An IAEA report in November 2003 showed that Iran had, in a series of contraventions of its safeguards agreement over 22 years, systematically concealed its development of key techniques which are capable of use for nuclear weapons. In particular, that uranium enrichment and plutonium separation from used fuel were carried out on a laboratory scale. Iran admitted to the activities but said they were trivial.
http://www.world-nuclear.org/info/Country-Profiles/Countries-G-N/Iran/
I thought at some point I read they were working on reprocessing.
Techniques are not capable of use for nuclear weapons.
Here's how this works.
Uranium 238 [FUEL grade]is not fissible (will not CREATE a fission nuclear chain reaction)
Uranium 235 [WEAPONS grade] is fissible. It does create a fission nuclear chain reaction.
Uranium-235 is an isotope of uranium making up about 0.72% of NATURAL uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a fission chain reaction.
U 238 can be /downblended/ to convert some* (very little) U 235 BUT the process also creates U 232, 233, 234, 236, 237
AND less 238 than they started with.
Depleted uranium (used as fuel already) has less 235 than natural ore.
Reprocessed uranium has less 235 than depleted uranium.
Downblended uranium has almost the full spectrum of isotopes and less 235 than reprocessed uranium.
They all need 235 in critical mass to weaponize.
Open source info.
The LAW OF CONSERVATION OF MASS. You CANNOT end up with more of a reactant after a chemical reaction. The conversion of mass into energy leaves LESS MASS than before the reaction.
