Revealing the mechanism of uranium anti hydrogen embrittlement modification: Segregation law and strengthening effect of metal solute doped grain boundaries

• The system explores the segregation behavior of 30 metal solute atoms at uranium grain boundaries and their regulation mechanisms on hydrogen behavior, providing comprehensive first principles data support for the hydrogen embrittlement resistance modification of uranium based materials. • Establish Bader volume as an effective descriptor for predicting the segregation behavior of transition metals at uranium grain boundaries. • The mechanical contribution of doped atoms to grain boundary strengthening is positively correlated with radius mismatch, while the chemical contribution originates from solute uranium bonding strength. • Elucidating the intrinsic mechanism of solute doping improving the hydrogen resistance of uranium grain boundaries at the atomic scale. Hydrogen embrittlement at grain boundaries (GBs) critically compromises the performance of uranium-based nuclear fuels. Designing solute-doped alloys offers a promising route to mitigate this degradation by tailoring GB properties. This study employs first-principles calculations to systematically screen 30 metal solute elements for their efficacy in strengthening a uranium ∑3[110]( 1 ¯ 11) and suppressing hydrogen segregation. We identify Bader volume as a predictive descriptor for solute segregation tendency to the GB core. The GB strengthening effect varies across the periodic table: most 3d dopants enhance cohesion, while the influence of 4d and 5d dopants follows a non-monotonic trend across their series. We further establish a radius-mismatch descriptor that quantifies the mechanical contribution to strengthening, which is complemented by the chemical contribution from solute-Uranium bond strength. Our multi-criteria screening identifies V, Cr, Mn, Fe, Co, Ni, Nb, Mo, Tc, Ru, and Ir as optimal solutes that simultaneously strengthen the GB and inhibit hydrogen segregation. This work provides atomistic design principles and specific element candidates for engineering hydrogen-resistant uranium alloys, bridging atomic-scale mechanisms to macroscopic material performance.