(ELI5) I just read that plutonium is very rare. I have little to no knowledge of science etc. where in the natural world does it come from? How do you source it?
There is no natural source of plutonium. It is artificially made in nuclear reactors by bombarding uranium with neutrons. Then, the resulting plutonium is purified.
Hence, why it is super rare.
short answer: almost all the plutonium we have is manufactured in a nuclear reactor.
longer answer: radioactive elements, basically, are unstable. they want to fall apart into a more stable format. when uranium is used in a reactor, it undergoes fission (splitting), with the atom shedding protons and neutrons in an attempt to reach a more “stable” state.
One of the decay chains leads to Plutonium, a more unstable and radioactive material than uranium, which makes it possible to make smaller bombs form it as you need less materail to reach critical mass.
this higher instability is why its extremely rare in nature. it decays into something else.
As the others are saying, we make Plutonium by adding Neutrons to Uranium.
For this you have to know that an atom’s core is made up of Protons and Neutrons. Tue number of Protons is what defines which element it is. So if we add one neutron to Uranium, but that neutron then decays into an Proton and an Electron, we have effectively added one Proton to it – changing it into Plutonium.
Chemical elements are collections of protons (positively charged particle), neutrons (as the name suggest, particles with no net electric charge) and electrons (negatively charged little devils).
What makes elements different is the number of protons: hydrogen has one proton, helium has two and so on up the periodic table. This property is also known as the “atomic number”.
The heavier elements such as Uranium, Plutonium have atomic numbers of 92 and 94, respectively.
Now, elements with a given atomic number but exists as several variants with different numbers of neutrons are called isotopes. Some isotopes are long lived and stable, and some are unstable and quickly break up into other things. This is what we mean by “radioactive”: the isotope is unstable and emits radiation to turn into different isotopes or entirely into chunks of different elements with smaller atomic numbers.
Crucially, this property goes the other way too: you can grab an isotope of, say, Uranium-238, a commonly found isotope of Uranium that is non fissile, bombard it with deuterium (essentially a hydrogen that has a neutron in addition to its usual single proton), and voila, you obtain Plutonium when the Uranium captures two protons to go from an atomic number of 92 to one of 94.
It is a bit more involved than this, with the first product of the reaction being neptunium that subsequently decays into Plutonium-238, but you see the picture. In fact this is how Plutonium was first synthetically made. This process can also occur naturally: any Uranium-238 occurring naturally may capture some decay products from other decaying Uranium (or other isotopes), and voila, you have naturally occurring Plutonium. That process however is exceedingly rare, which is why Plutonium occurs naturally only in trace amounts.
The number in “Uranium-238” or “Plutonium-238” is the “mass number”, the sum of the number of protons and that of the neutrons.
It doesn’t, other than trace amounts. We *made* it, by irradiating uranium with neutrons. The simplest route is U-238 + n –> U-239* –> neptunium-239 –> Pu-239.