A breakthrough moment for thorium nuclear energy?

Originally published on guardian.co.uk.

Parliamentary events are often dull affairs, but Thursday night’s launch of the Weinberg Foundation – a new pressure group advocating thorium nuclear energy – was quite the opposite. I can’t remember the last time I stood in a room full of people concerned about climate change that was also so full of optimism.

Part of the warm glow may have been the result of a small pang of pride at the Guardian’s involvement. Two of the key people behind it all – the host, Bryony Worthington, and the keynote speaker, nuclear engineer Kirk Sorensen – met at the Manchester Report, a Guardian event on climate solutions that I organised a couple of years ago. Worthington was on the judging panel; Sorensen was advocating a little-known nuclear reactor design based on liquid thorium fuel.

In the two years since, Worthington has been appointed to the House of Lords and Sorensen quit his day job to set up FLIBE energy, a company dedicated to commercialising liquid-fluoride thorium reactors. Their collective enthusiasm for the technology played a key role in the creation of the Weinberg Foundation, which was set up “to drive awareness, research and commercialisation of cleaner and safer nuclear technologies, fuelled by thorium.”

The idea is to create a new generation of nuclear reactors based on the element thorium, as opposed to the uranium used to produce nuclear power today. Thorium, its advocates claim, is beneficial not only because it’s far more abundant and widely distributed in the Earth’s crust than uranium; in addition, liquid-fluoride thorium reactors (LFTRs, pronounced “lifters”) could theoretically be much smaller, much cheaper and much safer than conventional nuclear reactors. The waste they produce would remain dangerous for a far shorter period and, crucially, couldn’t be used to create nuclear weapons. As a bonus, these fourth-generation nuclear plants could even burn up the dangerous plutonium stored in existing nuclear waste stockpiles, using it as a fuel. The Weinberg team is already talking to Sellafield about this idea.

LFTRs aren’t the only way to use thorium to create energy. In a solid-oxide form, thorium can be used in existing, conventional light-water reactors. But that has a number of downsides, including the fact that it converts only a tiny proportion of the energy in the fuel into electricity. Particle physicists such as Nobel-prize-winner Carlo Rubbia have also advocated the use of sub-critical accelerator-driven thorium reactors, but this remains in the realm of scientific theory rather than nuclear engineering.

By contrast, liquid-fluoride thorium reactors are not just efficient but also proven – albeit some time ago. The US military produced a working prototype more than half a century ago at the Oak Ridge Laboratory in Tennessee. It ran for a number of years before the programme was suddenly shut down and the US government’s stocks of thorium buried. The most likely reason for this decision, it seems, is that LFTRs – unlike uranium reactors – didn’t go hand-in-hand with nuclear weapons production.

The speakers at last night’s launch included Richard Weinberg, son of Alvin, the new foundation’s namesake and the man who led the Oak Ridge thorium project until its untimely demise. Obviously a busy man in his day, Alvin, who died in 2006, is also credited with designing the uranium pressurised water reactor that dominates today’s nuclear industry, being one of the first scientists to warn about the risks of CO2 emissions and writing eloquently on how science and policy connect.

There’s no way to know whether LFTR technology will live up to its promoters’ vision of safe mini reactors rolling off production lines in the 2020s at low enough prices – and in sufficient quantities – to completely change the global energy and emissions picture. But what I’ve found striking discussing and reading about the technology over the past few years is that no one seems to disagree that it’s a good idea. There’s no obvious scientific case why it couldn’t work, and even many of the traditionally anti-nuclear green groups seem to be cautiously in favour – a point emphasised last night when Craig Bennett, policy and campaigns director of Friends of the Earth, said he supported thorium research and wished the Weinberg group the best of luck. (That said, the same NGO’s head of science, policy and research wrote in a blogpost earlier this year that “thorium nuclear reactors aren’t going to be ready in time [to avoid dangerous climate change].”)

Launching an advocacy group and winning support in principle is only a first step, of course. The harder bit will be persuading governments or investors to stump up the millions or billions needed to get the technology back up and running in prototype – and then commercialised. But judging from the atmosphere last night, thorium’s promoters aren’t going to take no for an answer.

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