4 ms·

I still don't understand how this stuff is so hard. The US pulled it off in a few years, in the 40s. Total cost of a few billion. The biggest issue is enrichmen

I still don't understand how this stuff is so hard. The US pulled it off in a few years, in the 40s. Total cost of a few billion. The biggest issue is enrichment, but again, they did it within that time and budget. Several other countries/physicists were on to the same idea. Even a simple gun type with a 20kton yield is enough to severely harm a city, right? So even without the complexities of implosion or thermonuclear, it seems any dedicated actor, even a private one, should be able to pull it off. Delivery systems aside; I'd guess testing ICBMs would be difficult enough by itself. What am I missing?

paulmd 11y ago
You can't disregard delivery systems, that's a major piece of the picture. Nuclear bombs are most effective when airburst. If you are going to deliver by ICBM or with a military aircraft then you need an implosion design with plutonium. You might be able to sneak it in with a civilian aircraft, or via a ship or something (obviously then you can't airburst). If you want to fully open up your delivery options, you want an implosion design with plutonium. This involves running a reactor for a couple years and reprocessing the waste. And you'll have to avoid regulatory scrutiny from the IAEA to do so (which is also true of a uranium bomb). At this point the biggest problem with building a nuke of either type is getting the material. As an experiment, some college students were asked to design a nuclear weapon back in the 70s, and they apparently got it close enough that the FBI freaked out and tried to suppress their work. It would be even easier nowadays, but refining requires a lot of energy and specialized materials (eg maraging steel) that are watched really closely, and so are the materials that would be used as feedstock.
- grkvlt 11y ago
  > some college students were asked to design a nuclear weapon Also known as the Nth Country Experiment. See https://en.wikipedia.org/wiki/Nth_Country_Experiment https://en.wikipedia.org/wiki/Nth_Country_Experiment for details, also the final report [1] is interesting. [1] http://nsarchive.gwu.edu/news/20030701/nth-country.pdf http://nsarchive.gwu.edu/news/20030701/nth-country.pdf
Animats 11y ago
Making a gun-type bomb from enriched uranium isn't that hard. Any shop capable of building an auto engine could do it. Even machining uranium isn't that hard; there's a Union Carbide tech note on that. It requires a respirator and protective gear, but not remote controlled machine tools. That's why anti-proliferation people are so concerned about enriched uranium. But enriched uranium is hard to make. The old gaseous diffusion process was incredibly inefficient - plants over a mile long to make tens of kilograms. Centrifuges have changed that. Centrifuge plants aren't all that big, about Wal-Mart sized. They're still expensive. Highly enriched uranium is only made for bomb purposes; power reactors don't need it (although some submarine reactors have used it), so it's not made without good reason. There's some concern about laser enrichment, which apparently works quite well and is seldom discussed. The US has at least one laser enrichment plant. Plutonium bombs are hard to get right. A gun bomb with plutonium will pre-detonate. It takes an implosion. Making a perfectly symmetrical implosion is hard. The explosive lenses have to be very uniform in density and accurate in dimension, while being made out of a soft plastic explosive. There are tricks to the joints where the lenses meet, some of which are still classified. Then there's the whole detonator thing, although getting the big pulse required is easier than it was 50 years ago. Plutonium is a by-product of reactor operation. Thus, there's more of it around than is really needed. The US and the former USSR made way too much (tons). But working with plutonium is a huge headache. The dust is radioactive and poisonous. The PUREX chemical process to refine it from reactor fuel rods is difficult; places which did it tend to be toxic waste sites now. Its machining properties are strange; it expands when heated but then doesn't contract fully. Plutonium bombs usually have a neutron generator to get things started, and surrounding shells to perform neutron reflection and tamping. While the general principles are well known, it takes a lot of engineering R&D to get it working right, including many non-nuclear test explosions. That's why we don't see terrorist groups making bombs from spent fuel rods.
- teh_klev 11y ago
  > Plutonium is a by-product of reactor operation. Thus, there's more of it around than is really needed. The US and the former USSR made way too much (tons). I was under the impression that there's not that much plutonium kicking about, unless it's the Russians and former USSR states that have the lion's share: http://archive.is/UleJ1#selection-2455.625-2467.68 http://archive.is/UleJ1#selection-2455.625-2467.68 (src: http://www.wired.com/2013/09/plutonium-238-problem/all/ http://www.wired.com/2013/09/plutonium-238-problem/all/) "So, we depend on plutonium-238, a fuel largely acquired as by-product of making nuclear weapons. But there’s a problem: We’ve almost run out. “We’ve got enough to last to the end of this decade. That’s it,” said Steve Johnson, a nuclear chemist at Idaho National Laboratory. And it’s not just the U.S. reserves that are in jeopardy. The entire planet’s stores are nearly depleted. The country’s scientific stockpile has dwindled to around 36 pounds." Previous HN discussion: https://news.ycombinator.com/item?id=6414717 https://news.ycombinator.com/item?id=6414717
bsder 11y ago
Creating U-235 takes a lot of work by almost all chemical/physical methods. https://www.osti.gov/opennet/manhattan-project-history/Events/1942-1945/come_through.htm https://www.osti.gov/opennet/manhattan-project-history/Event... Of course, once you can bootstrap a nuclear reactor, things get a lot easier because now you have Plutonium. Of course, Plutonium is rather toxic and working it metallurgically is problematic. Edit: Plutonium also seems to require an implosion device. Implosion engineering is quite hard.
rdl 11y ago
The only genuinely hard part is the fissile material. It would be trivial for a country like Japan to do this in days/weeks (going from materials they have to weapons); a country like, say, Sweden with less of a nuclear industry could also become a nuclear state fairly quickly. Plenty of companies or individuals could do it. The difference is -- if the US/Russia/etc. detect that someone is trying to make a nuclear weapon, all means up to an including a preemptive strike (nuclear or conventional) is on the table. Diplomatic pressure is the first step, but unless you're in a position to essentially blackmail/stalemate everyone, it would not run to completion. If, say, Nigeria were taken over by a crazed regime which wanted to make a nuclear weapon, and it didn't have either the US or Russia protecting it (or possibly China), all national means would be expended to prevent this from happening. (Stuxnet was a horrible Pandora's box opening, but IMO the US/Israelis behind it probably saved the world from a nuclear conflict, which is win/win for basically everyone. If it were a private individual or group, it would be even easier to go after them.) Theoretically, it may be possible to do "fission free fusion"; if someone can develop a reasonable, cheap, undetectable procedure for that, we are utterly fucked. The other thing which terrifies me would be laser separation/enrichment. Basically anything which could be done surreptitiously or in a widely dispersed way, vs. at a small number of detectable, centralized plants. (My money is on bioweapons destroying civilization, if not humanity, within 50 years, though, before nuclear weapons have a chance. Bioweapons are far easier to develop surreptitiously, and with very small scale initial capital requirements.)
- adventured 11y ago
  > all means up to an including a preemptive strike (nuclear or conventional) is on the table >all national means would be expended to prevent this from happening What you're saying is overly dramatic to say the least. If any of that were actually true, the US would have nuked or invaded North Korea in the mid 1990s. It was extremely well understood they were developing a nuclear weapon. We knew it for two decades. The same is true for Pakistan, we knew they had a program, why didn't the US invade / nuke / attack / subdue them in response (even afterward)? The US hardly did anything of consequence to Pakistan in response, they got a slap on the wrist and the runway to develop a hundred nuclear warheads.
caf 11y ago
The cost ($2bn in 1945 dollars) ends up being over $30bn in present-day terms, which isn't really in the reach of many private entities. Close to 1% of the total US labor force ended up working for the Manhattan Project in the period up to August '45. It was pretty big.
- hga 11y ago
  The US government also wasn't exactly paying market rates for what they bought during the war, and the Manhattan Project also had the highest priority call on materials, after the super-Mulberry we were building for the invasion of the Kanto plain in Honshu, the main island island in Japan and where Tokyo is located (look up Operation's Downfall (the general one) and Coronet for more details).

paulmd 11y ago

You can't disregard delivery systems, that's a major piece of the picture. Nuclear bombs are most effective when airburst. If you are going to deliver by ICBM or with a military aircraft then you need an implosion design with plutonium. You might be able to sneak it in with a civilian aircraft, or via a ship or something (obviously then you can't airburst). If you want to fully open up your delivery options, you want an implosion design with plutonium. This involves running a reactor for a couple years and reprocessing the waste. And you'll have to avoid regulatory scrutiny from the IAEA to do so (which is also true of a uranium bomb). At this point the biggest problem with building a nuke of either type is getting the material. As an experiment, some college students were asked to design a nuclear weapon back in the 70s, and they apparently got it close enough that the FBI freaked out and tried to suppress their work. It would be even easier nowadays, but refining requires a lot of energy and specialized materials (eg maraging steel) that are watched really closely, and so are the materials that would be used as feedstock.

grkvlt 11y ago
> some college students were asked to design a nuclear weapon Also known as the Nth Country Experiment. See https://en.wikipedia.org/wiki/Nth_Country_Experiment https://en.wikipedia.org/wiki/Nth_Country_Experiment for details, also the final report [1] is interesting. [1] http://nsarchive.gwu.edu/news/20030701/nth-country.pdf http://nsarchive.gwu.edu/news/20030701/nth-country.pdf

Animats 11y ago

Making a gun-type bomb from enriched uranium isn't that hard. Any shop capable of building an auto engine could do it. Even machining uranium isn't that hard; there's a Union Carbide tech note on that. It requires a respirator and protective gear, but not remote controlled machine tools. That's why anti-proliferation people are so concerned about enriched uranium. But enriched uranium is hard to make. The old gaseous diffusion process was incredibly inefficient - plants over a mile long to make tens of kilograms. Centrifuges have changed that. Centrifuge plants aren't all that big, about Wal-Mart sized. They're still expensive. Highly enriched uranium is only made for bomb purposes; power reactors don't need it (although some submarine reactors have used it), so it's not made without good reason. There's some concern about laser enrichment, which apparently works quite well and is seldom discussed. The US has at least one laser enrichment plant. Plutonium bombs are hard to get right. A gun bomb with plutonium will pre-detonate. It takes an implosion. Making a perfectly symmetrical implosion is hard. The explosive lenses have to be very uniform in density and accurate in dimension, while being made out of a soft plastic explosive. There are tricks to the joints where the lenses meet, some of which are still classified. Then there's the whole detonator thing, although getting the big pulse required is easier than it was 50 years ago. Plutonium is a by-product of reactor operation. Thus, there's more of it around than is really needed. The US and the former USSR made way too much (tons). But working with plutonium is a huge headache. The dust is radioactive and poisonous. The PUREX chemical process to refine it from reactor fuel rods is difficult; places which did it tend to be toxic waste sites now. Its machining properties are strange; it expands when heated but then doesn't contract fully. Plutonium bombs usually have a neutron generator to get things started, and surrounding shells to perform neutron reflection and tamping. While the general principles are well known, it takes a lot of engineering R&D to get it working right, including many non-nuclear test explosions. That's why we don't see terrorist groups making bombs from spent fuel rods.

teh_klev 11y ago
> Plutonium is a by-product of reactor operation. Thus, there's more of it around than is really needed. The US and the former USSR made way too much (tons). I was under the impression that there's not that much plutonium kicking about, unless it's the Russians and former USSR states that have the lion's share: http://archive.is/UleJ1#selection-2455.625-2467.68 http://archive.is/UleJ1#selection-2455.625-2467.68 (src: http://www.wired.com/2013/09/plutonium-238-problem/all/ http://www.wired.com/2013/09/plutonium-238-problem/all/) "So, we depend on plutonium-238, a fuel largely acquired as by-product of making nuclear weapons. But there’s a problem: We’ve almost run out. “We’ve got enough to last to the end of this decade. That’s it,” said Steve Johnson, a nuclear chemist at Idaho National Laboratory. And it’s not just the U.S. reserves that are in jeopardy. The entire planet’s stores are nearly depleted. The country’s scientific stockpile has dwindled to around 36 pounds." Previous HN discussion: https://news.ycombinator.com/item?id=6414717 https://news.ycombinator.com/item?id=6414717

bsder 11y ago

Creating U-235 takes a lot of work by almost all chemical/physical methods. https://www.osti.gov/opennet/manhattan-project-history/Events/1942-1945/come_through.htm https://www.osti.gov/opennet/manhattan-project-history/Event... Of course, once you can bootstrap a nuclear reactor, things get a lot easier because now you have Plutonium. Of course, Plutonium is rather toxic and working it metallurgically is problematic. Edit: Plutonium also seems to require an implosion device. Implosion engineering is quite hard.

rdl 11y ago

The only genuinely hard part is the fissile material. It would be trivial for a country like Japan to do this in days/weeks (going from materials they have to weapons); a country like, say, Sweden with less of a nuclear industry could also become a nuclear state fairly quickly. Plenty of companies or individuals could do it. The difference is -- if the US/Russia/etc. detect that someone is trying to make a nuclear weapon, all means up to an including a preemptive strike (nuclear or conventional) is on the table. Diplomatic pressure is the first step, but unless you're in a position to essentially blackmail/stalemate everyone, it would not run to completion. If, say, Nigeria were taken over by a crazed regime which wanted to make a nuclear weapon, and it didn't have either the US or Russia protecting it (or possibly China), all national means would be expended to prevent this from happening. (Stuxnet was a horrible Pandora's box opening, but IMO the US/Israelis behind it probably saved the world from a nuclear conflict, which is win/win for basically everyone. If it were a private individual or group, it would be even easier to go after them.) Theoretically, it may be possible to do "fission free fusion"; if someone can develop a reasonable, cheap, undetectable procedure for that, we are utterly fucked. The other thing which terrifies me would be laser separation/enrichment. Basically anything which could be done surreptitiously or in a widely dispersed way, vs. at a small number of detectable, centralized plants. (My money is on bioweapons destroying civilization, if not humanity, within 50 years, though, before nuclear weapons have a chance. Bioweapons are far easier to develop surreptitiously, and with very small scale initial capital requirements.)

adventured 11y ago
> all means up to an including a preemptive strike (nuclear or conventional) is on the table >all national means would be expended to prevent this from happening What you're saying is overly dramatic to say the least. If any of that were actually true, the US would have nuked or invaded North Korea in the mid 1990s. It was extremely well understood they were developing a nuclear weapon. We knew it for two decades. The same is true for Pakistan, we knew they had a program, why didn't the US invade / nuke / attack / subdue them in response (even afterward)? The US hardly did anything of consequence to Pakistan in response, they got a slap on the wrist and the runway to develop a hundred nuclear warheads.

caf 11y ago

The cost ($2bn in 1945 dollars) ends up being over $30bn in present-day terms, which isn't really in the reach of many private entities. Close to 1% of the total US labor force ended up working for the Manhattan Project in the period up to August '45. It was pretty big.

hga 11y ago
The US government also wasn't exactly paying market rates for what they bought during the war, and the Manhattan Project also had the highest priority call on materials, after the super-Mulberry we were building for the invasion of the Kanto plain in Honshu, the main island island in Japan and where Tokyo is located (look up Operation's Downfall (the general one) and Coronet for more details).