Advanced method for depletion calculation of control rods in sodium fast reactors

Abstract Neutronic simulations with high accuracy are required for the development of future sodium fast reactors. The “lattice-core” paradigm used for deterministic codes is able to save computation resources and improve calculation speed, but it defies the accurate depletion calculation. This paper focuses on the development and validation of an improved method, in the deterministic code APOLLO3®, for the depletion calculation of control rods. The absorber depletion is validated for different control rods designs from cluster type configuration to core configuration. The lattice calculation in APOLLO3® shows a good adaptability to complex geometries with alternative absorbers and moderators. The self-shielding effect and its variation under neutron irradiation is the key issue for the accurate simulation of control rods. Therefore, updating cross-sections according to the burn-up improves significantly the accuracy on the depletion calculation.