Hacker News Reader

Comment by alan_cx | Hacker News Reader

I might be missing a huge point here, but aren't very high precision, high end cnc machines virtually vital for the production of nuclear devices? If thats the level of machine we are talking about, I can well understand this.

View on HN

They were not 'vital' in 1945. And were not 'vital' 40 years after that. It may be convenient but far from vital.

So are computers. Should computers be shipped with mandatory GPS units that shut them down when they go into "bad guy" countries?

I don't agree with the general theme of restricting things in this way. However, to be fair, powerful computing technologies are sometimes restricted from export to certain countries. It was only fairly recently that this sort of regulation was eased a bit wrt Iran.

http://news.cnet.com/8301-1023_3-57586991-93/u.s-lifts-ban-o...

Shh! Stop giving them ideas. Before long, being amidst an Occupy Wall Street type protest will result in your laptop shutting down.

Have you not seen the paperwork that come with high end computer equipment - I helped by some Pr1me gear back in the day and along with the kit came a sheaf of paperwork explaining just how much shit you would be in if you reexported it to one of the country's on the naughty list.

That's not a bad point. I can see the desire to keep these away from certain places, but if that's the case, why geo-lock them so much? Why couldn't you allow a large region of GPS coordinates and add a mandatory blacklist of locations? Instead of solving the "problem" (stop the machines from working in Iran), the manufacturer turned this into a profit center. Blocking a company from rearranging their work floor seems a bit much.

I would guess that part of the problem is that relying entire on GPS would not be practical, considering the likelihood that many machines would be located within large warehouses or industrial buildings that block a GPS signal.

The article mentions that gyros are also used, so I suspect that the company prefers to have a defensible list of purchasers, with the confidence that this would not change without their knowledge.

Similar in results to a blacklist, but somewhat more reliable from the manufacturer's perspective.

GPS by itself could be easily spoofed. It's a well-known protocol that is broadcast in the clear.

Modern, fancy nuclear devices, perhaps.

But I suspect that the machining to make something that goes boom is probably well within the means of a traditional machine shop.

Actually, my understanding is that the tolerances, at least for implosion-type weapons, are extreme and required scientific advances to achieve during the Manhattan Project, not to mention the fact that Uranium and Plutonium are much, much denser than any material that would be encountered at a typical shop.

Ah yes, that was another point in the book. Its took them ages to very slowly and precisely machine the material to a very high tolerance. IIRC, the tools didn't last long at all.

Cards on table...

My main knowledge of , er, building nukes (hello GCHQ) comes from the widely accepted to be well researched book by Tom Clancy, The Sum of All Fears. Apparently it is a very good account of how to make a nuke, but with some very crucial details missed out of changed. And, yeah, very fair enough.

What I got from reading that book only once was that, even for a nuke bomb made from the remnants of an old nuke missile ("hacked, if you will") was that a fair amount of very, very high precision machining was necessary. In the plot, it was a massive big deal to get the right machine tools (Swiss, IIRC), and that alone was a massive task. Not just getting the tools, but getting one person with the skills necessary to do that machining.

Now, could well be the case the the precision needed to make a nuke is much higher than the machines mentioned in the article, don't know. Also could be that in that book plot, they needed very high precision to maximise the yield from old material, and of course perhaps a relatively small amount of material. So, its quite possible my point is redundant.

Another thought. Might be that the machine tools in the book were manual, not CNC. Might be that you needed high precision tools and a highly skilled machinist. So two things to required to make the bomb. Might be that now you dont need the skills because high spec CNC enabled less skilled people to do the work. So, that might be even more reason to keep tabs on the machines.

And thats all I know(, or think I know). Im merely suggesting that this might be a good reason to bolt down high precision CNC machines tools.

The detonation apparatus for a fission bomb is trivial. Students can build them, and they have. Someone even brought one onto the floor of Congress to prove a point in a committee hearing on nuclear proliferation. Without the uranium, of course.

Achieving fusion is tricky and requires extremely precise machining (you basically have to build a perfect sphere). The detonation condition for fission is simply a critical mass of U-235 sitting in one place. Typical design is two piles of uranium in a container, separated by a lead wall. TNT blows the wall and drives the piles into each other; nature does the rest.

Fortunately, enriching uranium is a massive (expensive, time-consuming, and not particularly subtle) operation. Really only within the reach of states. But if you got your hands on weapons-grade uranium, the bomb part wouldn't be hard at all.

Source: my high school chem teacher.

"Typical design is two piles of uranium in a container, separated by a lead wall."

Even the simplest nuclear weapons design is slightly more involved than that - the gun-based design used in the "Little Boy" bomb that destroyed Hiroshima used an actual section of gun barrel to fire one chunk of uranium at the other.

More modern designs of fission bombs, either as stand-alone weapons or as primaries for H-bombs, are actually pretty complex - balancing the need to be efficient (plutonium and U235 are rather expensive), light, robust and safe is a non-trivial problem.

The W88 warhead with its prolate (egg-shaped) primary is the most advanced nuclear weapon that has had design details leaked to the public:

http://en.wikipedia.org/wiki/W88

In the case of the Sum of All Fears the terrorists were trying to build a strategic level bomb (i.e. hundreds of kt) using a fusion boosted fission design to try and start a global war - so they were actually trying to build something relatively advanced, not just a basic bomb.

Edit: Another real problem with working with plutonium is that it is fairly nasty stuff to deal with - I can recommend the book "Making a Real Killing: Rocky Flats and the Nuclear West" to get some idea of the horrors of working with plutonium on an industrial scale:

http://www.amazon.com/Making-Real-Killing-Rocky-Nuclear/dp/0...

True, but the prototypical modern terrorist doesn't need robust or safe, nor does he need to get the device airborne. He just needs a detonation, which (once you have the uranium) doesn't require sophisticated machining.

That's a good point, though I am not sure how effective these sort of measures would be against an adversary technologically capable enough to be designing precision nuclear weapons (or against an adversary with enough money to acquire the necessary material).

Not really, but they'd certainly make it easier.

However, high precision CNC machines are useful in a wide range of high-tech applications, and keeping Iran poorer makes the rate at which they can gain power slower. Harder to make smaller or more powerful jet engines, harder to make centrifuges for nuclear enrichment, harder to make more advanced computing fabs - and so on.

If you can make it more expensive for Iran to advance to a particular level, then your investment in your own technologies puts you further ahead when they get there. If you get to cheap anti-ICBM defences first, then the threat of nukes is somewhat neutered, for instance. If you get to jet engines small enough for high performance combat drones first, then the threat of whatever airforce Iran can muster matters less. And so on.

I would imagine that the reasoning behind such embargoes covers more grounds than just whether you can stop someone getting nukes or the like ever and has more to do with balance of power in general.

No, the first functioning nuclear explosives were built in 1945, before the transistor even existed.

CNC machines don't vaporize cities; people with CNC machines vaporize cities.

Or they make submarine propellers or something... you get the idea!

The US exports exactly how many centrifuges to Iran? Or Nukes don't vaporise cities, the man with his finger on the button does?

So, free trade with Iran and let everyone have nice safe nukes, right?

Oddly enough, that would be my position, but for very, very different reasons.

Reply on news.ycombinator.com