Where do the nuclear source come from?

There are a lot of nuclear sources, like those used in medicine or those used in industry, or those used in nuclear power stations.

Most long half-life nuclear sources are naturally occuring. They are purified and refined after excavation. Examples are uranium-235, radium-226 etc.
However, some trans-uranium elements are made artifically, like plutonium-239 or Americium-241 (used in ionization chanber smoke detectors).

Short half-life nuclear sources are mainly artificial (man-made). They are fabricated in nuclear reactors. Examples are those used in medicine, like iodine-131, caesium-137, strontium-90, phosphorus-32, cobalt-57, and some very short half-life positron emitters like flourine-18 (half-life of 110 minutes).

(1) Nuclear source of our present nuclear fission plants is uranium (uranium ore is mined, milled, enriched, and fabricated into nuclear fuel and then irradiated in a reactor), Uranium mining is carried out in more than 25 countries around the world. Major uranium mines are located in Canada, Australia and Kazakhstan that contribute more than half of world's uranium production.

List of working Uranium mines
http://en.wikipedia.org/wiki/List_of_uranium_mines

(2) Source of nuclear fusion is Hydrogen which is come from water electrolysis
http://www.jet.efda.org/pages/fusion-basics.html

What is your real meaning? The source of nuclear power? or the source of the radiation? or the nuclear fuels comes from? It can be a chemical, physically or astronomy problem.