Archeological analogs for the lifetime prediction of the canister for spent nuclear fuel in the deep geological repository: Part II. Evolution of the corrosion rate over time

Abstract

This work focused on evaluating the evolution of the corrosion product layer and associated corrosion rates on archeological artifacts from 16 sites. Sites with clay soils and maximum waterlogging (pond bottoms and wetlands) were monitored. The corrosion products were evaluated by X-ray imaging, X-ray diffraction, scanning electron microscope, Brunauer–Emmett–Teller, and nanoindentation. Two stages of corrosion attack with slightly different mechanisms were observed. Corrosion rates observed at sites with continuous flooding show average corrosion rates of 0.4–1 μm.a⁻¹. These values demonstrate a minimum service life of the container outer case of 15 × 10³ years, which is several times longer than the required lifetime of the outer case.