The IAEA has issued a “confidential report” confirming something that Iran had already publicly admitted, that they were slightly in excess of their “soft limit” under the P5+1 nuclear deal on capacity of heavy water. The limit is 130.0 metric tonnes, and Iran reportedly has 130.1 metric tonnes, with an export of 5 metric tonnes pending.
The IAEA has said they’ve “expressed concern” to Iran about the matter, since this is the second time this year that Iran has gone slightly in excess of this soft cap. In both cases, the technical “violations” were the result of Iran struggling to find a trading partner.
Under the P5+1 nuclear deal, Iran’s heavy water refinery was handled with a “soft cap” that obliged the P5+1 nations to buy the heavy water for export. Heavy water is not radioactive, or indeed dangerous in any way. The whole deal was designed to resolve Iran’s creation of the refinery for a heavy water reactor redesigned under the deal, giving Iran the ability to export the water onto the international market.
That was working at the very start of the deal, with the US buying the first batch and sending it to various laboratories around the country. A Congressional backlash meant the US hasn’t bought any since, and means that while Iran is continuing to operate the refinery, as they ought to by able to under the deal, they are struggling to find the export markets that were supposed to be guaranteed to them.