Volatile plutonium gas compound

[megalomania]

I was researching an unrelated explosive when I came across some interesting data about waste plutonium reclamation. Apparently there is a kind of plutonium trimethylsilyl amine compound that is quite volatile and readily sublimes.

The compound in question, Pu[N(Si(CH3)3)2]3 , is made by dissolving plutonium metal in a solution of iodine in THF to make PuI3. The plutonium triiodide is then converted to the trimethylsilyl compound. I don’t know how that is done, but I would assume with some trimethylsilyl amine compound via halogen substitution.

This solid compound readily sublimes at 50 C. Now, assuming you can get your hands on plutonium this would be far easier to weaponize than an atomic device. Having a plutonium gas that is slowly released through sublimation would potentially expose far more people than using the plutonium in a pyrotechnic smoke bomb that disperses quickly. Of course it would take longer to kill anyone exposed to a smaller quantity of plutonium. However, dead is dead.

[tom haggen]

Did it say if the plutonium gas had an odor or not? If this type of weapon was hidden well in a public place, would it go unnoticed exposing much more people to lethal levels of radiation? Your evil ideas fit your avatar megalomania.

[megalomania]

I seriously doubt if anyone has ever smelled this compound given that A) its plutonium for gods sake and B) very few people would have access to it in government labs and C) the compound is rather new. If some poor shmuck does get a whiff he has more important things to worry about than describing the scent :(

[Joeychemist]

Did it say if the plutonium gas had an odor or not? If this type of weapon was hidden well in a public place, would it go unnoticed exposing much more people to lethal levels of radiation? Your evil ideas fit your avatar megalomania.

It’s not the human nose you have to worry about detecting this weapon, It is the “mechanical nose’s” that are all around our countries designed to pick up even the slightest trace amounts of radiation from nuclear material . I know in that in Canada there is one the not to far from where I live. After Sept 11 the U.S has installed “a wide range of specialized radiation detectors intended to sniff out the signatures of nuclear bombs–both traditional warheads and so-called dirty bombs” all over the country, They are in airports, there is one in time square, and there are several on capital hill. There are hundreds working today throughout the world and hundreds more ready to be installed.

I love the idea Mega and like Tom said you're evil ideas fit you're avatar perfectly. But do you really think this weapon would go unnoticed for to long?

[Bugger]

I thought that the most volatile Pu compound would be the hexafluoride, PuF6, with properties similar to UF6 (used for U-235 enrichment) but rather more strongly oxidizing. There may also be a Pu(VII) heptafluoride, PuF7. But they are very readily hydrolysed by traces of H20. I have read that a volatile Pu(VIII) tetroxide, PuO4, has been obtained, which would somewhat resemble OsO4. All these should be more volatile than Pu[N(Si(CH3)3)2]3 because their molecular weights are substantially less. One whiff of these compounds would certainly do you in, because of both the chemical toxicity of Pu compounds and their highly oxidizing nature.

[Marvin]

"because their molecular weights are substantially less."

No. MW of an individual species is a secondary influence, it only really applies within classes of chemicals. Intermolecular bonding creates effective massive molecules which have corrispondingly higher boiling points etc. This why at STP water is a liquid and xenon is a gas.

PuF6 is thermodynamically unstable, ie it evolves fluorine. You lose about 0.1% a day if its kept in the vapour form. The funny thing here is that keeping it solid which is normally the best way to preserve it loses you about 1.5% a day due to the radiactivity inducing decomposition (these values will therefore be for a certain value of specific radioactivity probably corrisponding to pure 239). One of the ways of making this is to run PuF4 and F2 into a furnace at 700C and condensing the products very fast. PuF6 melts at 51C, which means at the temperature the trimethyl silane derivitive is readily subliming PuF6 hasnt even made the Solid>liquid transition and has fa vapour pressure.

I'm a little unsure what you mean by 'one whiff', but I was under the impression Pu was a calcium analog building up in the bones and eventually causing cancer/lukemia by alpha irradiation. It also forms a flaky oxide by air oxidation which can easily float off and be trapped in the lungs causing cancer in almost unfeasable sounding amounts. I was also under the impression the 'most toxic element' often applied to plutonium was only a result of its radioacitivy in combination with the human bodies tendency to bind it up and keep it or fail to expell it fromt he lungs.

Normally I would not be interested in a Battlefield Chemistry post, but I was wondering if a uranium analog exists that might provide a much less corrosive substrate for enrichement. Sadly I think obtaining the precursor as a single molecular weight is a problem that would outweigh any chemical gains. Fluorine of course only has one stable isotope making the mw of UF6 soley dependent on the U isotope.

[megalomania]

The toxicity of plutonium is due to its radioactivity. IIRC a single plutonium atom can kill you given enough time. One whiff would be quite sufficient to contaminate your body with enough plutonium to finish you in short order.

A slowly subliming plutonium chemical is ideal because it allows for maximum contamination of an area over an extended length of time. A volatile gas would quickly disperse and contaminate the air quite heavily at first, but then would float away above breathing level. A slowly subliming gas would create a radioactive gas cloud near ground level (where people are breathing) for an extended period. The Pu source being in a trash can for example. It is also probable this gas would be less detectable at lower concentrations if indeed it does have an odor. I can't imagine plutonium hexafluoride smells very plesant if it is contaminated with fluorine.

[rancid_matt]

If one would get his hands on Pu, It would be very very stupid, to waste it on something like a toxis gas bomb (wich have been proven unifficient), while one can make a nuclear weapon with relative ease from any isotope of Pu.

[Marvin]

"IIRC a single plutonium atom can kill you given enough time"

I'll put this down to temperary insanity, it makes no sense from either chemistry or physics.

Long past time we had some reliable data though, from a random web encyclopedia,

"Orally, plutonium is less toxic than several common substances, including caffeine, acetominophen, some vitamins, (pseudo)ephedrine, all narcotic pain killers (including codeine) and any number of plants and fungi. It is perhaps somewhat more toxic than absolute alcohol, but less so than tobacco and most illegal drugs (some such as LSD and marijuana are not or barely toxic). As such, it is debatable whether plutonium should even be classified as a poison. "

"As of 2003, there has yet to be a single human death officially attributed to plutonium exposure. "

"..., so far, no human is known to have died because of inhaling or ingesting plutonium and many people have measurable amounts of plutonium in their bodies"

"That said, there is no doubt that plutonium may be extremely dangerous when handled incorrectly. The alpha radiation it emits does not penetrate the skin, but can irradiate internal organs when plutonium is inhaled or ingested; particularly at risk are the skeleton, which it is liable to be absorbed onto the surface of, and the liver, where it will collect and become concentrated. Extremely small particles of plutonium on the order of micrograms have a (small) chance to cause lung cancer if inhaled into the lungs. "

I'm with rancid matt. We ever get a few kilograms of plutonium, lets build a bomb.

[tom haggen]

One way to detect chemicals in the air is to use large, expensive laboratory machines such as gas chromatographs and time-of-flight mas spectrometers. Thes devices can very accurately detect miniscule amounts of volatile chemicals in air samples-but they also detect substances that have nothing to do with smell, so determining just which parts of their output are relevant adds more complexity to the problem. More direct, and more compact methods of artificial smell detection are under development. Examples:

A quartz crystal microbalance (QCM) sensor is a tiny device that can detect a single, arbitrary chemical. This sensor consists of a quartz crystal vibrating at a known frequency. It's coated with a material that can absorb molecules only of a very specific size and shape. When it does, its mass increases slightly. This changes the frequency of the crystal's vibration. A simple circuit detects the change and signals that the chemical in question present.

An entirely different approach being studied at the University of Illinois involves using vapor sensitive dyes called metalloporphyrins that change color when exposed to certain chemicals. By examining the "Before" and "After" states of an array of these dyes, a computer can essentially "see" smells.

Decoding output from an array of sensors is a challange, because subtances that are very similar chemically somtimes smell much different from each other. Also, substances that smell nearly the same can be completely different at the molecular level. For this task researchers often rely on neural networks, software that can be trained to identify patterns and make educated guesses about new combinations based on their similarities to patterns that have already been verified.

Now, will a machine really be able to tell what we humans think Pu[N(Si(CH3)3)2]3 smells like? I guess we will never know because there is no way for us to find out unless we test it on some incarcerated individuals who donate their lives for the sake of science. Or perhaps someone could take an ungoddly amount of potassium iodide pills and see if the live after exposing themself to extreme amounts of radiation.

http://itotd.com/index.alt?ArticleID=240

[zeocrash]

I agree with marvin about the plutonium toxicity thing. Chemically plutonium is not very toxic. The problems are caused because it is readily absorbed into the body where it irradiates your organs.
It would be very unlilely that a single atom of Pu would kill you. It's not impossible, if the radiation emmited by a single Pu atom were to dammage the DNA in a cell and make it cancerous it would eventually kill you.
I think that this is probably not the best use for Pu though, a bomb would be far more destructive and would cause far more fear in the population.

[Marvin]

I agree, its not impossble, but it makes no sense as a statement. Half life of the commonest plutonium isotope is 24 thousand years, so a single atom and 'enough time' ends up dying of old age with or without the plutonium, and if its just the several decays of plutonium then why not uranium? Or radon? We are exposed to more radiation every hour of every day, most of which comes from inside our own bodies so even if its possible the atom decays within a human lifetime and that event however unlikley causes cancer it cant be significant overall compaired to a single day's exposure to background.

[tom haggen]

"while one can make a nuclear weapon with relative ease from any isotope of Pu. "

Ok wise guy when you get your hands on some plutonium I would like to see you whip up an atom bomb. The explosion is not the difficult part of an atom bomb to reproduce. Its the extreme amount of engineering that goes into the design of the bomb that is hard to reproduce.

[rancid_matt]

You might not think it, but a lot of the actual needed info for building a bomb (cross-sections being the most important) can be found on the internet. I'm not talking about howto's like Nuclear Weapons FAQ and such, but more like website like http://wwwndc.tokai.jaeri.go.jp/Figs/endfplot.html, http://ie.lbl.gov/ and so one. Once we've calculated the exactly critical mass, the only thing we need to do, is to create a specific shockwave wich creates this critical mass from a non-critical one. Using "simple" equations this isn't too hard. You might be right for the fact the a beginner can't build a A-Bomb, but once one has learned nuclear fission physics, fluid dynamics and strengthlearn (sorry, i don't know how it is called in English). It isn't too hard. The books I think are the most valuable for someone with a university degree for building a bomb are the next : Theoretical Nuclear Physics (Blatt & Weiskoppf), An Introduction to Nuclear Physics (from the Cambridge press) and An Introduction To Nuclear Engineering. You can also consult the DOE manuals, but you won't learn enough to build a bomb. Though they are interesting.

[megalomania]

Indeed I have been misinformed. A little research has revealed this groundbreaking paper, scientificially accurate, but largely ignored by the media.

http://www.fortfreedom.org/p22.htm

This is quite a revelation for me. If indeed this paper is correct, and I have no reason to doubt it because it has been referenced in numerous scientific publications, than the whole "dirty bomb" concept is a media created red herring. Sure its deadly, but only in large doses. A dirty bomb would be a weapon of terror if everyone still buys the media verson, but it would not actually kill anyone.

That means the whole purpose of this thread, the volatile plutonium gas, is unlikely to work at all. Rhadon gas would be far more dangerous, and a whole hell of a lot easier to get.

[Marvin]

rancid_matt,

Normally for this matter I'd quote the bits of your post I objected to and attempt to correct them. In this case though, its *all* wrong.

For example, you quote a website giving the ENDF data, but fail to note that the information needed for a bomb is actually missing. You assume you have to calculate the parameters for a bomb from the physics, which is wrong, and you also assume that you can, and thats also wrong.

More tellingly matt, you are arguing in this thread,
"one can make a nuclear weapon with relative ease from any isotope of Pu"
and in another,
"There are two reasons why normal people (including terrorists) can't build a nuke:"

Which strangly doesnt include lack of access to fissionable material. How do you expect to argue if you cant make up your mind? I suggest you read the available information, everything you can find, currently you seem to be arguing for the sake of arguing. Its not enough to assume that the secrets to building a nuke are tied up in a physics degreee anymore than for building a transistor radio.

[rancid_matt]

I think we're both, partialy, wrong/right.

It is not impossible to design a bomb, it is impossible to build one.

If I remember the Nuclear Weapons FAQ, they said somewhere that a few university students where given the asignment to design a weapon, and failed. I might be mistaken ofcourse.

With a degree in nuclear physics, it is possible to design a bomb in the long run (if you work within a team). The task at hands is merly calculating the critical mass, diameter and the time/velocity in which it must be compressed.

A appologise for the constant nagging. It's my nature you see, a lot of people condem nuclear physics to something simple these days, and I don't really like that.

PS: The Japanese site, did gave you the most important information you need: the cross-section.

[Marvin]

You are still speaking more than reading rancid.

All you need for a bomb is a supercritical mass of fissionable material. Ideally you also need a burst of neutrons at the right time but this is only important if the supercritical state is short lived, as with the implosive design. The amount of bang you get depends on what you have in excess of the critical mass (primarily).

2 complications. Knowing what the critical mass is so you can make a target and projectile a safe margin below this, and less importantly with uranium, but important with plutonium doing the insertion fast enough that you only have a small chance of preignition.

How to determine critical mass? If you have enough for a gun type bomb you only need bring it together neer a neutron counter until the intrinsic flux starts to go asymptotic. That gets you a critical mass value for that geometry without going into the realms of a criticality accident. Doing this is much easier with plutonium. Keeping away anything that can act as a moderator is extremely important for that stage.

Thats the hands on method. The theory method is in deep water before it starts. There is no 'cross-section' for U-235. What there is, is a cross section for every reaction possible for that isotope. The useful ones we'd need would be a total neutron fission cross section, with an avarage number of neutrons per fission versus energy, and this would do. The US ENDF data gets you the total fission cross section but only for low energies, so you can design a reactor but not a bomb.

The Japanese site has things listed seperatly and the ideal data, seperate cross section curves for neutron induced fission producing 0,1,2,3 neutrons are *missing*. There are even gaps that show where that data should be, and internal references to the missing data. Neutron induced fission producing 4 neutrons has not been removed because this only occurs for energies outside the range produced in fission, ie useless for designing a bomb. Goverments arnt stupid, they know what information needs to be supressed to prevent the design of high yeild weapons.

If the amount you have isnt enough for a gun type and you cant get any more, your choice is an implosive lens and you have no physics maths to do at all. There is nothing to optimise, knowing the critical density is unimportant, it will either go nuclear or it wont and design or simulation of nuclear effects in the core wont change that.

Keeping the terrorists away from the fuel is the only security against a bomb. Everything that needs to be known to get a bang (eg 2kt) is public. Going from 2kt to 20kt requires much better engineering/physics etc and using Pu instead of U-235 is harder, but to get recogniseable nuclear bang everything is public.

Physics graduates are mostly clueless to the real world of physics. Of the 7 or so I know only 1 recognised a photomultiplier when given one to look at.

[akinrog]

"while one can make a nuclear weapon with relative ease from any isotope of Pu. "
Sorry my friend but above statement, I believe, is incorrect. As far as I know the even numbered isotopes (especially Pu240) must be excluded from the weapon grade plutionium, since they cause premature initiation. If content of even numbered isotopes is higher then you should receive a poof instead of a bang (of course relatively).

In order to decrease content of even numbered isotopes, uranium blankets are irradiated for a certain period of time (3 weeks IIRC) with neutrons in reactor core. Then they are removed from the reactor core and separated from Uranium by means of bizmuth phosphate method or recently by means of another method which I cannot recall the name (but I believe) involving a fancy organic solvent. Regards

[Bugger]

Marvin, are you trying to tell us that plutonium is good for us? Have you tried it?

Akinrog: The most usual isotope used in plutonium atomic bombs and plutonium powered nuclear power stations is Pu-239, which has a critical mass of about 300 gm. It is generated in enriched (with U-235) uranium fuel rods in nuclear power stations when the U-235 decays by self-induced fission, releasing neutrons and lighter nuclei among other things. The neutrons are absorbed by the non-fissionable U-238 present, which mostly becomes Pu-239 (via Np-239 which quickly decays), which has a half-life of about 24,000 years. Heavier plutonium isotopes require additional neutron capture and thus are produced more slowly than Pu-239.

Plutonium has 15 known isotopes with mass numbers ranging from 232 to 246, of which the heavier ones are mostly the more long-lived. Plutonium's most stable isotope by far, Pu-244, has a half-life of about 82,000,000 years, decaying by alpha-emission and to a small extent through spontaneous fission. (This is only 1/55 the age of Earth, so only 1/2^55 of any originally present would be left.). The next longest-lived is Pu-242, half-life 376,000 years. They are mostly alpha-emitters, and all are fissionable.

[mrcfitzgerald]

Are you sure that plutonium has a Critical Mass of 300 grams? I remember the bare sphere critical mass as 10.46 kilograms... Then again, I suppose a nuclear reactor requires less then bare sphere due to the moderater. Anyway, I think it is likely that, if given ~100lbs of U-235, a terrorist would be able to reach that 15-20 kiloton mark. Why? Because, the rate of insertion for the ~2.4 Critical Masses present is well below that which could be attained through the use of planar explosive waves driving together Uranium projectiles. Infact, this method could be used for plutonium devices too due to the speed of the insertion (3.5 kilometers per second.) All the terrorist need is: Explosives(check), Planar Lens design (check), electronic system (check), fcg or other high energy device to power the detonators (check), Foil Slapper style detonators (check) a large quantity of natural Uranium for the tamper (check), Generall -in-the-ball-park know how (check), and fissle material (not obtained...).

[Bugger]

I saw the critical mass of Pu-239 given as 300 gm on a website, whih also said it was only about 1/3 of the critical mass of U-235.

[Marvin]

"Marvin, are you trying to tell us that plutonium is good for us? Have you tried it?
"

I fail to see how after my covering lukemia and lung cancer its possible to come to that conclusion.

300g for Pu-239 is either wrong or irrelavent, some people suggest a bomb might be possible with just 1 Kg but I was under the impression 5Kg was generally accepted as required. This isnt critical of course, but it can be compressed to beyond criticality by an implosive lens.

mrcfitzgerald,
You raise some good points. I dont consider insertion time for a U-235 bomb to be a limiting factor for performance though. In the scenario for a gun type design I limit my imagination to 1 target and 1 projectile and thus a critical mass of somewhere around 2 giving quite a poor yeild. Yeild will of course go up considerably with increasing fuel but if you have enough for 2 bombs (say 4 critical masses), the sane terrorist would in my opinion build 2 even if that meant the total yeild would be less than for a single bomb. If you can get a news report compairing the blast to Hiroshima thats all the public would need to hear to go into a full scale panic.

akinrog,

I think for seperation you may be thinking of the butyl phosphate method in which changes in oxidation state are used to push plutonium preferentially into and then out of the organic solvent. I fully agree with your point on even numbered isotopes and this is the primary problem with reactor grade fuel, which is normally close to equilibrium wrt neutron irradiation.

Edit,

In fact Ive made a mistake, I was under the impression the yeild of little boy was much less than fat man. At 15kt there isnt that much in it and I revise my estimate at the low end of possible of 2kt to around 10kt accordingly for in the region of 2 critical masses.

[megalomania]

The minimum critical mass for Pu-239 is a little over 10 Kg when explosively compressed with the best possible compression man could muster. More conventionally it is 16 Kg. Pu also has a critical mass that would explode if you just lumped it all together, but that is in the tons. Yield of a regular explosively compressed Pu core is around 20 kilotons per Kg.

[Jacks Complete]

Surely the use of a moderator would reduce the critical mass by a large amount?

[mrcfitzgerald]

The use of a moderator is only viable in reactor designs, this is because a moderater "slows down" neutrons to the point where it is easier for them to hit a U-235 nucleus. In a nuclear bomb, there is simply not enough time for these slow (or thermal neutrons) to fission nuclei. Instead, a bomb is designed assuming that only fast neutrons (in the range of ~1.5 MeV) can actually cary out the chain reaction before disassembly. There is something similar to a moderator though (in terms of increasing efficiency), bomb designers can use neutron reflectors to scatter back neutrons from the edge of the core -normally, these neutrons would be lost forever. Anyway, through the use of a beryllium reflector weapon designers have managed to reduce critical yield (for plutonium anyway) to the 4.5 Kilogram area.

Marvin: Good points! However, you dont need to limit your imagination to just 2 critical masses of uranium for the gun-type weapon. Much greater amounts may be assembled. Why? Because, assuming the target is a squat, hollow cylinder and not the ideal spherical shape -much larger amounts of material may be assembled without reaching critical mass. This is because the shape is just not geometricly viable for the spread of neutrons. The same thing applies to the Uranium bullet, it is generally longer in legnth than in width and is also geometricly unviable. It is not untill the bullet approaches the target that a more viable assembly can take place. Indeed, in the little boy device -the bomb went critical before the bullet ever entered the target. Infact, it seems that assemblies may be made using the gun configuration up to 3.4 critical masses or so.

The question of Uranium aquisition is, prehaps, the most serious issue interms of nuclear security. I think, however, that the aquisition of reactor grade plutonium also posses a severe threat... Consider the fact that reactor grade material is split into two differing isotopes 60% Pu-239 and 40% Pu-240, that means that for a conservative design using a large tamper/reflector 8-9 kilograms of material is needed. By itself, reactor grade is certainly not ideal bomb material -it emits millions of neutrons per kilogram and gives off about 100watts of heat per kilogram. A fizzle is almost certain if used by itself. If the isotopes in reactor grade material are seperated, however, it allows one to discard the useless contaminating isotopes. Thus, if a terrorist had only reactor grade material on hand, it is possible that they could separate the isotope mixture inorder to discard the useless isotopes and build a better bomb.

This certainly is a challanging proposition, but since the desireable isotope concentration is so much higher than in Uranium, it is possible for terrorist to use high speed centrifuges or vortex separation apparati. This is accomplished in only a few cascade steps rather than hundreds as required by uranium.

Also, many feel that explosive lens design is extrodinarily difficult for terrorist. This is true, in a three dimensional implosion scheme the bending of detonation waves to mesh together into a single smooth implosion wave (from singular point detonators) is extreamly complex and unlikely. Unfortuantly, this kind of scheme is not need for nominal yield weapons. Consider a cylindrical device, it is rather easy to initiated the outer edge of the explosive cylinder (more of a disk in shape really, though) through the use of a high power fcg and many hundreds of fine wires positioned symmetrically accross the surface. I have actually seen online physics papers commenting on this type of detonator scheme and the shockwave produced is nothing short of perfect in appearance (pictures were taken via X-ray cameras.) Also, there is a certain type of flexible detonation sheet material that may cause the same effect. (This was in a patent somewhere that I have long since lost the number too :( ) At any rate, it appears that one can create a viable, smooth implosion wave -only cylindrical though...
Well, enough rambling -just my 2 cents.

[akinrog]

use of a high power fcg and many hundreds of fine wires positioned symmetrically accross the surface........

Sorry mrfitzgerald but what is high power fcg? Regards

[mrcfitzgerald]

FCG is shorthand for flux compression generator, it translates the energy in high explosive to electrical energy. It is common for a flux compression generator that weighs about 100lbs and utilizes about 20lbs of high explosive to generate a pulse on the order of 10's of terrawatts and many mega amps. The energy storage is on the order of 10's of megajoules, and the out-put time is on the order of a few microseconds.

[nbk2000]

There's a nifty patent that details the design of lens for spherical and cylindrical implosion that are composed of nothing more than polymeric foam, heavy foil (think reynolds wrap foil), and thin sheet explosives. :)

The explosive wave expands outward parallel to the layers faster than it transitions through them, with the wave assuming a flat wavefront after about 9 layers.

[mrcfitzgerald]

What is the patent number? Ive searched all over the place for a spherical lens patent and the best I could come up with was a planar lensed system as well as this .pdf concerning the multi wired array for cylindrical and planar systems: (http://www.autodyn.com/autodyn/papers/paper148.pdf). For those interested, I also found a vortex isotope separator (4,092,130), a nice fcg patent with lots of detail including dimensions (4,370,576) as well as an improvement on the design in the previous patent (H148).

Edit: I forgot to mention a nice little explosive-crowbar switch patent (3,932,717) -It would be very usefull to those interested in FCG manufacture...