A solution of safe isolation of radioactive waste represents a multidisciplinary problem. The waste isolation is to be provided by a multi-barrier system of an underground repository based on a system of several barriers. The system will consist of a container with high level radioactive wastes itself, an engineering barrier — currently intended to be based on ‘bentonites’ — and natural barrier formed with a suitable rock environment. Each of those barriers alone should prevent spreading of hazardous radionuclides from the container to the biosphere.
In its main part, this paper deals with laboratory research of some most important geotechnical requirements for the engineering barrier, assumedly based on bentonites materials. The group of tested properties contains:
• Hydrophysical properties - permeability, swelling ability, Atterberg’s consistency limits
• Physico-technical properties - thermal properties
Creation of mathematical and physical models forms an independent part of the complex research project for materials of the geotechnical part of the engineering barrier. In the conclusion a short consideration on a prepared physical model of container has been made.