VIENNA, Austria — Diplomats say Iran's production of enriched uranium has stagnated for months, even though Tehran has continued to install machines that carry out the process.
The diplomats - who demanded anonymity because their information was confidential - emphasized that the possibility Iran was running out of uranium oxide was only one of several possible explanations of why it had not increased its output of enriched uranium since May.
But they said it seemed unlikely the Islamic Republic had deliberately decided to curb its production.
They noted that, despite the stagnation in output, Iran continued over the past three months to expand its capabilities by installing hundreds more of the centrifuges that spin uranium hexafluoride gas derived from uranium oxide into enriched uranium.
With Iran under strict United Nations embargoes and on an international watch list meant to cripple its ability to import nuclear materials illegally, it could find it difficult to procure enough uranium oxide to feed its enrichment program. That, in turn, would deal a blow to its stated goal of expanding enrichment to the point where it can supply fuel for a nationwide nuclear network - and reflect the success of U.N sanctions.
The existence of a secret Iranian enrichment program built on black-market technology was revealed seven years ago, and since then the country has continued to expand it with only a few interruptions as it works toward its stated goal of a 50,000-centrifuge enrichment plan.
Iran is under three sets of U.N. Security Council sanctions for refusing to freeze uranium enrichment. These were imposed out of fears Iran is using the pretext of building a peaceful nuclear program - including enrichment to low levels suited for making nuclear fuel - to eventually make weaponsgrade enriched uranium.
In its last report on Iran in June, the International Atomic Energy Agency said that nearly 5,000 centrifuges were operating at Iran's underground enriching facility at Natanz as of May.
Diplomats said Tuesday that it had expanded to about 6,000 by last month.
The Washington-based Institute for Science and International Security recently estimated that, even taking the 5,000-centrifuge figure as a basis, Iran could accumulate enough material to produce weapons-grade uranium for two warheads by February 2010.
Iran refuses to stop enriching despite the sanctions. But it is believed to depend on rapidly diminishing outside sources of uranium oxide, with domestic mining yielding only relatively small quantities of inferior ore.
The U.N. agency and independent experts believe Iran's rapidly expanding uraniumenrichment program has been built on 600 tons of so-called yellowcake, or uranium oxide, that it imported from South Africa during the 1970s as part of ambitious plans by the former regime of Shah Reza Pahlavi to build a network of nuclear reactors.
Extrapolating on statistics contained in the energy agency's November report on Iran, the Institute for Science and International Security think tank said these indicated that, by that date, Iran had used up just under three-quarters of its original South African supply.
One of the diplomats - who like the others who commented for this article is accredited to the International Atomic Energy Agency and closely follows the enrichment issue - said that the international community has for months been closely watching Iran in anticipation it will try to secure uranium oxide through illicit channels.
The agency next reports on Iran sometime this week, ahead of a meeting of its 35-nation board starting Sept. 7.
Front Section, Pages 6 on 08/26/2009