Development of a mechanistic model for He release from PuO2 powders

This 4-year PhD project will support the NDA mission to clean up the UK's earliest Nuclear Sites safely, securely and cost effectively by developing a predictive model for the release of radiogenic helium from plutonium oxide powders, both during storage and in any processing of the powders for use as a fuel or disposal.

The model will exploit the rapid development of available computational resources to perform molecular dynamics simulations of realistically sized PuO2 powder particles.

Initially, the project will explore the diffusivity within the powder crystallites and reproduce the experimentally observed relationship between the specific surface area of the powder and the helium release fraction.

The project will then explore the interaction between powder particles and determine whether crystallite growth provides a pathway for helium release. Following this, the role of radiation will be studied by performing cascade simulations within the crystallites.

These simulations will be used to identify the most important processes contributing to helium release and the parameterisation of a mechanistic release model.