A new irradiation capsule for accelerated ageing of graphite, which is used in Advanced Gas-cooled Reactors (AGRs), has begun irradiation at NRG’s High Flux Reactor in Petten in the Netherlands. NRG said on 12 September that the irradiation had started two months ahead of schedule. The work is part of Project Blackstone, initiated by an alliance of EDF Energy, NRG, Frazer Nash Consultancy and Atkins in support of ageing management of AGR reactors in the UK. The project will run for four more years and is expected to provide data that can be used in safety cases to support AGR plant operating life extensions. NRG said the online monitoring results demonstrate excellent control of the irradiation conditions.

Phase 3 of Project Blackstone focuses on the graphite from the Heysham 2 and Torness reactors and is a follow-up of the previous phases in which graphite from other AGRs was successfully characterised to support life time extension. Graphite material extracted from AGRs is irradiated in the High Flux Reactor and Petten (the Netherlands) that is operated by NRG. During the HFR irradiation and both the in-core neutron and oxidation damage mechanisms that take place in an AGR are simulated and accelerated under representative conditions. Following the irradiation, graphite specimens are characterised in the NRG Hot Cell Laboratories to provide high quality material behaviour data, providing essential input to graphite property models which are used to assess the future structural integrity of AGR cores. Data from the project has already been used in safety studies for reactor lifetime extensions.