Basically DU is what’s left after they take the potent stuff out to make bombs.
I don’t know about the characteristics of Uranium that would make it useful as armor. As a projectile it’s used for the same reason that lead is used. It’s HEAVY (i.e. very dense). Uranium is even more dense than lead which has been the traditional material for projectiles (bullets). The reason for this is simple…more weight equals more kinetic energy. You never see a ‘nickel’ bullet because it’s too light…not as much punch when it reaches the target (and also loss of accuracy…more easily affected by wind and what not).
There are many requirements I imagine when choosing what to make armor out of. Density obviously can’t be too important or at least not the only consideration otherwise we’d see lead armor (but lead is too soft). Given that weight plays a role when deciding on how much armor to use it would seem that Uranium also may not be a good choice. But for all I know Uranium has fantastic charateristics making it ideal for armor or perhaps to create some super-alloy. I don’t know…just thinking out loud here.
Racing yachts ? We can probably conclude that this is not an extreme radiological risk. (It’s used for radiation shielding, right ?) But obviously, it might be poisonous.
Well, my back-of-the-envelope calculations say that U-238 is about a Curie a ton… Anyone have any data on safe exposure limits for humans, or for how much is used in the armor of a typical tank? Of course, most of the radiation from depleted uranium isn’t from the 238, it’s from the residual 235 that’s still in it, for which I don’t recall the half-life off the top of my head. Still, it’s undoubtable that the total radioactivity is significantly less than natural uranium, which isn’t even a controlled substance.
The figures I have found vary (slightly different figures for different ores), but natural uranium has the approximate constituents[ul]
.000055 [sup]234[/sup]U, t[sub]½[/sub] = 2.45 × 10[sup]5[/sup]
.007200 [sup]235[/sup]U, t[sub]½[/sub] = 7.04 × 10[sup]8[/sup]
.992745 [sup]238[/sup]U, t[sub]½[/sub] = 4.46 × 10[sup]9[/sup]
[/ul]
My estimate is that 238 and 234 each contribute about 48% of the radioactivity of natural uranium, and 235 only about 2%. This explains the quotation that Spiny Norman gave
CRC Handbook of Chemistry and Physics 74[sup]th[/sup] Edition** says (p. 16-33n.)
I don’t know how to square this with the ballpark estimate of disintegration rates for U-238 made by Chronos (about 1 Ci / ton) and my calculation (about 0.35 Ci / ton).
Hmmm. I didn’t know that there were any stable isotopes of Uranium. Perhaps the stuff is fairly inert after all. Still, if DU shells can penetrate DU armor (as mentioned above) then the whole reason for having DU armor has been refuted, hasn’t it. And the GWS=Shell Shock=PTSS argument sounds pretty good to me. Still, according to the veterans webpages, the gov’t didn’t do much about that, either, so mayby they still have a right to bitch.
Re: weight of armor. During the build-up to the Gulf War, a news report said that M1A1 tanks have a fuel efficiency of only 3/5 mpg! Any more DU armor, and they’ll need extension cords to run the damn things
I would say it hasn’t. No simple paper-defeats-rock analysis can have much validity hear. A DU round will be able to defeat armor at a greater range than a lead- or tungsten-core round. DU armor of a given thickness will (presumably) be able to defeat incoming rounds at closer ranges than steel, titanium, or composite armors. Nobody uses DU shells much, other than the U.S. (I don’t know of many non-US 30mm aircraft cannon either, as far as I know), so it might not really matter.
I’m still not wholly sold on uranium as a building material. The laminated and composite armor sprees of the 70s and 80s were informed partly by Israeli experience in the Yom Kippur war. The same goes for the reactive armor phase. Now we have DU armor. To keep our tanks from being knocked out by…? T-85s, that we have outclassed pretty much from the start? Enemy aircraft that rarely come in effective anti-tank configurations? Land mines?
NATO fire control is the best in the world. NATO airland thinking is much more advanced than most of our potential opponents. DU seems like a techno-happy incremental improvement in an area where we have an acceptable advantage (I don’t trust active armor, either). The U.S. will continue to win wars, because we have the largest tax base, the most technical expertise, and the best and most relevant allies (war in the Balkans: who do you want on your team - Germany or North Korea?)
Bibliophage: I think that all of the numbers can be reconciled. My estimate of the radioactivity of 238 was really only good to about an order of magnitude, so it squares with yours, a half-order lower. As to reconciling that with the CRC, they’re referring to natural uranium, not U-238. I think that the problem is in your estimate that the 238 contributes 2% of the total radioactivity… It should be a good bit less.
Diceman, there aren’t any completely stable isotopes of uranium, but U-238 is awfully close-- Half-life of about 4 and a half gigayears.
Hey Diceman, as a civvie the one thing i noticed was the pollution caused by the oil wells burning. The oceans nearby had oil washing up on them for months and the rain (those few instances when it did) was greyish black. Has this been explored as a possible source for GWS?
I always thought that the “depleted” meant that it was, for lack of a better word, “un-radioactivated”. IOW, it’s not (as) radioactive (as nuke fuel-type uranium).
I want to thank you all for this DU thread – recently around where I live there’s been a lot of mentioning of the stuff.
Among the whole hoo-hah over the safety and further use of the Vieques Island Naval Range (which has a strong component that everyone suspects the Navy’s been dumping nasty stuff there) it came out that at some point in the late 80’s the Marines “mistakenly” fired off some 200 DU rounds, which were not even authorized for training use at Vieques.
Anyway, it looks to me as if the DU round would be a “natural” idea for the armies who had a heapin’ lot of uranium lying about from their countries’ nuke arms/energy programs. I wonder if the then-USSR deployed it, too?
The SU-25, the Soviet version of the A-10, packs a 30mm cannon. It isint the lead, um, DU, flinging 6 barrled gun that is on the A-10, but it is 30mm just the same
