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Reducing risk: Waste remaining from the Prism process would be in a relatively safe form
A new kind of fast reactor has emerged as a “credible option” for dealing with Britain’s stockpiled plutonium and should undergo further assessment, a report by the Nuclear Decommissioning Authority (NDA) has said.
Britain has a 112-tonne stockpile of plutonium, which costs £80 million a year to store. The material could feasibly be used in the proliferation of nuclear weapons.
One means of dealing with the material would be to convert it to mixed-oxide fuel (Mox) for nuclear reactors. But a Mox plant built at Sellafield in the late 1990s encountered a decade of technical difficulties, forcing the government to consider other methods of disposal.
The sodium-cooled Prism fast reactor being proposed by General Electric-Hitachi would effectively use plutonium as a fuel, ‘burning’ it so that all isotopes of plutonium are fissioned, and creating low-carbon energy in the process. After the fuel is spent, the remaining waste is safer than plutonium in the form stored today, making it less liable to be used in weapons, and therefore cheaper and easier to store.
The Prism reactor would convert separated plutonium oxide to a sodium-bonded uranium/plutonium/zirconium metal fuel using direct electrolytic reduction, pyro-processing and metal casting techniques. Irradiation of this fuel in a Prism reactor would take place in a burn, rather than breed, mode. The spent fuel could then be
stored according to a long-term disposal strategy.
The NDA has spent two years assessing the feasibility of a Prism reactor. It stated: “Based on the information available at this time, Prism appears to be a credible option against our criteria.”
The NDA added that it would hold discussions with GE-Hitachi over the next two years to further understand what it described as “technical uncertainties” surrounding the reactor.
Mark Elborne, chief executive of GE UK and Ireland, said: “The UK has the largest storage of civil plutonium anywhere. We believe Prism offers the most effective solution for reusing that material as an asset rather than a liability, maximising taxpayer benefits.”
The Institution of Mechanical Engineers has issued a policy statement calling on the government to push forward with the development of a fast reactor programme by committing to pay for the disposition of the plutonium stockpile in an operational reactor.
Tim Fox, head of energy and environment at the IMechE, said: “Once initial development has been stimulated to follow a commercial pathway, an operational reactor will emerge earlier than if a long-term government-funded research and development programme is pursued. This would benefit the UK through disposition of the plutonium stockpile in a shorter timescale than via alternative approaches.
“However, for the commercial solution to be sufficiently attractive, it will be necessary for the government to commit to pay for the disposition of the plutonium stockpile once a reactor is operational,” he added.
Development of a fast reactor programme would present the UK with the chance to become a world leader in the associated engineering and manufacturing, said Fox.
“This would lead to a long-term export opportunity and enable the UK to regain a position as a leading player in nuclear power,” he said.
The NDA report said that a Prism reactor could be operational within 14 years.