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[*] posted on 11-4-2006 at 21:12
Nuclear Reactions


I am more and more concerned about how nuclear power is provided to the public.

I am on a loss why it is told that centrifuges and shit are necessary to build a working reactor or bomb.

It is known that uranium enriched to about 30% with sufficient shielding is to make a bomb.

30% is about natural in certain ores.

Am I on a loss here?
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[*] posted on 11-4-2006 at 21:52


Rich uranium ores could contain ~30% elemental uranium, but I don't think there are any natural materials that contain U-235 enriched to ~30%. Without enrichment, you can make a self-sustaining reaction for power production or transmutation, but it needs to use a very good neutron moderator like high-purity graphite or heavy water. If the uranium is isotopically enriched by centrifuge or otherwise then it can be used in a light water reactor. I don't think it is at all possible to make a nuclear bomb from uranium without heavy isotopic enrichment. It's possible to split natural uranium with fast neutrons for a great release of energy, but the only neutron source intense enough to make a usable weapon that way is a thermonuclear explosion, which itself needs a fission trigger. So it is possible to build a reactor without uranium enrichment, but it is less common. It is not possible to make a uranium fission weapon without isotopic enrichment.

[Edited on 4-12-2006 by Polverone]




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[*] posted on 12-4-2006 at 02:08


The U235 which is the lighter explosive izotope it's always found in a 0.7% percentage, no matter what ore from what region of the world.
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[*] posted on 12-4-2006 at 03:27


Disposal of nuclear wastes remains a rather troubling problem, centrifuge separation remains the only feasilbe process for commercial production of enriched fissile material. Some links with some facts and opinions that may be helpful:

http://www.world-nuclear.org/info/printable_information_pape...

http://www.uic.com.au/nip33.htm

http://www.llnl.gov/str/Hargrove.html

http://www.llnl.gov/str/Strauch.html

http://www.fas.org/nuke/intro/nuke/uranium.htm

http://www.fas.org/RLG/v095pcwp.htm

http://www.earthisland.org/yggdrasil/uep11_01.html

http://www.nti.org/db/nisprofs/russia/exports/rusiran/nukede...

http://www.nti.org/db/china/uenrich.htm

http://www.francenuc.org/en_chn/enrichment_e.htm

http://www.absoluteastronomy.com/ref/nuclear_fuel_cycle

http://www.absoluteastronomy.com/ref/isotope_separation

http://nuclearweaponarchive.org/Israel/

http://nuclearweaponarchive.org/Nwfaq/Nfaq6.html

http://www.photonics.com/content/spectra/1997/October/tech/7...

http://www.ornl.gov/info/ornlreview/v37_1_04/article_04.shtm...

http://cns.miis.edu/pubs/week/041109.htm

http://www.wise-uranium.org/eproj.html

:P

[Edited on 12-4-2006 by leu]

[Edited on 12-4-2006 by leu]




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[*] posted on 12-4-2006 at 04:42


Natural uranium like the other elements from which we are composed is the leftovers of a supernova. Hence metorites etc. have the same ratio as found on earth. The only natural places on earth where the isotope ratio is different are the natural reactors such as in Gabon.

The enrichment necessary to sustain a chain reaction depends on the moderator used: with a graphite or heavy water moderator, natural unenriched uranium can be used (as used by Fermi in the first man-made reactor and Chernobyl). With a water moderator, the isotope ratio needs to be several percent as it was a 1.5 billion years ago, allowing natural reactors to occur in uranium deposits.

Uranium enriched to 3.5% for use in water moderated reactors is not weapons grade. Weapons grade is at least 85% 235U, but 20% is sufficient though very inefficient for a bomb.




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[*] posted on 12-4-2006 at 06:24


I want a few tons of natural uranium (in whatever form, oxide pellets would be fine), and about as much graphite. And some boron or cadmium. It would be fun to make backyard plutonium.

Tim




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[*] posted on 12-4-2006 at 07:24


Ofcourse the nuclear weapons threat is bull. Unless you believe that the US will supply India with special centrifuges that can in no way be used for malevolent enrichment. But you would still have to answer the question why they wouldn't be selling those to Iran.

Anyway, the whole debate is pointless as Iran will be attacked by the neocons anyhow, nothing is going to stop that. Iraqi and Irani citizens, will, as usual, pay the price.

Meanwhile oil prices skyrocket which means more money for the Bush clique. Smart, isn't it?




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[*] posted on 12-4-2006 at 15:01


Yeah vulture, Iran is years away from enriching enough uranium to make a practical bomb. Even if it had a bomb, it would be more of a defence against US and Israeli aggression than an offensive thing. One way to stop them building such a weapon would be to be nice to them and stop threatening them.



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[*] posted on 12-4-2006 at 15:25


Yeah, but they've been hate-mongering for *decades*. I mean, just about everyone is Muslim, and just about everyone goes to a mosque where several times daily the people are told to hate Americans. At least, that's what they said on the History Channel, a rather partial channel as television goes. Whether or not you believe it, hearing it that much is going to warp your mind.

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[*] posted on 12-4-2006 at 18:26


Quote:
Originally posted by MargaretThatcher
Yeah vulture, Iran is years away from enriching enough uranium to make a practical bomb. Even if it had a bomb, it would be more of a defence against US and Israeli aggression than an offensive thing. One way to stop them building such a weapon would be to be nice to them and stop threatening them.


It is for certain that Iran already has a nuclear weapon and its inert remains are guaranteed to be found as evidence amidst the rubble from the preemptive strike which will be necessitated to prevent its use ....just in the nick of time , you see . So it was never a matter of preventing them from developing it , but from using it .....that thing they should have never even thought about . After all we are the thought police , so people should be careful what they are thinking or we might get ideas of our own . Regime change is what is needed in Iran . Hey here's an idea , lets not invade Iran on the pretext of any noble cause ....but simply for the joy of raping and pillaging . Sounds like a plan :D

[Edited on 13-4-2006 by Rosco Bodine]
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[*] posted on 12-4-2006 at 18:52


This started out as a technical question but seems to be teetering on the edge of Shit Canyon like a few other threads we've just had. Please keep the political fisticuffs to the designated forum.



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[*] posted on 13-4-2006 at 15:45


Iran maybe years away from enriching enough uranium to make a bomb, but if you are going to develop nuclear weapons in defience of the US you do it the way the UK did it when it developed nuclear weapons in defience of the US.

Build a reactor, poison the villagers and make a plutonium bomb. Didnt half make the US upset, they imposed trade restrictions when they found out, tried to throttle the UK economically the way the rest of the world was throttling Iraq. Of course, its not popular to remind people of this anymore. The US is embarrased it ever tried to the stop the UK getting nukes - but only now they have them, and the UK is embarrassed the air cooled reactor it resorted to on the basis of time contraints caught fire or leaked lethal clouds of dust from the core so many times.

The main thing is that everyone that gets nukes wants to be the last. Noone thinks anyone other than themselves can be trusted with them. The sad fact is, every country that wants them will get them eventually. The best long term solution would be to lead these countries to the path of stability as they aquire them, not invade everyone that blinks twice when whichever inbred hick of a US president says nu-cu-lur.
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[*] posted on 13-4-2006 at 17:55


"Build a reactor, poison the villagers and make a plutonium bomb. Didnt half make the US upset, they imposed trade restrictions when they found out, tried to throttle the UK economically the way the rest of the world was throttling Iraq. Of course, its not popular to remind people of this anymore. The US is embarrased it ever tried to the stop the UK getting nukes - but only now they have them, and the UK is embarrassed the air cooled reactor it resorted to on the basis of time contraints caught fire or leaked lethal clouds of dust from the core so many times."

That is rather erroneous.




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[*] posted on 14-4-2006 at 07:15


Can someone explain what is so hi tech about these centrifuges? Surely, anything that could be built in the 40's can now be built by the average Joe in his garage? Is it just a problem of scale thing? Also, if you get hold of a ton of Uranium and process it to get 9Kg of 235, can you then sit the 238 around the 235 and make yourself some Plutonium?:o

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[*] posted on 14-4-2006 at 09:25


Quote:

It is for certain that Iran already has a nuclear weapon and its inert remains are guaranteed to be found as evidence amidst the rubble from the preemptive strike which will be necessitated to prevent its use ....just in the nick of time , you see .


You're crazy if you think Iran would use a nuclear weapon as a means of aggression. They'd maybe take out Tel Aviv and then what? They get wiped off the face of the earth by the Israeli Nukes (which no one seems to object to) before they even could survey the damage.
They're crazy, but they're not stupid. They hatemonger against the US because it keeps the population from seeing their ineptness to lead a country, not because they want to attack the US.

That said, what do you think will happen after a strike on their installations? Insurgency in Iraq will skyrocket along with US casualties. More moderate islamic countries will also turn against the US.

Want to attack Iran? Fine, just don't come whining for help after you've stirred up the hornet's nest. We warned you guys about Vietraq...
Solving problems that aren't there only creates problems.


IIRC uranium enrichment centrifuges concentrate UF6, which makes it somewhat more complicated than solid centrifugation. That said, it was possible in the 40's, so...

[Edited on 14-4-2006 by vulture]




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[*] posted on 14-4-2006 at 10:57


Quote:
Originally posted by Pommie
Can someone explain what is so hi tech about these centrifuges?


They aren't just any centrifuge. To isotopically seperate uranium, accelerations of the order 1,000,000g are required. This is a major engineering feat.

The rotor in such a centrifuge will spin in excess of a thousand revolutions per second. To overcome friction, it will need to operate in vacuum, and will require extremely advanced bearings along its drive shaft. It will also need to be extremely well balanced, as even a minute inbalance in mass will cause a colossal imbalance in force

The materials used in the rotor are pushed to their mechanical limits and so must be of superlative quality. Forging a metal that won't disintegrate under the strain is an engineering feat in itself (and indeed, metals of the required quality are sometimes referred to as "centrifuge grade"). If any part of the rotor does fail, it will explosively disintegrate, with chunks of metal being thrown out at supersonic speeds.

Finally, such a device must operate whilst an extremely toxic and corrosive gas (uranium hexafluoride) is being simultaneously pumped into and out of it.




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[*] posted on 14-4-2006 at 11:09


"Surely, anything that could be built in the 40's can now be built by the average Joe in his garage? "

I'm sorry, but that's pure crap.

Would you be able to make liquid air in your garage? It was done more than 100 years ago.

Or how about an 30 KW arc furnance Moissan used to make? Can you isolate lithium from mineral waters?

There are countless examples of old things the average Joe wouldn't be able to make, let alone in the garage. It's a matter of resources rather than knowledge.

[Edited on 14-4-2006 by a_bab]
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[*] posted on 14-4-2006 at 11:39


Actually a_bab liquid air woud be quite trivial in a garage, as would be an arc furnace.

Materials that will withstand 10,000rpm centrifuge operation and not be corroded by UF6 gas though are still rather exotic. Just making UF6 would require the ability to handle fluorine.

I do wonder if single crystal steel technology would work, but thats usually limited to tiny parts inside jet engines.


MargaretThatcher, If there are specific faults with it, feel free to correct them. US refused to release details of the bomb to the countries that helped develop it. The first windscale pile went critical in 1950, with an air cooling system later found to leak radioactive particles. When US found out the UK were building a bomb, talks broke down and they threatened trade sanctions unless they stop. They may not have had time to apply them, the plutonium produced was augmented with purchased plutonium from canada and 'hurricane' was detonated just two years after the first windscale pile went critical. Just a few years later, still producing plutonium for the bomb project one of the two reactors caught fire, resulting in the release of massive amounts of radioactive iodine and polonium (the latter being manufacturered for the bomb triggers).

All this is a matter of historical record.

If you want nuclear weapons, don't enrich! Build a pile! Its not safe, but it is fast. UK was a nuclear power before it had nuclear power and against the wishes of the US.
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[*] posted on 14-4-2006 at 12:30


Quote:
Originally posted by Marvin
I do wonder if single crystal steel technology would work, but thats usually limited to tiny parts inside jet engines.


I recently translated Nuclear Material Trigger List of IAEI. This is a list by which IAEI watches if a specific country is a proliferator.

In certain parts of a very long list, there was an article mentioning about nickel alloys, which are placed in the trigger list for they are resistant to UF6 and heavily used in both diffusion and enrichment centrifuges.

For obtaining hints about nuclear technology, I recommend taking a look at that trigger list. HTH. Regards.
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[*] posted on 14-4-2006 at 12:33


"Actually a_bab liquid air woud be quite trivial in a garage, as would be an arc furnace."
Have you tried?
Once you have got that sorted out you might want to try making a copy of John Harrison's chronometer.
Anyway.
Surely the problem isn't nuclear weapons?
Imagine the West gave Iran a nuke as a present.
Then they reminded the Iranians that, if they ever used it, they would get wiped off the face of the earth in retaliation.
Most plausible governments would probably not want to try firing it.
Even if they did their neighbours would put a lot of effort into stopping them.

Iran can't even maintain decent roads- their rail system is shot and their healthcare isn't much better.
It simply doesn't make sense to let them build a nuclear power plant; Windscale, TMI and Chernobyl (and the French and Japanese ones that I can't remember the names of) taught us it's difficult to build a safe one, even if you have reasonable infrastructure and good engineering. We should be telling the Iranian people that, since they have lots of oil, they don't need nasty dangerous, expensive nuclear power. (And the first one to disagree about the cost gets beaten to death with the slogan "too cheap to meter"). While we are at it me might ask them if they need a government that is prepared to risk the citizens' lives for an ego trip. (er, actually, come to think of it, that probably goes for the US and the UK too)
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[*] posted on 14-4-2006 at 14:49


The physics prof at my school keeps talking about building bombs. He said one class accomplished the task of designing a bomb, inside and out, presumably, calculating cross sections and critical mass and kinetic energy (i.e. explosives) needed to detonate this thing and whatnot. A mini Manhattan project I guess, but without the groundbreaking physics research (it's already been done!) and unfortunately, no active materials. *Shrug*, it's just textbook information, all you have to do is assemble it. An academic curiosity.

The best way to go about nuclear anything IMO is natural uranium, requiring a minimum of refinement, combined with a graphite and/or water moderator (natural water could be used for cooling a graphite moderated reactor, but heavy water is preferrable because normal water tends to absorb neutrons) and I guess boron or cadmium control rods. Let it cook for a while and monitor the activity. After a while, it should start heating up as U238 is kicked up to Pu239, which can then be chemically refined far easier than U235 from U238.

For that matter, since H2O absorbs neutrons, you should be able to cook the whole pile with H2O and graphite and chunks of uranium fuel and, after a probably much longer time, get D2O, Pu239 and so on.

Not to mention all those wild byproducts, ranging from oh I don't know, taking arbitrary bounds of yields, say, atomic mass numbers 85-110, and uh, a minima around 123, and then about 127-152, corresponding to (assuming only beta decays to stable products) Kr to Ag and Te to Sm, plus little bits of lots of stuff all around. (I think pH would generally rise from all the alkali and alkaline earth metals produced.) Probably a good bit of trouble with residual activity of a lot of those, though. It would be neat to look through those nucleides and see which have a short half life (under a year, say) before decaying to a mostly stable nucleide (more than 10^9 years or so), then chemically seperate them after leaving the spent fuel to cool down for a while.

Reactor design wouldn't be that hard, you just need to keep everything sealed and shielded. American reactors all have very thick concrete reactor containment buildings, not a bad idea. A sealed stainless steel vessel with an extra container beside it to divert pressure in event of shit hitting the fan, and on top of that, another vessel sealing both in, would be pretty nice I think. Add feedthroughs for pipes, wires, etc., then wrap it with an inch or two of lead sheet or a couple feet of concrete. Radiation hardened robotics and cameras would be a pretty good idea for manipulating things you can't handle in the design with servos and whatnot.

Tim

[Edited on 4-14-2006 by 12AX7]




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[*] posted on 14-4-2006 at 21:11


For the centrifuge thing:

It was done in the 40's, requiring billions of 40's money (it would be massive amounts of $$$ today) and an entire CITY and a massive industrial commitment. Not something you can do in your garage. Centrifuging UF6 requires numerous stages and cannot be done on any sort of scale on anything short of a massive sized industrial plant.

For fun, calculate the ENERGY required to run those centrifuges and seperate out all the UF6. You'd need your own 500kV three phase feed line to run it!

Just because it was done in the 40's doesn't mean it is possible nowadays. I mean, if countries will massive amounts of money, engineers and such (even a poor country can get quite a few) can't do it, you're sure as hell not going to do it in your garage unless you are a freaking mastermind with millions of dollars and massive amounts of time, equipment and minions.

Designing the basics of a nuclear bomb, IMO, is not hard. In fact, I think all parts of a bomb, EXCEPT the crucial core of uranium or plutonium, could be assembled by someone such as us, assuming a implosion type single stage fission weapon of roughly 10-30kT. It would be a very large challenge but I think it could be done.

I have done a lot of research into the possibility of doing it at home, and have come to the conclusion it simply can't be done in your garage, unless your garage is massive and you have millions of dollars to spend.

It is dissapointing, but hey, you CAN do bio weapons in your garage, so if WMDs are your thing...
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[*] posted on 14-4-2006 at 23:31


The implosion system for a Pu or U core is also going to be a problem. Even if you can get the 30 kg or so of RDX and a slower explosive, detonating them in the proper time frames - now that's going to be a problem. You'll have to make very precise blasting caps, and a "AP filled christmas light initiated drink straw" is not going to work here.
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[*] posted on 14-4-2006 at 23:41


Yep, HV capacitor initiated exploding bridgewire slapper type detonators, or something to that general effect, are needed. I never said it would be easy, but making 100 of those, and having them fire within milliseconds of each other, is still a simple task compared to making the Pu or U core for the device.
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[*] posted on 15-4-2006 at 03:20


It's not as simple since the americans worked alot on this issue while the Pu was cooking... I don't know exactly what the limit of the explosion between the caps is, but I feel is under 1 ms.

EDIT: quote from Wiki

"The lenses must be accurately shaped, chemically pure and homogeneous for precise control of the speed of the detonation front. The casting and testing of these lenses was a massive technical challenge in the development of the implosion method in the 1940s, as was measuring the speed of the shock wave and the performance of prototype shells. It also required electric exploding-bridgewire detonators to be developed which would explode at exactly the same moment so that the explosion starts at the centre of each of the lenses simultaneously (within less than 100 nanoseconds). Once the shock wave has been shaped, there may also be an inner homogeneous spherical shell of explosive to give it greater force, known as a supercharge."

[Edited on 15-4-2006 by a_bab]
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