Abstract

One of the factors that may affect the operating lifetime of the UK Advanced Gas Reactors (AGR) is the ageing of the neutron-moderating graphite core; the combined effects of neutron irradiation and radiolytic oxidation gradually change the material properties of the graphite. The continued operation of the reactors relies on a sound understanding of these changes and their consequences, supported by regular monitoring and inspection to verify the conservatism of the predictive models. The methodology is multi-scale, from the physics of graphite crystals to the behaviour of the entire reactor core; the talk will describe some of the elements of this methodology, using current research on the mechanical properties of graphite structures (strength, toughness, stiffness) as an example.