Plutonium residues project

An NNL-led project to develop a glass ceramic wasteform to encapsulate plutonium residues using Hot Isostatic Pressing (HIP) has been shortlisted for the Institution of Chemical Engineers annual award for “Chemical Engineering Project of the Year”.

The IChemE awards are global in reach and recognise all aspects of chemical, process and biochemical engineering. Widely regarded as the most coveted industry awards throughout the process industries, IChemE Chief Executive David Brown says: “The IChemE awards go from strength to strength and it’s been another strong year in terms of entries. To be shortlisted for an award demonstrates high achievement and I offer my congratulations to all of the shortlisted participants.”

Competition for the award is strong. The other short-listed entries are from Syngenta, AstraZeneca, ABB Australia, Sellafield Ltd and Costain, with the winner to be announced at an event in Birmingham on 3rd November.

In its submission to IChemE, NNL’s project team explained:

“Plutonium-239 and plutonium-240 together contribute just over 4% of the radioactivity that will be disposed to a planned geological disposal facility for UK’s radioactive wastes. The half-life of plutonium-239 is 24,100 years and that of plutonium-240 is 6,560 years. The retention of plutonium in the very long term is essential to ensure it does not migrate into the human environment. This project has developed durable plutonium-containing glass ceramic waste formulations that successfully mimic natural minerals such as zirconolite that persist over many millions of years. Small scale active trials have demonstrated exceptional durability.

Consequently, our solution provides a step change in environmental benefit and profileration-resistance as compared to established technology, and has done so by overcoming substantial technical challenges of operating at high temperatures and pressures in a nuclear environment – higher than in a nuclear reactor!

The difficulty in introducing new technology to an industry which requires substantial underpinning for any new process should not be underestimated and the project team has needed to convince a range of stakeholders with differing interests as to the efficacy of the solution proposed.
The introduction of glass ceramics technology has the potential to discharge a liability estimated at in excess of £100m in the provision of the lifetime baseline plan for the Sellafield site. In addition it is expected that the demonstration of such technology in one specific area has the potential to open up other target waste markets which the project team have already been developing.

Challenges still lie ahead in implementing the solution in NNL’s Central Laboratory, but it is considered that the advances made in understanding the process has significantly reduced the risk of immobilising the plutonium wastes and residues.”

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