Iran in September started operations at the Bushehr plant with the help of Moscow. Russia, under an agreement with Iran, operates and supplies fuel for the plant.
Russia's state-run news agency RIA Novosti reports that the facility began operating at full service last week after Unit 1 was ramped up to 100 percent capacity.
Igor Mezenin, the head of Iranian construction for Russian contractor Atomstroyexport, said Russian officials were ready to hand the facility over to the Iranians.
"We believe that the unit will be transferred to the client in the last week of December," he was quoted as saying.
Iranian delegates met in late August in Vienna with members of the International Atomic Energy Agency. The IAEA described the meetings as amicable but inspectors said they were concerned about potential military aspects of Iran's nuclear program.
Iranian Supreme Leader Ali Khamenei said at a meeting of the Non-Aligned Movement last week that Tehran considers nuclear, chemical and similar weapons "a great and unforgivable sin," however.