MULTI-PHYSICS MODELING OF INNOVATIVE LEAD-COOLED NUCLEAR FAST REACTORS

Generation IV reactors, including lead-cooled fast systems, are characterized by physical features that require the development of new multi-physics simulation tools. Existing multi-physics codes usually include highly simplified models for neutronic (NE) and thermal hydraulic (TH) calculations, which may be unsatisfactory for many design and safety assessments. In this work, as a first step towards the development of a modular full-core coupled NE/TH computational model, the coupling of simplified NE/TH modules for the analysis of a single assembly is presented for lead-cooled fast reactors and applied to the analysis of the hexagonal fuel assembly currently proposed within the framework of the European project LEADER. Concerning the NE module, a point kinetic method is adopted for the determination of the neutron distribution and provides the fission energy source to the TH module. A TH module for the determination of coolant temperature and density distributions in the assembly, used in the NE module to evaluate the temperature coefficients, is developed, considering advection and conduction in the compressible flow of the coolant coupled to pure conduction in the fuel rods. A test case performed introducing NE perturbation is presented and convergence study is carried out.