Thread by @simonahac

🤓@senbmckenzie facts are important…

while there's an immense amount of energy in all matter — E=mc² and all that — we *don't* have technology to get a lifetime's energy for a person out of a golfball sized lump of uranium.

since we can't rely on @MineralsCouncil, a thread:

https://twitter.com/senbmckenzie/status/1367663287270211585

if you did want to power an average australian's lifetime energy needs from uranium, what would it take? 🧐

…by a couple of different methods (link at end), i estimate that 2.1GWh would cover all the energy needs of an average australian lifetime, assuming full electrification.

working back from this handy chart from @WorldNuclear, in the best case you'd need 417cc of nuclear fuel (mainly UO₂) for a single australian's lifetime.

but how do you get that? read on…

world-nuclear.org/information-li…

first, if you are using traditional mining techniques, you'd need between 4.8 and 96 tonnes of uranium ore, depending on ore quality.

you then mill this to produce 46kg of yellowcake.

…you now have ~4.8 to ~96 tonnes of mill tailings to dispose of.

at this point only 0.7% is the useful uranium-235 isotope, but you need it to be ~5%.

so you convert it to 58kg of uranium hexafluoride (UFl₆) — an extremely toxic compound — and run it through cascades of centrifuges to create a sample that has the right concentration.

thanks to the centrifuges, you've now got ~6kg of enriched UFl₆. awesome!

unfortunately, you've also got 52kg (10.2 litres) of UFl₆ "tails".

what to do with it?

put it in cylinders and store it, could come in handy some day! (not joking. just make sure it doesn't leak!)

now, you take the enriched UFl₆ and convert it into 4.6kg of UO₂ (plus a few other materials), put it into tubes (fuel rods) and configure into a fuel assembly.

then you stick it in a reactor where it participates in a controlled chain reaction, producing heat that boils water, which ultimately drives a steam turbine and makes lots of lovely, very low CO₂ electricity.

after ~5 years the fuel has done its useful work, and it's time to dispose of it.

…but it's still a bit too spicy, so it sits in a spent fuel pool for a few years.

then, generally when the pool is full, you take it out & put it into casks.

it's quite safe when encased in (lots of) concrete & steel — but if you plan to eat it, wait 130,000 years until it's as _radioactively_ benign as natural uranium.

(uranium is toxic. pls don't eat it.)

so, @senbmckenzie,

for an aussie lifestime, you'll need 4.8–96t of uranium ore, leaving:
• almost as much mill tailings
• 10 litres of toxic UFl₆
• a bit more than a coke can lump of toxic & radioactive waste

a lot less than coal, but a *lot* more than "a golf ball amount".

don't get me wrong… it's freaking amazing that humans worked out how to do this… but let's not confuse the public with false claims.

[nb. i haven't tackled costs above. hoo boy, that's another massive subject!]

calcs here:
docs.google.com/spreadsheets/d…

erratum:

uranium hexafluoride is UF₆, not UFl₆.

(mr edwards, my chemistry teacher would be most disappointed!)

https://twitter.com/nuclearkatie/status/1368255847998967809

erratum #2:

wrong to say we don’t have the technology!

technically we do… we can put U into a breeder reactor (quite rare), reprocess (quite expensive) & repeat.

it’s not economic, and to my knowledge has never been done, but it’s _theoretically_ possible with existing tech.

so, in commercial/standard practice, you’d need the equivalent of ~100 golf balls of natural uranium to power an average aussie life.

...but if money was no object we know how to build a process that could approach the theoretical potential.