The secondary circuit of the Arak heavy water nuclear reactor will be operational within two weeks, Ali Asghar Zarean, a special assistant to the chief of Iran’s Atomic Energy Organisation, was quoted as saying on Sunday by the semi-official Tasnim news agency.
The starting of the secondary circuit will not violate restrictions placed on Iran's nuclear programme under a landmark 2015 deal with world powers.
Last week, Iranian President Hassan Rouhani said Tehran will continue to reduce its commitments to the deal, removing curbs on its nuclear programme, until European parties to the pact protect Iran’s economy from US penalties.
Iran has the capacity to produce up to 25 tonnes of heavy water per year, Mr Zarean said, noting that the Islamic Republic currently produces 20 tonnes of heavy water annually, which is exported to other countries.
Heavy water can be employed in reactors to produce plutonium, a fuel used in nuclear warheads.
Despite having nuclear technology, Iran has never pursued building or using nuclear weapons, which its religion forbids, the country’s highest political authority, Ayatollah Ali Khamenei, said earlier this month.
Iran has responded to US "maximum pressure" by scaling back commitments to the nuclear deal since May. Britain, France and Germany, all signatories to the pact, have urged Iran to refrain from any concrete act breaching the agreement.
The reduction of commitments can be reversed, Iranian officials said, if the remaining parties to the deal uphold their promises.
