Interactions of Colloids with Radionuclides in Geosphere

MON, 01/31/2011 - 4:00PM TO 5:00PM
Spring 2011 Colloquium Series

Radioactive waste disposal is an inevitable issue in all countries where pursue the sustainable use of not only nuclear energy but also radioisotopes in industries and medical services. From the engineering point of view, it is important to improve the reliability of performance assessment and safety assessment of the disposal for the societal and public acceptance. To achieve this goal, in the University of Tokyo, the adsorption/desorption of fission products and actinides on colloids and the migration of colloids in the geologic media have been investigated, since the colloids associated with fission products and actinides can act as a carrier for them in geosphere and biosphere. In the seminar, our recent research activities shown below will be introduced. (1) Metal adsorption in Mz+/natural organic materials (NOM)/mineral ternary systems An extended surface complexation model of a Mz+/NOM/mineral ternary system is developed, by taking into account various interactions between a NOM and a mineral surface and with the help of spectroscopy. (2) Multi-mode factor analysis for time-resolved laser-induced fluorescence spectroscopy (TRLFS) Parallel factor analysis is applied to a series of TRLFS data, and the speciation of a target metal ion is studied. (3) Field-flow fractionation (FFF) studies for environmental nanocolloids FFF is performed to investigate aggregation/disaggregation of nanocolloids in response to a change in chemical conditions and size-dependent binding of metal ions.

About the Speaker:

Prof. Nagasaki was graduated from Department of Nuclear Engineering, The University of Tokyo in 1988. After working in electric power company about 3 years, Nagasaki worked as Research Associate of Dept. Nuclear Engineering (1991-1993), Lecturer (1993-1995), Associate Professor (1995-2005) and Professor (2005-) at the University of Tokyo. Prof. Nagasaki is now a visiting professor at the Department of Nuclear Engineering, UC Berkeley. Research interests are interaction and migration of actinides and actinide colloids, and recent education interest is development of education program with widely distributed social scientific literacy for engineering students.