Depleted Uranium munitions.
This is not a post about nuclear energy. It’s a post about the use of Uranium in munitions. Now, I’m not pro- or anti- Uranium weapons. If there’s a credible case to be made that they have significant on-going indiscriminate health effects on civilians, and on military personnel for that matter, and on the environment, then they probably shouldn’t be used, just because they’re cheaper and a bit better than the Tungsten alternatives. We have better things we could be using that Uranium-235 for, anyway. I’m more interested in seeing an end to War in general to seeing and end to the use of Uranium in weapons.
Here’s what captured my interest. Some work from our friends over at the Low Level Radiation Campaign, looking at the use of Uranium in weapons by the Israeli military in Lebanon. These guys are rather famous for a bit of fringe science, in some cases, but on this issue, I found what they have to say interesting.
Now, at face value, I trust the numbers they’re presenting here. I’m confident that the people who these people consult with, who have access to the gamma spectrometers, mass spectrometers and the like, know how to use these instruments.
Now, they’re reporting samples containing Uranium with Uranium-238 and Uranium-238 atoms in, say, a 108:1 ratio. That corresponds to a Uranium-235 concentration of about 0.9% by mass – greater than the 0.72% or so that you’ll find in nature, so they’re calling it enriched uranium.
Now, there is no factory that churns out 0.9% enriched U-235. There’s no technological, scientific or industrial application, in nuclear engineering or anything else, that uses such uranium. And there’s absolutely no way, that I can understand, that it makes sense to manufacture a munition from such material, as opposed to Depleted Uranium, or at least Natural Uranium. It won’t give you a better armour penetrator, and it’s energy intensive and expensive to enrich Uranium – plus, U-235 is a valuable nuclear fuel!
Israel doesn’t have a large (actually, they don’t have any) nuclear power program, and they are not expected to have surplus depleted uranium laying around. From our limited knowledge of their nuclear weapons technology, it is reasonable to assume that their fission weapons are based on plutonium, and that they are not enriching large quantities of Uranium for the weapons industry. It is interesting to ask where these weapons are coming from – where is the Uranium, with what may be a slightly enriched isotopic composition – coming from?
The only thing that came to my mind that this material could be is reprocessed Uranium, seperated from used reactor fuel. A quick look at Wikipedia (I don’t have any better reference for that number at the moment) tells me that used fuel contains Uranium with a U-235 concentration of, at most, about 0.83%.
The figures that they give on pages 3 and , of U-238:U-235 atomic number ratios of 113, 117, 123 and 133 correspond to Uranium-235 compositions, by mass, of 0.87%, 0.84%, 0.80% and 0.74% , and seem to give support to this theory.
But the authors of this document have gone looking for Plutonium-239, Pu-240 and Cs-137 to determine if this material came from used nuclear fuel – which is obviously not going to tell us anything, as I doubt anybody is going to make munitions out of straight unprocessed used uranium fuel. Obviously, these different chemical elements are seperated during nuclear reprocessing. I would not expect any such material to contaminate the seperated Uranium in detectable quantities.
What they should be looking for – the clear signature of reprocessed Uranium as distinct from natural Uranium, enriched or not – are the Uranium-236 and Uranium-232 isotopes, which do not occur in nature to any appreciable degree, although they are produced in Uranium-fuelled reactors.
The ICPMS and nuclear spectroscopy techniques employed in this study would be perfectly suitable for looking for such nuclides.
I’m not discounting what they say completely at this stage, but I’d like to see more independent study and review along these lines.