Coupled ERANOS/TRACE system for HPLWR 3 pass core analyses

The High Performance Light Water Reactor (HPLWR) is the European Supercritical Water cooled Reactor concept which has an innovative coolant flow path within the core to comply with safety constraints mainly related to hot-channel factors. The high enthalpy gain of the coolant, together with the multi-pass core design, enhance the coupling which exists between the power generations and the material properties distribution within the core which results in a coupling between reactor physics and thermal-hydraulics analyses. These calculations are beyond the current state-of-the-art steady-state core analyses and, hence, a new coupled system has been developed: two stand-alone codes for neutronic and thermal-hydraulic core analyses, ERANOS and TRACE respectively, are run in an iterative procedure in which the results of one code are fed as input data into the other code. Firstly this coupled system is applied to a single fuel assembly geometry. Then a successful coupling strategy for whole core analyses is presented describing the changes of the material properties - coolant and moderator temperatures and densities as well as fuel temperature - due to the power generation and the corresponding in-core power redistribution originating from the variations of material properties. (authors)