Archaeological analogues for the lifetime prediction of the canister for spent nuclear fuel in the deep geological repository: Part I. Composition of pore water and corrosion products

Abstract

This work focuses on archaeological analogues as a way of obtaining long-term data for assessing the lifetime of a spent nuclear fuel canister. An analysis of the environment around the excavated artefacts is presented, followed by geochemical modelling of the likely corrosion products and subsequent comparison with real phases in the corrosion layer estimated by X-ray diffraction. A total of 16 archaeological sites with fine clay soils and the potential for long-term flooding were evaluated. Although the soil pore solution contained high levels of silicates, no such phases with iron in the corrosion products were confirmed. Carbonate corrosion products, typical of bentonite environments, were also not observed. Although oxygen access is very limited in the environments of all sites, even low concentrations shifted the equilibrium of corrosion products formed in favour of (hydroxy)oxides.