Continuing developments in ab initio and atomistic methods increase the probability of making direct comparisons between their predictions and relevant experimental results. The timescale for radiation-induced defect formation in atomic displacement cascades is ~10-20x10-12 sec. This is followed by short-term evolution processes (~10-3 sec), that ultimately lead to defect diffusion and damage accumulation for times up to many years. The longest time scale is associated with significant levels of microstructural evolution and mechanical property changes that limit the service life of these materials in current and advanced nuclear energy systems. The shortest timescale is amenable to accurate atomistic simulations, but it is challenging to make comparisons with experimental data at such short times. Methods such as mean-field reaction rate theory or object kinetic Monte Carlo are available for simulating long time evolution and making direct comparisons with experimental results. In practice, such methods suffer from the requirement of an extensive set of predetermined, and often poorly defined, material parameters. However, is now possible to improve the parameterization of these models using both ab initio calculations and atomistic simulations. New insights into defect formation and evolution obtained in the ORNL Center for Defect Physics will be described with a focus on providing a direct link between computational simulations and experimental measurements; implications for improved radiation resistance of structural materials will also be discussed.

Radiation-induced defect formation and short-term evolution: Computational methods and experimental results

247th National Meeting (2014)

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