The Alvin Weinberg Foundation in London is tracking seven proposals across the world for molten salt reactors (MSRs) rather than relying on solid uranium fuel. Unlike conventional reactors, these operate at atmospheric pressure. They do not need vast reinforced domes. There is no risk of blowing off the top.

The reactors are more efficient. They burn up 30 times as much of the nuclear fuel and can run off spent fuel. The molten salt is inert so that even if there is a leak, it cools and solidifies. The fission process stops automatically in an accident. There can be no chain-reaction, and therefore no possible disaster along the lines of Chernobyl or Fukushima. That at least is the claim.

The most revolutionary design is by British scientists at Moltex. "I started this three years ago because I was so shocked that EDF was being paid 9.25p per kWh for electricity," said Ian Scott, the chief inventor. "We believe we can achieve parity with gas (in the UK) at 5.5p, and our real goal is to reach 3.5p and drive coal of out of business," he said.

The Moltex project can feed off low-grade spent uranium, cleaning up toxic waste in the process. "There are 120 tonnes of purified plutonium from nuclear weapons in Britain. We could burn that up in 10 to 15 years," he said. What remained would be greatly purified, with a shorter half-life, and could be left safely in salt mines. It does not have to be buried in steel tanks deep underground for 240,000 years. Thereafter the plant could be redesigned to use thorium, a cleaner fuel.

The reactor can be built in factories at low cost. It uses tubes that rest in molten salt, working through a convection process rather than by pumping the material around the reactor. This cuts corrosion. There is minimal risk of leaking deadly cesium or iodine for hundreds of miles around.

Transatomic Power, in Boston, says it can build a "waste-burning reactor" using molten salts in three years, after regulatory approval. The design is based on models built by US physicist Alvin Weinberg at Oak Ridge National Laboratory in the 1960s, but never pursued - some say because the Pentagon wanted the plutonium residue for nuclear warheads.

It would cost $2bn (overnight cost) for a 550-megawatt plant, less than half the Hinkley Point project on a pro-rata basis. Transatomic says it can generate 75 times as much electricity per tonne of uranium as a conventional light-water reactor. The waste would be cut by 95pc, and the worst would be eliminated. It operates in a sub-critical state. If the system overheats, a plug melts at the bottom and salts drain into a cooling basin. Again, these are the claims.

The most advanced project is another Oak Ridge variant designed by Terrestrial's David LeBlanc, who worked on the original models with Weinberg. It aims to produce power by the early 2020s from small molten salt reactors of up to 300MW, for remote regions and industrial plants. "We think we can take on fossil fuel power on a pure commercial basis. This is a revolution for global energy," said Simon Irish, the company's chief executive.

David Fuller's view

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Molten salt reactors that provide cheap energy, consume most of our nuclear waste, are vastly safer than nuclear plants in use today, and much cheaper to build, sounds too good to be true.  That is the reality today, but theoretically, the potential of future technologies is virtually unlimited. 

The prospect of commercially competitive molten salt reactors is presumably at least a decade away, assuming this fledgling industry receives the development capital required.  That will prove to be more of a political than economic challenge, I fear.  Backers of today’s various energy sources will be opposed, as will most militant greens, and governments are too often looking for short-term solutions.  

Nevertheless, there is a clear ‘needs must’ incentive for reliable, economic, 24-hour a day energy at a consistent rate, which does not pollute the atmosphere.  Molten salt reactor projects are certainly worth developing.

Looking ahead, I would welcome any informative articles and reports on this subject that readers are able to share with our Collective of Subscribers.