A Study on the Vitrification Tests of the Low Level Radioactive Wastes Using Plasma Arc Melter System

For the research on the vitrification of the low-level radioactive wastes (LLRW) produced in nuclear power plants, one pilot plant with plasma arc melter system was built and several tests were done on it. Some surrogate wastes, which were spiked with several materials and were made very similar to the real LLRW, were used for these tests. For the vitrification of the surrogate wastes, the surrogate wastes were classified into the combustible, the non-combustible and the resin. Then each waste was spiked with special materials and was melted in separate. Off-gases produced in each test were picked up and analyzed. Real radioactive materials cesium (Cs) and cobalt (Co) were spiked in each wastes. Data gained from the final glass formulation were follows. Glass density is 2.42 ∼ 2.95(g/cm³), the compressive strength is 30 ∼ 175 Mpa, micro hardness is 5.5 ∼ 5.8 Gpa. The leaching ratio for Co is 1.27×10⁻⁴ ∼ 1.08×10⁻³ (10mL/g) and that for Cs is 2.46×10⁻³ ∼ 3.23×10⁻² (10mL/g). The leaching speed for Co is 4.14×10⁻⁷ ∼ 5.53×10⁻⁶ (g/m²) and that for Cs is 4.58×10⁻⁵ ∼ 3.87×10⁻⁴ (g/m²). In off-gas, dioxin & furan is 0.016 mano gram on the average, CO is about 20 ppm, NO₂ is about 15 ppm and SO₂ is about 15 ppm.