Radiation damage effects on helium diffusion in zircon

TL;DR

This study investigates how radiation damage influences helium diffusion in zircon, revealing increased activation energy with damage, and discusses implications for nuclear waste containment.

Contribution

It provides molecular dynamics simulation data showing how radiation damage alters helium diffusion pathways and activation energy in zircon.

Findings

Radiation damage increases activation energy for helium diffusion.

Damaged zircon accumulates helium, affecting bubble formation.

Remaining order in damaged structures influences diffusion behavior.

Abstract

We report the effects of radiation damage on helium diffusion in zircon using data from molecular dynamics simulations. We observe an increase in activation energy for helium diffusion as a result of radiation damage and increasing structural disorder. The activation energy in a heavily damaged region is smaller than in a completely amorphous system which is correlated with remaining order in the cation sublattices of the damaged structure not present in the fully amorphized system. The reduction of activation energy is related to the disappearance of fast diffusion pathways that present in the crystal. Consistent with the change in activation energy, we observe the accumulation of helium atoms in the damaged structure and discuss the implications of this effect for the formation of helium bubbles and zircon's performance as an encapsulation material for nuclear waste.