Armenia seeks a new 1,000 MW reactor for the nuclear power plant, built in 1980 about 30 kilometers (19 miles) west of the capital, Yerevan, which was shut down after a devastating earthquake in 1988 but reactivated in 1995 due to energy shortages caused by blockades imposed by Azerbaijan and Turkey.
The ex-Soviet Caucasus state's energy and natural resources ministry estimated the project at about $5 billion.
"Individuals and firms are welcome to take part in the tender," ministry spokesperson Lusina Arutyunyan said. "The deadline for filing bids is April 1."
Armenia's parliament abolished state monopoly on the ownership of new reactors at the plant in 2006 in a bid to attract foreign investment. Russia, the United States and France have shown interest in the project.
One of the plant's two VVER-440 Model V230 reactors has been shut down. The other generates 40-50% of the country's electricity.
The plant has been operated by Russia's Inter RAO UES since 2003, as part of a 10-year deal to help pay off Armenia's debts. The facility will reach the end of its operational life by 2016.
