Last fall, Iran chose to bluff. It announced that it was going to enrich it's own fuel for the Tehran Research Reactor. A single cascade at the Natanz Pilot Fuel Enrichment Plant was put to work enriching 3.5% fuel to the 19.75% necessary for the Tehran Research Reactor. The last IAEA report (GOV/2010) details the small amount of Uranium enriched. Even though a second cascade has been brought on line, production is still too low to refuel the Tehran Research Reactor the fuel of which is just about burned out. The bluff, the weakness of which was apparent at the time it was made, failed to work and now Iran is facing a serious shortage of industrial and medical isotopes.
from the article: Report: Iran ready to begin immediate nuclear fuel swap talks