High Resolution Neutron Bragg Imaging of Gilsocarbon Graphite for the Investigation of Crystal Reorientation

Quasi-brittle materials can accommodate a limited permanent deformation before fracture, which improves their toughness. Examples include concrete, graphite and ceramic composites, which are used in safety-critical industries; the UK Advanced Gas Cooled Reactors use Gilsocarbon graphite as their neutron moderator and cracking may limit the reactor lifetime. It is essential to understand how damage is localised within the graphite microstructure, as this will affect its response to load at high temperatures and with irradiation. This experiment aims to show that in-situ Bragg edge imaging of graphite can detect the magnitude and nature of local changes in crystal orientation, and this will distinguish between several different proposed mechanisms of deformation. This will lead to more detailed studies that support the design of new graphites for advanced nuclear energy systems.