Assessment of the uniform corrosion behaviour of carbon steel radioactive waste packages with respect to the disposal concept in the geological Dutch Boom Clay formation

Bruno Kursten, Frank Druyts, Frank Druyts

Research outputpeer-review

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Abstract

The OPERA disposal concept for the final management of Dutch radioactive waste in the 'Rupel' Clay formation is based on the current Belgian Supercontainer concept. In this concept, the radioactive waste is packed in a carbon steel container (i.e. the overpack), which is entirely surrounded by a concrete buffer. In this high alkaline environment (pH ~ 13.6) and under normal conditions (i.e. without the ingress of aggressive species), carbon steel is protected by a passive oxide film, which is believed to result in very low uniform corrosion rates. Considering the long time scales involved in geological disposal, an accurate estimation of the uniform corrosion rate is a crucial part in the safety study. This report provides a best estimate of the uniform corrosion rate of carbon steel exposed to the concrete buffer material. The reported corrosion rate data are based on a state-of-the-art database, which was build on an extensive review of the published literature. This database was composed in the framework of the Belgian disposal programme. Also included is a brief description of the corrosion processes under aerobic and anerobic conditions, the integrated scientific approach that is adopted within the RD&D corrosion studies and the various methods reported in the literature to measure the corrosion rate of carbon steel in alkaline media. The outcome of preliminary geochemical calculations to gain a first level of understanding of the long-term evolution of the environmental conditions surrounding the carbon steel overpack is discussed.
Original languageEnglish
PublisherCOVRA
Number of pages108
VolumeOPERA-PU-SCK513
StatePublished - 1 May 2016

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