Japan sets new nuclear fusion record

If we could harness the heat from nuclear fusion here on Earth, we could use it to generate electricity on-demand without worrying about carbon emissions, nuclear waste, or running out of fuel

I don't want to detract from this exciting milestone. Fusion is an absolute requirement for the complete end of our reliance on fossil fuels and there are no problems significant enough to warrant the end to fusion experiments. However, this statement is definitely not true with tokamak reactors. They typically use deuterium and tritium for fuel, which are limited resources. Fusion reactions are far more difficult with other light elemental isotopes. These reactors also use beryllium as shielding, which is a carcinogen. When the shielding needs to be replaced, it actually is radioactive.

Those are entirely accurate facts, but those downsides are absolutely dwarfed by the upsides to the technology's potential. It's like getting your own spaceship, then pointing out that it lacks cup holders.
- I agree, fusion reactors will absolutely revolutionize everything, and even if we can't do better than tokamak reactors, these problems are still pretty mild. I just expect more from scientific journalism
I really appreciate this. It's important to be aware of all the facts
Deuterium is pretty common, and tritium can be produced by lithium irradiation. They are finite resources, but still much larger than pretty much any existing resource.
It is true that fusion equipment suffers from neutron radiation, however this is a potential for breeding tritium.
- Like I said elsewhere, the problems I pointed out are relatively mild in comparison to all the good from fusion energy. However, there's only approximately 25kg of tritium in the entire world. ITER is expected to use a majority of this world-wide supply. The mass manufacturing of tritium also presents another problem you pointed out with the supply: a super rare isotope needs rare earth metals to manufacture, one that is already in extremely high demand. I love this research and I want to succeed in any way possible. But we have to face reality and the material problems the science has to overcome.
Also, can they be built without fossil fuels ?
- weaning off fossil fuels completely is going to be a long complicated process. for now we will need to use fossil fuels to build greener infrastructure.
- Possibly. Industrial processes are very energy intense.
  For example, melting steel takes a certain amount of energy per mass to liquify, and since you're trying to liquify it, you need that energy quickly, otherwise it'll just get warm but stay solid. Nuclear could do it, maybe even wind if all other energy sinks (e.g. houses, apartments, etc) aren't using too much of that renewable energy when the melt is occurring.
  We do our best, but once the process starts, it must be completed no matter where the energy is coming from, otherwise it was just a waste of time and money.

What's new ? this :

Stepping stone: At 52 feet tall, the JT-60SA is now the biggest tokamak to reach first plasma anywhere in the world — but it likely won’t be for long.

I'd be surprised if they don't start setting performance records soon. First plasma was a few weeks ago.

Tony Stark was able to build this in a cave!

Well I'm sorry. I'm not Tonny Stark

I've read the article and I'm still not clear what the breakthrough is.

They still need to figure out how to harness that plasma, right now its creating plasma but sadly this is the easy part. Extracting energy from that contained plasma will be 100x harder than creating it in the first place. If only we had some other type of reactor that was far simpler and could be up in running and producing electricity for the masses in a relatively short time span...

Taken these smart people and have them work on MOLTEN SALT REACTORS FFS

Ah, I'm glad to see the thorium / MSR bros are still spewing their nonsense after all those years.
- And how long have fusion dipshits been spouting their crap? 1938 was the first attempt. Look how far we've got so far? There was a working MSR(E) that produced 10MW through out the 1960's but we are the crackpots. Gotcha...
So you'd argue that fission is a better way to go rather than fusion? I see China has built, but hasn't activated, a molten salt reactor. Why aren't they more popular?
- Basically, because of where all the thorium is. India would have a near stranglehold on the economy, and they're already heading into Saudi Arabia part 2 territory.
- Yes ignore the fact that fusion has been under development since early 2000's by how many countries? But point out 1 country working off of partial plans from the 1960's. Yep that means its a total failure....
  If there was as much money put into MSR as fissiob the world would be using them as the defacto reactors seriously what a stupid argument
MSRs are a boondoggle, a waste of effort.
What are the claimed benefits? Simplified piping, abundant fuel, self limiting power, etc.
Trivial engineering counterpoints:
Piping remains extremely complex, the activated thorium becomes U235 eventually, irradiating the hell out of the entire system. How do you change a valve when it gets damaged? You have other valves, and bypasses, and check valves, and... ~~Piping is simpler~~.
Abundant fuel.. we keep extracting from the Earth, and cutting huge ugly gashes in her. Let's not.
Self-limiting power... Some materials are very, very corrosive by themselves. Want to make them nastier? Add energy to them in the form of heat. MSRs use Sodium or Fluorine salts, both of which strongly react with water in the atmosphere, if not the air itself in an exothermic manner. And they do so with a bang, under the right conditions. So yeah, self limiting. But at a very risky cost.
materials: prior reason also effects material selection. Inconel is expensive, and very damn hard to machine, even with our modern carbide tooling. Materials keep coming along, and maybe that'll reduce cost. But just like fusion, it's a maybe.
MSRs: nah.
Extracting energy from fusion: some systems can be solid state. Depending on the process and the inputs, it's possible to directly extract electrical energy from neutrons crossing a charged grid, and dump that power (after some filtering and such) right into the national electrical grid, no steam needed.
Need to find a working fusion reactor? Look up.
- Need to find a working fusion reactor? Look up.
  Oh me so smart. Did we creatbthe sun? Seriously bad argument. Best solar panels are only 30% efficient.
  Also things that are worth it are hard, and expensive. Look at the average cost of a Light or heavy water reactor. Another moot argument
  Yes salts are corrosive but that's what Hasteloy-N solves along with Inconel
  And maintenance can be done by robots as they currently do in current reactors where the radation is so bad humans can't go there.
  You are the worst at this
- Fusion reactors will ALWAYS be 30 years away. Not only that they will concentrate energy resources with in the very wealthiest of nations because they are EXTREMELY hard to build and expensive. Molten salt reactors or even light water reactors are the solution too our energy needs. They are available now and the waste can be managed despite the endless fear mongering. Fusion is a waste of time for now. Even fission reactors are wildly expensive to build and you think we as a species can move on to fusion reactors in the near future? Changing mildly radioactive value or dealing with corrosive materials is 100000x less of an engineering feat than achieving cheap and reliable nuclear fusion. The reason it's not wide spread is because counties love their oil and have fear mongered fission so that little to no research goes that way. Fusion is a pipe dream

It's not limitless clean energy. It's awesome, but technically it still uses water and turbines to turn the heat to electricity. In a world with vastly more electric demand this will eventually lead to global warming as well, because a lot of the heat is released into the environment.

That's on a totally different scale though ;)

Do you have a source on the claim that nuclear fusion will lead to global warming? I did a very cursory search and I've found articles that talk about how the technology is being exaggerated but all the ones I've seen said that it does not contribute to global warming.
- Sabine Hossenfedler did a video on the topic: https://youtu.be/9vRtA7STvH4?si=y4_KuLbd1DzKmIX8 Basically, it is an issue humanity will likely have to solve eventually, but nowhere near as pressing as our current problems.
- He’s assuming that making energy cheap and abundant will drive up demand as we find other uses
  In a world with vastly more electric demand
  Historically this has been true but I’m not convinced. We’ve definitely entered an era where efficiency and low energy are important, and I think that trend will continue
  More people will need AC, but AC is becoming much more efficient. The entire fossil fuel supply will be transitioned to electrical ….. damn, maybe he’s right. I started thinking in terms of how I used electricity, as an American, and I believe it’s generally plateaued, but consider the vast majority of the globe does not yet live like an American and may want to ….
Yeah at the scale of a Type I civilization probably one that is close to Type II. No reason to worry about it now. And even so we already have tech that can radiate heat into space without it heating the surrounding air.