Sorption Behavior of Alpha-ray Emitting Nuclides on Concrete in Contact with Radioactive Contaminated Water

The contamination of the concrete inside the buildings at the Fukushima Daiichi Nuclear Power Station was caused by the presence of radioactive nuclides, including alpha-ray emitting actinides such as Pu and Am, which were contained in the contaminated water.The behavior of Pu and Am in aqueous solution is complex, and an understanding of the contamination distribution of these nuclides is therefore important.To simulate the contact between construction materials and contaminated water in the reactor buildings, cement pastes, aggregates and carbon steels were immersed in solutions containing Pu and Am.The distribution ratio of Pu and Am was found to be significantly influenced by pH, which was observed to be markedly reduced when the cement paste was in a carbonated condition.It was noted that carbon steel corroded to form rust, and most of Pu and Am were incorporated in the rust during the process of rust formation, rather than sorption on the formed rust.