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More invested in nuclear fusion in last 12 months than past decade

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Re: More invested in nuclear fusion in last 12 months than past decade

#351

Post by mlindner »

acidburnNSA wrote: post #153

But where are the fusion neutrons? (See Voodoo Fusion [1]) [1] https://vixra.org/pdf/1812.0382v1.pdf I'm a professional fission guy. I started out in fusion and switched to advanced fission. These days I don't see why we don't just build lots more regular old LWR fission reactors. Imagining that somehow fusion is going to a) work, b) be cheap (fuel cost is only 5% of total nuclear fission cost so who cares), and c) n…

> Imagining that somehow fusion is going to a) work, b) be cheap (fuel cost is only 5% of total nuclear fission cost so who cares), and c) not have the same stigma as fission is kind of weird in my mind.

The cost of fission comes doubly from the nuclear proliferation risk and the safety risk, neither of which apply at all to fusion. The levels of radioactive waste produced is at basically the same levels as medical practices.

> Plutonium is made by irradiating natural uranium from the dirt with neutrons. Practical fusion reactors have lots of neutrons. Really high energy ones too.

In that case you're intentionally trying to irradiate something, you can do the opposite and engineer for things to not be irradiated, and even then it tends to be long lived low radiation isotopes.

Re: More invested in nuclear fusion in last 12 months than past decade

#352

Post by mlindner »

pfdietz wrote: post #250
acidburnNSA wrote: post #153

But where are the fusion neutrons? (See Voodoo Fusion [1]) [1] https://vixra.org/pdf/1812.0382v1.pdf I'm a professional fission guy. I started out in fusion and switched to advanced fission. These days I don't see why we don't just build lots more regular old LWR fission reactors. Imagining that somehow fusion is going to a) work, b) be cheap (fuel cost is only 5% of total nuclear fission cost so who cares), and c) n…

> I started out in fusion and switched to advanced fission. You are in good company. Lawrence Lidsky, the fusion guy at MIT who wrote the famous article "The Trouble with Fusion" back in the 1980s, also switched to advanced fission reactors. His critique of DT fusion is still worth reading. The big issue, the lousy volumetric power density of DT fusion reactors compared to fission reactors, is still a huge albatross…

> His critique of DT fusion is still worth reading. The big issue, the lousy volumetric power density of DT fusion reactors compared to fission reactors, is still a huge albatross around the necks of all these private DT efforts.

That was largely a product of the times, before high magnetic fields could be achieved. ITER has all those problems, but newer ideas do not.

Re: More invested in nuclear fusion in last 12 months than past decade

#353

Post by mlindner »

dongobongo wrote: post #330
lawrenceyan wrote: post #315

Earlier quoted context omitted.

Please correct me if I’m wrong, but isn’t it impossible for fusion to generate a nuclear meltdown scenario that fission has the potential for?

Meltdown accident: basically, reactor is turned off, however heat continues to be generated because of a thing called decay heat which is when isotopes generated by the fission reactions decay to more stable isotopes and release energy. It's about 7% of a fission reactor's power and continues for a few hours until it's negligible. 7% of a gigawatt reactor is like having a couple of jet engines going full blast inside…

> I read recently that fusion reactor will also generate decay heat from all the activated components and this is comparable to a fission reactor.

I'd like to know where you read that as the entire idea is to build a reactor out of things that don't activate or are very hard to activate. i.e. things that thermalize or reflect neutrons.

Fission reactors produce tons of neutrons too (they kind of have to to work more so than fusion even) and that doesn't leave the containment vessel anywhere near as radioactive as the nuclear waste itself.

Re: More invested in nuclear fusion in last 12 months than past decade

#354

Post by acidburnNSA »

mlindner wrote: post #351
acidburnNSA wrote: post #153

But where are the fusion neutrons? (See Voodoo Fusion [1]) [1] https://vixra.org/pdf/1812.0382v1.pdf I'm a professional fission guy. I started out in fusion and switched to advanced fission. These days I don't see why we don't just build lots more regular old LWR fission reactors. Imagining that somehow fusion is going to a) work, b) be cheap (fuel cost is only 5% of total nuclear fission cost so who cares), and c) n…

> Imagining that somehow fusion is going to a) work, b) be cheap (fuel cost is only 5% of total nuclear fission cost so who cares), and c) not have the same stigma as fission is kind of weird in my mind. The cost of fission comes doubly from the nuclear proliferation risk and the safety risk, neither of which apply at all to fusion. The levels of radioactive waste produced is at basically the same levels as medical p…

No proliferation risk at all in a tritium fountain full of 14 MeV neutrons? Are you sure you know what you're talking about?

These will all be guarded with pseudo military guns guards and gates just like fission, and monitored by the IAEA.

As for radiological safety, see point about tritium. And google tritium leak nuclear plant for good measure.

Youre right that there is less radioactivity in fusion plants, but maybe not enough less to really matter.

Re: More invested in nuclear fusion in last 12 months than past decade

#355

Post by mlindner »

tejohnso wrote: post #225
acidburnNSA wrote: post #197

Earlier quoted context omitted.

Uranium and thorium fuel on earth can make 100% of today's primary energy for about 4 billion years, using breeder reactors, which were proven in 1952 near Arco Idaho at the Experimental Breeder Reactor 1. Writeup explaining this with lots of actual scientific references at the bottom here: https://whatisnuclear.com/blog/2020-10-28-nuclear-energy-is-... People who say uranium will last 50 years either aren't aware of…

This is so depressing. It's nearly impossible to form a confident opinion these days without a ton of effort. I heard Sabine, I said to myself...makes sense...and it looks like she's put a lot of work into understanding all of this, and she is a professional. So that was it. Now you're saying she's wrong. Very wrong. And you're a nuclear reactor physicist (thanks for comment!) Am I going to go read all of the relevan…

Sabine I've found to be spreading nothing but FUD personally. I've only watched a few of her videos but she seems to enjoy inflating minor issues into major ones and then proclaiming everything can't work.

Re: More invested in nuclear fusion in last 12 months than past decade

#356

Post by geysersam »

acidburnNSA wrote: post #197
spawarotti wrote: post #194

Earlier quoted context omitted.

How long will the fuel last? Sabine Hossenfelder references studies in which we have enough Uranium for 50 years max. 6:08 here: https://youtu.be/0kahih8RT1k

Uranium and thorium fuel on earth can make 100% of today's primary energy for about 4 billion years, using breeder reactors, which were proven in 1952 near Arco Idaho at the Experimental Breeder Reactor 1. Writeup explaining this with lots of actual scientific references at the bottom here: https://whatisnuclear.com/blog/2020-10-28-nuclear-energy-is-... People who say uranium will last 50 years either aren't aware of…

What are the disadvantages of thorium reactors, making them so rare in practice? Cost?

Re: More invested in nuclear fusion in last 12 months than past decade

#357

Post by shawn-butler »

acidburnNSA wrote: post #153

But where are the fusion neutrons? (See Voodoo Fusion [1]) [1] https://vixra.org/pdf/1812.0382v1.pdf I'm a professional fission guy. I started out in fusion and switched to advanced fission. These days I don't see why we don't just build lots more regular old LWR fission reactors. Imagining that somehow fusion is going to a) work, b) be cheap (fuel cost is only 5% of total nuclear fission cost so who cares), and c) n…

fusion has better marketing in the marketplace of the uninformed. "Harnesses the power of the sun" vs "nuclear bombs"

I'm sure the greens will try and tear it down it if it ever comes to commercial viability and start calling it thermonuclear power or some nonsense.

Re: More invested in nuclear fusion in last 12 months than past decade

#358

Post by adgjlsfhk1 »

acidburnNSA wrote: post #341
adgjlsfhk1 wrote: post #338

Earlier quoted context omitted.

This is making a lot of assumptions about what uranium is economically viable to extract. Specifically, this link appears to be assuming that it is possible to filter the entire oceans and Earth's entire crust for all the uranium and thorium they store. Those are both obviously unreasonable assumptions.

For seawater extraction, you just put enough uranium capture fibers in a few places and the uranium is delivered to you slowly over billions of years via ocean currents. This is well supported by the various articles and entire scientific issue featured in the See Also section. But if you don't buy seawater extraction, check out the Weinberg 1959 reference ( https://doi.org/10.1063/1.3060564 ), which contains a calcu…

this has some serious problems in the analysis. First of all, about half of the earth's crust is under an ocean. Second, of the remaining half, it is on average about 10 miles deep. There is no way that digging up 10 miles of rock to get to some scattered uranium atoms is net positive from an energy perspective. The deepest mines in the world are 2.5 miles under ground, and is in a location with a very high concentration of gold. Most of the uranium in the earth's crust is at concentrations of less than 1 part in 1 million, and one ton of uranium can only (being maximally optimistic) lift 1 million tons of rock by about 1 mile, so any uranium lower than that (not in a major vein) will produce negative energy to mine. Also, just because it's technically net energy positive, doesn't mean it's efficient at all. If we want mining to be at least somewhat efficient, we will only be getting roughly 1/3rd of that (since by the time you are lower, you will be losing too much energy to be cost competitive).

This very basic analysis suggests that your link is off by at least a factor of 100, which doesn't inspire much confidence in their results.

Re: More invested in nuclear fusion in last 12 months than past decade

#359

Post by borissk »

Kukumber wrote: post #213
dotnet00 wrote: post #129

Earlier quoted context omitted.

Yes, clearly that's why SpaceX was successful in an industry where the adage was "How do you become a millionaire in aviation? Start with a billion!".

SpaceX is not successful as an industry It is a government funded project at this point

No post body was provided.

Re: More invested in nuclear fusion in last 12 months than past decade

#360

Post by baxtr »

acidburnNSA wrote: post #153

But where are the fusion neutrons? (See Voodoo Fusion [1]) [1] https://vixra.org/pdf/1812.0382v1.pdf I'm a professional fission guy. I started out in fusion and switched to advanced fission. These days I don't see why we don't just build lots more regular old LWR fission reactors. Imagining that somehow fusion is going to a) work, b) be cheap (fuel cost is only 5% of total nuclear fission cost so who cares), and c) n…

Fusion is just around the corner! Just 20 years away!
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