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Comment by lunar-whitey | Hacker News Reader

No country has seriously invested in the thorium fuel cycle because it cannot be used to create weapons. Unfortunately, the technology also began to look most promising as an energy source around the same time the Three Mile Island nuclear accident effectively ended all interest in nuclear energy in the United States.

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India has shown some of the most interest to date, due to their lack of domestic uranium reserves. But it's been slow going their fast breeder reactor plans were delayed by like two decades. But it is built and it was loaded with fuel last month [0]

The French interest in breeder reactors and nuclear reprocessing also originates from a similar concern about lack of domestic access to raw uranium. Though Super-phoenix [0] was a more traditional uranium -> plutonium approach and not thorium. They gave up because just using uranium is way, way cheaper than synthesizing your own fissile materials.

[0] https://www.world-nuclear-news.org/articles/indias-prototype...

[1] https://en.wikipedia.org/wiki/Superph%C3%A9nix

Thorium can be used to make weapons via the breeding cycle. It's much less convenient and straightforward than uranium/plutonium, but it is possible.

Theoretically, perhaps, but I don’t think anyone with a serious interest in weapons would pursue it. From a nonproliferation perspective, I’d guess the infrastructure necessary to remove contaminants from uranium bred through the thorium cycle would be costly and difficult to conceal.

Multiple countries have detonated nuclear bombs using U-233 derived from thorium reactors! [0] Practically I agree with you that thorium is proliferation resistant and if someone is bomb hungry they won't prioritize it, but if you want to set up the bomb and all you have is thorium... The infrastructure wouldn't necessarily be significantly larger or worse than conventional enrichment.

0 - https://en.wikipedia.org/wiki/Uranium-233

Seems presence of U-232 is more manageable than I thought.

Also, it’s only energy positive under some specific carefully managed conditions, and is a real pain to make work.

If you have easy access to uranium, you just use it directly instead.

Depends on what you want out of your reactor. You want to make a synthetic fuel, Thorium not Uranium. You want a liquid fueled reactor (because its safer and proliferation resistant), Thorium not Uranium. You want 900C heat instead of 300C heat, Thorium not Uranium.

The fuel costs of a NPP are a tiny rounding error. If you want electricity and want to build it today, Uranium not Thorium. You are using arguments from 50 years ago when many incorrect assumptions about cost structure and fuel availability were used to make decisions.

The cope is strong here. The only liquid fueled reactors with any operational experience got shut down because of corrosion issues causing major leaks.

The pros you mention are theoretical - because the cons came out in force when actually tried, and they’ve been tried many times by many different countries.

Weapons are irrelevant for power generation. No modern classic pwr was used to create weapons- because it's cheaper to have dedicated infra

You can absolutely make nuclear weapons with U233.

Technically true and practically false. Only once has anyone done that. The bomb was considered a dud and the research was ultimately destroyed. So while you could, it would require completely reinventing all the original research that went into making the original one. Lookup operation teapot for more details.

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