"There is more (weapons grade) material on civilian sites than all weapons stockpiles put together"

[struggle4progress]

27. As far as I can tell, the OP concerns the possibility that significant quantities of HEU

remain unsecured at civilian sites, posing a continuing proliferation concern

The resulting thread, in familiar manner, wanders over various other topics, such as depleted uranium, before settling in familiar grooves

txlibdem in #14 would have us believe that 57,000 pounds of weapons grade Uranium come out of each coal plant each year
http://www.democraticunderground.com/?com=view_post&forum=1127&pid=10459
This is (of course) blatant nonsense: what comes out of coal plants, beyond lots of CO2 we don't need and lots of acid gases, is a bunch of fly-ash that's roughly as radioactive as some shales. If this fly-ash were comparable to weapons grade Uranium, it would spontaneously experience run-away fission; it doesn't, and the shale beds don't, and nobody is going to build an atomic bomb using critical masses of shale or coal fly-ash, since neither of these substances has a sufficiently high density of fissile materials to have a critical mass. "Weapons grade Uranium" (on the other hand) does have a critical mass, and it's been sufficiently enriched in productive isotopes of uranium that if a critical mass is assembled quickly enough, it does spontaneously experience a catastrophic run-away fission reaction

txlibdem's post is followed by PamW's obligatory repost of Alex Gabbard's ancient idiotic "article." Gabbard claims to believe that coal ash is rich in exploitable mineral products with commercial value; that by collecting uranium from coal combustion, significant quantities of fissionable material could be accumulated; and that any country with coal-fired plants therefore poses a proliferation risk. These arguments are roughly of the caliber of the crank posts we sometimes see calculating how much gold there is in the ocean and how rich we could become by extracting it. Crudely put, coal has about the uranium content of the soil in an average backyard, and coal fly-ash is slightly more concentrated than that, but still has pretty low levels: if there were any real prospect for extracting uranium profitably from the fly-ash, somebody would have already done so, but the concentration is nowhere near the levels of even low-productivity uranium ores

In the course of the discussion, participants do manage to discover some sloppy writing of mine from a year or so ago: Weapons-grade uranium is about 85% U-235, with a critical mass of some tens of kilograms. Natural uranium is about 2% U-235 49% U-238, and 49% U-234. Thus, you need to start with at least 40x more natural uranium than the amount of weapons-grade uranium you hope to obtain. It is true that the "2% U-235 49% U-238, and 49% U-234" are activity levels for natural U and that the per weight levels 0.71% U-235 99.28% U-238 and 0.005% U-234. That was sloppy of me, and I applaud my ideological opponents for their diligence in rooting out my error, to the benefit of all of us who prefer reality based argument, but in fact by correcting my error they have only strengthened the argument I was making, since the following sentence should then be amended to Thus, you need to start with at least 85%/0.71% = 120x more natural uranium than the amount of weapons-grade uranium you hope to obtain -- which means that producing weapons grade material is even harder than I previously claimed