Final disposal


The results of investigations carried out in Olkiluoto both from surface and from ONKALO are utilised for producing different three-dimensional models. Modelling provides an overall view of the area.

The results of investigations carried out in Olkiluoto are compiled into

  • geological
  • geochemical
  • hydro-geological
  • rock mechanical models.

Modeller can then produce three-dimensional illustrations of these models. Finally, an integrated rock model of the final disposal area is produced on the basis of the geological model.

Geological Model

Geological modelling utilises the data obtained from investigation trenches, outcrops, drill core samples and ONKALO regarding, among others, types of rock, their degree of foliation and fracture/deformation zones.

The geological model consists of four sub-models

  • the ductile deformation model
  • lithological model
  • alteration model
  • brittle deformation model.

The geological model acts as the basic point for other modelling, and together with the hydro-geological, hydro-geochemical and rockmechanics model, it will constitute an integrated rock model.

Hydrogeological and Hydrogeochemical Model

The main purpose of hydrogeological and hydrogeochemical modelling is to combine hydro-geological and groundwaterchemical investigation data and interpretations to produce a consistent description of groundwater flows and developments. Another objective is to describe the baseline characteristics of the flow and chemistry of groundwater deep in the bedrock before ONKALO is built.

Among, others, the hydrogeochemical model provides information on the salinity of groundwater. The hydrogeological model shows the rock structures where water flows are present.

Rock Mechanics Model

In rock-mechanics modelling, the basic data is interpreted both by computational methods and by modelling the mechanical properties near excavated facilities. The modelling utilises, among others, information on the quality, strength and state of stress of the rock. They are used to produce, for example, an estimate of the probability of rock damage, spalling, in different parts of ONKALO.

The basic data used for rock-mechanics modelling includes the results of rock mechanical, geological and geophysical surveys carried out through drillholes and from ONKALO.


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