Hydrogen uptake and accommodation into U 3 Si 2 , a candidate accident-tolerant fuel system, has been modelled on the atomic scale using the density functional theory. The solution energy of multiple H atoms is computed, reaching a stoichiometry of U 3 Si 2 H 2 which has been experimentally observed in previous work (reported as U 3 Si 2 H 1.8 ). The absorption of hydrogen is found to be favourable up to U 3 Si 2 H 2 and the associated volume change is computed, closely matching experimental data. Entropic effects are considered to assess the dissociation temperature of H 2 , estimated to be at ∼800 K – again in good agreement with the experimentally observed transition temperature.