Sofia plans to pick a strategic investor or investors by May 22 next year to install and run two Russian-made 1,000 megawatt reactors at Belene project on the river Danube. The plant, estimated to cost about 10 billion euros (9.2 billion pounds), should be operational in 10 years.
Energy Minister Temenuzhka Petkova will announce the bidders on Tuesday morning, the energy ministry said, a move preempted by Russia's state-owned Rosatom which said it had applied to take part in the project.
The sources who declined to be identified said China's state-owned CNNC and state-run Korea Hydro & Nuclear Power Co (KHNP), a subsidiary of Korea Electric Power Corp, had also filed applications.
Shortlisted candidates will be asked to file binding offers.
France's Framatome, a unit of EDF, and General Electric have filed letters saying they are interested in providing conventional power generation equipment and carrying out work for the Belene project, one of the sources said.
Bulgaria cancelled Belene in 2012 after failing to find investors and facing pressure from the United States and the European Union to limit its energy dependence on Russia, which had been under contract to build the plant.
It has been sitting on unused nuclear equipment since paying Rosatom more than 620 million euros for scrapping the project, and in June 2018 its parliament ordered the government to revive it.
Sofia plans to keep a blocking stake in the venture and participate with the site, the nuclear reactors and the acquired licences, but would not extend state or corporate guarantees or offer to buy electricity from the plant under long-term contracts at preferential rates.
The deadline for submitting letters of interest for investing in the project expires later on Monday. A Rosatom spokesman declined to provide any further details of the company's application.
(Reporting by Maria Kiselyova in Moscow and Tsvetelia Tsolova in Sofia; Additional reporting by Anastasia Lyrchikova in Moscow; Editing by Susan Fenton and David Holmes)
By Tsvetelia Tsolova and Maria Kiselyova