Energy Content of the US Inventory of Depleted Uranium in Comparison to World Energy Demand.
Recently in this space, I posted data from the 2021 IEA World Energy Outlook (page 294) giving Energy Demand and Sources, the data historical up to 2020, with projections out to 2050 based on "stated policies," said policies being based on "by 2050" rhetoric issued by governments to conceal that they have, after many decades of "by 'such and such' a year" statements by governments in the United States and around the world have all proved meaningless. (They have by and large proved meaningless because they all rely on the destruction of vast land areas and the combustion of mass amounts of dangerous fossil fuels to service so called "renewable energy." )
The table of that data is here: 
The comments connected with the post in which I placed this table were, um...um...um..., to be nice, should we say "predictable," and involved someone defending the inexcusable, at least that's my view.
Here is a report on the 1997 inventory of depleted uranium, most of it stored at former enrichment sites, at that time in the form of cylinders of UF6 gas: Availability of Uranium Feed for the Fissile Materials Disposition Program Volume 1 : Depleted Uranium Hexafluoride (White, ORNL/TM-13417, Rev. 1)
Here is a table from that report:
The "assay" column refers to the U-235 content, but for the most part this inventory has much lower fissionable U-235 than natural uranium, although some natural uranium (U-235 content = 0.711%) is present in the inventory. For the purpose of the calculation below I will assume that it is nearly pure U-238.
U-238 is among those actinides for which there is no critical mass; no matter how large an assembly is made, a fission chain reaction cannot occur in it. (Other such nuclides include Th-232 and U-236, the latter which went extinct on Earth but is now available synthetically and as a side product of the use of nuclear power.) U-238 has a small fission cross section in the fast spectrum, (neutron energy in the 1-2 MeV range), but it is dwarfed by the scattering cross section, and as a result of scattering collisions, the neutron energy falls rapidly into the epithermal range, hence no critical mass.
However, U-238 is a fertile nucleus; it can be transmuted with the capture of one neutron and two beta decays into plutonium. This event is routine in all nuclear reactors; all nuclear reactors produce plutonium, but fast reactors produce more plutonium than they fission. These, of course, are breeder reactors.
A happy event in sustainable energy is the development of "breed and burn" reactors by multiple US companies, and, I assume, multiple foreign countries as well. These can use depleted uranium as a fuel by transmuting it and "burning" it largely in situ without refueling for decades.
Thus it is worthwhile to consider what the energy content of depleted uranium is.
I do calculations involving plutonium all the time and have been doing so for many years. Among the spreadsheets I use for this purpose, some include the breakdown of plutonium fission energy by type on an atomic scale. Here is a section of a table in one such sheet:
The source of this data is the BNL Nuclear Data Center's Evaluated Nuclear Data File (ENDF) Retrieval & Plotting
Further down in the same table the energy content of a kg of plutonium is calculated:
A kg of Pu-239 (produced from U-238) has an energy content of a little over 80 trillion joules.
From the above, it appears that there is about 500,000 MT of depleted uranium in the form of UF6, a volatile compound having a molecular weight of 352.0193 daltons, with a mass fraction that is 67.618% uranium and 32.382% fluorine. Thus we have about 338,000 tons of uranium already mined and isolated.
338,000 tons of U-238 translates to 338,000,000 kg, already mined and refined, usable as fuel in "breed and burn" reactors with a plutonium "spark," a critical mass of plutonium. Some years back I posted in this space the critical mass of some plutonium isotopes, and for convenience, I reproduce the table from that post here:
Bare Metal Critical Masses of Commonly Available Plutonium Isotopes.
We have plenty of plutonium on hand to act as "sparks" for breed and burn reactors, now, at a time that the concentration of the deadly dangerous fossil fuel waste as of yesterday reached 421 ppm.
Now.
338,000,000 of plutonium thus, with an energy content of 80 trillion joules/kg is thus equal to 27 Zetajoules of energy.
World Energy consumption in the Covid lockdown year of 2020 fell to 589 Exajoules, but we can assume it will rise at least to 600 Exajoules in 2022, perhaps more; we are about to set a new worldwide record for the consumption of coal. Thus the US alone has about 55 years worth of all the energy in the world, no dangerous natural gas, no coal, no petroleum, no forests trashed for biomass, no wilderness on land or sea trashed to make industrial parks for wind turbines, already mined and isolated. The US of course only has some of the isolated uranium; it possesses less than 1/4 of the world's nuclear reactors. Other countries all around the world enrich uranium, and thus all of them have depleted uranium stores.
The world has foolishly set about to mine vast quantities of lanthanide elements to support the "renewable energy" fantasy which has failed miserably to address climate change at a cost of trillions of dollars. The mine tailings of lanthanide all contain the radioactive element thorium, which is concentrated with respect to the original ores from processing to obtain lanthanides. The inventory of this high grade thorium is less clear, but it is also a fertile nucleus, and it thus would not be absurd to assume that the inventories of "waste" thorium are similar. It is therefore easy to estimate that mining of uranium, oil, natural gas, coal, and for that matter lanthanides, cobalt for batteries, nickel for batteries, lithium for batteries, iron and coal for steel for wind turbines, vast quantities of copper to interconnect diffuse energy energy sources, can be minimized if not wholly eliminated for centuries with the uranium and thorium already mined.
It is important to note that as utilized now, largely in light water reactors, the thermodynamic efficiency of nuclear power plants as Rankine cycle devices is rather low, around 33%. It is easy to consider that VHTRs, "very high temperature reactors" can achieve much higher thermodynamic efficiency - I estimate around 70 - 80% - and thus we can exploit higher efficiency to address human development goals and the elimination of poverty.
Ultimately, as most people who have studied the issue - and let's be clear anti-nukes and "I'm not an anti-nuke" anti-nukes besides selective attention, very little real knowledge of nuclear issues; in fact they are functionally illiterate when they try to discuss these issues - recognize that the long term source for inexhaustible uranium is seawater, but the requirement for using this source is centuries away. This said, it is probably the case that the world will ultimately require vast amounts of desalination, which will only be possible using nuclear energy, and thus uranium might well fall out of this process with appropriate resins and/or selective membranes. It is also true that any attempt to remove the dangerous fossil fuel waste carbon dioxide by the future generations we've so contemptuously screwed, will best proceed via extraction from seawater, and thus we can start collecting uranium from this source any time we want to do so.
(I analyzed geological aqueous flows on a planetary scale here, Is Uranium Exhaustible and in less detail here: On Plutonium, Nuclear War, and Nuclear Peace)
Recently I've had two "I'm not an anti-nuke" anti-nukes whine about mining of all things; in response to them I cited the "I'm not an anti-nuke" anti-nuke Benjamin Sovacool's analysis - in a very rare burst of honesty from a "renewables will save us" anti-nuke - about the mining requirements associated with so called "renewable energy." Sovacool's solution is to tear the shit out of the seafloor screwing it up even to a larger extent than even the detestable wind industry is doing all over the world already.
The absurd selective attention of these bourgeois poor thinkers inspired this remark in the case of one of them" thus:
We hit 421 ppm of CO2 concentrations in the planetary atmosphere yesterday. It may be time to think anew and stop spinning our wheels with illiterate fantasies.
March 27: 421.00 ppm
March 26: 419.64 ppm
March 25: 417.99 ppm
March 24: 417.98 ppm
March 23: 418.03 ppm
Last Updated: March 28, 2022
Recent Daily Average Mauna Loa CO2
Have a nice day tomorrow.