SFR mechanical scenarios and neutron transport transients with CAST3M code

[Display omitted] •Several mechanical excitations of SFR core are studied using Cast3M code.•The Fluid-Structure Interaction is comprised in the mechanical core model.•Computed deformations are applied in Cast3M Neutron Transport Tool.•Power evolution is predicted and validity of the methodology is discussed.•Applied approach provides a tool for safety assessments dedicated to SFR. In this paper we focus on of Sodium Fast Reactor core undergoing several mechanical scenarios. The mechanical full-core model in Cast3M code is described using finite elements method and Fluid-Structure Interaction is taken into account. We consider several system excitations: fluid injection, seismic excitation and compressive/opening forces applied to the bundle of assemblies. The geometry deformation is next applied for transient neutron transport simulations using a diffusion tool built in Cast3M code, named Cast3M Neutron Transport Tool (CNTT). We expose and analyze variation of power, change of fissile zone volume and assembly displacements. CNTT succeeded in code-to-code comparison using TRIPOLI-4 (a Monte Carlo code) and APOLLO3 (a deterministic code). The novelty of CNTT is the use of remeshing to take into account core distortion. The validity of assumptions applied in our approach and prospects for the future are discussed as well. The developed methodology may serve as a general tool for analysis of fast reactor systems under various mechanical excitation. Cast3M based tools provide new possibilities for safety assessments, fundamental for current and upcoming nuclear designs.