After years of stops and starts, Iran began loading fuel into the core of its first nuclear power plant near Bushehr on Tuesday.
"Today, we witnessed an important development in the start up process. After fuel is injected into the heart of the reactor, the reactor door is closed. Then, it will take one or two months to reach a 40 or 50 percent nominal power," Vice President Ali Akbar Salehi told a press conference broadcast on state TV. "We hope the reactor will produce electricity by mid February."
In August, a reported leak in a storage pool of the 1,000-megawatt plant delayed the injection of the fuel, causing a setback of several months.
Western leaders are worried that Iran's program to enrich uranium for nuclear fuel could be upgraded to create nuclear weapons. However, the U.S. recently withdrew its long-standing opposition to the plant after Russia satisfied concerns over how it would be fueled and the fate of the spent fuel rods.
Russia has been Iran's main partner in the nuclear project that was first commissioned in the 1970s.
Under a deal signed in 2005, Russia will provide nuclear fuel to Iran, then take back the spent fuel, a step meant as a safeguard to ensure it cannot be diverted into a weapons program. Iran has also agreed to allow the U.N.'s nuclear agency to monitor Bushehr and the fuel deliveries.
Iran is already producing its own nuclear fuel - uranium enriched to about 3.5 percent. It also has started a pilot program of enriching uranium to 20 percent, which officials say is needed for a medical research reactor.
Weapons grade material has to be enriched to 90 percent.
The nuclear plant is well guarded. Soldiers maintain a 24-hour watch on roads leading up to the plant, manning anti-aircraft guns, which are also supported by numerous radar stations.