physicists: a question about depleted uranium

[unblock]

my understanding of depleted uranium is:

when converting naturally occuring uranium for nuclear energy/weapons purposes, you must increase the proportion of u235 (more radioactive and fissile) to u238 (more stable and less fissile) because naturally occuring uranium has much too low a concentration of u235 to be useful.

so there's some process that produces one pile of uranium with more-that-naturally-occurring u235, and another pile of uranium with less-than-naturally-occurring u235. the 'more' pile gets used for nuclear energy/weapons and the 'less' pile is 'depleted uranium', used in weaponry and armor for its density, not its radioactivity.

so, if the depleted uranium has less u235 than occurs in nature and is therefore less radioactive than naturally occurring uranium, is it really all that bad?


i'm not disputing that it is, i'm just wondering about the physics/chemistry behind the radioactive damage it does.

[Cell17N]

1. Why did you omit chemists.

YES. It can not be used for a nuclear explosion, but it can ENHANCE a thermonuclear explosion greatly.

14MeV neutron + U-238 --> fission + 3 neutrons + 200MeV.

[Dogmudgeon]

2. That equation

14MeV neutron + U-238 --> fission + 3 neutrons + 200MeV.

Zowie!

You know, if they could just harnass that 186 MeV surplus, we could have a source of energy to replace oil! It would be so cheap, we wouldn't even have to meter it! It could revolutionize the world!

:)

Incidentally, most of the lay public thinks that nuclear energy is strictly the province of physicists; chemistry suffers from terrible P.R.

--bkl
"Without Chemistry, Physics itself would be impossible."

[Cell17N]

4. Technical difficulties.

> You know, if they could just harnass that 186 MeV surplus,
> we could have a source of energy to replace oil! It would
> be so cheap, we wouldn't even have to meter it! It could
> revolutionize the world!

That's what they tried to do since 1950 almost giving up since 1980.

[alexwcovington]

3. Radioactive is radioactive.

Having a ton of depleted uranium strewn about (say, as in a modern battlefield) can be just as bad as being near a small amount of more intensely radioactive isotopes.

I'm fine with Nuclear Power. But putting this stuff out in the open? Unshielded? As WEAPONS? No thanks.

[Cell17N]

7. In nature.

Every ton of Earth contains 3g U-238 and 15g Th-232.

[treepig]

12. right, and way more radiation is released into the environment from coal

than from weapons use of DU.

Gulf War I/Kosovo/Gulf War II: estimated < 2,000 tons of DU.

Worldwide release (from combustion of 637,409 million tons of coal):

Uranium: 828,632 tons (containing 5883 tons of uranium-235)

Thorium: 2,039,709 tons

http://www.ornl.gov/info/ornlreview/rev26-34/text/colmain.html

so, leaving aside the question of whether or not DU is a health hazard, those who believe that it is would be better served at getting coal banned than weapons use of DU.

[treepig]

19. more on the environmental release of radioactive waste from coal

is available in this thread:

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=115x2038

[Renew Deal]

5. Word is that they are splitting atoms in the Environment/Energy/Science

forum. You might want to ask there.

[priller]

6. Aside from the radioactive business

DU is a heavy metal and is highly toxic. You have a much greater danger of chemical poisoning than from the radioactivity. From that alone it is pretty bad.

Yeah, we definitely need the chemists (and biochemists) in on this one.

[Journeyman]

8. A couple of websites to check. . .

The International Depleted Uranium Study Team

www.idust.net/


The Campaign Against Depleted Uranium

www.cadu.org.uk/


Lots of great info on both sites.

[Cell17N]

9. As a scientist.

I know that all that radioactive stuff is far far far less dangerous then cars. But politicians who play by the paranoia of the masses get points by stopping the research.

[Dudley_DUright]

10. U235 is more fissile

which means that is easier to split when bombarded with neutrons, but U238 is radioactive (an alpha particle emitter with a half life of roughly 4 billion years). Also the decay products of U238 are radioactive (a decay chain that stops at a stable isotope of lead). Alpha particles are much less penetrating than gamma rays, but the problem is that DU rounds that hit are partially converted into small dust particles that can get into the body and cause harm. The following PDF document is a fairly good even handed treatment of the "myths" of DU.

http://www.antenna.nl/wise/uranium/pdf/dumyths.pdf

[treepig]

11. i've been accused of being a DU apologist before here on DU

but i don't see any harm in trying to point out the facts as generally accepted by the scientific community.

first, depleted uranium is not a radiation threat. if you calculate the amount of DU strewn around a battlefield, the total amount of uranium would not increase measurably (there is already a significant amount of uranium in the natural environment - in fact it is permissible for bottled water to contain 30 mg of uranium per liter).

second, DU is actually used a radiation shield - there is a company in tennessee who specializes in this application (do a google search!). also, a 747 (and other aircraft) has a couple of tons of DU on board as counterweights. some tanks also use DU as armor, and as a consequence the radiation within the tank is lower than outside (i.e., the tanks' occupants are shielded from naturally-occurring radiation).

third, the half life of DU's radiation is 4.5 billion years - right there, that should indicate that there's no way in hell it could reasonably be a radiation hazard (and if one does the math, the point is easily confirmed - i've posted the calculations before to great apathy, so i won't bother again right now).

fourth, there is a paper published in peer-reviewed literature that states that the only persons who had demonstrated health problems from DU are those in vehicles impacted by DU-containing munitions. generally, such persons are dead because they're "blowed up real good" but if they survive it is possible that they were subject to high enough levels of DU to suffer health problems. once again, these problems are still a subject of debate, but reputable scientists consider the possibility to be worthy of investigation.

fifth, for the group of people mentioned in the fourth point (above) who apparently suffer DU-related health problems (and this may possibly include decontamination crews as well, such as those made infamous by a major rokke (if i've spelled his name correctly)) - the health hazards are due to the chemical toxicity, not the radioactivity, of DU. there is a study that shows that the chemical toxicity of a given amount of DU is one million times greater than the radiation toxicity (and it's still an open question whether the chemical toxicity is a health hazard in adults, although rat studies have shown it to be a teratogen).

[booley]

13. I think you missed something...

"only persons who had demonstrated health problems from DU are those in vehicles impacted by DU-containing munitions. generally, such persons are dead because they're "blowed up real good" but if they survive it is possible that they were subject to high enough levels of DU to suffer health problems."

Well firstly remeber that a lot of the research is hard to come by on DU. But I think you also forgett soemthing... when DU munitions explodes it doesn't just go away. it settles into a dust that coats everything. And then gets breathed in and stays iin the lungs. For life apparently.

So the only thing really making a variable between the guys immediatly affected byt he DU and everybody else is time. Stay around the stuff long enough and you won't need to survive a balst for it to poisen you.

It's as if I spread abestos particles all over your house on day. You don't need to have breathed in the abestos when it first came into your house. You just need to stay in the house on a regular enough basis...

And the PENTAGON has already said it has no plans to clean up the battle sites from the two gulf wars.

[treepig]

14. it's a matter of concentration/dose

once the dust is dispersed into the environment, the amount is way to low to be harmful - in fact the amount of weapons-derived uranium "contamination" does not measurably increase the amount of uranium above the levels already present. by contrast, higher levels of dust may stay within an impacted vehicle and thus be dangerous.

seriously, don't believe me, go have a look at peer-reviewed literature yourself - which you can find at the NIH's PUBMED search engine (i don't have the papers available right now, but might be able to find them and send them to you tomorrow if you're interested):

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed

interestingly, your house analogy does have relevance to uranium in the environment as one of the decay product of U238 is radon, a gas that is often trapped in basements and is probably the greatest source of radiation exposure for most people in the usa. but, in the preparation of DU, all the decay intermediates are removed from the uranium, therefore DU is actually much "safer" than than the naturally occurring uranium that underlies your house and gives rise to the radon seeping into your basement.

finally, if you are concerned about DU, then i suggest that you turn your attention to coal burning, which has released 400 times more uranium, included the non-depleted U235 form, as well as several times more thorium, into the environment in a similar fine particular form that results from weapons use. further, much of this "contamination" is right here in the usa harming you and your family, not a bunch of iraqis no one gives a damn about (i know that's not the mentality of the readers of this forum, but if you're going to get the general population concerned, that's the reality).

[mobuto]

15. I'm not a DU alarmist

And I agree that DU can't have much of an effect when dispersed in the environment. But what about DU dust around targets that have been hit by DU shells and bombs? A destroyed tank or building might be covered with the stuff, and I think there's a legitimate question of what the effects on locals are of breathing that dust.

The form that uranium takes is extremely important. FiestaWare dishes may have a U-238 containing glaze, but there's little risk of danger, whereas there may well be from inhaled dust.

BTW, nothing pisses me off more than the couple of uninformed righteous nimrods who run around DU (the Democratic Underground, not depleted Uranium) and say that DU (depleted Uranium, not the Dem Underground) is a "nuclear" weapon.

[treepig]

17. i've seen pictures of children playing on wrecked vehicles

which i assume have been destroyed by DU munitions. now, after a good rainstorm the DU dust is probably washed away so they're in much greater danger from cutting themselves on jagged metal and bleeding to death - but since it doesn't rain that much in iraq the effects of DU on people thusly exposed is probably a legitimate concern. but once again, any deleterious health effects would be solely due to the chemical toxicity of DU and not to its extremely low levels of radiation. activists who are concerned about DU do themselves a great dis-service by hyping the (virtually non-existent) radiation aspect (because it makes them appear to be ill-informed and completely without credibility).

and as far as people who are actually in buildings or vehicles hit by DU munitions - together in both gulf wars there are probably getting to be close to 100,000 who have been killed by explosions. there have yet to be any deaths unambiguously attributed to the long-term health effects of DU (and given the other toxic agents present on the battlefield, there probably never will be). the bottom line is that i'm as outraged as anyone about the use of DU on the battlefield, but my outrage is quite incidental to the exact chemical or physical properties of the metal in question - rather it is due to the outrageous and manufacter basis of the gulf wars in the first place.

[meow mix]

16. "once the dust is dispersed" thats not a good enough apology, for me

just my opinion - i still think its reckless and evil, same goes for the apologists.

[treepig]

18. the point i've been trying to make is that anti-DU activists

tend to make complete asses of themselves by advancing scientifically impossible arguments. of course, that's their right.

the bigger concern is finding an answer to the question "what is actually causing the elevated levels of birth defects in iraqi children and gulf war syndrome in coalition troops?" when the activists demand an exclusive, or wrongly focused, emphasis on DU there's a huge chance that the "real killer" will be overlooked and the people in need will never receive the help they need. so i submit that the real "reckless and evil" approach is to attribute qualities to DU that it cannot possibly have just to make a political point.

[Eloriel]

20. Well, you haven't convinced me

And the fact that your take on the issue just happens to coincide with the "see no evil, hear no evil" Pentagon assurances doesn't help.

BTW, birth defects are but one part of it:

Vieques http://www.thegully.com/essays/puertorico/010212depleted_uranium.html

NATO troops stationed in Kosovo
http://www.iacenter.org/depleted/du_eur.htm

[iverglas]

22. "Once ze rockets are up ...

Who cares where zey come down?
Zat's not my department."
says Werner von Braun.

- Tom Lehrer, somewhere in the 60s, on the new job take up by leading Nazi Germany rocket scientist von Braun with the US government.

Couldn't resist. ;)

[billyskank]

21. One problem with DU munitions is

that the stuff gets pulverised to dust when the shell explodes. This dust can be inhaled and then sits in the lung slowly emitting low-level radiation for a long time. I understand this long-term exposure can be harmful.

You're quite right that DU is less radioactive than natural uranium. It's not like having a block of plute lying around.