article posted 8 April 2016
Dr Clare L. Thorpe is Post Doctoral Research Associate at the University of Sheffield’s Immobilisation Science Laboratory.
She graduated from the University of Manchester in 2008 with a MEarth Sci in Geochemistry and completed a PhD in Radionuclide Biogeochemistry in 2012. Prior to commencing
her current PRDA position Clare worked for three years on a collaborative Knowledge Exchange project funded jointly by the University of Manchester and Sellafield Ltd
studying radionuclide mobility in the Sellafield subsurface.
Leaching methodologies to evaluate the durability of Immobilized Low Activity Waste (ILAW) glasses
1Clare L. Thorpe*, 1Russell J. Hand, 1Neil C. Hyatt, 3Albert A. Kruger, 2David Kosson and 1Claire L. Corkhill
1Department of Materials Science & Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD, United Kingdom.
2Vanderbilt School of Engineering, 2301 Vanderbilt Place, Nashville, TN.
3U.S. Department of Energy, Office of River Protection, Richland, WA 99352
At the Hanford site, USA, low activity tank wastes will be immobilised by vitrification to create 150-350,000m3
of Immobilised Low Activity Waste (ILAW) destined for
disposal in a shallow subsurface Integrated Disposal Facility (IDF). During reprocessing, tank wastes have a separable low activity waste fraction that will report
to the LAW facility for treatment. Radionuclides of concern in LAW glasses will include 60
Tc and 90
Sr alongside toxic metal contaminants. Conditions
in the IDF are expected to differ from those within a deep geological disposal facility for high level waste with temperatures expected to be ~ 15° C, an arid climate,
variable pH and groundwater flow rates.
Project GLAD (Glass Leaching Assessment for Disposability) investigates newly developed leaching technologies for assessing the durability of ILAW glasses. Four new
methodologies developed by the U.S. Environmental Protection Agency for application to the accelerated ageing of ILAW glass are compared to established leaching tests
accepted for evaluation of high level waste glasses, including PCT and MCC-1 protocols. The GLAD project studies the process of glass dissolution and constituent leaching
as a function of temperature, pH, groundwater composition and flow rate.
Here, the durability of three candidate glasses were analysed and compared to simplified glasses. Results of ‘Method 1313’, a batch leaching test to assess performance as
a function of pH, are compared to results obtained from standard PCT-B and MCC-1 tests.
Fig 1: candidate glasses: ORP-LB2, LAWA23 and LAWA44
Fig 2: pH dependent release of Al from candidate glasses
Funding for this work was provided by William F. Hamel, Jr., Federal Project Director, of the U.S. Department of Energy Waste Treatment & Immobilization Plant Project.
Project collaborators: Pacific Northwest National Laboratory (PNNL) and the Consortium for Risk Evaluation with Stakeholder Participation (CRESP).