DescriptionThis work deals with transport of radionuclides in the geosphere. The subject is investigated through
characterization of water conducting fractures, determining of rock transport properties and development
of new methods for characterizing geological samples. Here, as is often the case, radionuclide
transport is investigated indirectly by characterizing the structures where the transport takes place
and by using gas phase measurements in the transport experiments to save time.
First water conducting fractures of dierent types and the rock matrix surrounding them were
analyzed through rock samples from Olkiluoto. The analysis was done using X-ray tomography, the
14C-PMMA autoradiography technique and petrographical methods. The rock properties around
the fractures were found to be highly heterogeneous, but some combining features were found. This
experiment also showed the strength of combining dierent analysis methods.
Second, a method for converting local porosities obtained through the 14C-PMMA autoradiography
technique was developed by analyzing the radiation emitted from a the 14C-PMMA lled fracture
by Monte Carlo simulations and comparing them to fracture apertures. A connection was found and
the method vas validated by manufacturing articial glass plate samples with fractures of known
apertures and analyzing the autoradiographic images obtained from them. The method needs further
development before it can be used on real rock samples, but it was shown to be extremely promising
in the studies conducted.
Title of thesis: TRACER MIGRATION IN GEOLOGICAL SAMPLES - APPLICATION TO
|Period||2010 → 2016|
|Examination held at||University of Jyväskylä|