By definition, a plutonium 239 is a specific kind of nuclear isotope where it is known to have produced from transmutation of uranium in fuel rods. In addition, among it, main advantages would be that it has a significantly higher chance of being involved in a nuclear fission as compared to uranium.
Nothing happens to these particles when it comes to size however if it were to be speed, the sample would increase. Fact: The size of a particle will never change!
