Immobilization of simulated high level nuclear wastes with tholeiite-type basalt

The powder mixtures of tholeiite-type basalt containing 5, 10 and 20 wt% of simulated high-level nuclear wastes were sintered at 1000, 1050, and 1100degC for 5, 10, 30, 50 and 100 h. Compressive strength, thermal expansion coefficient, chemical durability, apparent density, porosity, leaching test into alkali and acid solution were examined. The maximum compressive strength of the sample sintered at 1100degC for 100 h was slightly greater than that of commercial quartz glassrod. Judging from the results of various tests, the optimum condition of sintering for a good waste disposal material is as follows: amount of simulated waste; 10 wt%, firing temperature; 1100degC, sintering duration; 100 h. (author)