A study of the sorption of the radioelements: technetium; uranium;
neptunium; and curium onto geological materials has been carried out as part
of the PNC programme to increase confidence in the performance assessment
for a high-level radioactive waste repository in Japan. Batch sorption
experiments have been performed in order to study the sorption of the
radioelements onto bentonite, tuff and granodiorite from equilibrated
de-ionised water under strongly-reducing conditions at both room temperature
and at 60°C.
Mathematical modelling using the geochemical speciation program HARPHRQ in
conjunction with the HATCHES database has been undertaken in order to
interpret the experimental results.