Molecular dynamics simulation of energetic uranium recoil damage in zircon

R. Devanathan (1) , L. R Corrales (1) , W. J. Weber (1) , A. Chartier (2) , C. Meis (3)

1 PNNL - Pacific Northwest National Laboratory
2 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
3 INSTN - Institut National des Sciences et Techniques Nucléaires

Defect production and amorphization due to energetic uranium recoils in zircon (ZrSiO$_4$), which is a promising ceramic nuclear waste form, is studied using molecular dynamics simulations with a partial charge model. An algorithm that distinguishes between undamaged crystal, crystalline defects and amorphous regions is used to develop a fundamental understanding of the primary damage state. The damage consists of under-coordinated Zr and polymerised Si leading to amorphization and phase separation on a nanometer scale into Zr-and Si-rich regions. This separation could play an important role in the experimentally observed formation of nanoscale ZrO$_2$ in ZrSiO$_4$ irradiated at elevated temperatures. The observed amorphisation and the associated volume expansion have the potential to enhance leaching of cations by providing diffusion pathways for cations and water molecules.

Mots clés: Molecular dynamics; amorphisation; nuclear waste form; uranium

Domaines: Physique Nucléaire Expérimentale [nucl-ex]

R. Devanathan, L. R Corrales, W. J. Weber, A. Chartier, C. Meis. Molecular dynamics simulation of energetic uranium recoil damage in zircon. Molecular Simulation, 2006, 32 (12-13), pp.1069-1077. ⟨10.1080/08927020600959929⟩. ⟨cea-02513503⟩