Novel Approaches to Investigate Structural Properties of Nuclear Materials

Irradiation and high temperatures can change the mechanical properties (stiffness, strength and toughness) of structural materials in nuclear fission and fusion reactors,  To study this, neutron irradiated materials must be extracted from operating reactors or obtained from Material Test Reactors that simulate or accelerate the reactor conditions, but this imposes very significant constraints on specimen size (typically < 1 cm) and measurement techniques. New methods are needed to evaluate and qualify novel materials for new reactor designs and to monitor material performance for the safety of operating reactors.

Our approach is to use experimental measurements of the full field deformations (total and elastic strains), measured in situ by imaging (optical, X-ray, neutron) and diffraction (X-ray, neutron) . Some examples include nuclear graphite (http://dx.doi.org/10.1016/j.carbon.2020.09.072, http://dx.doi.org/10.1016/j.jnucmat.2022.153642, http://dx.doi.org/10.1016/j.carbon.2023.118378), and ceramic composites (http://dx.doi.org/10.1007/s11340-022-00916-9). This approach has the potential to be applied under extreme conditions of temperature and irradiation.  

Projects in this area aim to develop and apply efficient numerical methods to extract the mechanical properties of structural materials for nuclear energy from observations of 2D and 3D displacement fields, measured in situ during mechanical tests in extreme conditions. The materials include ceramics, refractory metals, nuclear graphite and ceramic composites, with the objective of developing a better understanding of the relationships between microstructure, damage and mechanical properties. The experimental techniques will include digital image correlation, X-ray tomography and X-ray/neutron diffraction. Modelling and optimisation approaches may include finite element inverse methods, virtual fields and machine learning. The projects are suitable for graduates with an engineering, mathematical or physical sciences background.