8 ms·
Of all the ideas surrounding fusion, this one I've always had the most difficult in imagining it working at any level of production. The kid in me says this wa
by irjustin 4y ago
Of all the ideas surrounding fusion, this one I've always had the most difficult in imagining it working at any level of production.
The kid in me says this was/is the coolest option.
Regardless of outcome, I'm glad we were able to test the idea.
- pram 4y agoIIRC it seems impractical because it was intended for nuclear weapons research or something like that. It's a military boondoggle.
- RF_Savage 4y agoYep. It's an alternative to nuclear tests to see how the physics work in real life. Sometimes it's just nice to have something to compare your simulation results to.
- adastra22 4y agoAlso if you wanted to make really small fission bombs—like hand grenade sized—I would guess this is how you’d go around doing it.
- ncmncm 4y agoYou may guess that if you like, but it is physically impossible in this universe.
- adastra22 4y agoProject Orion used fission bombs "the size of a soda can" to power its propulsion. Designing such bombs was a big part of the military aspect of the project and how it got government funding. Now the results are still classified, of course, but it appears they were successful from a design angle. At least the scientists involved seem to think it was possible. This source gives an estimate that a 1 kg fissile mass plutonium can yield about 100 tonnes of explosive power, which is a sphere of plutonium about 2 inches in diameter: http://nuclearweaponarchive.org/Nwfaq/Nfaq4-2.html http://nuclearweaponarchive.org/Nwfaq/Nfaq4-2.html In principle there isn't really a limit to how small you can make it, just with decreasing efficiency and (with traditional implosive designs) a higher detinator-to-fissile material ratio. Things like laser implosion remove this design constraint, however, and would let you consider things like millimeter-sized pellets.
- ncmncm 4y ago1 kg is the amount of fissile material, but it needs quite a lot of high explosive around it. The file you linked says 16kg, and 28 cm by 30 cm. I suspect the soda-can sized charges you recall were conventional explosives for the small, non-nuke prototype they tried out.
- pfdietz 4y agoProject Orion did not use fission bombs the size of a soda can. It may have used bombs whose CORE was the size of a soda can, but to get that to explode requires much more high explosive (than in a typical nuclear weapon) to implode it more aggressively. That's fine, as the mass of all that high explosive acts as reaction mass.
- ISL 4y agoExperiment is the arbiter of truth -- being able to verify that aging fissile materials continue to function as-expected is very important. It really matters that nuclear weapons go bang when you want, but not when you don't. An example of why one needs to care about such things in stockpile stewardship -- plutonium's own radioactivity means that helium is effectively being born within the crystal lattice, causing damage, distortion, and swelling. It isn't a guarantee that a bomb that worked 50 years ago will work today. https://www.osti.gov/servlets/purl/1241955 https://www.osti.gov/servlets/purl/1241955
- 4pkjai 4y agoI’m actually okay with nuclear weapons not working when someone wants them to
- aplummer 4y agoAre you ok with them working when someone doesn’t want them to though?
- labster 4y agoOnly if they’re on Russian military bases.
- geysersam 4y agoDo you need fusion plasma simulation to achieve that? Don't think so.
- JumpCrisscross 4y ago> Do you need fusion plasma simulation to achieve that? Don't think so. Would you prefer to know? Or go off a hunch?
- geysersam 4y agoI'll admit it's just a hunch telling me you don't actually need experiments on extremely high temperature plasma to prevent a reaction that never naturally takes place on earth. Intuitively, simply not building a bomb seems sufficient to prevent any accidental detonations. But I'm of course no expert.
- XorNot 4y agoI wouldn't say boondoggle. The need for nuclear deterrent is back in focus, and so long as that exists then I'd much prefer we do anything but actual weapons tests.
- deleted 4y ago[deleted]
- hangonhn 4y agoWhat was the expected long term outcome of the nuclear test ban treaties? It seems unless there is some breakthrough in simulations and NIF type experiments, all countries with nuclear weapons will end up unsure of their weapons efficacy. Is this intentional? Is the hoped for outcome that no one has nuclear weapons they are sure will work and thus effectively disarming them? If not, are facilities like NIF what was envisioned by all the countries who have nuclear weapons? Thanks.
- lovemenot 4y agoI cannot speak for the people responsible for drafting those treaties, but it appears to have been a timely effort to apply multi-lateral pressure against proliferation. Put another way: for some nations to pull up the ladder. Not long-term thinking perhaps, but medium term at least. In the longer term, who could have known then or even cared how to maintain the transition to a no-test regime? What the treaties' drafters might have been thinking is now moot. Those people are long gone, it's your problem now.
- pjc50 4y agoThis is a serious albatross round the neck of nuclear technologies; if they're dual-use, they'll get lots of funding, making them look expensive, while the true purpose and feature set is obscured, making them look nonsensical.
- mavhc 4y agoThat's why we got the nuclear reactors we have today, the ones that can make nuclear weapon material
- JumpCrisscross 4y ago> why we got the nuclear reactors we have today, the ones that can make nuclear weapon material No, we got ones designed to work in nuclear submarines [1]. Civil reactors don’t make weapons-grade anything. [1] https://www.sciencedirect.com/science/article/pii/0301421584900260 https://www.sciencedirect.com/science/article/pii/0301421584...
- etrautmann 4y agoIt does seem like fusion research based on tokamak or stellerator designs will yield usable power first.
- kersplody 4y agoAnd even then, we are decades away from a commercial design due to the large number of engineering challenges needing to be solved. The next major milestone is getting a plasma gain of > 5, where helium-4 interactions become the dominant source of heating and dramatically change the behavior of the plasma. This has been simulated but never experimentally archived. Hopefully ITER will achieve this by 2030. Keep in mind that continuous operation with a Q plasma gain of at least 75 will be required for a commercially viable reactor. ITER will be lucky to hit 15 with upgrades through 2040.
- ncmncm 4y agoIn other words, there will be no commercial design, ever.
- binbag 4y agoNo, that is not the right conclusion.
- ncmncm 4y agoExcept, it is. Fusion would necessarily be a lot more expensive than fission. But fission is itself not competitive, and gets less so with each passing day. So, the longer it takes before fusion is actually, technically possible, the less value there is in it.
- crubier 4y agoWhy do you think that Fusion would necessarily be a lot more expensive than fission? I don’t see any reason to believe this long term
- TomMasz 4y agoThe University of Rochester's Laboratory for Laser Energetics was working on laser fusion back in the late 70s. Despite multiple upgrades, they never achieved the goal, eventually outgrew the facility and the DoE moved on to the NIF. It really underscores how difficult laser fusion is and how important it must be to merit pouring all that money into.
- jinto36 4y agoThe LLE at least wasn't a single purpose build-abandon-dismantle project, and still operates for research. https://en.wikipedia.org/wiki/Laboratory_for_Laser_Energetics https://en.wikipedia.org/wiki/Laboratory_for_Laser_Energetic...