[en] The solidification of nuclear power station wastes with cement is one of the main initial treating methods leading to storage. The so-called radwaste concrete created, or the system of the radwaste concrete proper and its container, must be durable especially as regards the prevention of the transfer of the radioactive material to the environment. In the report it has been attempted to study expecially those properties which affect the long-term durability and leaching of porous materials, or permeability and porosity properties. These studies include tests on water suction, drying, water permeability, sorption isotherm with surface determination, porosity and mechanical strength, as well as other determinations and clarifications of relationships considered necessary. The report could for its part be preliminary data of the properties of ion-exchange radwaste concrete and its testing methods. The service life requirement of the radwaste concreate, or more generally, the system of the radwaste concrete proper and its container, with special reference to prevention of the transfer of radionuclides from the system to the environment, is about one hundred years, or several hundred years or even more. If the radwaste concrete itself is not durable enough, its containers or the multibarrier system, which surrounds it, must be able to withstand the deterioration or leaching factors