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  • Nuclear programs are constantly in the newswith reports that theyre enriching uranium.

  • Usually, the stories mention percentages and centrifuges, but to the uninitiated, it’s

  • not clear why these things are important.

  • What exactly does it mean to enrich uranium? And at what point should we be worried?

  • Now when I imagine enriching uranium, I picture teaching uranium to paint, or dance, or something,

  • but I looked it up... and that’s not what it is.

  • For nuclear power or weapons, the isotope of uranium were after is U-235, which has

  • 92 protons and 143 neutrons.

  • But the vast majority of uranium we pull out of mines, 99.3% of it, is the isotope U-238

  • which has 3 more neutrons, and behaves differently.

  • Only about 0.7% of Uranium in the world is U-235.

  • U-235 is fissile, meaning all you need to do to split it is hit it with a low-energy

  • thermal neutron. The neutron doesn’t smash the nucleus apart, but instead is absorbed

  • by the atom, making it unstable.

  • When it splits, it releases energy and more neutrons that can then repeat the reaction

  • with other U-235 atoms.

  • You can still split U-238 atoms, but you’d need high-energy neutrons to do it, which

  • is less efficient.

  • So when it comes to producing energy, the higher concentration of U-235 relative to

  • U-238, the easier it will be.

  • Nuclear power plants that aim to produce energy steadily over a long period use pellets that

  • are between about three to five percent U235, while nuclear bombs that want to release a lot of

  • energy all at once have concentrations as high as 90% U235.

  • The challenge is, how do you take naturally-occurring Uranium that’s 0.7% U-235, and up its concentration

  • to those lofty numbers?

  • That’s where enrichment comes in. A couple of approaches have been used to enrich uranium.

  • The one used by the Manhattan Project to build the first atomic weapons was

  • gaseous diffusion.

  • In order to separate the uranium isotopes, the first step was to turn it into a gas by

  • adding six fluorine atoms.

  • Once gaseous, the uranium hexafluoride was pushed through membranes whose holes were

  • just big enough to let the molecules through. The lighter U-235 moved slightly more quickly

  • through the barriers, so after several hundred membranes, the gas at the other end had the

  • required amount of U-235.

  • The more modern method is using centrifuges, which are cylinders that spin at very high

  • speeds, enough to separate the lighter U-235 from U-238.

  • The first step is the same: turn all the uranium into gaseous uranium hexafluoride. Then, like

  • a hipster with a vinyl collection, get spinning.

  • As the gas is spun around, the heavier U-238 will move towards the outside of the cylinder,

  • while the U-235 will drift towards the center. The slightly enriched gas there will be piped

  • out, and fed into another centrifuge.

  • And on and on it goes, using thousands of centrifuges connected in series and parallel

  • formations, steadily upping the amount of U-235 in the mix.

  • Once uranium is 20% enriched, it’s a simple matter of rearranging the centrifuges to create

  • weapons-grade uranium very quickly. That’s why a vital part of ensuring a country is

  • only using their nuclear program for peaceful pursuits is inspecting how their centrifuges

  • are arranged.

  • The proliferation of nuclear weapons remains one of the most serious threats to the world.

  • But nuclear power’s potential to provide energy without adding greenhouse gasses to

  • our atmosphere is a huge possible benefit for humanity.

  • If were going to use uranium for the good of us and the planet, then it just needs a

  • little enrichment.

  • While the centrifuges enrich uranium, theyre also feeding the more concentrated U-238 the

  • opposite direction, producing depleted uranium at the other end.

  • Nuclear power is still something that worries a lot of people, and recently Russia decided

  • to turn a boat into a floating power plant. To see if this is a bad idea, check out my

  • video on it here.

  • If you like this video, let us know in the comments below. Make sure to subscribe to

  • Seeker and thanks for watching.

Nuclear programs are constantly in the newswith reports that theyre enriching uranium.

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