Verbal agreements are only as good as the paper they are written on. If your friend hasn't paid you for almost a year I wouldn't hold my breath waiting. Just be glad it only cost yo $500 to find out how good a friend they were. It could have cost you thousands of dollars.
Nuclear Materials. Nuclear materials are the key ingredients in nuclear weapons. They include fissile, fussionable and source materials. Fissile materials are those which are composed of atoms that can be split by neutrons in a self-sustaining chain-reaction to release energy, and include plutonium-239 and uranium-235.
Uses. Uranium is a very important element because it provides us with nuclear fuel used to generate electricity in nuclear power stations. It is also the major material from which other synthetic transuranium elements are made. Naturally occurring uranium consists of 99% uranium-238 and 1% uranium-235. Uranium-235 is the only naturally occurring fissionable fuel (a fuel that can sustain a chain reaction). Uranium fuel used in nuclear reactors is enriched with uranium-235.