Colleen Mann, UK

After graduating from Queen's University, Belfast, in 2013 with an MSc in Chemistry, Colleen embarked upon a PhD working within the Immobilisation Science Laboratory at the University of Sheffield. The focus of her work is to determine the durability of glass in conditions that simulate that of a Geological Disposal Facility (GDF). An understanding of the reaction mechanisms and dissolution chemistry involved can help predict how the glass wasteform will behave in a GDF, which is key for safe geological disposal of nuclear waste.

Colleen's work, part of which has been field work in association with the British Geological Survey, has been presented at IGDTP, Thermal Treatment of Rad Waste and GeoRepNet conferences. Additionally, after being awarded funding by the Mineralogical Society of Great Britain and Ireland, and the Sheffield Metallurgical and Engineering Association, she was able to travel to speak at the prestigious Goldschmidt conference in Prague.

When she's not busy in the lab, Colleen relishes her role as a STEM ambassador in which capacity she has worked with schools during National Science Week and with the Museum of Science and Industry, where she engaged with the public about nuclear power and waste disposal. She is also involved in the Global Engineering Challenge at the University of Sheffield, facilitating 1st year undergraduates in tackling real-world problems from a global perspective.

In the Bin for 100,000 Years: An Intergenerational Burden

The UK Government have stated their preference for the final disposal of nuclear waste within a GDF, at a depth of between 200m and 1km. The GDF will incorporate Engineered Barrier Systems (EBS) that will be optimised to physically and chemically retard the transport of radionuclides to the biosphere. Groundwater will interact with the cementitious EBS which will produce alkaline conditions within the GDF; it is not well understood how such solutions will affect the durability of vitrified nuclear waste.

The results of an experimental study using simulant glass wasteforms exposed to cementitious leachate will be discussed. Additionally, Colleen will describe a natural analogue study in which 60-year old glass bottles, discarded in high pH leachate pools (pH~12.5) at a lime-waste site in the UK, are being investigated to understand the nature of alteration layers and the evolution of ground water at the site.


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