Enhancements to the Nodal Drift Method for a Rod Ejection Accident in a PWR-like mini-core with lumped thermal model

Previous burnup calculations of High Conversion Water Reactor (HCWR) options have given promising fuel cycle results. Now safety must be assessed. This requires the development of academic computing tools, coupling as simply as possible neutronics and thermal-hydraulics. The diffusion-based Nodal Drift Method (NDM) for spatial core analysis has been developed towards a broad and coarse safety review of the most promising candidates. NDM has been already validated on a simplified CANDU LOCA benchmark, without thermal coupling. Dedicated to the calculation of a Rod Ejection Accident (REA) as defined by a recent PWR-like mini-core benchmark, the present work describes and validates all the necessary enhancements to NDM. A first 2D geometry with coupling to a lumped thermal model has been validated. Then, 3D features including a refined model for the ejected control rod have been added. Particular attention has been paid on the analysis of discrepancies with reference results. Limitations due to the oversimplified lumped thermal model are finally discussed.