Disposal of Low- and Intermediate-Level Radioactive Waste

摘要

As for isolation of high-level radioactive waste by use of smectite clay it serves verywell also for hindering radionuclides from low- and intermediate-level waste tocontaminate groundwater. It can be used for minimizing groundwater flow throughand along waste packages and for providing them with ductile embedment foreliminating the risk of damage caused by displacements in host rock or concretevaults. The clay can have the form of liners placed and compacted on site over vaultsconstructed on the ground surface, or consist of compacted blocks of clay granulesthat are tightly placed around waste packages in underground drifts and rooms. Ineither case the initially incompletely water saturated clay will swell in conjunctionwith water uptake until tight contact with the confining medium has beenestablished. The clay seals must be sufficiently dense to fulfill criteria set withrespect to hydraulic conductivity and swelling capacity, paying due attention to thesalt content in the porewater. Their physical and chemical stabilities must beacceptable in short- and long-term perspectives, which is a few hundred years formost low-level wastes up to tens of thousands of years for long-lived waste.