Water corrosion of spent nuclear fuel: radiolysis driven dissolution at the UO2/water interface

Ross Springell (1) , Sophie Rennie (1) , Leila Costelle (1) , James Darnbrough (1) , Camilla Stitt (1) , Elizabeth Cocklin (2) , Chris Lucas (2) , Robert Burrows (3) , Howard Sims (4) , Didier Wermeille (5) , Jonathan Rawle (6) , Chris Nicklin (6) , William Nuttall (7) , Thomas Scott (1) , Gerard Lander (8)

1 University of Bristol [Bristol]
2 Univ Liverpool, Dept Phys, Liverpool L69 7ZE, Merseyside, England
3 National Nuclear Laboratory
4 Natl Nucl Lab, Kidlington OX11 0QT, Oxon, England
5 ESRF - European Synchrotron Radiation Facility
6 DIAMOND Light source
7 OU - The Open University [Milton Keynes]
8 Commiss European Communities, Joint Res Ctr, Inst Transuranium Elements, D-76125 Karlsruhe, Germany

X-ray diffraction has been used to probe the radiolytic corrosion of uranium dioxide. Single crystal thin films of UO2 were exposed to an intense X-ray beam at a synchrotron source in the presence of water, in order to simultaneously provide radiation fields required to split the water into highly oxidising radiolytic products, and to probe the crystal structure and composition of the UO2 layer, and the morphology of the UO2/water interface. By modeling the electron density, surface roughness and layer thickness, we have been able to reproduce the observed reflectivity and diffraction profiles and detect changes in oxide composition and rate of dissolution at the Angstrom level, over a timescale of several minutes. A finite element calculation of the highly oxidising hydrogen peroxide product suggests that a more complex surface interaction than simple reaction with H2O2 is responsible for an enhancement in the corrosion rate directly at the interface of water and UO2, and this may impact on models of long-term storage of spent nuclear fuel

Domaines: Chimie

Ross Springell, Sophie Rennie, Leila Costelle, James Darnbrough, Camilla Stitt, et al.. Water corrosion of spent nuclear fuel: radiolysis driven dissolution at the UO2/water interface. Faraday Discussions, 2015, 180, pp.301-311. ⟨10.1039/c4fd00254g⟩. ⟨hal-01572751⟩