Glass - Back to the Future!

Presenting Author:
Adam J Fisher

article posted 21 March 2016

Adam J. Fisher is a first year PhD research student at the University of Sheffield’s Immobilisation Science Laboratory, and part of the EPSRC Next Generation Nuclear Centre for Doctoral training. In 2014 Adam graduated from the University of Sheffield with a Master of Physics degree. His research involves the dissolution of UK HLW glass using advanced flow-through and surface analytical approaches to mechanistic and kinetic understanding. Adam is supervised by Dr. Claire Corkhill, Professor Neil Hyatt and Professor Russell Hand and is part funded by Radioactive Waste Management Ltd.

Measurement of the Forward Dissolution Rate of the International Simple Glass using the Single-Pass-Flow-Through Method

Adam J. Fisher, Russell J. Hand, Neil C. Hyatt & Claire L. Corkhill
Department of Materials Science & Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD, United Kingdom

Abstract Fig.1 The International Simple Glass.
Fig.2 The SPFT experimental set-up.
Fig.3 Stages of glass dissolution.
Fig.4 ISG glass particles before being subject to SPFT experiments.
Vitrified high level waste (HLW) from the reprocessing of spent nuclear fuel is destined for final disposal in a geological disposal facility. In this scenario, the release of radionuclides to the geo-sphere and bio-sphere will be controlled by the dissolution of the glass matrix, hence developing an understanding of glass dissolution is critical to building a robust safety case for geological disposal. In particular, an assessment of the kinetics of glass dissolution is required, as a function of the long-term conditions within the repository, e.g. under relevant temperature and groundwater pH environments. We present the results of an investigation of the forward rate of dissolution of the International Simple Glass (ISG), a reference HLW simulant base glass used by a collaborative group of nations interested in the advancement of glass dissolution knowledge. Using the Single-Pass-Flow-Through (SPFT) method we determined the inherent forward rate of ISG dissolution over the temperature range 40°C to 90°C and alkaline pH range of 7.5 to 11.5. Through application of the transition state theory, we obtained the fundamental parameters necessary to model the dissolution kinetics; activation energy (Ea), pH power law coefficient (?) and the intrinsic rate constant (k0). These results are discussed in comparison with those obtained on the same glass using the micro-channel flow through method [1], and also with those for a UK simulant nuclear waste glass [2]. [1] Inagaki et al. (2013) International Journal of Applied Glass Science 4 [4] 317-327 [2] Cassingham et al. (2015) Mineralogical Magazine 79 [6] 1529-1542