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Comment by roenxi | Hacker News Reader

Until they've made a billion dollars I'd assume the situation is not that rosy. It is easy enough to do a cool science experiment for $65 million. That being said, I applaud anyone achieving any result when it comes to energy.

My first test for Chinese success is "would this have been legal in the US?". I'm not sure who regulates tokamaks but I assume they have a similar risk profile to nuclear reactors (nuclear process releases a vast amount of energy in a tiny space) and so it would be normal if building one commercially was prohibited.

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But they don't have the stored energy density of fissile nuclear reactors; they have the stored energy density of a big particle accelerator. Shutting down a particle accelerator (either temporarily or permanently) is way easier than shutting down a fission pile, because a particle accelerator or fusion reactor would just dump the plasma into a graphite bed and dump the stored magnetic field energy into a bunch of large copper bars acting as big resistors.

EDIT: If you shot a hole in a fusion reactor, the cold air would immediately quench the plasma down to room temperature.

https://www.fusionindustryassociation.org/nrc-decision-separ...

Supporting letter from Helion Energy: https://www.nrc.gov/docs/ML2224/ML22243A083.pdf

Fission has a very different risk profile than fusion.

Additionally making a fusion plant isn't a stepping stone to making a nuclear bomb

> making a fusion plant isn't a stepping stone to making a nuclear bomb

In theory a fusion plant can use the neutrons to irradiate the right chemical element to produce Plutonium-239 or Uranium-233.

  It has been estimated that each 14.1 MeV fusion neutron could be used to produce up to 0.64 plutonium or 233U atoms [4] assuming a TBR of 1.06. This corresponds to 2.85 kg plutonium per MW-year of DT fusion power production, assuming that all of the neutrons are captured in the blanket.

https://duckduckgo.com/?q=proliferation+risk+fusion for more info

> making a fusion plant isn't a stepping stone to making a nuclear bomb

What about a hydrogen bomb?

How would you make a bomb out of a tokamak? It is barely stable enough to generate the little heat required to generate energy, any disruption to that will just put out the reaction it wont explode.

Fusion bombs requires fission bombs as a fuse to have enough heat to explode, fusion reactors wont even come close to that.

Their risk profile is basically zero.

I doubt (nuclear) regulations are stifling much innovation here.

certainly not zero: fusion reactors still contain a decent amount of toxic materials, some of which radioactive, and when working make all kinds of highly radioactive elements inside the structure of the reactor. Probably less of a risk than fission, though (it's pretty unlikely a failure will result in an explosion or runaway reaction which spreads those radioisotopes far and wide).

Why would you assume fusion has the same risk profile as fission? They are opposite ends of the periodic table :)

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