A primer to nuclear fusion and First Light Fusion
startuppirate.substack.com
startuppirate.substack.com
I'm too lazy to even back-of-a-napkin calculation. Though it seems like you'd need either a way to highly compress the fissile material or a really good neutron reflector to reach any sorta criticality. Neither seem likely exist though.
Smallest AHRs were ~2 feet or so in diameter and put out ~5kWth, so it’s at least possible that you could deploy them buried in your backyard or something like that.
The power plant design they show has a 150MWe target power. Will be an interesting engineering challenge scaling it up and keeping all the finicky little parts and seals in the gun working when by design it's connected to a (small) nuclear explosion by a long pipe. If the timing is right you could have a heavy rotating shutter shielding the muzzle from the backblast.
They're a lot like the other fusion startups in the current scene. They have a machine, about which they make various surprising claims, but keep almost all the specifications secret, since it's a privately held venture rather than a public government-funded experiment. It's not obvious incoherent nonsense like solar roadways from a couple years back. Maybe it will work, maybe it won't. Check back in 10 years.
I was wondering if there was some incoherent nonsense I'd missed.
The NRC and their UK equivalent have already been moving towards lighter regulation for fusion reactors, and that's for D-T reactors. A reactor like Helion's could well be regulated more like medical devices than fission reactors.
They count on D-D side reactions for neutrons to use breeding tritium, which decays over decades to the 3He they need. I don't see how that could produce enough. If not, their thing might still end up usable to power outer solar system space probes, using 3He decayed from the usual CANDU-produced tritium.
The Princeton FRC design is intended for spacecraft propulsion. I don't know if it is more or less practical.
On top of that, First Light says they'll use natural lithium without enriching it to lithium-6, which makes things even worse.
Literally anything can seem, to somebody.
A 1GW fusion reactor would consume about a ton of fuel per year.[1] That's about 600 kilograms of tritium. Over the course of the year a reactor with a positive breeding ratio will produce more than that.
The breeding blanket for ITER will be about 2000 tons[2] and ITER is designed to produce 500MW.[3]
This means that ITER will produce at least 300 kg tritium in 2000 tons of blanket, over the course of a year. Collect the tritium annually and you've got a concentration level of 150 parts per million, or 150,000 PPB.
[1] https://ccfe.ukaea.uk/fusion-energy/fusion-in-brief/
> But there would be no point, because they would have no way to refine it out
I would expect that hydrogen and lithium should be able to be refined chemically, as both are very reactive elements. And even if mechanical refining is necessary, we have much industry experience with that: Uranium isotopes have been mechanically refined for almost a century. Furthermore, lithium and hydrogen are far more dissimilar than are U235 and U238 - lithium has six times the atomic weight of standard hydrogen and double the atomic weight of tritium.
The guy in the article said you just do the same thing as coal or any other plant - generate steam. But we're talking about millions of degrees vs a couple thousand. Does it really scale that simply?
I think this is somewhat similar to how a fission reactor is used to drive a steam turbine in an ordinary nuclear (fission) power plant.
This is how you get heat out, it's also how you breed more tritium from lithium.
That is to say, none of the investors will get any of their money back. If they are OK with that, fine. But probably most are not. You can think of it as a stupidity tax: enough money to invest was also enough to hire somebody to explain how they are throwing their money away. But they didn't.
One reason (of several) that it is a scam is that, to get the power out usefully, you need a thousand tons of "blanket" to absorb kinetic neutrons and turn them into heat. You need a high proportion of lithium in your blanket, so that the neutrons hitting it can breed the tritium you will need for fuel tomorrow.
But running a full-scale power plant all day will only breed a few grams of tritium, that you must somehow sift out of your thousand tons of "blanket", at parts-per-billion concentration. Nobody knows any way to do this. But without doing it, you have no fuel to use tomorrow.
Even if you could get enough tritium, those hot kinetic neutrons are blasting all of the physical structure of your reactor, weakening it, and also making it extremely radioactive. After a remarkably short time, you have to replace all the solid parts. But they are all fantastically radioactive, so you need robots to do it with. Those robots do not exist. The used-up parts are, anyway, not like regular nuke waste; they will mostly decay in a century or two, probably.
Until then, presuming you could scare up tritium fuel, you would have a thousand tons of super-hot "blanket" you need to run water through pipes in, to boil and drive a steam turbine. But steam turbines, too, need expensive periodic overhauls.
Meanwhile, solar panels and wind turbines are producing the cheapest power the world has ever known, today. No radioactivity, no tritium, no persnickety steam turbines. Just clean power.
So, nobody would buy your super-expensive fusion plant even if it worked, because it would cost so much to operate you would need to ask a lot more money for its output than anybody will pay.
But the people running the startup have no need to care about any of that. They have fun making big expensive experiments with your money, cater in expensive lunches, and drive Ferraris, because why not? When the money runs out, they go do something else.
There is no force on Earth powerful enough to make them give any of the money back.
Another big scam, BTW, is NRGV, "Energy Vault", traded on public markets at $2B cap last I checked. Apparently it is not considered fraud to collect investment money for things that cannot work.
No dispatching either
Correction: you don't know any way to do this.
https://www.osti.gov/pages/servlets/purl/1394392
Meanwhile the super expensive power plant can run in the winter and not require fossil fuels or magic energy storage.
Do futile jabs at renewables, which are being deployed at industrial scale as I write this, serve to make fusion startups less scammy?
Renewables will not replace fossil fuels to an acceptable degree without first solving energy storage. The question is "is industrial energy storage cheaper than fusion energy". Not such a clear answer when the order of magnitude of either of those is not established.
Do futile jabs at fusion, but also try to keep in mind the goal is legacy, not identity.
I suppose it boils down to what the “saturation threshold” of nuclear reactors is, where you can’t pump more energy in without breaking the thing.
In any case, what are the benchmarks that engineers are shooting for?
ITER is as large as it is because within reasonable magnetic field strengths, you still need a certain amount of distance to curve the charged particles back towards the centre - and probability means you have a distribution, some but not all will make it. Bigger vacuum vessel, the more particles you can loop back into your reactor.
So, if we can provably get over 1, and validate our plasma behaviour models, we can then derive the correct engineering equations to target a specific Q factor when building the production type reactors.
[1] https://physics.stackexchange.com/questions/175830/nuclear-f...
High temperatures are usually used because the nuclei must have a lot of force to counter that of the liked charged partner. The most obvious way to do this is with heating the plasma because individual particles, when they collide head on, can have the combined momentum to plow their way together.
But Philo T Farnsworth found a clever way to get them close with electrostatic forces. If it weren't for those darned wires.
With millions of degrees that plasma viciously expands. An even more incredible contraction force must be used to keep this together long enough for "interesting results". This is done with inertial confinement like the Hbomb or emulations of it. Magnetic confinement merely slows the expansion, but it must at some point touch the walls.
Actually, heat is not wanted. You only need to get the nuclei close enough that they quantum tunnel to each other to relieve their own stress in their environment. 2 Dueterons spread farther than helium3 does. Think of it like phase changes in condensed matter. Except we don't care at all about electrons, simply move them somewhere that the fuel ions wish to congregate at. Fortunately this can be a single point, as charges are concentrated on pointy things, as Faraday found in his experiments. The other side is full of the fuel ions. They don't have to be hot but warming them a little in an environment that is under 770 giga-pascals of pressure might be enough to moderate a nuclear combination process. It isn't hard to create two chambers in a crystal and make them undergo reductions or oxidations to free ions or electrons (tragically this happens with lithium ion batteries all the time). If they are surrounded in an environment that is very hard, very good dielectric strength, ions or electrons can be freed with no where to go. This is known as a meta-stable state and many crystal patterns exhibit this. The best dielectric known is diamond and it's also the hardest and has a ton of other helpful properties. If diamond couldn't do this, then nothing can. A mad genius with money and time would not have to go further than it to rule it out completely.
Say my fancy idea doesn't work, if colliding macro projectiles is something useful to the author have they tried something like levitating pyrolytic carbon and propelling it with laser ablation? It could be done in a loop if part of the magnet can de-energize fast enough to allow the tiny block of carbon to escape.
The plan they have seems very Wile E. Coyote to me but fun and cool. I hope they succeed.
If you have two atoms in a vacuum with one moving directly towards the other at a not very high speed, I’m pretty sure they don’t fuse.
There’s a repulsive force, right? Like, the (expectation of) potential energy goes up (up to a certain point) as the centers of their nuclei get closer together (after perhaps getting lower for a bit because maybe they form a bond or something)?
So, presumably the “fingers” would have to do enough work to get past this potential energy barrier? (Or at least, make it high enough up this barrier that the probability of tunneling through becomes non-negligible?)
In nature, those "fingers" are more often than not hydrogen atoms, and the force acting on them is gravity. 10^30 kilograms of hydrogen, in a stack 600,000 kilometers tall, makes for high enough forces for the hydrogen to fuse.
To me, it feels like it shouldn't be able to? (I say "feels" because I have not like, looked up any of the numbers about this or anything like that, and I could easily be wrong)
And, perhaps this could be the/a reason one might doubt that containing it in a diamond would work as an alternative to things like parts being brought together suddenly through precise collisions or using confinement from magnetic fields and such?
Though, of course, I'm not saying that doubting for that reason would probably lead to a correct conclusion. I wouldn't know much of anything about how one would achieve nuclear fusion, or how strong chemical bonds are, etc. .
There was a movie with Gene Wilder and Zero Mostel, a few years back, about this business model.
And, yes, classic.