysis (with an optimisation proposal) of selected Accident Tolerant Fuel (ATF) concepts of fuel pellets. The behaviour of ATFs in large cores has already been investigated in depth, but analyses in small cores have not yet been studied in more detail. Macroscopic nuclear data were prepared using the SCALE-Triton computational code on an infinite fuel assembly model. Subsequently, a 3D full-core calculation is performed in the deterministic macrocode PARCS on the model of a light-water Small Modular Reactor (SMR) developed by the NuScale Power company. For proper interpretation of results, coupling of PARCS with an external thermohydraulic solver PATHS, is studied. The behaviour of selected ATFs and deviations of various neutronic parameters from the referenced UO2 fuel are analysed in this complex model. Together with the analyses, a proposal on the optimisation of the referenced core with the (U10Mo/UN/ThO2) pellets combination for the use on this model, is presented. This optimisation proposal brought the possibility of extending the fuel campaign (while maintaining the same average fuel enrichment), reducing the average fuel temperature and improving the inherent safety parameters, at the expense of a slight increase in the value of the maximum peaking factors.