Why are nukes considered hard to build?

[beowulff]

@Stranger_On_A_Train

Given your here demonstrated ignorance of manufacturing, the design process, mechanical and electrical engineering, and nuclear physics, what makes you believe that you have any standing to authoritatively dismiss answers to your question as “bullshit”?

A VLSI microchip is indeed a complicated part…but it is one single component, and not build to the reliability requirements or critical tolerances of the components of a nuclear weapon. It is accepted by semiconductor manufacturers that a certain number of chips will be defective, and most of those will be caught in testing and disposed of. But many of the critical components of a nuclear device (explosive lenses, x-ray reflectors, initiators, et cetera) have tighter mechanical tolerances than anything except very high end optics and timing requirements that are measured in tens of nanoseconds. Most of these components can only be inspected, not functionally tested before use (and of course cannot be tested in a “full up” configuration) and yet are expected to operate at three sigma or better reliability after being subjected to acceleration, shock, and vibration requirements that would destroy pretty much any commercial electronic or mechanical hardware.

Stranger

OK, this is ridiculous.
Comparing this difficulty of manufacturing a VLSI device and an atomic bomb is like comparing which is “better” - a computer or a camera.

Clearly, it’s impossible to make a current VLSI device without an entire 50 year old industry creating the tools, chemicals and equipment necessary. That said, once you have that enormous infrastructure, making a single chip is not that difficult.

Making a modern atomic device - one which is compact and efficient - might be equally daunting, but creating a crude bomb is a different story. Even N. Korea (one of the most low-tech countries on the planet) was able to do it, albeit one with a very low yield (more of a fizzle). So, one needs to define the parameters - if the goal is to create a Hiroshima-type bomb, and one has a supply of HEU, then it’s not a difficult task. Making a modern fusion weapon is clearly more difficult.

Back to the VLSI vs A-bomb comparison: In 1943, if the government had a separate project to duplicate a Core Duo chip (brought back from the future) running in parallel with the Manhattan project, the A-Bomb would finish first. There is simply too much technology required that didn’t exist back then - and also too much knowledge that we didn’t have.

[billfish678]

@beowulff

Making a modern atomic device - one which is compact and efficient - might be equally daunting, but creating a crude bomb is a different story. Even N. Korea (one of the most low-tech countries on the planet) was able to do it, albeit one with a very low yield (more of a fizzle). So, one needs to define the parameters - if the goal is to create a Hiroshima-type bomb, and one has a supply of HEU, then it’s not a difficult task. .

A WHOLE country was able to make one bomb that sorta maybe worked.

Even a dung hole like north korea is gonna have way more resources than a terrorist group, or even a darn large terrorist group.

Isn’t North Korea doing pretty good on the missile/rocket front? I don’t see terrorist making any big rockets or missiles either (nit pickers, note the word big).

[Stranger_On_A_Train]

@beowulff

Making a modern atomic device - one which is compact and efficient - might be equally daunting, but creating a crude bomb is a different story. Even N. Korea (one of the most low-tech countries on the planet) was able to do it, albeit one with a very low yield (more of a fizzle). So, one needs to define the parameters - if the goal is to create a Hiroshima-type bomb, and one has a supply of HEU, then it’s not a difficult task. Making a modern fusion weapon is clearly more difficult.

The North Korean device, if it was genuine at all (about which there is much doubt), was an utter fizzle with about 1kT of yield, and was almost certainly nonportable. Similarly, the first fission devices were barely deliverable, requiring modified B-29s. Any weapon usable in modern conflict would either need to be compact enough to fit in the payload envelope of a missile or covertly transported (i.e. capable of fitting in a panel truck). A gun-type device might barely fit in the latter, but would require enriched uranium. An implosion weapon would require precisely designed and machined explosive lenses, highly precise krytron switches and exploding bridgewire detonators, and a host of other innovations that require engineering expertise and a broad technological base.

Of course, some of these components, while export controlled, can now be procured commercially, and the engineering expertise for the specifics of nuclear weapon design is available from not only the former Soviet Union but a number of other nuclear-capable states (word is that China is providing some guidance to Iran and perhaps other nations). The equipment necessary to precisely machine the implosion shell and explosive lenses is essentially the same used to produce aspheric lenses. So while I agree with Crafter_Man that a nuclear device–even one of mid-Sixties vintage–is one of the most highly engineering devices on the planet, the design can be reproduced by a group with sufficient fiscal and manufacturing resources (i.e. an industrial nation or large corporation). The real holdup is acquiring or producing the fissile material suitable for weapon use. This is beyond the means of a terrorist group or private individual.

Stranger