According to the terms of the 2015 agreement, the Islamic Republic was required to remove the core, or calandria, of its Arak nuclear reactor and fill it with cement, thus preventing its further use. It would then be allowed to rebuild and redesign the reactor so that it could be used for research but could not easily produce weapons-grade plutonium. But in recent public statements, Ali Akbar Salehi, the head of the Iranian Atomic Energy Organization, stated that these requirements had not been fulfilled. Michael Segall writes:
Salehi suggested that Iran would continue to “discover and mine” uranium . . . and continue with its activities at the heavy-water reactor in Arak. Iran has purchased new equipment for the facility and did not even fill in the core of the reactor with cement in January 2016 in accordance with the nuclear deal, because “if we had done that, there would not be a reactor.” . . .
On January 16, 2016, the International Atomic Energy Agency’s Board of Governors released a report, . . . which confirmed that Iran had removed and “rendered inoperable” the Arak facility’s calandria. [But] during an interview [on Iranian television] on January 22, 2019, Salehi criticized claims by the conservative camp that Iran had completely sealed the core of the reactor. He claimed that images published [of the sealed reactor in 2016] were photoshopped, and Iran was never required by the agreement to seal the core of the reactor with concrete. . . . Salehi emphasized throughout the interview [the Iranian nuclear program’s] progress [despite] the implementation of the nuclear agreement. . . .
Salehi’s words follow his statement on January 15, 2019, that Iran is capable of increasing its percentage of uranium enrichment to 20 percent within three or four days.
Read more on Jerusalem Center for Public Affairs: http://jcpa.org/article/iran-continues-with-its-nuclear-activities-unabated/