Is hyperfission an easier goal than fusion?

Spacescifi · July 26, 2019

The more I google fusion, the more it seems not viable right now. It is basically trying to put a star in a jar without the planets worth of mass and density that a star has.

To compensate we use lots of heat which can cause fusion with plasma that is basically infintesmal when compared to the mass of the sun.

Yet the challenge is not over, since we try to manage the plasma with magnetic fields, but plasma create magnetic fields of it's own which interfere.

End result? Plasma escapes the containment field and hits the chamber wall, turning part of the wall into plasma which cools the wannabe mini-star just enough to kill the fusion processs.

So in light of all this and more that I have not even mentioned, what are the chances that we could improve fission?

Hyperfission: More. More. More. More split atom, more energy released, more dangerous radiation in it's wake.

Basically you take an atom and convert more of it into energy than we currently do with fission. How about oh... 25% of the atom converted into energy after it is split? Instead of the standard 2%?

Would we even need antimatter or fusion at that point?

And yea I know, using it as an SSTO is still hazardous to public health, only probably more so.

And yea... epic nukes too. More epic.

What do ya think? And yea, this is partly inspired for scifi. Partly over fusion frustration?

Edited July 26, 2019 by Spacescifi

July 26, 2019

Fusion is only 20 years away ^_^

kerbiloid · July 27, 2019

4 hours ago, Spacescifi said:

density that a star has.

1400 kg/m³?

4 hours ago, Spacescifi said:

So in light of all this and more that I have not even mentioned, what are the chances that we could improve fission?

Hyperfission: More. More. More. More split atom, more energy released, more dangerous radiation in it's wake.

We have the way of doing that!

A fusion inside a fission.

StrandedonEarth · July 27, 2019

4 hours ago, Spacescifi said:

Basically you take an atom and convert more of it into energy than we currently do with fission. How about oh... 25% of the atom converted into energy after it is split? Instead of the standard 2%?

Unfortunately, that's not how fission works. To turn 25% of an atom into energy would require hitting it with 25% of its mass in antimatter; you can't just fission it away.

This is overly simplified, but the gist of it is: Heavier elements are formed by lighter atoms fusing. If that fusion releases energy (hydrogen fusion), then it will take that much energy to break that new atom apart again. But if fusing two atoms (usually heavier atoms) takes energy (consumes energy), then fissioning that new atom will release that energy again.

Years ago, I learned from an astronomy textbook that a massive star burns up (fuses) the lighter elements sequentially up the periodic table (releasing energy) until it tries to fuse iron, which consumes energy. The core then cools and the star collapses until the outer atmosphere of the star rebounds off the core in a supernova, creating all the heavier elements in the process. Depending on the mass involved in the collapse, the remnant is generally a neutron star or black hole.

AngrybobH · July 27, 2019

5 hours ago, Dale Christopher said:

Fusion is only 20 years away

Didn't they say that 20 years ago?

StrandedonEarth · July 27, 2019

58 minutes ago, AngrybobH said:

Didn't they say that 20 years ago?

And they'll say it again in 20 years...

Flying dutchman · July 27, 2019

Don't forget that supercomputers and ai continue to develop at a rapid pace. Perhaps in some time a computer can design a working fusion reactor.

kerbiloid · July 27, 2019

1 hour ago, StrandedonEarth said:

2 hours ago, AngrybobH said:

Didn't they say that 20 years ago?

And they'll say it again in 20 years...

At least we always know precise timing.

July 27, 2019

I feel pretty confident that ITER https://en.wikipedia.org/wiki/ITER will be able to produce a net positive reaction, it should just be a matter of experimentation to develop the techniques needed for a commercial reactor to be viable. (I bet you once ITER is running the former will be knocked out relatively quickly, but the latter (commercially viable reactor) will probably take the rest of the project's lifetime.)

(Side note we could actually quite easily harness the power of a fusion reaction now, and have been technologically capable of doing it for quite some time @_@ but not in a reactor plant form. More in a detonate a thermonuclear device underground and then harvest the thermal output captured in the rock afterwards... form. But also if you could create small enough bombs you could even let one off in some kind of containment area, maybe filled with water instantly super heating and pressurizing it. )

Edited July 27, 2019 by Guest

Aelipse · July 27, 2019

1 hour ago, Dale Christopher said:

(Side note we could actually quite easily harness the power of a fusion reaction now, and have been technologically capable of doing it for quite some time @_@ but not in a reactor plant form. More in a detonate a thermonuclear device underground and then harvest the thermal output captured in the rock afterwards... form. But also if you could create small enough bombs you could even let one off in some kind of containment area, maybe filled with water instantly super heating and pressurizing it. )

Funnily enough, scientists already had the same idea. The approach you talk about is called "inertial confinement" and they basically produce small balls of very dense nuclear fuel (deuterium and tritium) the size of a pea and then they shoot superpowerful pulse lasers onto it from all sides, heating it up rapidly and theoretically producing a successful fusion reaction.

I'm saying theoretically, because this approach has many many flaws. First of all, you have to produce a ball of pure deuterium and tritium that is such a perfect sphere that the price of this single fuel pellet is in tens of thousands of USD. Any slight imperfection to the shape will cause non-zero net forces during the laser pulse, which will jettison the rest of the pellet away. They use a little metallic casing around the fuel pellet (called "hohlraum") to increase the stability and thus chance of ignition, but further increasing the production costs. A power plant running on this principle would have to burn tens of these pellets each second! Not to mention the horribly low efficiency of the lasers: of all the energy that is pumped into them, only about 0.2 % is converted into energy of the laser beam, or pulse rather, which is no way to build a self-efficient power plant. The efficiency number might be a bit higher today as the laser technologies are constantly improving, but it is still far too low for any commercial use.

The largest facility that does this is NIF (National Ignition Facility) in the US.

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

The most hopeful approach to nuclear fusion reactors though is magnetic confinement, and the number one design they go with is "tokamak". Tokamaks are basically doughnut-shaped chambers surrounded by conductive coils. Change in the current flowing through those coils creates magnetic field, and if you wind the coils in correct geometry, the magnetic field they produce will follow the doughnut-shaped cavity of the reactor. Superheated particles of deuterium / tritium fuel become plasma - a mix of electrically charged particles, which then follow (or rather spiral around) the magnetic line of force.

There are of course many problems to be solved. It has been mentioned above that unwanted particles of heavier elements (usually originating in the surface layer of the reactor chamber) find their way into the hot plasma fuel, and since the fast deuterium and tritium nuclei collide with the heavier particles, they transfer a lot of energy onto them, effectively losing heat. Modern designs of tokamaks, like ITER which is being built, or JET which is currently the largest operational tokamak in the world, have a segment called "divertor", which by clever shaping of the magnetic lines of force can suck the unwanted heavy particles away.

Another problem is heating. The temperatures we're talking about here are over 100 million °C, with the world record being some 400 million °C in a tokamak device. How do you heat anything to such temperatures? Microwaves are used, just like when you're warming up your food; they have tiny accelerators which shoot extremely energetic particles into the plasma within the reactor chamber (you can think of it as playing pool - one very fast ball will set all the other balls into motion through collisions), but by far most significant and most important method of heating up the nuclear fuel is through electromagnetic induction. Because if you actually change the magnitude of the magnetic field, an electric current will occur within the highly conductive plasma fuel. The principle is quite the same as any inductive cooker. The issue with this is that you can only keep changing the magnetic field for so long. Once you reach the maximum of what your coils are capable of producing, the whole discharge feeding your fuel with heat will collapse.

Still, tokamaks are some of the coolest (and hottest! ) devices people have built. Think about it. The coils in the largest tokamaks have to be made of superconductors in order not to overheat and melt, but superconductors require helium cooling to incredibly low temperatures - some of the lowest temperatures in the universe actually. A couple of centimeters aside you'd find yourself inside the reactor chamber, which reaches more than 100 million °C, which is actually higher than the cores of the hottest stars. The lowest and the highest temperatures right next to each other.

Edited July 27, 2019 by Aelipse

farmerben · July 27, 2019

The first nuclear reaction discovered goes by the name "disintegration". "Disintegration of Lithium by Swift Protons" JD Cockcroft 1932.

Lithium, Beryllium, and Boron barely exist in main sequence stars because the radiation blasts them apart, or fuses them into carbon. Lithium disintegrations are extremely exothermic, and release tritium. Lithium 7 and Boron 11 are the best proton beam eaters (low input energy, high exothermic release, high cross section)

Lithium 6 and Boron 10 can be disintegrated exothermically by slow or fast neutrons.

Beryllium 8 has the lowest barrier to alpha particle absorbtion. The triple alpha process, which makes carbon plus a neutron. +7 MeV

The rest of the periodic table can be made to do interesting things when struck with high energy particles. Most of these reactions are called "spallation". It is a good way to multiply the number of particles, but usually endothermic.

https://www.oecd-nea.org/janis/book/book-proton.pdf

I'd love to find similar data for deuteron beams and alpha beams, but I haven't found it yet.

At energies above the rest mass of a proton >1GeV, the kinetic energy of the beam creates new massive particles within the target. As I understand it, these collisions throw off a shower of Kaons - quark, anti-quark pairs, which live long enough to reach nearby atoms, but not much longer.

kerbiloid · July 27, 2019

Humans use fusion power since stone age.

For thousands years the benighted peasants were praying a fusion reactor and were growing crops and fruits in rays of its secondary radiation.

They called it "sun", "sol", and so on. These words are an abbreviature of the stone age phrase "A remote long-term carbon-cycle fusion device".

We just have to make it portable.

Edited July 27, 2019 by kerbiloid

wumpus · July 27, 2019

Hyperfission? Basically we already split the low-hanging fruit of the nuclear reactor: splitting any more isn't clear it will add anymore power. You might also want to look up "plutonium poisoning", I think that is why current reactors pull the fuel rods. Breeder reactors were designed to allow more of the fuel to be used, that is probably what you are looking for (since the amount of nuclear fuel available never turned out to be the limiting factor, breeder reactors simply haven't been used).

Earth based or space based?

<RANT> Earth-based nuclear [fission] power seems unlikely in the West (especially USA and EU). Most of the reasons are political, although political/economic factors such as the nuclear power plant construction industry grew up with time&materials contracts and now appears completely incapable of developing a power plant remotely on time or schedule. Remember, these things are essentially pre-paid electricity. If you are paying interest on a debt while watching your nuclear power plant slowly being built while running into delay after delay, it is even more painful to look at (also prepaid electricity) solar farms being put up on time and schedule, and also watching the profits on such panels being pumped back into R&D making the next solar panels (which will compete with your electricity, assuming you ever go on line) much more efficient. I doubt any nuclear reactor constructed +/- 10 years will ever be profitable. *** NOTE *** This isn't suggesting Germany's abandonment of nuclear power remotely makes sense. Construction of the nuclear plant is a sunk cost and decommisioning the reactor isn't going to bring anything back. And nuclear power (especially after the sunk cost) is always going to be "more green" than any replacement over the expected life of the reactor. </RANT>

Note that after sufficient decades pass it might make sense to have another go at Earth-based nuclear power (especially if using designs made off world), but the whole infrastructure behind nuclear power is hopeless. Nevermind what can be done in the lab, your technology is your infrastructure (see anything by James Burke for a detailed analysis).

Spacebased ordinary nuclear power is likely sufficient, although cooling is even more of an issue and big, cheap, heatsinks (like gravity fed watertowers above the reactor) simply aren't an option off planet (maybe some liquid on Mars? Sounds difficult, but possible). Solar power (within Mars orbit or so) is going to be wildly more effective than anything on the ground, so I'd assume that engineers will go for the tried and true (solar) than the difficult and risky (non-RTG nuclear power).

And don't forget that there has been one fusion-powered SSTO developed and manufacturable with 1960s tech: the Orion (not the current use of that legendary name, the real Orion.) Unfortunately early calculations ignored the magnetosphere and Van Allen belts, so most of the "fallout" would return to Earth. This could still be avoided by manufacture and launch at Antarctica, but you might still face threat of a nuclear response from India once they realize that they would have the lion's share of deaths due to a planetwide barrage of nuclear pollution (and the Chinese might as well back them on this).

Kerbart · July 27, 2019

6 hours ago, Dale Christopher said:

I feel pretty confident that ITER https://en.wikipedia.org/wiki/ITER will be able to produce a net positive reaction, it should just be a matter of experimentation to develop the techniques needed for a commercial reactor to be viable. (I bet you once ITER is running the former will be knocked out in the relatively quickly, but the latter (commercially viable reactor) will probably take the rest of the project's lifetime.)

You are way too pessimistic. Five years, top. Possibly three.Within a decade humanity will stop using fossil fuels.

The Wright Brothers, Banister running the 4 minute mile, to name two of the most famous examples... once an “impossible” achievement is made, everyone else will be stumbling over each other to make it as well. With something that has the stakes so high, once ITER manages to run successfully, there will be commercial reactors running in a matter of years, I predict.

Aelipse · July 27, 2019

Hopefully, but ITER won't be running on fusible fuels for several years even after its construction is finished. They will use pure hydrogen and then start experimenting with deuterium for four years I think, just to see how the plasma behaves, what instabilities it suffers from and for how long they can hold the required temperatures up. That will take a lot of testing and a lot of time.

Because once you introduce radioactive tritium into the mix and start doing the actual fusion reactions, you are opening a whole different can of worms. Fast neutrons released by the reaction will make the inner shields of the reactor chamber radioactive, which will further complicate any repairs or adjustments to it, not to mention the handling of radioactive tritium itself. So... Ten years if I'm being optimistic?

kerbiloid · July 27, 2019

31 minutes ago, wumpus said:

<RANT> Earth-based nuclear [fission] power seems unlikely in the West (especially USA and EU).

Spoiler

Spacescifi · July 27, 2019

14 hours ago, StrandedonEarth said:

Unfortunately, that's not how fission works. To turn 25% of an atom into energy would require hitting it with 25% of its mass in antimatter; you can't just fission it away.

This is overly simplified, but the gist of it is: Heavier elements are formed by lighter atoms fusing. If that fusion releases energy (hydrogen fusion), then it will take that much energy to break that new atom apart again. But if fusing two atoms (usually heavier atoms) takes energy (consumes energy), then fissioning that new atom will release that energy again.

Years ago, I learned from an astronomy textbook that a massive star burns up (fuses) the lighter elements sequentially up the periodic table (releasing energy) until it tries to fuse iron, which consumes energy. The core then cools and the star collapses until the outer atmosphere of the star rebounds off the core in a supernova, creating all the heavier elements in the process. Depending on the mass involved in the collapse, the remnant is generally a neutron star or black hole.

Hmmm... if we could just do a chain reaction of fusion with say... 20 atoms exchanging their 2% for energy we can do it?

The irony is how fusion is depicted in scifi. The way they depict it, they would need and have other contrivance to make it work.

Since with known understanding, we need like kilometer size radiators for a fusion ship. The more performance, the more the radiator wings will GROSSLY dwarf the tiny spaceship it is attached to.

I dunno... perhaps they use duralium/unobtainum alloy, which can absorb massive amounts of radiation as potential energy before radiating it again (read explode).

Such fictional alloys would make lasers a lot less effective against it as a side effect.

It would also be used as a substitute for nuclear reactors, as you could extract the energy you needed and no more or less.

Edited July 27, 2019 by Spacescifi
Sub

Bill Phil · July 27, 2019

Well there are some ideas about dusty plasma radiators... those could be interesting and high performance.

farmerben · July 27, 2019

5 hours ago, wumpus said:

<RANT> Earth-based nuclear [fission] power seems unlikely in the West (especially USA and EU). Most of the reasons are political,

Bah, fission is so cheap they could give electricity away for free. The plutonium product alone can more than pay for the entire plant. The RBMK 1000 uses natural uranium and light water, so its inputs are drastically cheaper than any operating western reactor.

In vaporized sodium coolant with unclad metal fuel pellets the cesium and iodine come right out in the coolant, so the fuel pellets don't get poisoned.

HebaruSan · July 27, 2019

1 hour ago, Spacescifi said:

Hmmm... if we could just do a chain reaction of fusion with say... 20 atoms exchanging their 2% for energy we can do it?

I'm not a nuclear physicist, but I don't think they can design reactors by picking arbitrary numbers out of a hat like that. They have to work with known fuels / isotopes / reactions / decays, often in long complicated branching chains, each of which potentially has its own quirks and gotchas and tricks to make it work as desired.

Moreover, this misses the point:

20 hours ago, Spacescifi said:

More. More. More. More split atom, more energy released, more dangerous radiation in it's wake.

The goal is not just to release more energy all at once. We can already do that; it's called a "bomb". Rather, we want to sustain a certain energy supply over time (generally some number of megawatts based on the needs of the city being served). Bonus points if it can be tuned to the minute-by-minute needs of the grid, doesn't release carbon dioxide, doesn't rely on a scarce input, doesn't generate hazardous by-products, is fool-proof/fail-safe in all conditions, etc.

The hypothetical advantages of fusion over fission do include greater efficiency per mass input, but that's not really why it's appealing.

benzman · July 27, 2019

21 hours ago, Dale Christopher said:

Fusion is only 20 years away

And has been since the nineteen-fifties.

DDE · July 27, 2019

7 hours ago, wumpus said:

Unfortunately early calculations ignored the magnetosphere and Van Allen belts, so most of the "fallout" would return to Earth. This could still be avoided by manufacture and launch at Antarctica, but you might still face threat of a nuclear response from India once they realize that they would have the lion's share of deaths due to a planetwide barrage of nuclear pollution (and the Chinese might as well back them on this).

GA-9005 has charts for that. The safe zone is actually further north.

Oh, and the Chinese would thank you for preventing millions of cancer cases through additional exposure. They're sitting on a major study indicating radiation hormesis, one that even had a control group.

22 hours ago, Spacescifi said:

Hyperfission: More. More. More. More split atom, more energy released, more dangerous radiation in it's wake.

You got a reaction to go with that claim?

July 27, 2019

I should note that we have, actually, achieved break-even at NIF, some time ago. While NIF design is poorly suited for turning into a reactor, it is a possible avenue of research. I'd still bet on ITER, though. It just seems like more viable route to a commercial reactor.

I will tell you why "fusion is always 20 years ago". We move the goalposts every 20 years. Some 40 years ago, it meant "we'll have a device that can sustain fusion at all, for some time". We have that. 20 years ago, it was "we'll achieve break-even". NIF did that recently. Now it is "we'll have a functional, energy-producing tokamak reactor". ITER is on its way. When it's done, "we have fusion" will mean "a fusion plant produces power that goes to our wall sockets". Money permitting, another 20 years. Once that happens, it'll be "reactors are cheap enough so that they're built commercially instead of as a point of national pride". Might take a while, too. And if you meant "fusion will reduce our electricity prices to nothing" at any point of time, then that will probably not be true in 200, because there's a lot more to energy cost than just fuel.

I'll also tell you, in three words, why the last two steps might take even longer: lignite is cheaper. ITER is huge. It's also expensive. Those things take time to build. We wouldn't be building it if we didn't pretty much know that it will work. It will have unforeseen problems, like any new technology, and building is complicated by the fact it's the first time it's being done. The only reason we got fission when we did was that the US took half the most brilliant nuclear scientists in the world and had them work on this with basically unlimited budget. Then the Soviets took the other half, locked them up and told them to do the same thing, with a somewhat more limited budgets, but with some pilfered results from the US group. Note that at no point during Manhattan project, or in the USSR, anyone was talking profits. If you are talking profits, you build a great ol' smoking lignite plant. Unless governments are smart about doing something about it (take a wild guess how often that happens...), cheap, dirty lignite is the most economical way to make electricity that there is. Taxing carbon emissions, ironically, tends to kill everything but lignite, because it's just that bloody cheap, while coke, coal, gas, oil and so on cost more, and thus end up shut down first (IIRC, that's exactly what Germany ran into). Oh, did I mention why lignite is so cheap? It's mined by strip mining. If you want to devastate our planet, there's nothing better than powering it by burning lignite. But it's cheap, so it's still used quite a bit.

Edited July 27, 2019 by Guest

Cunjo Carl · July 28, 2019

3 hours ago, HebaruSan said:

I'm not a nuclear physicist, but I don't think they can design reactors by picking arbitrary numbers out of a hat like that. They have to work with known fuels / isotopes / reactions / decays, often in long complicated branching chains, each of which potentially has its own quirks and gotchas and tricks to make it work as desired.

Can confirm, this is exactly how it goes.

Nuke · July 28, 2019

On 7/26/2019 at 3:47 PM, Dale Christopher said:

Fusion is only 20 years away

if you use the tokamak yardstick. fringe fusion is always 5 years away.

Is hyperfission an easier goal than fusion?

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