Leaching behaviors and mechanisms of vitrified forms for the low-level radioactive solid wastes

Abstract

Leaching behaviors and mechanisms of commercialized glass wasteforms to sequester low-level solid-wastes were investigated: SG glass for resin waste and DG-2 glass for dry active waste. After ANS 16.1 leaching test, leachabilities of the nuclides, Co, Cs, and Sr, were all lager than 14, which met the requirement of the US-Nuclear Regulatory Commission. Holes of diameters 5-10 μm remained on the surface of the SG and crevices of lengths 10-50 μm were observed on the surface of the DG-2. We analyzed elemental compositions of the SG and the DG-2 with depths. For the SG, Si, Al, Ca, and Mg were accumulated and Na was depleted up to nearly 1.5 μm compared to an internal glass. For the DG-2, concentrations of B, Na, Al, Ca and Sr started to decrease from 2.5 μm even though other minor elements are still remained their concentrations. We suggested leaching mechanisms: alkali elements including H would diffuse through the holes on the SG, while most of the elements including Si and Al would diffuse through the crevices on the DG-2.

Keywords: Corrosion behavior; Glass wasteform; Leaching test; Low-level radioactive waste.