Reduced scale tests to assess corrosion of a steel overpack in the Belgian Supercontainer

A new corrosion sensor developed by the research group SURF of the Vrije Universiteit Brussel has been tested in a laboratory-scale test using a reduced scale model of the Supercontainer to evaluate its potential for use in the Belgian Supercontainer feasibility testing program. The Belgian Supercontainer is a conceptual design for the post conditioning of HLW. It incorporates a concrete buffer completely surrounding a carbon steel overpack. The concrete buffer is made using ordinary Portland cement and calcareous aggregates, which provide high alkaline conditions with pH above 13 to form passivation and to favour slow and homogeneous corrosion of the steel overpack. Preliminary results obtained with the new corrosion sensor indicate a rapid onset of corrosion at the beginning of the test followed by an equally rapid decrease in corrosion after only a few days. The results suggest that the new sensor is capable of detecting corrosion ‘as it happens’ and that it can measure the evolution of corrosion in the carbon steel overpack.