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Iran pursues plans for heavy water reactor
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| 14 November 2003 |
By Jack Boureston and Charles Mahaffey
Iran has admitted it is in the final phase of designing a 40MW heavy water nuclear reactor at Arak. Officials have said that the basic design of the reactor, called the IR-40, has already been completed, and that work has started on a more detailed design. Construction work is due to begin in early 2004. If this is the case, past historical data on the construction of heavy water reactors suggests that the IR-40 could be completed by 2009.
Although the Atomic Energy Agency of Iran has provided technical specifications of the reactor to the International Atomic Energy Agency (IAEA) for review, the international community remains deeply concerned over the intended purpose of IR-40, its possible configuration and its capabilities.
Iran has stated that the IR-40 will be used for research and development, radioisotope production, and training. One main advantage of a heavy water reactor is the high absorption factor of heavy water (D2O) over other moderators. This translates into a larger number of isotopes being produced to satisfy the increasing isotope requirements in the medical and agricultural industries.
However, a heavy water reactor is among the most dangerous in existence from a proliferation perspective. One reason is that the low neutron cross section of heavy water allows a high number of U238 (uranium-238 isotope) atoms to absorb neutrons, resulting in the production of a greater quantity and better quality of plutonium product from a heavy water reactor compared to a light water reactor. According to David Albright, Director of the Institute for Science and International Security, the IR-40 will be able to produce 8-10kg of plutonium per year - approximately one to two bombs' worth of nuclear material. The IAEA holds that 8kg of plutonium constitutes a "significant quantity" - enough to build a nuclear weapon.
However, such estimates of yield assume that the IR-40 will be running at full power throughout the year and the total amount of spent fuel will be used for plutonium production. Also, such estimates of plutonium yield are not realistic unless the Iranians construct a plutonium separation (reprocessing) facility of sufficient size and capacity to support a plutonium-based weapons programme. That facility, if properly designed, might also accommodate the irradiated fuel from the Bushehr reactor, should Iran decide not to return it to Russia.
It is also possible that the Iranians could separate the spent fuel from the IR-40 and clandestinely hide portions of separated plutonium for use in a weapon at a later date. In this case, it would take longer to finally get to a "significant quantity" of plutonium. Either way, this reactor is a cause for concern, given the fact that similar reactors have been used to produce plutonium in other countries in the past; Israel and India used reactors of comparable design to the IR-40 that were capable of generating similar levels of thermal power to produce their first fission bombs.
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