Is There More Uranium Two 35?

Uranium two 38 is harder to split than uranium two 35, because it just has three more neutrons. Neutrons are neutral, but they do have the strong force that holds the nucleus ther so the fact that neutrons are neutral doesn't mean they don't play a role in the strong force. So we use centrifuges and all sorts of other technologies to get uranium two 35 to be a larger percentage. And then we do things to slow down the neutrons that are produced so that they are much better at causing fision. In traditional reactors, we bathe these uranium rods in water which is really good at slowing down neutrons.