Development of a Spatial Dynamics Model Based on Semi-Analytic Nodal Method

Abstract Dynamic calculation based on neutronics and thermal-hydraulics (TH) coupling model is one of the crucial aspects in reactor safety analysis and system simulation. With the continual development of the numerical model of reactor physics and the high-performance computers, now 3D spatial dependent kinetics calculation is feasible and has been already widely applied in core simulator. In this work, a neutronics/TH coupled spatial dynamics model has been developed based on the multi-group neutron diffusion theory in 3D Cartesian geometry for next-generation advanced reactor steady state and transient analysis. The spatial variables are handled by employing a non-linear iterative semi-analytic nodal method (SANM) while for the neutron kinetics solver the fully implicit scheme and exponential transformation are adopted. In the TH module, a single channel model and its steam table is implemented. To test the performance of the coupled model, both static and transient characteristics of the three benchmarks including 3D-LMW, NEACRP 3D and PWR MOX/UO2 core are obtained and analyzed in detail. Numerical results show that accuracy of the developed spatial dynamics model is similar to that of other high performance nodal codes.