Influence of young cement water on the corrosion of the International Simple Glass

Colleen Mann,Claire Corkhill,Eric Pierce,Jeremy R Eskelsen,Sanheng Liu,Karel Lemmens,Karine Ferrand

doi:10.1038/s41529-018-0059-9

Abstract

Understanding the corrosion of nuclear waste glass is critical to predicting its safe disposal within a geological facility. The corrosion mechanisms and kinetics of the International Simple Glass, a simplified version of high-level nuclear waste glass, was shown to be significantly influenced by a high pH cement solution representative of disposal conditions. We provide the first microscopic characterisation of the porous, Zr-rich aluminoalkali-silica gel corrosion layer that was observed. Ca, Na and K from the cement solution were incorporated into the corrosion layer to charge compensate Si, Al and Zr species; the incorporation of Al was postulated to result in precipitation of an aluminosilicate-rich gel with large voids, facilitating rapid transport of species through the gel layer and significantly enhancing the corrosion rate. Precipitation of Al-containing zeolite and phyllosilicate phases was also observed, indicating that cementitious solutions may promote the detrimental ‘rate resumption’ stage of glass corrosion.

Highlights

It is the consensus of the regulatory agencies of a number of countries that vitrified nuclear waste should be disposed of within a deep geological disposal facility where it can safely undergo radioactive decay, isolated from the environment and future populations
The YCWCa solution maintained a high pH throughout the duration of the experiments; at 30 °C it was constant and remained at the value of the blank solution (pH(RT) 13.5), while at 70 °C a decline to pH(RT) 12 was observed (Supplementary Material Fig. S1)
The high pH and the composition of the cement leachate solution was found to exert a significant influence on the dissolution behaviour, as described below

Summary

Introduction

It is the consensus of the regulatory agencies of a number of countries that vitrified nuclear waste should be disposed of within a deep geological disposal facility where it can safely undergo radioactive decay, isolated from the environment and future populations. It is postulated that such longer-term resumption may be related to the continual leaching of Ca during the degradation of cement by infiltrating groundwater.[23]

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Methods

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Conclusion