On the Oxidation Mechanism of U3Si2 Accident Tolerant Nuclear Fuel

•Intermetallic silicide compounds being pursued for accident tolerant nuclear fuels programmes globally.•Oxidation reaction and mechanisms in U3Si2 system reported for first time using atomistic scale techniques.•Material decomposes from micron sized grains, forming complex oxide nanostructure causing pulverisation of material.•Passivation of nanoscale Si regions by U3O8 leads to the incomplete oxidation.•Formation of Si rich islands passivated by U3O8 shows dominance in kinetically driven reactions.