ILW makes up more than three quarters of the volume of material destined for geological disposal in the UK. (1)
Currently the UK's preferred method is to encapsulate ILW in specially formulated cement. The waste is mixed with cement and sealed in steel drums, in preparation for disposal deep underground.
Two studies, published in the latest issues of The Journal of Nuclear Materials and European Journal of Glass Science and Technology A show that turning this kind of waste into glass, a process called vitrification, could be a better method for its long-term storage, transport and eventual disposal.
HLW is already processed using this technology which reduces both the reactivity and the volume of the waste produced. Until now, this method has not been considered suitable for ILW because the technology was not developed to handle large quantities of waste composed from a variety of different materials.
The research programme, funded by the UK's NDA and led by Professor Neil Hyatt in the Department of Materials Science and Engineering, at the University of Sheffield, tested simulated radioactive waste materials those with the same chemical and physical makeup, but with non-radioactive isotopes to produce glass and assess its suitability for storing lower grades of nuclear waste.
The process used to produce the glass waste storage packages is straightforward: the waste is dried, mixed with glass forming materials such as iron oxide or sodium carbonate, heated to make glass and finally poured into a container. For certain wastes for example radioactively contaminated sand the waste is actually used in the glass-making process.
A key discovery made by the Sheffield team was that the glasses produced for ILW proved to be very resistant to damage by energetic gamma rays, produced from the decay of radioactive materials. "We found that gamma irradiation produced no change in the physical properti
|Contact: Abigail Chard|
University of Sheffield