An Iranian official on Wednesday set aside the idea of potentially altering a nuclear reactor that other nations fear could produce atomic-bomb fuel.
Iran cannot convert its Arak heavy-water reactor to a light-water facility, Hamid Babaei, a spokesman for Iran's delegation to the United Nations, wrote in a Wednesday commentary published by the London Guardian.
Such a change would reduce the unfinished site's capacity to produce weapon-usable plutonium once activated, addressing a major concern shared by world powers as they seek a deal with Iran aimed at preventing its atomic assets from supporting any nuclear-arms production. But the diplomatic official said this kind of modification would prove infeasible.
"It is now too late to change [the Arak reactor] into a light-water prototype, as some have suggested in the West," Babaei wrote. "This 'generous' offer should have been made much earlier."
His assertion came a week after Ali Akbar Salehi, head of the Iranian Atomic Energy Organization, reportedly expressed openness to modifying the Arak site "to produce less plutonium."
On Tuesday, a former U.S. national security staffer said shutting down or significantly altering the Arak reactor would be one of the Obama administration's "key considerations" in seeking a comprehensive nuclear agreement with Iran. The Persian Gulf power, which insists the site is strictly for medical use, is set on Feb. 18 to begin talks on the potential deal with China, Germany, France, Russia, the United Kingdom and the United States.
"If Iran genuinely intends Arak to be a facility that produces medical isotopes only, it should be able to agree to such modifications without significant fuss," Jofi Joseph, a former White House nonproliferation official, wrote in a Tuesday analysis for Harvard University's Belfer Center for Science and International Affairs.
In Senate testimony last week, the Obama administration's senior Iran negotiator dismissed Tehran's rationale for building the heavy-water facility.
"We do not believe there is any reason for a heavy-water reactor at all in a civil nuclear program of the type that Iran is interested in," Under Secretary of State Wendy Sherman said during a Senate Foreign Relations Committee hearing. She did not explicitly say in testimony whether the United States would demand the facility's closure or conversion.