  Uranium mononitride, UN, is considered a potential accident tolerant fuel due
to its high uranium density, high thermal conductivity, and high melting point.
Compared with the relatively inert UO2, UN has a high reactivity in water,
however, studies have not considered the significant effect of radiation, which
is known to cause corrosion of UO2. This study uses 0.1 M H2O2 to simulate the
effects of water radiolysis in order to compare the radiolytic corrosion rates
of UO2, UN, and U2N3 thin films at room temperature. X-ray reflectivity was
used to investigate the changes in film morphology as a function of H2O2
exposure time, allowing changes in film thickness and roughness to be observed
on the Angstrom length-scale. Results showed significant differences between
UO2, UN, and U2N3, with corrosion rates of 0.083(3), 0.020(4), and 0.47(8) A/s,
respectively, showing that UN corrodes more slowly than UO2 in 0.1 M H2O2.
