Interaction of Corroding Iron with Eight Bentonites in the Alternative Buffer Materials Field Experiment (ABM2)

Bentonite, a common smectite-rich buffer material, is in direct contact with corroding steel many high-level radioactive waste repository designs. The interaction of iron the clay may affect its swelling and sealing properties by processes such as alteration, redox reactions cementation. chemical interactions were investigated analysing Fe/clay interfaces eight bentonite blocks which had been exposed to temperatures up 130 °C for five years ABM2 borehole at Äspö Hard Rock Laboratory managed Swedish Nuclear Fuel Waste Management Co (SKB). Eleven interface samples characterised high spatial resolution methods, including scanning electron microscopy coupled energy dispersive X-ray spectroscopy ?-Raman well “bulk” methods diffraction, fluorescence 57Fe Mössbauer spectrometry. Corrosion induced an front 5–20 mm into bentonite, except high-Fe where no Fe increase was detected. This consisted mainly ferric (oxyhydr)oxides addition structural smectite fraction partially reduced process. Fe(II) also found extend further clay, but nature could not be identified. consistent behaviour explained evolution, shifts from oxidising reducing conditions during experiment. No indication alteration found.