Validation of the minimalistic Nodal Drift Method for spatial kinetics on a simple CANDU LOCA benchmark

The recently developed Nodal Drift Method (NDM) provides easy spatial kinetics with a view to broad and coarse safety studies of some promising thorium-fueled High Conversion Water Reactor (HCWR) options. It fills a gap between the extremes of rather loose approximate point kinetics and rather tightly defined and too sophisticated industrial schemes. NDM is based on the 2-group diffusion theory and a lumped parameter model with maximized mesh size. It is validated here on an elementary CANDU-like LOCA benchmark proposed by AECL in the seventies. Chosen for its model simplicity, this design transient allows one to describe NDM principles and to carefully check the accuracy without any need for thermal calculations. Thus precise modeling of the strong coupling between neutronics and thermal-hydraulics is deferred for further developments, and simplified within this framework. Based on a simple transposition of the benchmark, a first application of NDM assesses safety of CANDU with “Th” fuel (Th/233U oxide) compared to “NU” (Natural Uranium oxide).