Study on migration of actinide colloids through minute paths

Suzuki, Atsuyuki*; Nagasaki, Shinya*

For the safety assessment of high level waste disposal system, it is important to understand the migration behaviors of actinides in the near- or far-field. Although the importance of migration of actinides which form the colloids has been pointed out recently, the migration behaviors of colloids are not fully understood. In this study, the migration behaviors of colloids were investigated experimentally by column method. In the experiments, quartz powder was used as the solid. Ferric hydrous oxide colloids were prepared as the real colloids and neptunium(V) formed Np(V)-Fe(III) pseudocolloids by sorption. Some fractions of the colloids eluted with the eluting solution. Also observed were strongly retarded fractions. Non-negligible fractions were found to migrate faster than the eluting solution. These migration characteristics were qualitatively understood in this work.