What I Assumed You Knew.

How available is uranium and especially U-235?

• There is lots of uranium, largely as oxide in several countries.
• But only 0.7% of naturally occurring uranium is U-235. Most is U-238.
• The standard power reactors need about 4% U-235 to easily run a safe, steady-state operation with water as the moderator and coolant.

Increasing concentration of U-235

Basic scheme:
   turn uranium into a gas UF₆, then enrich with:

• Centrifuges: lots of them (now used abroad).
• Gaseous Diffusion on vast scale (ORNL).