The material to be studied is nuclear graphite used in the core of the Gas-cooled Reactors in the UK. It is a non-replaceable component and therefore life-limiting. During service, this material will be continuously bombarded by fast neutrons at high temperature (300-400°C) and its mechanical properties degrade with time. Understanding the deformation and fracture of the graphite, especially at conditions relevant to service, will help to maintain safe generation of energy to keep the UK's lights on. In this experiment, we will take such irradiated graphite samples, and deform it at 350°C and use neutron diffraction to collect information on the change in the crystal lattice. This is the first attempt to investigate the mechanical behaviour of such irradiated nuclear graphite using neutron diffraction at high temperature; the outcome will provide strong basis for forward prediction.