The Influence of Hydrogen on the Radiolytic Oxidation of UO2
Licentiate thesis, 2020
The UO2 matrix contains the majority of the long-lived radiotoxic elements. As the U(IV) form is highly insoluble, the release of the radiotoxic nuclides is largely governed by oxidation of the UO2 matrix into the much more soluble U(VI) form. Oxidation can occur due to the formation of radiolytic oxidants through the ionization or excitation of water molecules in contact with fuel.
Oxidation of UO2 pellets using external Am-241 sources was studied under conditions where the UO2 surface and the source were separated by 30 µm water. H2 was shown to suppress the surface oxidation as well as dissolution. This was shown by direct measurement of the surface oxidation state using XPS, as well as through concentration measurements in solution using mass spectrometry (ICP-MS).
Oxidative dissolution of 10 and 24 wt% Pu-doped MOX pellets was also studied under Ar and D2 atmospheres. The D2 atmosphere suppressed the uranium dissolution. However, corrosion of the stainless-steel materials present in the autoclave system was also observed. A calculation model was also developed for calculating dose-rates from α-doped UO2 based material.
Chalmers, Chemistry and Chemical Engineering, Energy and Material
The interaction of molecular hydrogen with α-radiolytic oxidants on a (U,Pu)O2 surface
Journal of Nuclear Materials,; Vol. 505(2018)p. 54-61
The fate of hydroxyl radicals produced during H2O2 decomposition on a SIMFUEL surface in the presence of dissolved hydrogen
Journal of Nuclear Materials,; Vol. 507(2018)p. 38-43
N.L. Hansson, P.L. Tam, C. Ekberg, K. Spahiu. XPS study of external α-radiolytic oxidation of UO2 in the presence of argon or hydrogen
N.L. Hansson, C. Ekberg, K. Spahiu. Alpha Dose Rate Calculations for UO2 Based Materials using Stopping Power Models
Other Chemistry Topics
Areas of Advance
Licentiatuppsatser vid Institutionen för kemi och kemiteknik, Chalmers tekniska högskola: Ny Serie Nr 2020:01
Opponent: Dr. Olivia Roth