Oct 31 2013

Thorium Reactors

Thorium is a radioactive element (atomic number 90), discovered by a Norwegian and named after the Norse god, Thor. It is fairly common in the earth’s crust, widely distributed throughout the world, with the largest deposits in Australia, the US, Turkey, and India.

If advocates have their way, you may be hearing more about thorium in the future. It is a potential fuel for nuclear reactors. We have not yet fully developed the technology for building thorium reactors, and the debate is on over whether or not this is a useful investment of energy development funds.

Carbon emissions and global climate change have raised the stakes of this controversy. I am with Bill Nye in advocating searching for the win-wins in combating carbon emissions – rather than asking people to sacrifice, find ways of improving their lives while lowering carbon emissions. The question is, is thorium a potential win-win?

Advocates argue that thorium is abundant and not concentrated in unstable parts of the world. There is about three times as much thorium as uranium in the earth’s crust, and it is more highly concentrated in its ores, making obtaining thorium more cost effective.

A thorium reactor is potentially safer than a uranium reactor. The thorium cycle is not as self-sustaining as uranium – thorium is not fissile on its own. In fact, most concepts use uranium to seed the thorium reaction. Uranium can also be used to keep the thorium reaction going at a higher rate, and disconnecting the uranium reaction (or whatever source of neutrons you are using to get the thorium cycle going) would quickly reduce or stop the thorium reaction when needed.

Thorium also does not create any long-lived radioactive waste. Thorium waste would dissipate its radioactivity in 400-500 years, compared to the uranium cycle which produces various waste products with half-lives ranging from tens of thousands to millions of years. Further, thorium waste could not be weaponized, as uranium waste can be. We can let Iran build thorium reactors without worrying about their weapons program.

Why, then, are we not powering our world with thorium reactors? The most common opinion I have found as to why the US chose uranium over thorium is the fact that the former can be weaponized. ¬†This was thought a beneficial byproduct during the cold war. Whether or not this is true, billions of dollars were invested in developing uranium technology. It’s like the qwerty keyboard – it may not be superior, but we’re stuck with it.

That leaves us with our current dilemma. Thorium seems like an excellent choice for an energy source that does not produce carbon. However, we would need to invest billions in developing the technology. One technological barrier is refining the ore, which requires very high temperatures and is therefore expensive. Reactor designs also need to be developed.

The question is – is this the best way to spend those billions of dollars on energy development?

Renewable energy advocates argue that we would be better off spending that money on wind, solar, and other renewable energies. Some have even argued that if we invested the same money we did in uranium power plants on renewables, we could already run our world on clean energy.

I don’t buy that argument. ¬†Investment certainly accelerates scientific and technological advance, but doesn’t alter the reality when the technology is simply not ready. Sometimes technological progress has to wait for other technological advances, for example in material science, battery design, and nanotechnology. Current advances in wind and solar especially are taking advantage of these technologies, that just were not around 50 years ago.

In any case, the question remains, how do we invest our energy money going forward? These are tough questions as they require predicting the future of technological development. My usual answer to such questions is to do everything, and let the technology sort itself out. Don’t try to pick winners and losers – let the market do it.

American car companies around the turn of the century invested in the coming hydrogen revolution. Japanese car companies hedged their bets and invested in hybrids and a bridging technology. The Japanese won that game, capturing the hybrid market, and leaving American companies in the dust nursing their hydrogen fuel cell dreams.

Wind, solar, and thorium are all clean energy sources. They all have their strengths and weaknesses, none are perfect. They will likely all have a niche in the future of energy production.

But the problem remains that thorium requires a huge investment up front. That is a big hurdle to get over. We can’t dabble in thorium, we would have to invest heavily. From everything I have read it does seem like a good investment to me. Perhaps this needs to be an international project to spread the cost around. In any case I think this is one technology to keep an eye on.

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