Iran has begun building its second nuclear power plant with Russian help, the first such project since last year's landmark nuclear deal with world powers.
The project was launched torday and will eventually include two power plants expected to go online in 10 years, according to Iranian state TV.
Construction on the second plant is set to begin in 2018.
The project will cost around US$10bn and produce 1,057 megawatts of electricity.
Iran's sole operational nuclear reactor produces 1,000 megawatts and went online in 2011 with Russian help.
Iran has rejected Western allegations that it is seeking nuclear weapons, insisting its atomic program is for entirely peaceful purposes.
Under the nuclear deal, it agreed to curb its program in return for an easing of sanctions.