PNNL

Abstract

The development of materials for next-generation nuclear reactors (GEN-IV) represents a significant challenge due to the extreme environments they operate in, including elevated temperatures, intense neutron bombardment, and corrosive coolants. Multi-Principal Element Alloys (MPEAs) are emerging as promising candidates for these applications due to their superior radiation tolerance, high-temperature stability, and compositional flexibility. This study introduces a versatile and customizable Robust Alloy Design (RAD) strategy for systematically designing and optimizing single-phase Body-Centered Cubic (BCC) MPEAs for GEN-IV reactor fuel cladding. The RAD strategy combines nuclear-relevant selection criteria, empirical parameter assessments, and high-throughput CALPHAD simulations to efficiently narrow the compositional space and identify highly suitable alloys. Key performance metrics, including fuel-clad chemical interaction (FCCI), neutron absorption cross-sections (NAC), valence electron configuration (VEC), and melting point factor (MPF), are integrated into a unified RAD score to rank candidate alloys. The flexibility of the RAD score allows customization based on reactor-specific priorities and operational requirements, making it adaptable across diverse reactor designs. Among 725 identified single-phase BCC alloys, the alloy V555 (5Al+5Cr+5Fe+85V) emerged as the top candidate, validated through experimental evaluations revealing a homogeneous single-phase BCC microstructure. This customizable and scalable RAD strategy provides a robust framework for designing advanced materials tailored to extreme reactor conditions while paving the way for further optimization through atomistic simulations and experimental characterization.