Iran gave atomic monitors freer rein to investigate decades-old activities while continuing to elevate the rate at which it’s stockpiling nuclear fuel.

International Atomic Energy Agency inspectors said they’ve already been to one of three sites they suspect may have hosted undeclared nuclear work some decades ago. They traveled to the location after IAEA Director General Rafael Mariano Grossi visited Tehran last month to negotiate access.

“The director general welcomes the agreement between the agency and Iran, which has the aim of reinforcing cooperation and enhancing mutual trust while resolving outstanding safeguards implementation issues,” the IAEA reported Friday in a 3-page restricted report seen by Bloomberg. Inspectors will visit the other two sites later this month, according to the document.

The release of the IAEA’s quarterly safeguards report follows high-level meetings convened this week in the Austrian capital in support of the 2015 landmark nuclear agreement between Iran and world powers. Chinese, European and Russian diplomats pushed back on Tuesday against continued U.S. efforts to scuttle the accord designed to cap the Persian Gulf country’s nuclear work in exchange for economic relief.

Iran’s store of low-enriched uranium increased to 2,105.4 kilograms (4,642 pounds) from 1,571.6 kilograms in the second quarter, according to a second restricted report. That’s enough of the heavy metal to create three bombs if Iran chose to enrich the material to weapons grade.

The Islamic Republic denies it ever pursued nuclear weapons research. It stopped abiding by some of the nuclear deal’s enrichment constraints in response to the U.S. leaving the accord in 2018 and reimposing its own sanctions.

The 34% rise in stockpiled uranium follows Iran’s decision to install advanced new centrifuges at a nuclear key facility struck by a blast in July. Installation of the machines, which spin at supersonic speeds to separate the uranium isotopes needed for nuclear fuel, was seen as a signal that saboteurs who targeted the facility in Natanz had failed to interrupt production.

Inspectors confirmed on Sept. 2 “that Iran had installed” key elements for “three cascades of IR-4, IR-2m and IR-6 centrifuges” which will be used to produce uranium at an even faster rate, according to the IAEA report.

Source » bloomberg