Leaching and migration of Np, Pu, and Am from α-doped SON68 HLW glass in contact with dense clay

ABSTRACTIn the frame of an integrated in situ test on the alteration of the SON68 reference glass in realistic disposal conditions, the leaching of Np, Pu, and Am from α-doped SON68 glass samples and their migration in three clay-based backfill materials at high density was measured. The addition of powdered glass frit to a Ca-bentonite decreased the glass alteration by two orders of magnitude, and resulted in a concomitant decrease of the radionuclide leaching in comparison with dried Boom Clay, which is the more agressive backfill. All actinides were selectively retained in the alteration layer, but the retention degree was lower for Np than for Pu and Am. All backfill materials proved to be efficient barriers against radionuclide migration. For nearly all radionuclides and backfill materials, the migration profile showed a contribution of colloidal transport.

7-Years Leaching Tests of NPP Vitrified Radioactive Waste

Long term tests of vitrified intermediate level waste from nuclear power plants were performed in a shallow ground repository as well as on an open testing area. Borosilicate glasses were tested. Radionuclide leaching differs significantly in natural conditions in contrast to laboratory behaviour. Average leaching factors were obtained for open area tests as well as for repository tests. These factors should be used for long term predictions since they take into account the real character of leaching.