I don’t believe this is correct. The reaction mass of a typical nuclear weapon is radioactive, but not dangerously so. The plutonium core of Fat Man could by handled safely with bare hands.
Somehow I don’t think “North Korea is trying to build a working automobile.” would result in questioning whether or not they could manage it.
Perhaps the uncertainty is more along the lines of “Could they manage to build one, secretly?”
Yes. See Plutonium - Wikipedia.
The material on it’s own is not too dangerous, but you need to ensure that you don’t let enough accumulate to allow criticality. The Manhatten project had two Criticality accidents , one when a tungsten carbide brick dropped on to a subcritical mass and started reflecting neutrons back into the mass, causing criticality. The scientist concerned pushed the brick off and died from radiation sickness. The second was as a scientist was showing “twisting the dragons tail” - pushing two subcritical masses of plutonium together to monitor neutron density. He slipped, pushed the masses together and the whole thing went critical. He tore the masses apart with his bare hands, saving everyone else in the room at the expense of a lethal dose of radiation. He took 10 days to die.
This is what makes processing fissile material such a problem. Plus most of the useful compounds you can make with these metals are toxic, corrosive and generally nasty (Uranium Hexaflouride being one)
Simon
Yes, certainly there are risks involved in handling bomb-making materials. But my post was intended to counter this post by ralph124c that implies that this stuff is lethal on contact:
With some fairly basic safety precautions (don’t store all your plutonium in one room, for example) a nuclear bomb can be constructed with NO loss in life.
To be precise, these accidents occurred at Los Alamos. The first occurred on August 21, 1945, the other in May 1946. You could argue that they occurred as part of the Manhattan Project, but no fatal accidents occurred during bomb development itself. Otto Frisch, who first explained why the uranium nucleus splits (along with his aunt, Lise Meitner) had an accident while pulling the dragon’s tail with plutonium, but managed to survive.
The movie Fat Man and Little Boy has a fictitious scientist (played by John Cusack) die from radiation poisoning before the bombs are dropped. Dramatic, but clearly a conflation of separate incidents and people.
I’ve read a great deal about the history, engineering, and physics/science of atomic weapons. Based on what I’ve seen (and haven’t seen), here are the issues:
[ol]
[li]The key parts of bomb technology are a closely guarded secret. Nothing you can find in a book gives enough detail for a non-expert to use.[/li][li]Therefore, you need people who have been trained in atomic bomb building.[/li][li]Those people cost money. You either have to buy them from an existing power, or give them tons of money to set up labs to do experiments, or both.[/li][li]At a minimum, the labs need a cyclotron and a large supply of highly purified uranium 235 or plutonium.[/li][li]U235 is incredibly expensive to isolate. During WWII, the US spent $1 billion dollars and two years doing it (the money is in 1945 dollars). You either build multiple cyclotrons, or devices to separate U235 using uranium hexafluoride, or huge centrifuges. The cyclotrons take tons of electricity. The separation devices take tons of energy and ways of handling “hex”, a noxious stuff that eats through just about everything except glass and teflon. The centrifuges take electricity and patience.[/li][li]You can also use Pu, but for that you need a reactor. Also costs tons of money, plus the technology to isolate Pu from all the other, highly radioactive stuff.[/li][li]If you’re lucky to get through to this point, you can make a bomb either from pure U235 or pure Pu. Unless you have a lot of secret knowledge, this bomb is going to be very inefficient, which means it will be huge. You’re gonna need more than a suitcase to transport it.[/li][li]Meanwhile, you have to hope that you don’t accidentally kill everyone.[/li][li]And finally, you need the initiator. This is a gadget that produces a flood of neutrons sufficient to fission the critical mass before it melts from its own heat and/or fizzles in an explosion that isn’t much better than you’d get from the equivalent weight of regular explosives. Rhodes, in his books, makes the point that initiator design is still highly secret.[/li][/ol]
In short, until recently the countries that had the bomb were high-tech “Western” countries that also wanted to spend gobs of money on bombs. Countries like Italy and the Netherlands probably have the technology, but figure that having atomic bombs is not worth the hassle.
The more recent entries in the atomic “bum” game make me more nervous: China, India, Pakistan, South Africa, and even Israel. The US built the bomb because we were worried about the Germans. Then (and you might well call us stupid) we kept building them because we thought we could control the USSR. They built them to keep even with us. Since then, I really think it’s been a matter of “national prestige”. The British built one because they could and because they still had a vision of the “British Empire.” In fairness, the British were way ahead of us in research and technology.
The French built one because the French have this need to prove that France can do anything anyone else can. Go figure.
The Chinese built one for the same reason. I am guessing that India built one because China built one, and too because they wanted national prestige. The Israelis built one probably because somebody told them they weren’t allowed to build one. They make the argument that it’s to preserve their security. I’m a supporter of Israel, but bums are dangerous…
Why the South Africans built one is beyond me. There were still some Afrikaaners that thought the Boer War was still going on. Sigh.
The Pakistanis and North Koreans obviously built one to make people listen. Good. We hear you. You’re a bunch of jerks. You apparently learned nothing from our nervousness over 30 years of brinksmanship with the USSR. 
Now the Iranians are building one. We ought to have a builder’s contest instead. Everything to remain secret. You build your bomb, show it to the panel of judges, and if it passes, congratulations! You’re in the club. I equate this to what little boys do for club initiations: hold the firecracker until the fuse burns all the way down, then throw it. You blow your hand off, but you’re in the club.
[hijack]
Out of curiosity, what kinds of tolerances are we talking about w.r.t. the plutonium core and the explosive lenses? Also, what type of explosives may be used? What did the Trinity bomb use? TNT, or something more exotic? Also, when you talk about a hollow sphere, does the inside have to be machined too? If so, how is that done? Does the core need to be plated?
Thanks,
Rob
[/hijack]
Very small tolerances. The FatMan bomb (Pu implosion) required specially-designed explosive lenses cast from molten explosive, and had to be fit together with tolerances of fractions of an inch. The FatMan used two types of explosives, with different burn rates. One was Baradol; I don’t remember the other. TNT was not used.
The hollow sphere has to be machined. They build them from separate halves, using machine tools that can handle the Pu/U235 mix.
BTW, I am sure the US no longer makes a fission core that is either pure Pu or pure U235. My guess is that they use an alloy that gives them exactly the critical mass and reaction rate they desire.
The core certainly has to be plated. Both pure Pu and pure U235 are reactive, not violently so, but enough so that they’ll oxidize if exposed to air for any length of time. The Trinity Pu core was nickel-plated, but they then discovered that plating solution seeped underneath the plating. They ground down the bubbles and plated the exposed surfaces with gold.
The exact structure of a hollow-sphere core is classified. John McPhee, in The Curve of Binding Energy surmises that the initiator is suspended by wires or threads within the core. All other info is top-secret. So is anything that might help you work out exactly what a Teller-Ulam (fission-fusion-fission) thermonuclear device looks like. The basic principles are published, so you could start there and then spend millions of dollars in a high-tech laboratory to figure it out.
Note that even having such a laboratory would not get you to the level of US development. The US has relied for many years on highly sophisticated and ultra-secret simulation programs that use the results of testing and lab experiments to predict yields, etc.
If you want to worry, don’t worry about a bomb. Worry about a cloud of plutonium gas released over NYC.
As for suitcase bombs, it’s been covered elsewhere. I do remember a joke from one of Rhodes’ books. The Los Alamos scientists joked that they weren’t worried about the USSR developing a suitcase bomb, because the Russians were still struggling to develop a reliable suitcase.
Joe
And nickel, which was used for the barrier material and to plate the interiors of the pipes and tanks used in the gaseous diffusion process.
Teflon was used to lubricate the valves because grease explodes in the presence of hex.