Development of an integrated deterministic neutronic/thermal-hydraulic model using a CFD solver
Examensarbete för masterexamen
Applied physics (MPAPP), MSc
In LWR cores, multiple fields of physics will need to be tackled. The power level is determined by the neutron density field, and the generated heat will determine the fuel conditions, which in turn affect the coolant/moderator flow and thermo-physical conditions. As the neutron cross- sections depend on both the fuel and moderator conditions, an interdependence between the neutronics and thermal-hydraulics is found. To perform accurate, high-resolution nuclear reactor core calculations, it is therefore necessary to couple strategies and methodologies from different areas of physics. In this work a finite volume approach is used to perform steady state, coupled calculations for thermal-hydraulics and neutronics on a shared high-resolution mesh. The thermal-hydraulics is solved by a standard CFD approach, using the SIMPLE algorithm for the pressure-velocity coupling together with an energy equation expressed in terms of temperature. The neutronic cross-sections are pre-calculated using a nuclear Monte Carlo code. The neutronics is added in to the CFD solver, avoiding any external software coupling, and is discretized according to standard finite volume approach. The criticality eigenvalue problem is solved by the power iteration method, which has been added to the CFD solver. To couple the thermal-hydraulics and neutronics an iterative scheme is proposed. The finite volume solver has been implemented in OpenFOAM. The developed direct coupled methodology is applied to a simplified PWR fuel sub-assembly. The physical dependencies between neutronics and thermal-hydraulics are correctly recovered. The achieved results suggest that this newly-developed coupling procedure provides an unprecendented level of details and accuracy as compared with standard non-direct coupled calculations.
Beräkningsfysik , Energi , Övrig teknisk fysik , Computational physics , Energy , Other engineering physics