Thorium: Climate Panacea, or Pipe Dream?

By Delany Higgins

2018’s dire report from the United Nations’ Intergovernmental Panel on Climate Change (IPCC) warned of poverty, extreme heat, submersion of coastal areas, drought, and severe ecological damage as a result of a half-degree of warming in the Earth’s temperature. While the IPCC’s hypothesised scenarios to mitigate this warming focus on cutting fossil fuel production and increasing bioenergy and carbon capture technology, many leaders and activists concerned with the potential tradeoffs of climate change action have proposed thorium technologies as a source of clean energy. Unfortunately, this fuel-of-the-future may not possess all of the wondrous qualities that its proponents proclaim.

Image Source: Theodore Gray

Thorium is an alternative nuclear power source to uranium, but one which researchers have indicated comes without the contamination, meltdown risks, proliferation problems, and high economic costs caused by uranium reactors. Proponents of thorium are growing more numerous. Indian Prime Minister Narendra Modi has recommitted his government to invigorating the country’s thorium program. A commission started by former U.S. president Barack Obama examined the matter, U.S. presidential candidate Pete Buttigieg indicated support for research into thorium, and fellow candidate Andrew Yang became a particularly vocal proponent. Yang contends that thorium has not become more widely used due to lack of funding for research and plant establishment. Nonetheless, thorium is beginning to make its way into policy. 

Image Source: Vox

The Netherlands recently opened an experimental thorium molten salt reactor, and in 2017, China pledged US$3.3 billion to developing thorium reactors. ‘Obama could kill fossil fuels overnight with a nuclear dash for thorium’, wrote one enthusiast in The Telegraph. 

Image Source: NRG

Pursuing energy generation that doesn’t cause a greenhouse effect, these leaders in thorium reactor development are investing in the technology as a safer alternative to conventional uranium-based reactors.  Yet India, with the world’s largest thorium reserves, and which has been pursuing the technology for over sixty years, has yet to establish sustainable thorium-based reactors. As enthusiasm for thorium to combat climate change heightens, so too do skeptics’ eyebrows.

The main arguments for thorium rest on the resistance of thorium reactors to meltdown, the safety of its waste, its lower risks of proliferation, and its economic efficiency. 

Claims that thorium reactors are safer derive from the ostensible safety of their waste, and from improvements in proposed reactor designs, known as molten-salt reactors (MSRs), rather than what would happen if countries switched all current uranium-based reactors to thorium-uranium fuels. The experimental Dutch design was the first of these MSRs to be created in forty-five years, though Indonesia has considered one; the former must be watched closely. Their safety in practice – most accidents do not arise from errors anticipated in theory – has yet to be demonstrated. With regard to hopes about their waste – such assertions as that found in Yang’s platform that ‘Thorium waste remains radioactive for several hundred years instead of several thousand years’ –  the U.S. Department of Energy found that over time, the opposite is the case. 

Image Source: Atlas Obscura

A further property of thorium that has attracted supporters is that its fuel cycle poses less proliferation risks, as it is not itself fissile and does not produce plutonium. The story goes that the wonder-fuel was abandoned because it did not serve the Cold War’s arms race. One Forbes writer’s rendition of the history, ‘The fact that thorium reactors could not produce fuel for nuclear weapons meant the better reactor fuel got short shrift’, is a common refrain. It is, however, possible to produce uranium-233 from thorium by chemically separating protractinium-233, which could be accomplished in labs not overseen by the International Atomic Energy Agency. The U.S. and India have both detonated weapons based on U-233. 

Thorium is far more naturally abundant than uranium, which has led some to believe that it would be less expensive as a fuel. This argument occludes the true source of the cost of nuclear energy, which is in the construction and maintenance of the reactors themselves. 

The cost of thorium reactors relative to uranium-based ones, the safety of such reactors, and their proliferation resistance have all been dramatically overstated. The MSRs still merit experimentation, but as India’s decades of experience have taught, thorium as a primary power source is far from a practical solution to climate change.

While the overall pressure for alternative energy sources, nuclear among them, grows, the safety and feasibility of thorium reactors remains tenuous. Whether societies wish to take on the risks of such technology to mitigate the risks of climate change does too. 

Cover Image Source: The Conversation

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