VIENNA — Iran has activated equipment to enrich uranium more efficiently in a move that defies the U.N. Security Council, the International Atomic Energy Agency said Monday.
The Vienna-based nuclear watchdog said Iran has started using a second set of 164 centrifuges linked in a cascade, or string of machines, to enrich uranium to up to 20 percent at its Natanz pilot fuel enrichment plant. Another cascade has been producing uranium enriched to near 20 percent since February.
If enriched to around 95 percent, uranium can be used in a nuclear bomb. At 20 percent, it can be turned into weapons-grade material more quickly than less-enriched uranium.
Tehran denies it has such aims and says its nuclear activities are for peaceful purposes only. But some in the international community — the United States and its allies — aren't convinced.
IAEA spokeswoman Gill Tudor said that when agency inspectors visited the facility on July 17, "Iran was feeding nuclear material to the two interconnected 164-machine centrifuge cascades."
This, she added, was "contrary to U.N. Security Council resolutions affirming that Iran should suspend all enrichment related activities."
The U.N. Security Council imposed a fourth round of sanctions on Iran in June because of its refusal to halt uranium enrichment. Tougher unilateral U.S. and European Union sanctions followed in July.
Iran had informed the IAEA in March of its intentions to link the two cascades, Tudor said.
The move upgrades the efficiency of production by recycling waste now being left by the first cascade to squeeze out more enriched uranium at near 20 percent levels, diplomats said in May when they disclosed that Iranian technicians had assembled the second 164-centrifuge cascade and appeared ready to activate it.
One of the diplomats familiar with Iran's enrichment programs emphasized at the time that the idea appeared not to produce greater amounts than the first operating cascade was turning out, but to improve productivity.