Behrouz Kamalvandi, who is the spokesman for the Atomic Energy Organization of Iran (AEOI), said on Thursday that Tehran and Moscow reached a deal on stable isotopes about a year ago.
Different Iranian delegates traveled to Russia and Russian experts visited Iran, he added.
"Today, we are at the stage of installing some equipment and Russian experts will arrive in Iran on Sunday to begin the installation work," Kamalvandi said, noting that the project will probably begin on Sunday or the following day.
Iran and the P5+1 countries — namely the US, Russia, China, France, Britain, and Germany — reached a nuclear deal, officially called the Joint Comprehensive Plan of Action (JCPOA), in July 2015 and started implementing it in January 2016.
Under the accord, Iran undertook to apply certain limits to its nuclear program in exchange for the termination of all nuclear-related sanctions against Tehran.
The International Atomic Energy Agency (IAEA), which is the official institution to verify Iranian compliance, has consistently confirmed the Islamic Republic's commitment to its contractual obligations.
However, US President Donald Trump is opposed to the JCPOA, which was negotiated by his predecessor, Barack Obama, and warned that he might ultimately “terminate” it.
Last month, Trump extended waivers of key economic sanctions on Iran, lifted under the nuclear agreement, for another 120 days but said he was doing so “for the last time.”
He further called on European allies and US Congress to work with him to “fix the disastrous flaws” in the pact or face a US exit.