THE STUDY ON PLASMA VITRIFICATION TECHNOLOGY FOR THE TREATMENT OF RADIOACTIVE AND HAZARDOUS WASTES

摘要

To evaluate the cost benefit of the treatment of low-level radioactive wastes and hazardous wastes by plasma technology, vitrificationrntests of nuclear surrogates and fly ashes from municipal waste incinerators are studied. The nuclear surrogate wastes suchrnas concentrate, cement solidified wastes, bottom ash from incinerator, resin, thermal insulators, high efficient particulate air filter,rnmetal, contaminated soil etc. were prepared according to the waste stream from one nuclear power plant in Taiwan. Non-radioactiverntracers with an amount of 0.1wt% are added into surrogate wastes to study the volatility of radioactive nuclides such as Cs-134,rnCs-137, Co-60, Co-58 etc. To control the quality of vitreous slag, to reduce the melting temperature and to obtain maximum volumernreduction ratio in each vitrification testing, no additional glass-formers were added and the strategy that one waste surrogaternwas mixed with another was used. Several tens of vitrification tests under the temperatures between 900℃ and 1650℃ are performedrnto screen out the proper waste mixtures which produce high-quality slag with satisfied volume reduction ratios. The evaluationrnof plasma vitrification treatment for the low level radioactive wastes of the nuclear power plant in Taiwan by using binaryrnwaste mixing strategy shows that the gross volume reduction ratio is greater than 2.8, which implies that the final disposal cost is tornbe greatly reduced. Vitrification tests of fly ashes and bottom ashes from two incinerators show that ash residues can be easilyrnprocessed without additives at 1500℃, and glassy slag with high compressive strength and low leaching rate has great potential tornbe reused as construction materials.