The head of the U.N. nuclear agency says Iran has invited its experts to inspect a facility linked to a reactor that could produce enough plutonium for up to two atomic weapons a year once it’s completed.

Yukiya Amano of the U.N.‘s International Atomic Energy Agency says the invitation to visit the Arak heavy water plant is for Dec. 8.

IAEA staff have had some access to the reactor. But they have not been able to inspect the heavy water plant since 2011. Heavy water helps control nuclear activity of some reactors’ fuel rods.

The invitation comes after Iran agreed to open some previously off-limits facilities to IAEA purview earlier this month.

Tehran agreed not to advance “activities” at the reactor as part of last weekend’s Geneva nuclear deal.

(AP)