Barriers to migration of radionuclides from radioactive waste repositories

Natural inorganic sorbents are known as effective barriers that reduce the migration of radionuclides from radioactive waste repositories and contaminated sites. They could be used as buffer, backfill and sealing materials in the repository and their presence in the host rock and the surrounding geological formations increases the retention properties of the strata. Natural occurring minerals from local origin are used in the study - zeolites (clinoptilolite and mordenite), celadonite and loess. Sorption of wide range of radionuclides is studies. Batch capacity is determined. Sorption of radionuclides from simulated natural solution is studied. Distribution coefficients are calculated from sorption isotherms. Desorption in presence of different natural solutions is studied. Sorption properties are compared. It is shown that clinoptilolite acts as effective barrier against migration of radionuclides from repositories. The presence of celadonite in the clinoptilolite rock increases the retention of polyvalent ions. The retention of radionuclides on loess samples fulfils the requirements for host media for repository for low and intermediate level waste. A method for construction of additional barrier to the existing in the country disposal vault for spent sealed sources is proposed