Abstract
The UK has decades of experience designing, operating and extending the lives of graphite moderated reactors, including the currently operating fleet of EDF’s Advanced Gas-cooled Reactors (AGR). This paper summarises some of the analysis used to substantiate the graphite safety cases for their continued operation. In particular, the use of graphite brick modelling, using a physically-based material model, to describe the behaviour of irradiated graphite. The material model is calibrated to measurements made during regular inspections of the cores, capturing variability and uncertainty in addition to a central estimate. A probabilistic wrapper is applied to the brick modelling, to make predictions of the onset and rate of keyway root cracking, which is a damage mechanism of particular concern. It is hoped that this experience can help inform the development of design codes required for the proposed future graphite-moderated reactor technologies.
