Glass could improve disposal of nuclear waste

This is according to researchers at the University of Sheffield, who tested simulated radioactive waste materials to produce glass and assess its suitability for storing lower grades of nuclear waste.

They have shown, for the first time, that 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.

ILW makes up more than three quarters of the volume of material destined for geological disposal in the UK.

A key discovery made by the Sheffield team was that the glass produced for ILW proved to be very resistant to damage by energetic gamma rays

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.

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 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.

A key discovery made by the Sheffield team was that the glass 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 properties of these glasses, and no evidence that the residual radiation caused defects,” said Professor Neil Hyatt in the Department of Materials Science and Engineering.

“We think this is due to the presence of iron in the glass, which helps heal any defects so they cannot damage the material.”

“For large volumes of waste that need to be stored securely, then transported to and eventually disposed of, vitrification could offer improved safety and cost effectiveness,” he added.