Radiation damage effects in amorphous zirconolite

JOURNAL OF NUCLEAR MATERIALS

卷:544

Article

Diver, A.¹  Dicks, O.¹  Todorov, I. T.²  Elena, A. M.²  Trachenko, K.¹ 

[1] Queen Mary Univ London, Sch Phys & Astron, Mile End Rd, London E1 4NS, England

[2] Daresbury Lab STFC UKRI, Sci Comp Dept, Keckwick Lane, Daresbury WA4 4AD, Cheshire, England

关键词: Radiation damage;    Molecular dynamics;    Zirconolite;    Amorphous;    Collision cascades;    Waste forms;   

DOI  :  10.1016/j.jnucmat.2020.152654

来源: Elsevier

【 摘 要 】

We report the results of a large-scale modelling study of radiation damage effects in the nuclear waste form zirconolite. We particularly focus on the effects of radiation damage in amorphous zirconolite and have developed a new way to analyse the damaged structure in terms of local coordination statistics. On the basis of this analysis, we find that the amorphous structure responds to radiation damage differently from the crystal. Amorphous zirconolite is found to be softer than crystalline zirconolite with a much larger number of atoms becoming displaced and changing coordination during a 70 keV cascade. The local coordination and connectivity analysis shows that the amorphous structure continues to evolve as a result of repeated radiation damage, changes which cannot be identified from globally averaged properties such as pair distribution functions. We also find large density inhomogeneities at the local level which we suggest may play an important role for future developments in nuclear waste storage. Finally, we find a correlation between the changes in enthalpy and local coordination, suggesting that measurements of enthalpy change can be linked quantitatively to structural radiation damage. Our results raise an interesting possibility of whether an evolution of the amorphous structure due to radiation damage can converge to a new equilibrium amorphous regime, posing the fundamental question of what that structure may be. (C) 2020 Elsevier B.V. All rights reserved.

【 授权许可】

Free