JET's fusion reactor, where physicists recreate conditions inside the sun, is the sort of experimental nuclear technology that could help the UK cut its emissions, government scientific advisers say. Photograph: Efda-Jet
The UK will need to develop a huge fleet of currently experimental nuclear reactors by the middle of the century, to generate around two-thirds of the country's electricity supply if it is to meet the most nuclear-intensive scenario for moving away from fossil fuels, according to a report by three of the government's most senior scientific advisers.
The expansion would involve developing nuclear generation technologies that are not currently used commercially anywhere in the world, and would also entail a huge expansion from the current electricity contribution of nuclear power to the UK grid. In 2011, nuclear supplied 18% of electricity demand.
If each reactor has the generating capacity of the Hinkley Point power station that would mean at least a trebling of the current number of reactors – 16 at nine different sites around the country. The eventual number could be much higher because the new unconventional reactors are expected to have a smaller generating capacity.
The expansion is necessary to fill the gap left by fossil fuels such as coal and gas, which the government has pledged to phase out to reduce carbon dioxide emissions.
The report, which is not yet published, encourages development of unconventional alternatives such as "fast reactors" powered off nuclear waste, designs using thorium rather than uranium, and even fusion power. It implies they could help nuclear to provide as much as two-thirds of UK electricity by 2050.
Sir John Beddington, the government's chief scientific adviser, along with David MacKay, the Department of Energy and Climate Change (Decc) chief scientific adviser, and John Perkins, scientific adviser to the Department of Business Innovation and Skills, are the report's authors.
They have already made "a number of recommendations" to ministers based on findings in the report, a Decc spokesman said.
Other technologies highlighted in the Civil Nuclear Industrial Strategy report include the use of thorium, a radioactive chemical element – the proponents of which say is more efficient than uranium and is more difficult to make into a nuclear weapon.
Researchers also want to fashion them into small, "modular" sizes that are more affordable and easier to produce than today's large nuclear power stations, and even transportable.
A Decc spokesman said of the report: "In order to potentially deliver against the upper end of this scope, it is likely that more advanced and diverse options will need to be explored by the market." He added: "Ensuring that these options are not foreclosed or essential skills lost will be an important long-term objective, and the R&D roadmap element of the work will set out a number of pathways and key decision points for any future R&D programmes to consider."
The report is due to be published in the coming months.