Iranians insist that the $1 billion (£695 million) Russian-built plant in Bushehr is part of a civilian energy programme, but Western powers fear that its covert purpose is to produce atomic weapons.
The tests, using lead in “virtual rods” and not enriched uranium, were carried out during a visit to the plant on Wednesday by Sergei Kiriyenko, the head of Rosatom, Russia’s state-owned nuclear firm which has built the power plant.
“The construction stage of the nuclear power plant is over, we are now in the pre-commissioning stage,” Mr Kiriyenko said.
He was accompanied by Gholamreza Aghazadeh, head of Iran’s Atomic Energy Organisation, who declared the test a success and said the plant was now closer to operating.
He also announced a nearly ten-fold expansion of Iran’s uranium enrichment capacity in the next five years.
Mr Aghazadeh was defiant at a press conference after a UN report had claimed that Iran’s nuclear activities had slowed.
He said 6,000 centrifuges were now enriching uranium, a process which can potentially produce the raw material for an atomic bomb, an increase of 1,000 since November.
“Our plan to install and run centrifuges is not based on political conditions,” he said. “America should face reality and accept living with a nuclear Iran.”
He said that Iran would announce a new nuclear achievement in April.
Stopping Iran’s nuclear programme is one of the main foreign policy challenges for President Barack Obama, who has said he is prepared to break with his predecessor’s policy and talk to Iran’s rulers.
The President has also warned of imposing tougher sanctions if Iran continues to defy UN demands to suspend enrichment, however.
Iranian radio also criticised the choice of Dennis Ross as the new US special adviser on Iran, calling him an extremist who was influenced by Israel.