Nuclear Fuel How-To 335
ATMosby writes "The BBC has an article that pretty much sums up everything you might need to know if you wanted to refine nuclear fuel and build some atomic weapons." From the article: "Uranium is the basic raw material of both civilian and military nuclear programmes. It is extracted from either open-cast pits or by underground mining. Although uranium occurs naturally all over the world, only a small fraction is found in concentrated ores. When certain atoms of uranium are split in a chain reaction, energy is released. This process is called nuclear fission."
Not Even Close (Score:5, Informative)
Sorry, but that site isn't even close to "everything you might need to know" about building a Bomb. That's more like the 5 minute capsule summary. If you really want to know everything about building a Bomb but don't want to get a security clearance, the best place to look is Carey Sublette's Nuclear Weapon Archive [nuclearweaponarchive.org]. It's amazing just how much non-classified information it contains.
Re:So? (Score:1, Informative)
I wonder how many of those will be our beloved chimp for president.
yeah yeah, mod me flamebait
Re:And while we're at it . . . (Score:4, Informative)
Re:Enrichment in USA? (Score:2, Informative)
You Forgot (Score:4, Informative)
The Curve of Binding Energy (Score:2, Informative)
Way short of "everything"! (Score:4, Informative)
I guess the slashdot editor thought it was a slow news day or something....
Re:Fission? No kidding! (Score:2, Informative)
Only U-233 or U-235 is useful for fission reactions. While U-238 can fission, it requires at least 5 MeV of kinetic energy from an incident neutron, while U-233 and U-235 require no energy. This makes U-238 fairly useless for fission except in the case where plutonium is made (U-238 + n -> (U-239)* -> Np-239 -> Pu-239). Pu-239 requires no energy to fission (and this is general of all heavy nuclides with odd atomic masses).
U-235 is 0.65% naturally occuring, and U-238 is 99.35% naturally occuring. In order to make a reactor undergo a self-sustaining fission reaction, the concentration of U-235 in increased (enriched). This has to be done for reactors and bombs (though there are methods to make a self-sustaining reaction with natural fuel--very large reactors). Since U-235 requires no energy from the neutron to undergo fission, a slow neutron that spends more time passing by the nucleus will cause fission to occur more often. This is why nuclear reactors are moderated (typically with water, heavy water, or graphite).
If a nuclear bomb were moderated, the time to moderate (slow down the neutron to thermal energies) would allow heat transfer to occur. This would expand the bomb and destroy its geometry bringing the fission reaction to a halt. For this reason, nuclear bombs are designed to operate on fast fission reactions. This is also why a nuclear reactor cannot explode like a nuclear bomb.
You want fusion? You got it! (Score:3, Informative)
"Good news, everyone!"
- Professor Hubert Farnsworth
Farnsworth Fusor [rexresearch.com]. More on Wikipedia [wikipedia.org].
Buildable and safely operable by any grad student. A non-fusing version (using only hydrogen) that serves as a proof-of-concept could be built and safely demonstrated by a group of bright, mechanically-inclined, and well-equipped high school student.
If, by "working", you mean "produces more energy than it takes to operate", the Farnsworth Fusor doesn't work. If, however, you mean "produces a neutron flux whose presence can only be explained by fusion", it works just fine.
Detailed reads... (Score:3, Informative)
That book inspired...
"Mushroom" by John Aristotle Philips about his paper at Princeton describing how to build a bomb. A student of Freeman Dyson, he got far more info than he ever dreamed he could get. The very impressive paper saved some less than stellar grades, and generated quite a buzz, more than a few cloaky phone calls and IIRC the paper got classified by the gummint.
Re:So? (Score:5, Informative)
Such capacitors and explosives are within the reach of a state like Iran (and Iraq claimed to have produced them before the first Gulf War), Krytrons, however, use beta from Ni-63 to help keep the gas in them ionized (to allow for a faster arc discharge), so they take more effort.
Try the nuke faq & friends (Score:3, Informative)
Now we need to enrich the stuff first. These guys http://www.urenco.com/ [urenco.com] do it for a living and have a few nifty articles on centrifuges.
We also need a suitable boiler to make the good stuff(tm). My personal favorite is the Canadian (take that you pacifists) Candu design http://www.nuclearfaq.ca/ [nuclearfaq.ca].
This should get you in the WMD business in no time. Now don't try this at home unless you've got your own TV-show...
Re:Errors I noticed (Score:3, Informative)
No, that's about right. Standard commercial PWR/BWR reactors use 3-5% enrichment; CANDU heavy water reactors can use lower enrichment. Research (and military?) reactors tend to use higher enrichments-- 20-90%. However, the NRC has been strongly encouraging universities to recalculate the load geometries to rely on fuel at the lower end of that range to limit the amount of highly enriched uranium in non-military facilities. The school I studied Nuclear Engineering at downgraded from 95% enriched to 19.9% enriched in 1992 or so.
-The gun and implosion types of bombs aren't tied to the fissile type. You could use either type with either plutonium or uranium.
Actually, I recall that because of the neutron energy profile from fission, Pu-gun type bombs do not work well-- you tend to get only partial fission before it blows apart.
Re:So? (Score:4, Informative)
Re:Only in America... (Score:3, Informative)
It is idiotic to believe that Iraq technology remained static for 10 years, and it is rather naive to believe that with that length of time to aquire material with the illbegotten oil-for-food revenue, that he didn't already have the equipment within his country to refine whatever uranium he was able to import. But this is America, where we allow people to believe whatever they want to believe...
Apparently you think reality is idiotic. Suit yourself.
Iraq Survey Group (ISG) discovered further evidence of the maturity and significance of the pre-1991 Iraqi Nuclear Program but found that Iraqs ability to reconstitute a nuclear weapons program progressively decayed after that date.
Saddam Husayn ended the nuclear program in 1991 following the Gulf war. ISG found no evidence to suggest concerted efforts to restart the program.
Although Saddam clearly assigned a high value to the nuclear progress and talent that had been developed up to the 1991 war, the program ended and the intellectual capital decayed in the succeeding years.
They go on to talk about how Iraq wanted to retain its knowlegable people in case the sanctions were ever lifted, but even its knowlege base eroded.
Note that the ISG had every motive to *overstate* the case (and its head was ardently pro-war). I've seen several reputable groups contest some of the measly "intent" evidence that they provide for the various investigated programs. If you want to discuss this more, we should probably take it off slashdot, or we'll get too off topic; the issue is how easy nuclear weapons are to make.
Re:So? (Score:3, Informative)
As for "bias", do you have an actual contradiction of the facts? Which "unbiased" source do you get your facts from? When you say "CBS", I expect you're referring to their simulated memos story last year, the facts of which were corroborated by the secretary who wrote the actual memos? And with "Newsweek", is that the story last week of Guantanamo prisoner abuse by Koran desecration, which is further corroborated by Pentagon reports going back to at latest 2002? Or are you referring to all the stories those outlets published, including the NY Times, promoting the Bush/Rumsfeld stories of Iraqi WMD, sending us to war in Iraq? All based on the uncorroborated "intelligence" of then-anonymous sources, revealed to be alternately the liar called "Screwball", or Chalabi, the Iranian agent?
The Los Alamos Primer (Score:2, Informative)
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The BBC has an article that pretty much sums up everything you might need to know if you wanted to refine nuclear fuel and build some atomic weapons.
Should read "...explains nothing of what you might need to know..."
Re:So? (Score:2, Informative)
Lord, I hope not. It's not going to go "boom", it's going to get REALLY hot and burn through a few things. Anybody standing near by would be wise to back off.
tell me why they need a beryllium source, vice using intrinsic neutrons from spontaneous fission
Because nuclear devices are dangerous? Gun type devices are no longer used in most applications because they're far too easy to detonate. Any accidental detonation of the internal munitions could result in the device being triggered. As a result, nuclear scientists prefer to have a controllable nuetron source for safety. i.e. A neutron source "trigger".
Why is a reflector needed if the bomb is designed to burn through from the center out?
Are we talking implosion or H-Bomb? The reflector on H-Bombs is a bit trickier. It's designed to temporarily withstand the power of the atomic detonation in order to compress the dueterium/lithium into a fusion event. The shaping of the reflector is EXTREMELY important to the success of the fusion event. That's part of the reason why H-Bombs are so tricky. (Even more so than an implosion weapon.)
On implosion weapons, the reflectors are designed to direct the charges inward toward the plutonium core. Without this outer shell, the bomb would fizzle. (This fact was used by some movie, who's name I no longer remember, to disable the "backpack nuke" by prying a plate free from the bomb.)
Reflectors are also used to help maintain the materials in a subcritical state.
What fraction of the fuel is actually burned?
The goal is "as much as possible", although the performance of weapons rarely reaches that degree. Off hand, I don't remember how much is usually burned, but I believe it's a fairly low amount.
Why are the specific energies of high energy neutrons released from fission more important than the average?
Ite all comes down to cross-section and capture ratios. Unlike the model often shown to the public, the nucleus of an atom is not directly "smashed" apart. The neutrons are instead captured by the atom. This destablizes the atom and causes it to split. Slower moving neutrons are more easily captured, and thus tend to be desirable in a reaction. However, since high speed neutrons are more common, they must be slowed down with some form of moderator. As I understand it, this is accomplished in bombs by making the material into a paste. Fast breeder reactors use these fast neutrons directly to create plutonium.
How is the fuel orientated to minimize the effect of gammas heating the fuel?
Off the top of my head? Dunno. Google has answers to this, but I believe it's something that can be easily found through experimentation.
Did I pass? Hopefully I understood all the questions well enough.
Seriously, are you suggesting that even with access to the basic nuclear information, plus the publically available equations, nuclear weapons are too difficult for most counties to build? Because the sheer number of counties who have them would seem to suggest otherwise.
Re:So? (Score:4, Informative)
64,1kg of HEU (80% average enrichment). The bullet was a cyllindrical stack of U-235 rings each 10cm wide and 16 cm long, containing 25.6kg total (6 rings). The stack was backed by a tungsten carbide disk and steel backplate, all within a 1/16th inch thick steel can to form a complete projectile. The target was a hollow cylinder 16 cm long and wide, weighing 38.4 kg. It was fabricated of two rings that were inserted into the bomb separately. The bullet contained 89% enriched HEU; the target the rest of the uranium.
The bullet was encased in a boron "safety sabot" to help prevent accidents; there was also a plug on the target. When fired, these would strip off. You could easily omit such safety features if you were unconcerned with safety.
The tamper assembly was thick tungsten carbide surrounded by a steel forging, 60cm wide, with a combined mass of 2300kg. A hole was bored in the forging to insert the tamper and the target; the hole was threaded to allow secure attachment of the gun. At the back of the hole, past the target, there was space for one or more polonium initiators (I can dig up several polonium initiator designs for you if you would like; Little Boy used four very inefficient ones - the bomb would have worked without an initiator, and the decision to use an initiator wasn't even established till March 1945).
The gun was a 3" antiaircraft gun, 6.5" wide, 6 feet long, bored out to 4", weighing 450kg, with a breech block of 34kg. Standard cordite propellant was used, to achieve a 300m/s (slow) velocity. Of course, given how unsafe the Little Boy design was, even dropping the device hard enough could have given some significant (even full) yield.
The complete weapon was 126 inches long, 28 inches in diameter, and 8900 pounds. Need a diagram?
Note that being "exact" doesn't matter; Little Boy was a very conservative design, and allows for very large tolerances of error. The worst you'll get is a lower yield.
P.S. - I found this information in 5 minutes. Imagine someone actually dedicated to the cause of building a nuclear weapon...