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POLICY AIMED at reducing the world’s nuclear weapons has led to odd international liaisons. In particular, the U.S. Department of Energy is buying 32 tons of heavy water, D2O, from the Atomic Energy Organization of Iran at a cost of $8.6 million.


“Critics Complain as U.S. Shops in Iran’s Nuclear Bazaar,” by Richard Stone, is in the April 29, 2016, issue of Science, the weekly magazine of the American Association for the Advancement of Science. This is an extremely complex subject, but I’m glad AAAS Science brought it up. Here are some high points.

Isotopes deuterium, D, and tritium, T, have the single proton of hydrogen, sometimes called protium, but with added neutrons. Deuterium has a single neutron; tritium has two of them.


Hydrogen, deuterium and tritium. Image by Lamiot from Hünninger.

Naturally occurring deuterium accounts for just one out of 6420 hydrogen atoms, so it’s hardly a common isotope of the universe’s most abundant element. On the other hand, deuterium has many applications, among them in nuclear MRI and in the production of optical fibers and semiconductors.

Some countries also use D2O as a moderator in nuclear reactors. Its extra neutrons make this heavy water more efficient than ordinary H2O for initiating fission. However, heavy water reactors have a dark side: They can transform uranium into weapons-grade plutonium.


Heavy water reactor in Arak, Iran. Image from United States Institute of Peace.

Notes Richard Stone in Science, “In 2002, an Iranian opposition group revealed that Iran was building a secret facility at Arak, later identified as a heavy water production plant, along with a reactor that could breed enough plutonium for one or two bombs a year.”

This led to international sanctions against Iran, rescinded only last year, not without controversy, in return for Iran’s sharp reduction in its nuclear program.


Key nuclear facilities in Iran, most of which were impacted by the July 2015 deal. Image from Forbes after the International Institute of Strategic Studies.

Mandated by the deal, Iran has cut its heavy water stockpile to less than 130 tons by shipping excess stock out of the country for storage. It has also put heavy water on its list of export offerings.


The U.S. DOE cut back on its own heavy water production back in 1981 for reasons of economy. Stone observes that, these days, Canada and India satisfy most of the global demand for nonnuclear uses, about 100 tons a year, by distilling heavy water from regular eau, like brandy from wine.

However, recall that 1:6420 ratio. It turns out that a single lb. of reactor-grade heavy water requires 340,000 lbs. of purified feed water.

The DOE is investing in research and development to restart U.S. heavy water production. In the meantime, there’s this controversial $8.6 million deal with Iran.

On the upside, Science reports Oak Ridge National Laboratory’s Thom Mason saying, “We’re securing material that will allow us to do great science.” On the other hand, Mark Dubowitz of the Foundation of Defense of Democracies, a Washington, D.C., think tank, says, “The U.S. subsidies will simply help Tehran perfect its heavy water production capabilities so it will be fully prepared to develop its plutonium bomb-making capabilities when restrictions on the program sunset.”

Stone concludes by citing a potential for peaceful collaborations: “Under the nuclear agreement, Iran’s Fordow uranium enrichment facility is slated to become an international science and technology center. There, Russia is reconfiguring uranium-enrichment centrifuges to produce iridium-191; adding a neutron at the reconfigured Arak reactor would yield iridium-192, which is used in gamma cameras to check for structural flaws in metal.”

As Stone notes, “a swords-to-ploughshares payoff.” I sure hope so. ds

© Dennis Simanaitis,, 2016


  1. Bill Urban
    May 11, 2016

    A comment from a self described “curious character” on deuterium, tritium, and these bedfellows would be most enlightening, but Richard Feynman passed in 1988. Also curious – or ironic- he was born on this day, May 11, in 1918.

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