Submitted by Robo-Connery t3_zl56h9 in science
isleepinahammock t1_j03kni5 wrote
Reply to comment by Robo-Connery in National Ignition Facility (NIF) announces net positive energy fusion experiment by Robo-Connery
So here's one thing I'm wondering. What's the proliferation risk of pulsed fusion technology?
So, as you note, a LOT of improvements would need to be made to this system before pulsed fusion could ever be possible. So we would need far, far better lasers, better in power, charge time, and efficiency, in order to make a practical pulsed fusion reactor.
But let's say we do manage to build these lasers. What I wonder is, what ELSE can you use these hyper-efficient, super-powered lasers for? Two disturbing scenarios that have crossed my mind:
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Could you build a pure fusion bomb, a thermonuclear weapon without any uranium needed at all? In principle, if you can direct enough energy at a sufficiently large chunk of fusion fuel, you could create a nuclear explosion without any uranium, plutonium, etc. Our current non-proliferation strategies rely on monitoring and tracking fissile materials like uranium, plutonium, etc. But this might make it possible to build nuclear weapons out of only mundane materials, no uranium needed. It will probably be a long time til we have to worry about someone building a nuke in their basement. But if sufficient numbers of sufficiently high-powered lasers find their way into many industries and applications, this might be something that we have to worry about.
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Creation of fissile materials from non-fissile materials. Miniaturizing the entire laser setup of NIF (let alone the super-NIF I was thinking of in part 1) small enough to fit on top of a missile may never be possible. However, what if someone were to use an NIF-type facility to breed fissile materials from non-fissile ones? I don't know enough about the nuclear chemistry to suggest possible elements. But there probably are some non-fissile elements that are abundant, currently unmonitored by international agencies, and can be transmuted into fissile materials through heavy neutron bombardment. What happens if you build a target for the NIF (or a super-NIF) filled with a combination of fusion fuel and some transmutable element? For example, imagine if someone figured out that ordinary lead could be transmuted into U-235 in the intense neutron flux of a super-NIF facility. In such a world, every fusion reactor we build would be a proliferation nightmare. Every one would have to be continuously monitored to make sure some nefarious government or private company isn't using it to turn mundane, untraceable lead into plutonium or similar.
Robo-Connery OP t1_j03mxri wrote
> What's the proliferation risk of pulsed fusion technology?
I mean the flippant answer is that you don't need lasers to make a bomb, it is much easier to compress your fuel with a fission explosion than with a laser. You also might be envisioning some sci-fi scenario where you lob your pellet at them then lase it to explode but that simply isnt possible, the symmetry required in the compression is almost absolute and the experiment requires a vacuum.
>Could you build a pure fusion bomb, a thermonuclear weapon without any uranium needed at all?
Yes, NIF though has a an entire building that generates the laser pulse and took years to build and it could only blow itself up, not easy to drop it on anyone.
As for question 2.
>were to use an NIF-type facility to breed fissile materials from non-fissile ones?
I believe there are just better ways to do this, and I mean much much much better ways. There are other neutron sources which are cheaper, easier and produce better neutrons than NIF and the actual fusion explosion doesn't help except as a neutron source. The most obvious neutron source is a fission reactor but there are others, any country could build a breeder reactor if they wanted to (though they might face consequences if they were seen to be using it for weapons tech).
isleepinahammock t1_j03tnpz wrote
>I believe there are just better ways to do this, and I mean much much much better ways. There are other neutron sources which are cheaper, easier and produce better neutrons than NIF and the actual fusion explosion doesn't help except as a neutron source. The most obvious neutron source is a fission reactor but there are others, any country could build a breeder reactor if they wanted to (though they might face consequences if they were seen to be using it for weapons tech).
There are other ways to do it. But the key thing to worry about is the production of fissile materials from entirely mundane elements. Sure, you can make plutonium in a breeder reactor, but you still need to at least get a hold of a good amount of U-238 to do so. If today I call up a uranium mine and ask to buy a few hundred tons of yellow cake, I'm going to have some very angry-looking men carrying automatic weapons showing up at my front door very quickly. If I want to do anything involving uranium, I need to obtain special licenses and permits, plus regular inspections to make sure I'm not doing something I shouldn't be doing.
But think of the incredible lasers needed for a practical pulsed-fusion plant. This current step is good progress, but really we need to do about 100x better if we want a practical pulsed-fusion plant. We need lasers that can get 100 MJ of fusion energy for 1 MJ of input laser energy; and they need to be able to fire several times a second 24 hours a day, 365 days a year. We need laser tech far, far beyond our current levels.
And the thing is, that technology is simply far too useful to see it used only in fusion power plants. Highly precise, high-power, high-efficiency lasers have all sorts of applications, including in manufacturing, communications, even things as mundane as drilling deep holes. If we get the tech needed for a pulsed-fusion plant, these lasers are going to be used everywhere, not just in fusion plants.
And that's the real concern. You have to worry about some terrorist group buying some surplus mining or manufacturing equipment, and then using it to breed lead into plutonium. Or, if the knowledge is public enough, they might just build the lasers themselves. It represents a path to nuclear weaponry without ever having to get a hold of an ounce of uranium.
Robo-Connery OP t1_j0401av wrote
The design goals for those commercial purposes are completely worlds apart. There are already much better suited lasers to the jobs you list than NIF which would be completely useless in any of those applications. Completely useless Even if it wasn't useless (which again it would be) it costs billions which isn't exactly gonna come down to a level that makes sense as a commercial product.
Blarg_III t1_j04uiz9 wrote
Anyone who has, and can run, a fusion reactor (Or some super-powerful laser array) is more than capable of making their own nuclear bombs more easily by another method.
>I'm going to have some very angry-looking men carrying automatic weapons showing up at my front door very quickly.
You can buy it online in the US, though not in particularly large amounts. Buy a company with a legitimate use for it, order it in bulk and voila, you have Uranium 238.
FrickinLazerBeams t1_j068q2s wrote
>Highly precise, high-power, high-efficiency lasers have all sorts of applications, including in manufacturing, communications, even things as mundane as drilling deep holes. If we get the tech needed for a pulsed-fusion plant, these lasers are going to be used everywhere, not just in fusion plants.
These lasers have absolutely no use in any of those applications. You're talking about a totally different definition of "high power".
>And that's the real concern. You have to worry about some terrorist group buying some surplus mining or manufacturing equipment, and then using it to breed lead into plutonium. Or, if the knowledge is public enough, they might just build the lasers themselves. It represents a path to nuclear weaponry without ever having to get a hold of an ounce of uranium.
That's hilariously absurd. Never will any kind of laser used for manufacturing, telecom, etc. be usable for laser driven fusion or nuclear weaponry. That's not how any of this works.
Kioer t1_j0431f6 wrote
Lasers shoot photons my man. There is no feasible way to transmute lower Z elements into higher Z elements with a laser. It is simply not possible. You might be able to induce beta decay on some isotopes but not at a scale to produce any measurable quantity of SNM
isleepinahammock t1_j045ate wrote
Fusion reactions can be triggered by lasers, and the fusion reaction emits most of its energy as high-energy neutrons. Literally the entire basis of fusion reactors is transmuting lower-Z elements to higher-Z elements.
Yes, hitting a nucleus with a photon will not cause it to gain new nucleons. However, intense laser light can cause nuclei to collide with sufficient energy to fuse. That's literally the entire basis for the fusion processes discussed here.
Kioer t1_j04b6al wrote
Just due to binding energy fusion does not apply to elements larger than iron. To create any of those we need neutron or proton capture. And if you're creating this massive state of the art laser array to create fusion to produce neutrons why not just build a neutron source to begin with? There are thousands of high flux neutron beams all over the world. Just build one of those for about 1/1000000 of the price or better yet just purchase one from a commercial supplier.
I'm not trying to be rude or anything, but proliferation of nuclear material is the least of the problems with fusion. It is just entirely unfeasible and way way way more expensive and technologically advanced than any other method.
m-in t1_j075dpf wrote
Lasers don’t directly induce fusion. They take some other “working fluid” like gold plasma and dump energy into it. That then can fuse something else that’s the actual nuclear energy source. Of course dumping a bunch of photons close to the visible spectrum (UV and IR are not far at all) will not cause anything to fuse on its own - not even if the photons had unceasingly high energies AFAIK.
m-in t1_j075ou0 wrote
The lasers we use for practical purposes in production environments you mention only share the name and general operating principle with those used at NIF. Calling both “lasers” is technically correct but practically absurd.
zbobet2012 t1_j0599dj wrote
Wouldn't the largest proliferation risk simply be the increased knowledge of the high density regime ICF uses making it easier to make a fission-fusion-fission bomb (an "h-bomb")? I believe some of results of research at NIF are classified no?
Robo-Connery OP t1_j06q0s8 wrote
Absolutely correct. Tonnes of high density matter stuff is classified, if you do work on this in general with laser plasmas the government is gonna come and steal your work (has happened to acquaintances).
I think though the limiting factor in making a passable h-bomb is the fission warhead though, not the fusion stage. The US and other nuclear powers care about this stuff to make efficient and clean weapons rather than to just make weapons (they made them in the 50s without any lasers or plasmas).
FrickinLazerBeams t1_j068cce wrote
>What's the proliferation risk of pulsed fusion technology?
Absolutely zero.
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