Sunday, April 22, 2012

Iran's path to nuclear weapons

by Joseph Sternberg

Have you ever noticed whenever there is a news story based on information from the UN's International Atomic Energy Agency (AIAE) or some other Intelligence source that reports Iranian progress towards developing nuclear weapons,  the article is invariably ended with a sentence stating that Iran authorities deny that Iran is developing nuclear weapons? Evidently journalistic ethics gives high priority to giving space to authorities who have a dubious record on this subject.

The Supreme Leader of Iran, Ayatollah Khamenei, has repeatedly asserted that the Iranian nation has never sought and will never seek nuclear weapons. He has been Supreme Leader since 1989 and was President from 1981 to 1989, so he should be well informed on what Iran is doing. In 2007 the US published a National Intelligence Estimate (NIE) that reported that Iran had stopped work on the design of a nuclear warhead. As we have just learned recently, the Intelligence was based on intercepted communications of scientists who were working on the warhead design and were complaining about the decision of the Iranian authorities to put the work on hold. You can't stop doing something that you were never doing. No matter how many times Ayatollah Khamenie says that Iran has never and would never seek to develop nuclear weapons, he is lying.

So why would the Iranians put the nuclear warhead work on hold in 2003, according to the NIE?  By 2002, the Iranians had decided that they must go underground with nuclear facilities  to improve their survivability.There were bad people out there who might decide to bomb them. Building facilities underground for the enrichment of uranium requires large areas that can accommodate thousands of centrifuges and so is an expensive and time-consuming task. There is not much point in having constructed a warhead if you don't have the weapons-grade uranium to put in it.

There was another reason to put the warhead work on hold, besides the fact that it would not be needed for some time. If the work on the warhead was discovered, the Ayatollah Khamenei's campaign to persuade doubters of the peaceful nature of the Iranian nuclear program would collapse, and the countries that were dragging their feet on tough sanctions would have little excuse to do so.

The Iranians are working hard on uranium enrichment. The identity of two underground enrichment sites was disclosed by dissidents, Natanz in 2002 and Fordow in 2007. Thousands of centrifuges are installed at these sites. Once the sites were disclosed, they were subject to inspection by the UN IAEA. The fission isotope in uranium is U-235, which is only 0.72% of natural uranium. Enrichment to 3-5% of U-235 is necessary to fuel standard nuclear power plants. However, Iran's first nuclear power plant at Bushehr has been fueled by the Russians. Iran has a Tehran Research Reactor (TRR) that runs on fuel enriched to about 20% of U-235. In 1993, Argentina provided 255 pounds of fuel elements sufficient for multiple refuelings of the reactor. Iran has been negotiating with various counties for a resupply of fuel for this reactor, which doesn't run continuously. Finally, uranium enriched to over 80 % U-235  is needed for a nuclear weapon. Such enriched uranium has no peaceful purpose.

So what is the enriched inventory reported by the IAEA in Feb. 2012? Between its two known enrichment sites, Iran now has a supply of a supply of 220 pounds of enriched uranium containing 19.75% of U-235. A modern uranium implosion-type nuclear weapon design would require about 33 pounds of uranium enriched to 80-90 %. The step from 20% enrichment to 90 % enrichment is a relatively small one and doesn't require  thousands of centrifuges.The 220 pounds of 20% enriched uranium contains 44 pounds of U-235, more than enough for a nuclear bomb when it is further enriched.  Based on present estimates of the rate at which Iran is enriching uranium at the known facilities, a year's production of 20% enriched uranium would be enough for one or two bombs.

It is clear that Iran is not satisfied with the rate of enrichment obtained with its IR-1 centrifuges.  It has informed the IAEA that it is working on more than four different advanced centrifuge designs. Further, prior to 2009, Iran had publicly announced that it intended to build ten new uranium enrichment facilities, but they didn't say where or when.So Iran may have more enriched uranium than known to the IAEA.

What about the suspended nuclear warhead work? Clearly if this work was resumed, it would be done in underground facilities and Iran would make every effort to keep it secret. The size of such a facility would be much smaller than the facilities required for uranium enrichment and so, presumably, easier to conceal. In 2010 the IAEA informed Iran that they had extensive information about undisclosed activities relevant to critical nuclear weapon design issues being carried out by Iranian military organizations. Iran has refused to discuss these issues and has maintained that the allegations are baseless, and that the information referred to by the IAEA is based on forgeries. It has also refused access to Parchin, a key explosives development military facility.

In congressional testimony this year, the US Director of National Intelligence James Clapper stated his view that Iran has not yet decided to make a nuclear weapon but is only keeping themselves in the position to do so. He did not claim to have any specific information to support his view of the intentions of the Iranian leadership. Perhaps a more accurate statement would have been that there is no evidence (none was cited) that Iran ever gave up its goal of developing nuclear weapons but that the threat of severe sanctions and or military attack provide a strong incentive to keep crucial nuclear warhead work secret. The size of an underground facility needed for warhead development is much smaller than what is needed for uranium enrichment and so is easier to hide. A key problem for Intelligence is to uncover any relevant secret underground facilities.

I am reminded of a story told to me by an old French friend. A Frenchman became concerned that his wife might be seeing another man, so he hired an investigator to follow his wife. A few days later, the investigator reported the bad news. His wife had met a man at a particular hotel and they had entered the hotel and rented a room. The husband demanded to know more. The investigator said he had been able to find out the number of the hotel room and quickly went there. The door had a large keyhole, and he was able to see what was going on in the interior. The two occupants had started to remove their clothes. "And what happened then?" cried the husband. "I don't know," said the investigator, "the light in the room was turned off." "Oh," sighed the husband. "The Incertitude."
Dr. Sternberg served as Scientific Advisor to the Supreme Allied Commander Europe 1971-1974. He is a retired professor of physics, Naval Postgraduate School, Monterey, CA

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