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Arak IR-40 Heavy Water Reactor

Iran claims to have decided to construct a heavy water reactor in the 1980s.  After presumably successful testing activities at the Esfahan nuclear research center, Iran decided to build a heavy water reactor in the mid-1990s. The reactor, the IR-40, is designed to produce 40 megawatts thermal (MWth) of power and use natural uranium oxide fuel, which will be produced at Esfahan conversion and fuel fabrication facilities.

The start date of the reactor is difficult to determine.  Officially, Iran has said that the reactor will will achieve criticality in 2013.  However, this date could be delayed because of problems acquiring necessary items overseas or in building the reactor.

If operating optimally, the IR-40 would produce about 9 kilograms of plutonium annually or enough for about two nuclear weapons each year. Before it could use any of the plutonium in a nuclear weapon, however, it would first have to separate the plutonium from the irradiated fuel.

Intermittently, Iran has allowed the IAEA access to the IR-40 reactor at Arak.  In recent years, Iran has justified its refusal to grant the Agency full access to the IR-40 reactor by saying that “since the IR-40 was not in a situation to receive nuclear material, no design-inventory-verification was required.” (See ISIS Report, “Misconceptions about Iran’s Nuclear Program”) Iran has softened its position and allowed the IAEA to visit the reactor. (See IAEA Safeguards Report, November 16, 2009).

Because Iran has completed the external structure of the IR-40 reactor, commercial satellite images can no longer monitor the progress of the reactor.  In mid 2010, through visits to the reactor, the IAEA verified that the civil construction of the buildings was almost complete, and that the main crane in the reactor building and the pressurizer for the reactor cooler system had been installed. See IAEA Safeguards Report, September 6, 2010).

Fuel Assembly

In the spring of 2010, President Ahmadinejad proudly unveiled a fuel assembly, which purportedly is for the Arak reactor. The fuel assembly on display by President Ahmadinejad is of a surprising shape for a small, 40 megawatt-thermal heavy water reactor and confirms that Russian entities were important in designing this fuel and reactor. 

As can be seen in Figure 1, this fuel element is extremely long and thin.  It closely resembles the fuel used in an RBMK (Reaktor Bolshoy Moshchnosti Kanalniy), Soviet-era reactor.  Figure 2 shows a sketch of the RBMK element from a Russian web site and the similar characteristics are obvious, including the length, shape, types of pins and fitting on the ends.

Based on interviews with knowledgeable officials, NIKIET and a Russian company in Obninsk provided technology for the Arak reactor.  (See ISIS Report, “Update on Arak Reactor”) This assistance included modifying the design of a RBMK fuel rod bundle for use in the Arak heavy water reactor.  As a result of U.S. pressure, their assistance to the Arak reactor project stopped in the late 1990s.

The Arak fuel pin is designed to have a zirconium cladding.  Iran has built a zirconium plant at Esfahan that is expected to supply cladding for the Arak fuel pins, although the plant’s operational status is unknown. (See ISIS Satellite Imagery of Esfahan)