What was the solution?
The nuclear graphite programme at the University of Sussex ran from 1997–2012, headed by Professor Malcolm Heggie and funded by EDF Energy Generation’s Plant Life Extension (PLEX) project and EPSRC. Heggie investigated how atoms in graphite layers bonded together by creating mathematical models that generated projections into future graphite behaviour, independent of the existing experimental models.
Radiation damage was known to affect graphite properties, changing the size and shape of graphite crystals and displacing atoms. Displaced atoms formed new sheets of graphite between existing layers, leaving behind vacant areas.
However, researchers at the University of Sussex indicated that the mobility and properties of the displaced atoms and vacant sites inferred from experiments were incorrect, and therefore previous theories of graphite radiation damage were producing erroneous results.
Heggie and colleagues showed that, following exposure to radiation, changes to the graphite structure arose from displaced atoms binding layers together, causing them to buckle. However, above 250°C the atoms became mobile, and the buckling effect was removed.
If the 14 UK operating Advanced Gas-cooled Nuclear Reactors closed unnecessarily early, by perhaps one year, it could lead to losses running into billions of pounds, threaten the UK’s carbon dioxide emission targets and widen the nation’s energy deficit.