"Turkish authorities have reached a positive conclusion on the technical aspect of our tender proposal for the construction of a nuclear power plant in Turkey," the source said.
The Turkish nuclear power agency said the Russian bid met "technological standards", the source said.
The bid's financial aspect has to be assessed before the Turkish government makes a final decision on whether to approve the bid.
Asked about the project's estimated cost, a spokesman for the Russian company, the only bidder for the project, said it was "fair market value."
Atomstroyexport, acting through a consortium with Russian power producer Inter RAO UES and Turkey's Ciner Group, is competing in a tender to build four nuclear reactors in Turkey.
The Turkish government was scheduled to declare the successful bidder in October, but has yet to do so.
Atomstroyexport, established in 1998, has completed or is working on reactors in Iran, Bulgaria, Hungary, the Czech Republic, Slovakia, China and India.
