Fact-check: Five claims about thorium made by Andrew Yang

It is useless to make claims about a particular fuel without looking at a concrete reactor design. Leftover isotopes for example are very dependent on neutron flux and neutron energy as well as general breeding properties of the reactor. This in turn decides the waste to be dealt with, proliferation risk and possible reuse of leftover fuels from previous generation reactors (which the submission didn't even discuss).

Also, the answers lack nuance. E.g. proliferation risk is present through U233, however, U233 seems very difficult to deal with in bombmaking. So at least it's less of a problem maybe.

They are not wrong, but also not right in all scenarios. Truth very much depends on the reactor design. Thorium is often associated with Gen4 reactors which are responsible for the claims of superior safety. Not much, but some of the safety benefit comes from thorium. Similar for the claim of less waste: Some reactors have better neutron economy, burning their own waste down to more shortlived and therefore "better" isotopes. Or, by the same mechanism, can utilize existing waste as fuel. Also, continuous loading and separation of isotopes only works well with liquid fuels which is a Gen4 idea.

Thorium is more of a side-topic there.

On the economic side of whether thorium is cheaper, the submission argues in a very underhanded manner. Yes, fuel is cheap compared to building the plant in all cases. But the fuel cost of thorium is an order of magnitude below uranium due to no enrichment (for light water reactors in the fuel, for heavy water reactors of the water). And possibly (for liquid core reactors) the unnecessary fuel elements production.

I'm involved in a public education nuclear website. We get tons of questions about thorium so we made a few pages to handle stuff like this. For instance, we have one on molten salt reactors specifically (which aren't always fueled with thorium) [1].

[1] https://whatisnuclear.com/msr.html

And then we have our most popular, the Thorium Myths page [2].

[2] https://whatisnuclear.com/thorium-myths.html

I love that Yang is bringing the discussion to the capabilities of nuclear technology even if I consider it a bit misguided to focus on the thorium fuel cycle. There's a phrase in nuclear advocacy today: "Come for the thorium, stay for the reactors"

Its easy to make bombs from U-233. In fact it is better than plutonium in some rare circumstances. Check out the discussion and cool declassified letter from the Livermore bomb letters here: https://whatisnuclear.com/thorium-myths.html#myth3

Exactly. The takeaway should be that Yang is approaching this issue from a position of technical merit and not on an irrational emotional basis like most others. This is to his credit. Properly technocratic leadership is rare in the USA and it's beyond time for them to experiment with it.

In my opinion the analysis linked to from HN is laughably flawed. It's not exactly wrong, but it's so terse and reductive that it might as well be. For example— while the waste from the thorium fuel cycle could be used to make weapons, but the fuel would always include some Uranium 232 (a gamma emitter) and therefore it's more difficult to handle safely and your entire weapon manufacturing pipeline is able to be monitored from afar by foreign governments.