Interaction of Hydrogen with Actinide Dioxide (011) Surfaces

The hydrogen catalysed oxidation of nuclear materials has led to containment vessel failure. The interaction of hydrogen with actinide dioxide (AnO₂, An = U, Np, Pu) (011) surfaces has been completed by DFT+U; where, spin-orbit interactions and noncollinear 3k antiferromagnetic behaviour have been included. The energy of atomic hydrogen adsorption for UO₂ (0.44 eV), NpO₂ (-0.47 eV), and PuO₂ (-1.71 eV) has been calculated, where the subsequent formation of an OH group is shown to distort the surface structure. The dissociation of hydrogen on the PuO₂ (011) surfaces has been found; however, UO₂ (011) and NpO₂ (011) surfaces are relatively inert. The recombination of hydrogen ions on the UO₂ (011) and NpO₂ (011) surfaces is highly-probable; whereas, hydroxide formation on the PuO₂ (011) surface has been shown. The results have consequences for fuel storage management.