Boron Transient Analysis By The Grs Coupled Code Systems Quabox-Cubbox/Athlet And Tort-Td/Athlet

The application of modern coupled thermal-hydraulic neutron-kinetic code systems is state of the art for performing safety analyses. In this paper a radially asymmetric boron dilution transient in a PWR MOX/UO2 core is defined. The transient is analysed using the coupled code system QUABOX-CUBBOX/ATHLET which is based on fuel-assembly coarse mesh diffusion theory, and the results are compared to the solution obtained with the transport theory-based coupled code system TORT-TD/ATHLET with a pin-wise representation of the core. The aim of this study is to investigate the impact of the transport approach and the diffusion approximation on the simulation results.