Partition characteristics of radionuclides during a melt decontamination of a contaminated metal waste

Abstract

Melt decontamination of radioactive contaminated metal waste using arc melting process is investigated the characteristic behavior phenomena of radioisotope cobalt-60 ( 60Co) and cesium-137 ( 137Cs) from a molten ingot, slag and dust for the effect of the basicity and various slag types. The composition of the slag former used to capture the contaminants ( 60Co, 137Cs) during the melt decontamination process generally consisted of silica (SiO 2), calcium oxide (CaO) and aluminum oxide (Al 2O 3). Also, calcium fluoride (CaF 2), magnesium oxide (MgO), and ferric oxide (Fe 2O 3) were added to provide an increase in the slag fluidity and oxidative potential. More 60Co was transfer to the slag phase in the carbon steel than the stainless steel. Most of the 60Co remained in the ingot phase at about above 90% present. 60Co was removed from the ingot phase to slag phase by up to 12% at about 0.8 of the slag basicity in carbon steel. There was found that significant amounts of 60Co remain in the ferric oxide slag at up to 32%. Flux containing CaF 2 was significantly captured to the slag phase by up to 30%. In all the tests, 137Cs was completely eliminated from the melt of the stainless steel as well as the carbon steel and distributed to the slag and dust phase. In the slag basicity at 0.5, a maximum of 25% of the 60Cs remained in the slag phase to the carbon steel. Fluoride slags favor a capture of cesium in the slag. A maximum of 30% of the 137Cs remained in a ferric oxide slag.