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Chinese Tokamak reaches over 100M degrees

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Re: Chinese Tokamak reaches over 100M degrees

#61

Post by kungtotte »

oldgradstudent wrote: post #52
kungtotte wrote: post #34

Earlier quoted context omitted.

The earthquake was the most powerful to ever hit Japan and the fourth most powerful in the world since modern record keeping began, and the investigation into the disaster showed that the safety precautions weren't adequate in the first place. You can't dismiss the technology based on that incident. Just like we don't ban cars because a lot of people don't operate them properly.

When I was in high school we visited a small 5MW nuclear reactor. It was a few years after Chernobyl and we got a very long lecture about how this was all the fault of the terrible Soviet design and that it could never happen in a western-designed nuclear reactor. As far as I remember from the news at the time, the tsunami was terrible, but not unprecedented. If this obvious risk was ignored, what other risks are bei…

A Chernobyl accident can't happen in a western reactor, and it wasn't what happened in Fukushima either, so the lecturers weren't wrong.

I don't know the facts of the tsunami whether it was unprecedented or not, but considering the magnitude of the quake I'm guessing it was one of the largest tsunamis to ever hit Japan. This is speculation on my part.

They didn't ignore the risk of tsunamis, they had precautions against them but they weren't up to par. It was a series of malfunctioning safeties that caused the accident. The backup power generators conked out, and the backup to the backup was washed away by the floods. And the floods only managed to get that far because the protective walls weren't enough.

"Build better walls" seems like a trivial problem to solve, don't you think?

International regulatory bodies could also be more proactive in finding these flaws prior to accidents.

It's not a hard problem to solve in the long run. It'll be easier and quicker than finding a viable non-nuclear energy option anyway.

Re: Chinese Tokamak reaches over 100M degrees

#62

Post by Nimelrian »

afraca wrote: post #37
i_am_proteus wrote: post #27

Earlier quoted context omitted.

I will add: - While the products of the fusion reaction are short-lived, operating a fusion reactor will active materials in the reactor and create some longer-lived radioisotopes. - Unlike a fission reactor, which is loaded with months to years worth of fuel, a fusion reactor would have fuel constantly injected. So operator action to stop injecting fuel would stop the nuclear reaction.

Can either you or your parent poster say what "short lived" and "longer-lived" would be roughly?

Longer-lived would be thousands of years for the steel structure until it is manually handable. 50-100 years for remote handling.

> It was shown that wait times are required in the order 50–100 years for the remote handling recycling option and hundreds (Li4SiO4) to thousands (Eurofer) years for hands-on handling.

Source: https://doi.org/10.1016/S0022-3115(02)01273-4

Re: Chinese Tokamak reaches over 100M degrees

#63

Post by lolc »

Cthulhu_ wrote: post #49
red75prime wrote: post #43

Earlier quoted context omitted.

> poison our ocean for millennia On global scale it negligibly increased ever-present background radiation. It's not a good thing, but far from poisoning.

Wasn't said ever-present background radiation only a thing after the nuclear bomb tests? I read a while ago that steel from old ships that sunk deep is highly valuable because it's not irradiated yet.

To a first approximation all matter on earth radiates because all matter is present with some isotopes that will eventually decay. Don't forget that we're sitting on top of a huge ball of molten metal kept hot by ongoing nuclear decay. That process produces all kinds of isotopes that eventually make their way to the surface.

The bomb tests did increase background radiation for us; irresponsibly so in my opinion. But so does burning coal. We have been lifting the level of background radiation over the natural level for centuries by now.

I don't see how sunk steel would be any more valuable than steel from freshly mined ore. But I like to be surprised about these things :-)

Re: Chinese Tokamak reaches over 100M degrees

#64

Post by consp »

thaumasiotes wrote: post #40
NamTaf wrote: post #8

Earlier quoted context omitted.

As I understand, this represents sufficient energy to overcome the Coulomb Barrier [1] which naturally repels atoms apart. To cause fusion, you need to push particles together either hard enough or fast enough that they push through this repulsion and fuse. The repulsion is a product of the electrostatic repulsion of the positive charges of the nuclei (pushing the positive ends of two magnets together, essentially).…

> you need to push particles together either hard enough or fast enough that they push through this repulsion What's the difference between "hard" and "fast"? What does pushing "hard" mean?

In my general understanding of these things:

Fast -> High kinetic energy since they won't acquire mass this is basically speed

Hard -> More attempts to make it happen (higher particle interaction)

But I might be wrong since plasma is weird stuff.

Re: Chinese Tokamak reaches over 100M degrees

#65

Post by rcxdude »

lolc wrote: post #63
Cthulhu_ wrote: post #49

Earlier quoted context omitted.

Wasn't said ever-present background radiation only a thing after the nuclear bomb tests? I read a while ago that steel from old ships that sunk deep is highly valuable because it's not irradiated yet.

To a first approximation all matter on earth radiates because all matter is present with some isotopes that will eventually decay. Don't forget that we're sitting on top of a huge ball of molten metal kept hot by ongoing nuclear decay. That process produces all kinds of isotopes that eventually make their way to the surface. The bomb tests did increase background radiation for us; irresponsibly so in my opinion. But…

> I don't see how sunk steel would be any more valuable than steel from freshly mined ore. But I like to be surprised about these things :-)

Steel production uses air from the atmosphere. Thus it picks up the increased background radiation while it is refined. It may be possible to scrub the radioactive components from the air to avoid contanimating the steel, but I expect the cost would be prohibitive (at the very least, more expensive than getting it from old battleships).

Re: Chinese Tokamak reaches over 100M degrees

#66

Post by elorant »

donkeyd wrote: post #57
txcwpalpha wrote: post #15

Earlier quoted context omitted.

The specific EAST reactor [1] mentioned in the article is a testbed that will enable new technologies to be used on the ITER project. The ITER project [2] is currently the largest fusion power research project underway (and the largest reactor under construction). ITER's goal is to provide research that enables new technologies to be used on the DEMO project. The DEMO project's goal [3] is to provide commercially ava…

Any idea on how much money we're spending on this? Also, I can imagine it's a joint project only partially because we can share the cost, I imagine another reason to work together is so that no one country gets this technology first.

Initial budget was €5bn. Current budget is four times that and with completion nowhere near estimates of the final cost are as high as $60bn. Go figure.

If by "we" you mean US's share, that's 9% of total costs. China, India, Japan, Russia, South Korea, and the US are paying 9% each and EU is paying 46%.

Re: Chinese Tokamak reaches over 100M degrees

#67

Post by jabl »

As there seems to be quite a lot of confusion in this thread about what this is, here's an excellent video giving an overview of the state of the art in fusion energy research that is understandable by a lay audience: https://www.youtube.com/watch?v=L0KuAx1COEk

(somebody posted that video on another recent HN fusion thread)

Re: Chinese Tokamak reaches over 100M degrees

#68

Post by SmellyGeekBoy »

docker_up wrote: post #11

Stories like this scare me. With all of the precautions, even things like Fukushima failed and will poison our ocean for millennia. What happens if we have a runaway fusion process through some pathway that was unexpected? With all the talk about the LHC possibly producing mini blackholes or magnetic monopoles that could potentially cause protons to decay spontaneously, I don't have enough nuclear physics background…

> I don't have enough nuclear physics background to know whether we are inherently safe, or if there is a real risk here.

Then don't spread FUD?

Re: Chinese Tokamak reaches over 100M degrees

#69

Post by SmellyGeekBoy »

Cthulhu_ wrote: post #47
hoffs wrote: post #33

Earlier quoted context omitted.

Isn't fusion reactor basically infinite energy, I mean sure it makes total sense to no share it with other because you can sell your free energy for cash, but considering that a lot of global scientists work on it and most of the findings are published, don't think that such strategy would last long.

> Isn't fusion reactor basically infinite energy It's probably not that easy; the reactors are extremely complicated and expensive to build, and I'm sure operating them isn't cheap either. And the one thing I haven't heard much about yet is the yield - how much energy can it generate vs how much will it cost to run. I don't think it'll be economically viable. I'll be happy to be proven wrong though.

> I don't think it'll be economically viable. I'll be happy to be proven wrong though.

I don't think current designs like the one discussed here will be. But I'm hoping it will lay the groundwork for much more useful reactors in the future.

Re: Chinese Tokamak reaches over 100M degrees

#70

Post by jabl »

hoffs wrote: post #33
adtac wrote: post #32

Once we achieve sustainable fusion, will it be possible to "share" the energy with everyone else to create more independent fusions? Kinda like keeping the candle burning so as to light more candles because matches are too costly. Now, I don't expect politics to allow sharing of fusion energy to help other countries.

Isn't fusion reactor basically infinite energy, I mean sure it makes total sense to no share it with other because you can sell your free energy for cash, but considering that a lot of global scientists work on it and most of the findings are published, don't think that such strategy would last long.

Just like previous predictions that the introduction of fission power plants would result in electricity 'too cheap to meter', I suspect the same will happen for fusion. Even if the fuel is nearly free, you still have to build and maintain the power plant, the grid etc., neither which is cheap.

But yes, the first ones to 'crack' the problem will have a head start in the commercial fusion power plant market, but I don't think it will last very long. As you say, most of the research is being published, and even if somebody manages to initially keep that final 'dot on the i' secret, it wouldn't take other researches long to figure it out.

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