New Molten Salt Thorium Reactor Powers Up for First Time in Decades

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Nuclear power was headed for something of a resurgence a few years back, but then the 2011 meltdown at Japan’s Fukushima reactor happened. Governments and investors around the world got cold feet, but there’s now renewed interest in a type of nuclear power that’s potentially much safer. A team from the Nuclear Research and Consultancy Group (NRG) the Netherlands has built the first molten salt reactor powered by thorium in decades.

There are several basic facts of nuclear power that have made it a tough sell around the world. For one, the uranium needed for nuclear power plants is rare and expensive. The uranium used in power plants can also be turned into weapons-grade material, requiring tight regulation. The other waste byproducts of nuclear energy are less useful, but still extremely dangerous. We don’t even know what to do with all that waste yet. Lastly, a nuclear power plant, no matter how well designed, could experience meltdown under certain circumstances.

You need different fissile material if you’re going to change any of that, and now we come to thorium (atomic number 90). Unlike uranium, thorium is abundant, and it’s not nearly as dangerous. Enrichment is not necessary, and thus it’s extremely difficult to create nuclear weapons with a thorium-based reactor. Most importantly, meltdowns aren’t possible with thorium reactors because the reaction is not self-sustaining.

That last safety advantage is also the main drawback of thorium. You need a little uranium and a neutron source to get the reaction kickstarted. Oak Ridge National Laboratory ran molten salt thorium reactor experiments from the 1960s until 1976. Now, the European team is giving it another shot.

thorium salt

Pure thorium salt being loaded into a sample container.

When bombarded by neutrons, thorium becomes radioactive uranium-233, which is shorter-lived and less dangerous than the uranium-235 used in conventional reactors. The molten salt design being developed at NRG is known as the Salt Irradiation Experiment (SALIENT). This radioactive slurry could potentially reach very high temperatures, which translates to a lot of energy generation. However, the molten salt isn’t just the fuel; it’s the coolant as well.

There are still several problems that need solving before NRG’s thorium reactor designs will be scaled up to industrial levels. While the waste is safer, scientists still need to figure out how much of it there will be and what can be done with it. The environment inside a molten salt reactor is also extremely corrosive. So, some creative materials might be needed. If it works, we could generate more power without pumping more carbon into the atmosphere — a win for everyone.

Now read: How does nuclear energy work?

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