[dennisp]

Joe I think ikanreed knows the difference. His point is that if they were able to maintain that power output for 1/8 second, it would be the the same energy as Hiroshima. They actually maintain it for a much shorter span of time, but the comparison still gives a good impression of the power level they’re talking about.

[dennisp]

Would this be practical for a power plant?

And would it have potential for a launch rocket (by adding reaction mass), or just for deep space propulsion?

[dennisp]

I added links on reddit:

http://www.reddit.com/r/technology/comments/sm1tt/tv_news_report_on_focus_fusion_cheap_small_scale/

TV news report on focus fusion
byu/ItsAConspiracy inenergy

[dennisp]

The oil companies have had methanol-to-gasoline conversion in production for decades. Google has lots of links. I read somewhere its efficiency is somewhere north of 90%.

Los Alamos proposed using it in their Green Freedom concept, for making gasoline from ambient CO2.

[dennisp]

Some fission products are gases at room temperature, but that’s the same for any fission reactor. It does have to be handled carefully but there are well-developed ways to do it. I think one is to embed them in blocks of glass.

I don’t want to give the impression that I think it’s as good as fusion. But I think it’s worth keeping an eye on, just for technology sharing if nothing else.

[dennisp]

For a power plant the idea is definitely not to vent the fission fragments to the atmosphere 🙂 …but rather to trap them electromagnetically and extract energy as you reduce their velocity to zero. That’s the part it might have in common with a focus fusion reactor.

After that you have to dispose of the waste, just like any fission reactor. But the problem is easier than for a light-water reactor, because the (relatively short-lived) fission products are separated from the heavy isotopes. I would guess you can also achieve high fuel burnup, which in a LWR is limited because fission products are trapped in the solid fuel. Some of them absorb a lot of neutrons, and some are gases that are bad for fuel integrity.

[dennisp]

How efficient does the onion have to be to give us practical net power?

If 40% is ok, then if the onion turns out slow to develop, a turbine would work. Pressurized water reactors run at only about 315 deg C:
http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/reactor.html

If water coolant doesn’t absorb X-rays well enough, maybe we could borrow from certain fast reactors and use lead, which melts at 327C and definitely isn’t transparent to X-rays. Molten salt and sodium are other options, though I have no idea how suitable they’d be.

Ideal Carnot efficiency at 600C on a warm day is around 65% according to this calculator:
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/carnot.html#c1

Of course you have to keep the lead above its freeze temp, which takes you down to 28% or so. But you could have a secondary loop of water coolant to take you from >327C to outside temp, with about the efficiency of PWR turbines, getting us in the neighborhood of 50% total. Now you’re approaching the complexity of the PWR power loop, but at least you don’t have a containment dome and a bunch of complicated safety systems. You can probably get in the neighborhood of coal power cost, especially given the relative lack of fuel expense, or of the regulatory and political delays that plague fission reactors.

It might not be the ultra-cheap power source we’re hoping for, but a zero-waste, zero-pollution, reasonably-cheap, perfectly safe power source is still good enough to go to production, and kick off a lot of investment in developing better options.

[dennisp]

Tom Murphy, a physicist, has been posting a great blog about the potential of various energy sources. He just did one on fusion, but focused on NIF and tokamak. I posted a reply about FF and others here:
http://physics.ucsd.edu/do-the-math/2012/01/nuclear-fusion/#comment-3240

[dennisp]

Yeah that’s pretty silly. Projecting nuclear costs to keep rising doesn’t make a lot of sense either. Standardized, simpler reactors like the AP-1000 should drop in price significantly as we build more of them. Fuel cost is already fairly low, and will drop to almost nothing as IFRs and LFTRs come on line…and those should be reasonably cheap to build, too.

[dennisp]

China infringes a lot of our IP already, and they’ve got serious energy demands, currently being met mostly by coal plants with emissions so bad they kill several hundred thousand Chinese every year. I think it’s safe to say that if anyone tries to lock down a technology that can solve their energy problems, they’ll take giant piss on the international patents. The only way these patents will be respected is if they’re licensed broadly with very reasonable fees.

[dennisp]

delt0r, interesting points. Regarding giant waves, I’ll mention that since LFTRs aren’t water-cooled, you can put them in the high desert if you want to. I think that’s also true of IFRs, but have to check.

Zapkitty, the worst nuclear accident ever still killed less people than coal does every year. If you’re concerned about climate change, I’m curious what your backup plan is, in the event fusion doesn’t work. We’re all agreed that if we get good news from Lerner next year, we can drop fission like yesterday’s news.

[dennisp]

Corrosion depends on what the pipes are made of. There’s an alloy that seems to work pretty well, and worst case. There’s no water to react with. You can make your passive cooling tank however big it needs to be…to get absurd about it, if you had a tank with a perfectly flat and level floor a mile in diameter, you’d probably be ok. If you can’t make it work at a GW, go with smaller reactors. LFTR works fine for small reactors; it was designed for a nuclear airplane.

[dennisp]

Zapkitty: How is the situation you describe any different than it’s been for the entire history of fission reactors, and the demonstrated safety record they’ve already achieved despite using technologies with far less inherent safety than what’s available now?

And LFTR would be superior to today’s technology. The fuel is an inert molten salt. If a pipe leaks, it just drips out and solidifies, nicely containing the radioactive stuff. The whole thing operates at atmospheric pressure, so that fuel will just drip, not spray. There’s no water, so there won’t be any source of the hydrogen that made the Fukushima building explode.

If the fuel starts to overheat, it expands and slows the reaction enough to stay in the proper temperature range. If it somehow gets too hot anyway, or the electricity fails, a frozen plug melts and all the fuel drains into a passive cooling tank. At one of the LFTR experimental reactors, that’s how they turned the reactor off for the weekend…just cut the power and went home.

It’s not as good as FF but in case we don’t achieve fusion, it’s probably our best shot at an energy-rich, carbon-free society. It’s nice to have backup plans.

[dennisp]

Heehee…I think, given that focus fusion would be a large number of small reactors (50MW and below), and they’ll be really cheap to build, we’ll have plenty of redundancy to smooth out any downtime.

[dennisp]

I suspect it would be instructive to see a similar accident list for fossil plants.

I doubt there’s anyone here who wouldn’t agree that if focus fusion works, all forms of fission will be obsolete. Or that we should spend some billions on researching FF and other alternative fusion projects.

But until somebody actually achieves net power using fusion, it looks to me like the best option for building new power plants today is fission. It’s way better than letting hundreds of thousands of people die every year from coal emissions. By comparison, we have:

Three Mile Island, which didn’t hurt anybody,

Chernobyl, which was an ancient design with a horrible positive feedback and no containment dome, and

Fukushima, which was a 1970s plant hit by a 9.0 earthquake and tsunami. Another fission plant right next door was built ten years later with improved safety features, and got through the same challenges just fine.

And that’s our record with GenII reactors, using active safety systems. GenIII+ is a lot better, and when you get into things like liquid thorium reactors, safety goes to a whole different level. There’s no meltdown potential there either, or anything that could cause an explosion.

Bottom line: the world is going to spend tens of trillions of dollars over the next several decades, replacing and expanding our energy infrastructure. It’s crazy not to spend mere billions now researching every advanced energy source we can.

But until we have better stuff available, I’d much rather build GenIII+ fission than fossil plants. As for cost, France is 80% nuclear with complicated old non-modular GenII plants, and has the cheapest electricity in Europe.

[Author]

Posts