The implications of radiolytic graphite corrosion on AGR brick integrity

The long term structural integrity of the major components of the Advanced Gas Cooled Reactor (AGR) is extremely important if economic and safe operation is to be ensured. In this context the integrity of the graphite core is vital in that it performs two prime functions, that of neutron moderation and of providing structural location of the fuel and control rods. Both of these functions must be maintained under all normal and fault conditions likely to be experienced throughout reactor life. The objective of this paper is to show how information from the study of the graphite/ CO2 reaction can be used in the complex assessment of brick integrity. A simplified review is given of the steps taken in such an assessment, including the types of loads experienced by bricks within the core and the graphite property changes associated with radiolytic corrosion. Finally, a number of modelling techniques are considered for simulating these property changes so that the resulting brick strength can be assessed. (author)