Comment by keepamovin | Hacker News Reader

Comment by keepamovin | Hacker News Reader

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The real killer feature isn’t "more thorium than uranium" (thorium is already 4× more abundant). The real win is that thorium MSRs can eat the existing mountain of "spent" fuel rods from regular reactors and turn what we currently call high-level waste into electricity while leaving waste that’s safe in a few hundred years instead of tens of thousands. That’s hundreds of thousands of tons of "waste" suddnely becoming centuries of clean fuel. That alone flips the economics on its head.

Also: passive safety (the thing just drains and freezes if anything goes wrong), no pressure vessel, tiny physical footprint, way less long-lived actinides, and U-233 is basically proliferation-proof because of the hard gamma from U-232. Uranium feels cheap and plentiful right now exactly the way oil felt infinite in the 1950s. China is playing the long game, and this little 2 MW rig lighting up and breeding U-233 last month is the “Sputnik moment” for the thorium cycle.

So...Three decades? Maybe if the West keeps sitting on its hands. China says 10 MW by 2030 and 100 MW demo by 2035. I wouldn’t bet against them.

So yeah, exciting as hell actually.

1. There is no mountain of nuclear waste.

Literally almost all the waste that’s ever been generated is stored on site at the nuclear power plants where it was created. That’s how little of it there is.

Talking about “thousands of tonnes” of nuclear waste is comically misleading when you realise how tiny the volume is.

2. There is no high level waste that is both very dangerous right now, and will remain so for tens of thousands of years. It’s either highly radioactive for not very long, or not very radioactive for very long, but never both.

How do these myths persist in otherwise educated people.

> Talking about “thousands of tonnes” of nuclear waste is comically misleading when you realise how tiny the volume is.

Yeah, it’s really easy to forget how dense these materials are. A jug of milk (4L/1gal) weighs 4kg/8.8lb. Milk has about the same density as water, 1g/cm^3. Uranium has a density around 19g/cm^3, making that same gallon jug weigh 76kg/167lb. A metric ton of uranium (1000kg) is about 13 gallons.

> Talking about “thousands of tonnes” of nuclear waste is comically misleading when you realise how tiny the volume is.

What is the actual volume?

Long life, high activity nuclear waste represents less than 3500m3 (one Olympic swimming pool), and this, since the start of civil nuclear electrical production in the 50's. World wide.

Global waste is 400,000+ tons (https://www.stimson.org/2020/spent-nuclear-fuel-storage-and-...). Even 1 pool full is ~28,000 tons (UO2 package 8tons/m3). Urainium is dense.

20 swimming pools of total waste isn't that impressive. I don't want to live near that, but I'm sure I'd we can find a place to put that in that will have minimal impact on people's lives.

Exactly. The waste isn't really a problem. But it doesn't have to be waste. That's the point. All that U235 in 'spent' silos? You can get 60x - 100x its OG power feeding it to nextgen reactors. So cool

Properly contained nuclear waste is almost as concerning to me as my wifi router is.

I wrote about the high energy, long life waste. The part really causing issues.

I guess you mean the "super hot for centuries" minor actinides (Np-237, Am-241/243, Cm-242/244/245 etc..)? These are less than 1% global waste, but next gen reactors can still eat them. The majority of waste (95%+) is U-235, then Pu, which nextgen also eats.

Many magnitudes of order less than any of: all the steel, glass, aluminium, wood, or plastic, ever produced, and we aren’t yet drowning in cubic miles of any of those.

But a disposed sachet from Australia isnt going to enter my cranium here in India... oh wait

> Talking about “thousands of tonnes” of nuclear waste is comically misleading when you realise how tiny the volume is.

You’re mixing mass and volume here. From what I can tell, their numbers were essentially right. Are you saying we don’t have thousands of tonnes of nuclear waste produced?

You sound butthurt by what the person youre responding to is saying. There's no liability in their statement, its severe optimism.

> The real win is that thorium MSRs can eat the existing mountain of "spent" fuel rods from regular reactors

That's not true.

The spent fuel can burn in fast reactors. There are hundreds of molten salt reactor designs (see for example [1]), and some of them are fast reactors.

But thorium MSR are not fast. That's the attraction of thorium, it can undergo transmutation (into protactinium, which then decays into fissile uranium-233) using thermal neutrons. Nobody is proposing thorium MSR as a solution to burn spent nuclear fuel.

> So...Three decades? Maybe if the West keeps sitting on its hands.

The West does not keep sitting on its hands. There are dozens, maybe hundreds of nuclear startups in the West, and they are actually making progress.

However, thorium is hard. Very hard. Breeding plutonium from uranium is much easier than breeding uranium-233 from thorium.

Here's a good post [2] about the thorium myths written by a former active HN forum member, Nick Touran. It's a good read. But, now, for an even better understanding, you can just ask ChatGPT, or any other LLM, how thorium breeder reactors compare to plutonium breeder reactors, and which technology is closer to reality.

[1] https://www-pub.iaea.org/MTCD/Publications/PDF/STI-DOC-010-4...

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

Deferring to ye true experts here. My comment was overblown and inaccurate, confusing all next gen reactors with this work. Thanks

This can be done in usual breeders like superphenix or bn800. What china wants to experiment with is continuous filtration instead of using breeding+purex/pyroprocessing. Still, it's nothing more than an experiment, china is rather slow with nuclear compared to french messmer and sweden in the past

Well I'm just an interested outsider. I will defer to the true experts here.

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