Corrosion behavior of some glasses immobilized with REE in simulated mineralized solutions

Abstract

Bentonite clay is the most promising material with great waterproof properties, which is considered to hold a great potential as an engineering sealing barrier in deep geological repository use. However, the other properties of the said material after contact with groundwater may be of a huge concern in terms of longterm disposal of radioactive waste in a number of circumstances. This article analyses possible results of such interactions and their consequences. Samples of borosilicate, aluminophosphate, and iron phosphate glass, containing rare earth elements (REE) of the composition Ce0,12La0,19Nd0,31O as simulators of radioactive waste, were synthesized. Solutions of model underground water, imitating the water of the Nizhnekansky granitoid massif that passed through clay engineering barriers, were investigated. The analysis of the structure of glasses after contact with model bentonite, zeolite, and kaolin contact solutions at 120 °C, simulating the heat release of alpha-emitters immobilized in glass, was carried out. It was shown that glasses, upon contact with model solutions, were subject to the formation of a corrosion layer as well as depletion of the glass phase in structure-forming elements. Significant structural rearrangement after leaching in all samples was determined by IR spectrometry, while the smallest changes were typical for samples leached in bidistilled water and kaolin contact solution. This information could be crucial for modeling the long-term behavior of nuclear glass in various scenarios of geological repository degradation or accidents.