Point Kinetics LOCA Scenarios Assessment at the Using of Hafnium Absorber in Advanced CANDU Fuel Designs

The goal of the paper is to compare the results obtained through point kinetics calculations at the simulation of several CANDU^® LOCA scenarios in the case of using Hafnium as burnable absorber in advanced CANDU fuel designs (ACR™-1000 based) along with standard CANDU NU fuel. The 3D DIREN_MG diffusion code developed in INR Pitesti was used to accomplish this task after upgrading by original procedures, which allow for Neutronics and ThermalHydraulics coupled calculations. The intervention of SDS1 was modeled until the transient is terminate by SDS1 action. The CANDU community has always interested in the void reactivity reducing-the major drawback of this power reactor. The paper’s novelty elements consist in the using of a newer WIMS code version (WIMSDB5 from NEA Data Bank) and an updated IAEA WIMS library based on newly ENDF/B-VII version along with a simplified DIREN_MG ACR-1000 core model. The results emphasized the critical Hafnium shell thicknesses which allow for a slightly negative cell Void Reactivity (VR) target and the direct consequences in the full core safety analysis.