Civilian HEU: Canada

Oct 8, 2019

Part of the
Civilian HEU Reduction and Elimination Resource Collection


Canada is a non-nuclear weapon state party to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). Accordingly, its entire stockpile of highly enriched uranium (HEU) is civilian-use, and its facilities are all subject to International Atomic Energy Agency (IAEA) safeguards. There are, however, no public Canadian declarations of HEU holdings. Unlike Germany, France, and the United Kingdom, Canada does not provide this information to the IAEA as part of its annual declaration on plutonium stocks (INFCIRC/549). [1] A 2015 estimate by the Institute for Science and International Security approximated Canada's civil HEU holdings at 1,038 kg. [2] Although the United States and Canada do not publicly release information on HEU repatriation shipments for security reasons, the total HEU stockpile in Canada has likely diminished considerably, and Canada has committed to repatriate all U.S.-origin HEU by 2019.

Canada has been politically supportive of efforts to minimize HEU. At the final Nuclear Security Summit (NSS) in 2016, Canada pledged to reduce its use of HEU. [3] In fulfillment of this pledge, in 2018 Canada placed its National Research Universal (NRU) reactor, which had been used for HEU-based medical isotope production, into a safe shutdown state. [4] Canada is also in the process of decommissioning its last HEU-fueled research reactor.

HEU Production, Use, and Commerce

Canada does not have, nor does it plan to acquire, domestic HEU enrichment capabilities. Canada has historically used HEU in research reactors, and possessed a fleet of eleven HEU-fueled research reactors as recently as 1984. However, all HEU-fueled research reactors have been decommissioned, save one, the SLOWPOKE-2 reactor in Saskatchewan. Canada began the process of decommissioning the SLOWPOKE-2 reactor in 2018. [5]

Canada also used HEU targets to produce the medical radioisotope, molybdenum-99 (Mo-99). In 2018, Canada ended medical isotope production using HEU, and plans to resume production using alternative technologies. Since Canada does not produce HEU, it has used HEU imported from the United States (with exports licensed by the U.S. Nuclear Regulatory Commission). As part of the Global Threat Reduction Initiative (GTRI), now reorganized into the Office of Materials Management and Minimization (M3), Canada and the United States have an ongoing agreement to repatriate HEU to the United States.

Radioisotope Production

Radioisotope production has historically been a major part of Canada’s nuclear industry. Canada was North America’s primary supplier of medical isotopes until the shutdown of its main medical-isotope producing reactor, the NRU, in early 2018. The NRU was HEU-fueled from 1964 until its conversion to low enriched uranium (LEU) fuel in 1991. Thereafter, Canada continued using HEU targets for the production of the medical isotope Molybdenum-99, until production was halted in 2018. [6] The Canadian company MDS Nordion Inc., which until 2018 had been the world's leading producer of the radioisotope Mo-99, was acquired by U.S.-based BWX Technologies, Inc. in 2018. [7]

Several months after the NRU reactor was shut down, Canada announced that it would utilize existing CANDU reactors at the Darlington Nuclear power plant to produce Mo-99, with plans to begin medical isotope production by the end of 2019. [8] Mo-99 will be produced by inserting molybdenum targets during the normal operation of the reactor, effectively restoring the Canadian medical isotope supply, while eliminating the need to use HEU during the production process. While Canada’s medical isotope production is paused, North America relies on imported medical isotopes, primarily from Europe and South Africa. [9]


Canada has four research reactors in operation, one of which currently uses HEU fuel. The MNR pool reactor at McMaster University and the SLOWPOKE-2 reactor in Montreal originally used HEU fuel, but both have since been converted to LEU fuel. [10] The ZED-2 reactor at Chalk River Laboratories is used to mock-up core designs and test new fuels, and has not been used for HEU fuel testing in the recent past. [11] The reactor at the Royal Military College of Canada uses LEU. [12]

The only remaining HEU-fueled reactor operating in Canada is the SLOWPOKE-2 reactor, operated by the Saskatchewan Research Council (SRC) in Saskatoon. In December 2017, the SRC, along with the Canadian Nuclear Safety Commission, began the process of decommissioning the SLOWPOKE-2 reactor. The contract for decommissioning was awarded to engineering firm SNC-Lavalin in July 2018, and decommissioning is expected to be complete by 2020. [13]

Canada has shut down its NRX heavy water reactor (in 1993), and the SLOWPOKE reactors PTR (1990), Kanata (1989), Ottawa (1984), Toronto (1998), Halifax (2011), and Alberta (2017), all of which employed HEU fuel.

Efforts to Reduce or Eliminate Civilian HEU

At the fourth and final NSS in Washington, DC, Canada, along with twenty-one other countries, signed a Gift Basket pledging to "make every effort" to progress toward minimizing and eliminating the use of HEU in civil applications. [14] Canada has worked with the United States and the Office of Materials Management and Minimization (M3), formerly known as Global Threat Reduction Initiative (GTRI), to repatriate U.S.-origin HEU from Canada, as well as from third countries such as Mexico and Vietnam. [15]

According to one estimate, the United States supplied Canada with 2,169 kilograms (kg) of HEU through 1992. [16] Canada began participating in the M3 program in 2010, which seeks to repatriate HEU to the United States for permanent disposition. At the 2016 NSS, Canada committed to repatriate HEU spent fuel stored at the Chalk River Laboratory to the United States by May 2019. [17]

During the 2012 NSS, Canada expanded the repatriation efforts to include HEU-bearing liquids generated as a byproduct of medical isotope production. While nonproliferation advocates generally support this initiative, there has been vocal criticism of the initiative within Canada and the United States by those concerned about the transport of the liquid spent HEU fuel. [18] In November 2015, the U.S. Department of Energy released a report recommending guidelines and safe transportation criteria, and determined that the shipments of liquid HEU present a very low risk to human and environmental health. [19] In 2017, the Savannah River Site in South Carolina received its first shipment of HEU from the Chalk River Laboratory, although one of the radiological protection casings was found to have an unexpected hotspot. [20] Despite this incident, numerous shipments took place in 2018, all of which were successful. [21]

Given its overall support of global nonproliferation initiatives, Canada has recently made significant advancements in HEU minimization efforts, although a substantial amount of HEU still remains in Canada’s stockpile. The Canadian government has the opportunity to continue to play a leading role in building the global norm in favor of reducing civil uses of HEU.

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