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Hank addresses a highly requested topic - liquid fluoride thorium reactors - and tells us how LFTR might be the future of energy in ... China?

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Hank Green: One thing's for sure: we humans, we need electricity now, but since fossil fuels are turning our environment into a crap circus, some scientists are telling us not to discount nuclear energy. In fact, they say that maybe we should switch our uranium based nuclear reactors to safer, cheaper thorium based ones.

Thorium is an element, a metal, that's close to uranium on the periodic table, but with two fewer protons. And it's named after Thor, the Norse god of thunder, which is cool, but it's not an element that we've historically paid much attention to, seeing as it's pretty much as common as dirt. In fact, until recently, most mining operations literally threw it out while they were trying to get other stuff. But a small and growing group of thorium fans say that it is the future of power production.

These people are pushing the idea of adapting existing nuclear power plants to use thorium as a fuel, or just replacing them entirely with a completely new kind of reactor, called Liquid Fluoride Thorium Reactors, or LFTR, which they pronounce 'lifter'. LFTR uses a mixture of liquid salts to cool the reactor and to transfer the heat energy out of the fission chambers into something that can then power a turbine. Proponents say that such a system would be more efficient and safer than the pressurized water used to cool uranium fuel rods now and the boiling water and steam used to transfer the energy they create.

Because LFTR doesn't use water for cooling, there's no possibility of a hydrogen explosion, like what happened at Fukushima. Also, although thorium is a radioactive element, it emits alpha particles which are less biologically harmful than uranium's gamma particles. Thorium fueled reactors used a fraction of the material necessary to run a uranium based reactor, and they produce waste that's toxic for a shorter amount of time, 300 years compared with uranium's tens of thousands of years. And unlike uranium, it is very difficult to turn it into a weapon.

So why haven't we started building these things? Like yesterday? Well, we almost did. In the 1950s, there was essentially a competition between uranium and thorium based systems, it was determined that uranium used in a light water reactor was the quickest, easiest way to power a nuclear submarine. And as a bonus, the waste from the process could be used to make bombs. So Washington was like, yay, uranium! While the thorium based plant at the Oak Ridge National Laboratory in Tennessee was mothballed.

Today, the biggest problem of converting to thorium reactors is expense. The reactors themselves aren't that expensive and neither is the thorium, but the trouble is all of America's 104 nuclear power plants currently run on uranium and a lot of people doubt whether going through the expense to retrofit the existing plants would be worth it since they would still produce radioactive waste, just not as much.

In the meantime, you will be unsurprised to find that China is taking the lead on developing LFTR. So I guess maybe we should just see how that goes for them. What do you think?

Thank you for watching this episode of SciShow, if you have any questions or comments or ideas, please leave them down in the comments below or get to us on Facebook or Twitter. We'll see you next time.

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