Immobilizationof LanthanideOxides Waste fromPyrochemical Process

Abstract

Lanthanideradioactive wastes are generated during the LiCl-KCl waste salt purification process developed in KAERI.The phosphate-based ceramics were studied for the immobilization of the wastes. The immobilization matrix developed in this study(ZITceramic wasteform)composed of zinc titanate(Zn2TiO4), CaHPO4, SiO2and B2O3. The lanthanide oxides were reacted with CaHPO4during solid phase sintering. The reaction producs of lanthanides phosphate(LnPO4), which havea composition similar to monazite, has been developed as a high-level nuclear waste host. The physico-chemical properties (XRD, SEM, density and thermal conductivity) and leach resistance of the borosilicate glass and ZIT wasteforms are discussedin this paper.