Coupled 3D neutron kinetics/thermal-hydraulics calculation of PWR core using nodal Green's function method on Neumann boundary condition

摘要

In this paper, we proposed a numerical method to perform the coupled three dimensional (3D) neutron kinetics/thermal-hydraulics calculations for the pressurized water reactor (PWR) core and verified its accuracy. In the spatial neutron kinetics, the nodal Green's function method (NGFM) on Neumann boundary condition is applied for the space discretization procedure, and the implicit difference scheme is used for the time differential. It is assumed that the fission source term in the delayed neutron precursor concentration equation is linearly changed within each time step. For the thermal-hydraulic analysis, the single channel model in which a fuel assembly corresponds to one average thermal-hydraulic channel is applied, and cross flow between channels is not taken into account. And we considered the coolant as a single phase incompressible fluid. The model proposed in here was tested by comparison with the two dimensional (2D) TWIGL problem and the NEACRP-L-335 transient benchmark for the 3D PWR core. The numerical results are in good agreement with reference solutions.