OperaHPC & SCORPION: accelerated optimization of advanced fuels for Gen-II/III reactors via the synergy of high-performance computing with multiscale material engineering

The licensing of advanced fuel materials and designs for Gen-II/III reactors requires an extension of the qualification of industrial fuel performance codes to meet the requirements of nuclear safety authorities vis-à-vis the verification, validation, and uncertainties quantification process. To address these requirements, the OperaHPC project works on advanced simulation tools enabling 3D representation of fuel rods. In the first two years of this project, a creep test device for hot cell installation was designed and transmission electron microscopy was used to characterize the microstructure of an irradiated fuel on the nanoscale. In parallel, small-scale simulation and physics-based fuel mechanical modelling were initiated to study dislocation mobility. State-of-the-art fuel and fuel cladding mechanical laws were employed in preparation of advanced mechanical modelling. HPC fuel performance codes are being developed with OFFBEAT/SCIANTIX for macroscale fuel element simulations, and MMM for mesoscale fuel pellet microstructural simulations. The preparation of industrial applications with improved models involves exchanges on machine-learning methods alongside the computation of input data for fuel safety analysis. SiC/SiC composites are a candidate accident-tolerant fuel cladding material that exhibits inherent refractoriness, pseudo-ductility, and a lack of accelerated oxidation during loss-of-coolant scenarios. Due to its potential for exceptional accident tolerance, this ‘revolutionary’ fuel cladding material concept has claimed large global investments since the 2011 Fukushima Daiichi event. Regrettably, all state-of-the-art variants of the SiC/SiC composite material concept must still overcome shortcomings, such as the inadequate compatibility of SiC with water/steam and its early (> 2 dpa) saturation of radiation-induced swelling during nominal operation. The SCORPION project strives for the radical performance optimization of SiC/SiC composites via multiscale material tailoring, which entails material re-design on the nanoscale (e.g., grain boundary engineering), mesoscale (e.g., fiber/matrix interface), and macroscale (e.g., coating development). In the first two years of this project, candidate coating ceramics and grain boundary engineered/doped SiC were experimentally synthesized and their performance was assessed via autoclave tests, high-temperature steam oxidation tests, and combined proton irradiation/aqueous corrosion tests. The hitherto tested materials performed significantly better than monolithic SiC, highlighting the success of the multiscale material engineering approach. This article offers a high-level overview of the scope and midterm achievements of the OperaHPC & SCORPION projects, in view of the FISA-EURADWASTE & SNETP Forum 2025, organized in Warshaw, Poland, in the period 12-16 May 2025.