Thorium reactors. Do they exist? Are they still just theoretical? Why aren’t we investing more in it?


Thorium reactors. Do they exist? Are they still just theoretical? Why aren’t we investing more in it?

In: Chemistry

Some currently operational designs can use thorium, such as the canadian CANDU design. People are leery of investing in nuclear power because A. the capital outlay is gigantic and the payoff takes a LOOOOOOOONG time and B. political obstacles make it a very risky investment.

Yes, they exist, at research scale.

Much is being invested, but not in the US or Europe. These countries make their decisions based on public opinion, and the public is very uninformed about science in general and power generation in particular.

As of 2020, there are no operational thorium reactors in the world.

Investment in nuclear energy is strongly opposed by fossil fuel lobbyists and many environmentalists.

I’ve seen one guy claim that the technology [isn’t viable]( due to it requiring the production of [Protactinium]( which is so nasty that it makes the entire thing a no-go.

That said, IMO nuclear is dead anyway, because renewables are eating its lunch. Any nuclear tech (thorium or not) is expensive to build, which means it requires running at full blast as much as possible to pay off those loans. And if any tech like wind or solar can sell power cheaper, then they get the money and your nuclear plant sits idle not paying off those huge loans.

And I don’t see that changing. Nuclear is big and complicated. Wind is a set of blades, a gearbox and a motor on a pole. Solar is a bunch of solar modules. Both technologies are extremely amenable to mass production, their parts have other uses, and don’t need huge risks and billions if somebody wants to try a slightly different design, so that means they are and will be developed far faster than nuclear can be.

Why arent we investing more

Well. Nuclear power is widely disliked after Fukoshima and Chernobyl,

Environmentalists hate it.

And the residue has to be stored for Timescales that would mean that a barrel of nuclear waste has to be stored for as long as when the pyramids where made to today. imagen how many civilizations and societies have collapsed and risen in that time.

using a liquid fuel solves most of those issues, the fuel is the heat transfer medium so you dont need to pressurize the reactor, meaning no steam explosions.

98% of nuclear waste is because we dont process the nuclear waste, in solid nuclear waste, trans uranic elements aka fission products are produced inside the fuel and poison it. imagen it as if you had the exaust of your car connected to the fuel tank, and you had to trow away all the gasoline in your tank after driving 50 miles.

If the fuel is reprocessed to remove those elements, you can reuse it, the thing is that with solid fuel its an expensive and dangerous process with radioactive elements.

With liquid fuel you can just use centrifuges to separate them by weight or do chemical separation on site.

but the problem is that the thorium and uranium salts used in liquid fuel reactors are VERY corrosive, so the reactor requires constant maintenance, basically the fuel eats away at the reactor. and that is not good.

They only exist in research labs, there are some national and commercial investments, some in the US but most in China, trying to develop a commercially viable reactor. I, for one, don’t expect any of them to succeed. Ever.

The problem no one ever talks about is Protactinium.

You see, Th-232 isn’t nuclear fuel, but fuel stock. You use it to breed U-233, and THAT produces the fission, the heat, the steam, etc. But to get U-233, you must first produce Pa-233.

So the process is: Th-232+n -> Pa-233 -> U-233

Pa-233 has a half-life of 27 days. This is important, you can’t leave this stuff in a reactor or it will pick up neutrons and become something else, it has to be extracted. This is why Thorium research is all around MSRs, because if you’re going to have any chance of extracting Pa-233 economically and in time, you’re going to liquify your fuel.

So what’s the catch? 1g of Pa-233 has a radioactivity of 769 TBq and a dose rate of 20,800 mSv/h. Still don’t get it? The legal whole body exposure limit is 1 mSv/yr.

Think this through: if you have to replace a pump, an there’s 1 mg of Pa-233 left on the equipment, the technicians will receive their annual dose in under an hour. If you have any leak in the system, you can’t go in and fix it for MONTHS, and you’ll have lost revenue the whole time.

It’s not that the theory isn’t sound, it’s the very practical, tangible, physical, engineering constraints that will make this impossible. You have to actually build the thing, which is the easy part, but then you have to maintain it. With people. And you just can’t. The theoretical operating costs and revenue losses kill thorium reactors.