ASPECTS OF THE MIGRATION OF LONG·LIVED RADIONUCLIDES FROM UNDERGROUND WASTE REPOSITORIES

It is generally agreed that long-lived, high-level radioactive wastes should be disposed in deep-geological formations. To select the optimum rock type for waste disposal, scientists consider formations with minimal groundwater flow. To study the migration rate of the radioactive nuclides, so-called geological analogues are used. The geological analogue is the natural uranium deposit where the production of radionuclides has occurred since its formation. These long-lived radionuclides are in an equilibrium state and their possible migration to the adjacent rock can be calculated and in some cases measured. The natural production of radionuclides, however, also takes place in the rock and must be estimated for establishing the background of particular radionuclides. In this presentation, the physical phenomena involved in the natural production of radionuclides and the results of calculation of their concentration will be discussed.