Corrosion of AGR Fuel Pin Steel Under Conditions Relevant to Permanent Disposal

Fuel pins from the UK's Advanced Gas-cooled Reactors (AGR) consist of ceramic UO2 fuel encased in a 20/25/Nb stainless steel cladding. Spent AGR fuel is currently reprocessed, but the option of direct disposal of spent fuel in a sealed, underground Geological Disposal Facility (GDF) is now under examination. It is assumed that over several thousand years groundwater from the environment will penetrate these barriers and come into contact with the fuel surface and steel cladding.