The
modelling carried out for this project comprised calculations of the transport
of radionuclides from two repositories located within a clay layer. The clay
layer was bounded above and below by aquifers. A second clay layer was present
above the upper aquifer. Transport in the aquifers was dominated by advection,
while in the low permeability clay layers the transport was dominated by diffusion.
Both
two- and three-dimensional models were created. The models measured approximately
25km in the horizontal direction and 700m in the vertical direction. The 3D
model shown above was constructed using data taken from a GIS package, and used
boundary conditions taken from a pre-existing hydrogeological model.
The
calculations considered the transport of a non-sorbing long-lived radionuclide
and of a highly sorbing radioactive decay chain with 6 members. Time-dependent
source terms were included in the models. The total modelled time was 10 million
years.
