BUSHEHR, Iran - Iranian and Russian technicians are conducting a test run of Iran's first nuclear power plant, officials said Wednesday, a major step toward launching full operations at the facility, which has long raised worried the U.S. and its allies.
At the same time, Iran claimed another advance in its controversial nuclear program: The number of centrifuges operating at its uranium enrichment plant has increased to 6,000, the country's nuclear chief said -- up from 5,000 in November.
His announcement was the latest defiance of United Nations' demands that Tehran suspend its enrichment program because of fears it could be used to produce material for a warhead. Iran denies it seeks to build a nuclear bomb, saying its program aims only to generate electricity.
The United States has been worried over the nuclear plant at the southern port city of Bushehr because it fears Iran will reprocess the spent reactor fuel into plutonium, a potential material for a nuclear bomb. Russia has helped build the facility and is providing it enriched uranium fuel, and for a time Washington pressured Moscow to stop its assistance.
But U.S. concerns softened after Iran agreed to return spent fuel to Russia so it cannot be turned into plutonium. Washington largely dropped its opposition to the project and argued instead that the Russia fuel deal shows that Iran does not need its own domestic uranium enrichment program.
The Bushehr plant is meant to be the first in a number of reactors for Iran's energy program. But the opening of the 1,000-megawatt light-water reactor has long been delayed by construction and supply glitches.
Iran has said it aims to operate the reactor by the end of the year.
The tests, which began 10 days ago, "could take between four and seven months," the nuclear chief, Vice President Gholam Reza Aghazadeh, told reporters at Bushehr. It was not known how long after the tests the reactor could start up.
Scientists at the plant are carrying out a computer run of the equipment to ensure there are no malfunctions in the future when enriched uranium fuel is introduced into the reactor. No electricity is produced during the testing.
In the first stage of the test, technicians for the past 10 days have been loading a "virtual fuel" into the reactor. The virtual fuel consists of lead, which imitates the density of enriched uranium.
Once the fuel is fully loaded, "we will check to see how the reactor will operate," said Russian nuclear agency chief Sergei Kiriyenko, who was inspecting the process.
Bushehr has witnessed "remarkable progress in recent months," Kiriyenko said, adding that the Russian-Iranian team is "approaching the final stage" before the plant becomes operational.
Aghazadeh, who was accompanying Kiriyenko, said the test was going well so far and engineers told him they expected no problems.
"Today was one of the most important days for the Iranian nation," Aghazadeh said. "We are approaching full exploitation of this plant."
In Israel, which has been one of the most vocal nations accusing Iran of seeking a bomb, Foreign Ministry spokesman Yigal Palmor said the tests at Bushehr "should be understood as very bad news for the whole of the international community."
"The real issue here is the general Iranian program designed to obtain nuclear weapons, the Bushehr reactor is just one component of that program," he said. He called for "immediate and very determined steps in order to prevent Iran from becoming a nuclear power."
While Bushehr has been a concern, the main focus of international efforts to rein in Iran's nuclear program has been on getting it to suspend uranium enrichment. That is because the same process that enriches uranium to low levels for reactor fuel can also enrich it to higher levels to produce the material for a warhead.
In the enrichment process, uranium gas is pumped through a series of centrifuges and spun at supersonic speeds to remove impurities.
Aghazadeh announced that 6,000 centrifuges were now "operating" at Iran's enrichment facility in the town of Natanz. He said Iran hopes to install over 50,000 centrifuges there over the next five years.
"We are doing what we need to do in Natanz on the basis of a specific time schedule," he told a press conference.
Iran says it intends to use the enriched uranium fuel in its first domestically made nuclear power plant, in the town of Darkhovin, which it wants to start operating in 2016. Aghazadeh said any delay in enrichment will mean a delay in opening Darkhovin.
Iran has rejected proposals it import all its reactor fuel from abroad, saying that would leave it vulnerable to cutoffs of the material.
It was not clear if Aghazadeh meant all 6,000 centrifuges were actually enriching uranium. In a report last week, the U.N. nuclear watchdog, the International Atomic Energy Agency, said Iran had about 4,000 centrifuges enriching and 1,600 more "under vacuum," which means they are operating but not yet being fed uranium gas to spin.
An IAEA official said the Iranian numbers appeared to roughly tally with the agency's count, including machines under vacuum. The official spoke on condition of anonymity in exchange for commenting on a statement from an IAEA member nation. The official refused to comment on the Bushehr testing.
The Bushehr reactor was meant to start up in 2008. The project dates backs to 1974, when Iran's U.S.-backed Shah Mohammed Reza Pahlavi signed an agreement to build the reactor with the German company Siemens. The company withdrew from the project after the 1979 Islamic revolution toppled the shah.
In 1992, Iran signed an agreement with Russia to complete the project and work began on it in 1995.
Russia says there is no evidence that Iran is seeking nuclear weapons and has joined China in weakening Western-backed sanctions in the U.N. Security Council, arguing that punishing Tehran too harshly for its nuclear activities would be counterproductive.
The U.N. Security Council has passed three sets of sanctions against Iran over uranium enrichment and is considering further measures.
