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Past and Current Civilian HEU Reduction Efforts

  • Fresh fuel storage, Ukraine reactor Fresh fuel storage, Ukraine reactor
  • Removing fresh nuclear fuel from Rossendorf, Germany Removing fresh nuclear fuel from Rossendorf, Germany


Under the 1953 Atoms for Peace Program initiated by President Dwight D. Eisenhower, the United States transferred research reactors, as well as low enriched uranium (LEU) fuel (less than 20% U-235) for these reactors, to foreign states. However, the LEU fuel technology used at that time soon reached technical limits. In order to build more powerful reactors, the vast majority of research reactor designers turned to the use of highly enriched uranium (HEU) fuel (enriched to 20% or more U-235). In the decade after the launch of the Atoms for Peace program, the United States, the Soviet Union, and other nuclear weapon states exported research reactors fueled with HEU to approximately 40 countries. [1] In addition to research and test reactors, HEU was and continues to be used in other civilian technologies, including for naval and space propulsion, medical isotope production, and as fuel for commercial fast neutron reactors.

The 1974 "peaceful" nuclear test by India dramatically changed global views on exports of fissile materials and technologies. In 1975, the Nuclear Suppliers Group (NSG), a multinational body that sets guidelines for nuclear exports, including dual-use technologies and materials, was created. Since then, the major nuclear exporting states have required International Atomic Energy Agency (IAEA) full-scope safeguards for transfers of nuclear materials and technologies. The IAEA also established guidelines for the physical protection of civilian sites and material. Still, the level of protection has varied from country to country, and HEU vulnerability remains a concern at many civilian sites that were not originally designed with security considerations in mind.

India's nuclear test also spurred both the United States and the Soviet Union to launch programs in the 1970s to mitigate the threat of possible misuse of HEU from civilian installations. [2] These efforts received additional impetus following the September 11, 2001 terrorist attacks. Concerns that HEU from the civilian sector could be used to construct an improvised nuclear device increased international focus on HEU security. Programs to promote and assist civil HEU minimization have become mainstays of U.S. nonproliferation policy. These efforts have received widespread international acceptance and support.

Efforts to Convert Reactors to LEU and to Remove HEU from Sites

Comprehensive reactor conversion efforts typically involve three steps: the development of replacement LEU fuel, the conversion of the HEU-fueled reactor to use the new LEU fuel instead, and the removal of fresh and spent HEU from the reactor site and its associated facilities.

U.S. Reduced Enrichment for Research and Test Reactors (RERTR) Program
In 1978, the United States initiated the Reduced Enrichment for Research and Test Reactors Program (RERTR). The program's original mission was to develop LEU fuel for foreign research and test reactors with power levels of more than 1 MW that the United States was supplying with HEU. These reactors were prioritized because their cores contained several kilograms of HEU and required regular refueling. Additional missions to convert U.S. university reactors and to develop substitute LEU targets for medical isotope production were added in the 1980s. Other civilian reactors using HEU were also subsequently added to the program. [3]

Several types of replacement LEU fuels have been developed under RERTR. Uranium-silicide fuel developed in the 1980s has a uranium density sufficient to convert the vast majority of reactors. Uranium-molybdenum (U-Mo) fuels with very high uranium densities are currently under development and testing, and could potentially replace HEU fuel in the remaining reactors. Since RERTR's inception, many countries have joined the program and started their own efforts to convert reactors and isotope production to LEU. [4]

RERTR and other HEU minimization efforts have increased global awareness of the risks associated with the use of HEU for research and other civilian purposes. [5] Since the early 1980s, no new civilian research reactors with a power level of more than 1 MW that use HEU fuel have been built in Western countries, with the exception of Germany's FRM-II reactor. Despite its achievements, the RERTR program has had some shortcomings. For example, it largely ignored critical assemblies, which are reactors used to mock up future reactor designs, and pulsed reactors, which are often employed by the military for nuclear weapon detonation simulations, despite the large amounts of HEU present in these reactors. [6] Moreover, U.S. federal funding for the program was very low for several decades, which negatively affected the pace of the development of replacement fuels. The program also suffered some technical setbacks, including difficulties with the development of U-Mo dispersion fuel. As a consequence, LEU fuel availability and reactor conversion deadlines for reactors that require new fuels have been repeatedly extended. [7]

Global Threat Reduction Initiative (GTRI)
The slow progress of the RERTR program and international cooperation in this area in the late 1990s and early 2000s primarily can be attributed to meager lack of funding and government inattention to these activities. A newfound sense of urgency to issues of nuclear and radiological materials security arose in the wake of the 9/11 terrorist attacks. In 2004, the U.S. Department of Energy launched the Global Threat Reduction Initiative (GTRI). The GTRI Program subsumed LEU fuel development, reactor conversion, and HEU fuel repatriation activities worldwide, as well as a number of other initiatives addressing nuclear and radioactive material security. It encompassed the Reduced Enrichment for Research and Test Reactors (RERTR) Program, the Foreign Research Reactor Spent Nuclear Fuel (FRR SNF) Acceptance Program, the Russian Research Reactor Fuel Return (RRRFR) Program, the Global Research Reactor Security Program, the BN-350 Spent Fuel Disposition Program, and the Emerging Threats and Gap Material Program, which is designed to address vulnerable, high-risk nuclear and radiological materials throughout the world that are not currently being addressed under other programs. [8]

The GTRI program has become a U.S. national security priority, receiving high-level endorsement and enjoying consistent funding. GTRI targeted 200 reactors in the United States and around the world for conversion or shutdown prior to 2020. In 2009, Washington announced increased support for GTRI in an effort to lock down all nuclear weapons-usable materials in four years. The United States also convened high-level Nuclear Security Summits in 2010 and 2012, which have proven critical in leveraging commitments from countries to participate in HEU reduction efforts. As of 2012, GTRI had verified the conversion or shutdown of nearly 90 facilities that had previously used HEU. All U.S. reactors that could be converted with existing qualified LEU fuel have been converted or were verified as shut down. GTRI is currently working on the development and qualification of LEU fuel to convert the remaining U.S. research reactors. [9]

For more information on HEU minimization in the United States, and GTRI, see the U.S. Civilian HEU page.

U.S. Foreign Research Reactor Spent Nuclear Fuel (FRR SNF) Acceptance Program
Along with reactor conversion efforts, the United States takes back irradiated aluminum-based and TRIGA HEU and LEU fuels from U.S.-supplied research reactors. Fresh fuel is also accepted. In total, approximately 5 metric tons of HEU and 15 metric tons of LEU are eligible to be shipped back to the United States. By March 2012, 58 shipments had been completed with the participation of 30 countries, for a total of 9,261 fuel assemblies. [10] Removal of the spent fuel addresses security and nonproliferation concerns. Reactor operators must commit to convert to LEU in order for the United States to accept their spent fuel. As such, U.S. removal of spent fuel is an economic and environmental incentive for countries to convert to LEU.

U.S.-Russian RERTR Program
The Soviet Union followed the launch of RERTR with a similar initiative in 1978, and began reducing enrichment percentages necessary for Soviet reactors provided to other countries. [11] However, this initiative bogged down in the 1980s due to economic difficulties; the breakup of the USSR worsened the issue of ex-Soviet reactors abroad, as several former Soviet republics found themselves in possession of HEU-fueled research reactors. [12] In 1993, the U.S. Department of Energy initiated discussions with Russia's government and laboratories to restart efforts aimed at the conversion of Soviet-supplied reactors to LEU fuel. Russian scientists were invited to participate in annual International RERTR meetings, a program which Russia eventually joined. In September 1994, representatives of the U.S. Department of Energy and the Russian Ministry of Atomic Energy signed a protocol of intent on cooperation in the development of higher-density 19.75% enriched uranium fuels, and on demonstrating the LEU conversion feasibility of specific reactors. Concrete work in this area started in 1996.

In 1999, the U.S. government announced that it was willing to work with its Russian counterparts and the IAEA to help remove Soviet-origin HEU around the world. Fourteen states expressed interest in 2000, and the first HEU shipment was made in August 2002. [13]

In February 2005, U.S. President George W. Bush and Russian President Vladimir Putin signed the Bratislava Agreement, which committed their respective countries to launch joint work on the security of fissile material and nuclear weapons to prevent these materials from falling into terrorist hands. A bilateral interagency working group was tasked with reporting on the status of nuclear security cooperation to the presidents. Conversion of Soviet-supplied reactors followed suit. Conversion work, begun in 2005, targeted reactors in Libya, Vietnam, Uzbekistan, Hungary, Ukraine, Belarus, the Czech Republic, and Poland. [14] In October 2005, the VR-1 reactor in the Czech Republic became the first of these reactors to convert and receive new LEU fuel.

For more information on HEU minimization in Russia, see the Russian Civilian HEU page.

Ad Hoc Efforts to Repatriate Soviet-Origin HEU Fuel
Washington became concerned about fissile material security in the former Soviet states in the early 1990s. Ad hoc operations were organized in 1994 and 1998 to remove HEU from vulnerable nuclear facilities in the former Soviet republics.

The first operation, known as Project Sapphire, involved the removal of 581 kg of HEU, including some weapons-grade HEU, from the Ulba Metallurgy Plant, a nuclear fuel fabrication facility near Ust-Kamenogorsk, Kazakhstan. The considerable amount of material, its poor security, and allegations about Iranian interest in the material and the facility were driving forces behind the U.S. government's involvement. The Ulba HEU was transported to Oak Ridge National Laboratory in the United States in November 1994. [15]

The second operation, Auburn Endeavor, involved the removal on April 24, 1998 of approximately 4.3 kg of HEU fuel (mostly fresh HEU fuel) and 9.5 kg of fresh and spent LEU fuel from the Institute of Physics in Mtskheta, Georgia. The operation involved the governments of the United States, the United Kingdom, and Georgia. The material was transported to the Dounreay Nuclear Complex in Scotland. [16]

After the terrorist attacks of September 11, 2001, efforts to convert research reactors, particularly in third countries, and to take back HEU fuel received new impetus. The United States and Russia began to work closely on removing fresh and spent HEU fuel from countries they had earlier supplied with research reactors and HEU fuel.

In August 2002, the Vinca Institute of Nuclear Science, located on the outskirts of Belgrade in the Republic of Serbia and Montenegro, became the focus of a tripartite effort by the United States, Russia, and the International Atomic Energy Agency to remove 48 kilograms of fresh (unirradiated) HEU research reactor fuel. The removed material consisted of 5,046 cylinders of 80% enriched fresh fuel. [17] Although U.S. knowledge of the HEU at Vinca and its vulnerability dates back to at least 1994, the opportunity to recover the material was realized only in summer 2002. Only then were the United States and Russia finally able to come to an agreement about the return of Soviet-supplied HEU fuel to Russia (the actual government agreement was signed later, in 2004). The Vinca operation was a breakthrough in the repatriation of Soviet-supplied HEU fuel to its country of origin. A non-governmental organization, the Nuclear Threat Initiative (NTI), played a crucial role in convincing the Yugoslav government to part with the HEU. NTI provided $5 million to address radioactive hazards at Vinca, and this incentive, along with the funding for the operation itself by the U.S. government, made it possible to conclude the deal to remove the HEU from the country. [18] The final shipment was concluded in December 2010. [19]

Russian Research Reactor Fuel Return Program (RRRFR)
Since 2002, Russia has accepted Soviet-origin fuel containing HEU within the framework of the Russian Research Reactor Fuel Return Program (RRRFR). All returned fresh HEU fuel is downblended in Russia to LEU. The United States, Russia, and the International Atomic Energy Agency are closely involved in each HEU fuel take-back operation. Since 2002, they have successfully cooperated in efforts to remove more than 1,700 kg of Russian-origin HEU in forty-four shipments. Of these, over 600 kg were fresh fuel and nearly 1,000 kg were spent fuel. [20]

For more information on fuel returns to Russia, see the Russian Civilian HEU page.

Effort to Blend-Down HEU and to Consolidate Stockpiles

In addition to converting facilities to use LEU fuel and repatriating HEU, there have also been efforts to consolidate fresh and spent HEU fuel at a smaller number of relatively secure locations, and to blend-down excess HEU to LEU. Consolidation efforts are designed to improve overall nuclear material security by allowing states to concentrate their resources on defending fewer sites. The U.S.-Russian Materials Consolidation and Conversion (MCC) Program, established in 1999, reduces excess Russian civilian HEU by blending it down into LEU. This program has blended down more than 10 tons of HEU, and has led to the removal of HEU from the Krylov Shipbuilding Research Institute. [21] In light of the increased U.S. focus on locking down nuclear materials, some have called for a more focused and aggressive approach to consolidation in Russia. [22]

Both the United States and Russia have large quantities of HEU that are no longer needed in their defense programs. In Russia, large quantities of excess HEU from weapons were blended down to LEU within the framework of the "Megatons to Megawatts program" (also known as the HEU-LEU program). As per the 1993 U.S.-Russia agreement, 500 metric tons of weapons HEU were downblended by 2013. The resulting LEU was shipped to the United States to be used in LEU fuel for commercial nuclear power generation. [23] The United States initially declared some 174 metric tons of HEU as excess to military needs, designating this material as civilian. An additional 200 metric tons were officially removed from the U.S. weapons stockpile in November 2005; of this amount, approximately 20 metric tons will be down-blended to LEU. [24] Since the amount of HEU that is actually excess to military needs is likely greater than the amount that has officially been declared excess to date, there have been calls to continue such activities.

For more information on excess stockpiles and on "Megatons to Megawatts," see the U.S. and the Russian Civilian HEU pages.

Eliminating the Use of HEU in Medical Isotope Production

As discussed in the Civilian Uses of HEU page, the production of medical isotopes has required exports of HEU from the United States for reactor fuel and target material. In 1992, the United States adopted the Schumer Amendment to the Energy Policy Act, which required foreign reactors supplied with HEU fuel by the United States to commit to convert to LEU as quickly as possible, and prohibited U.S. HEU exports if foreign reactor operators did not agree to do so. The implementation of this amendment, in combination with LEU fuel development and a drop in the construction of new reactors, facilitated a rapid decline in U.S. HEU exports, from an annual peak of nearly three tons in the late 1960s to a few tens of kilograms or less by the early 1990s-a 99% reduction. [25] In 2005, however, an Energy bill passed by Congress included an amendment relaxing restrictions on HEU exports for medical isotope production.

Recent programs by the NNSA and the IAEA have supported the development of regional medical isotope production using LEU and other alternative technologies. [26] The NNSA has also pursued the development of an indigenous medical isotope production capability, concluding cooperative agreements with several U.S. companies to explore methods of Mo-99 production that would not involve the irradiation of targets in research reactors. [27]

Establishing a reliable supply of HEU-free medical isotopes has, however, proven difficult. The production of Mo-99 with HEU is presently cheaper, making commercial operations with HEU more competitive than their LEU counterparts. In order to decrease the reliance on old HEU-fueled isotope production reactors, U.S. policy has aimed to level the playing field for HEU-free producers through incentive payments. [28]

For more information on HEU minimization in the production of medical isotopes, see the Canadian, South African, U.S., and Russian Civilian HEU pages.

[1] Elena Sokova, Charles Streeper, "Elimination of Excess Fissile Material," in Nuclear Safeguards, Security and Nonproliferation: Achieving Security with Technology and Policy, James E. Doyle, ed., (Burlington: Butterworth-Heinemann, 2008), p. 361.
[2] Elena Sokova, Charles Streeper, "Elimination of Excess Fissile Material," in Nuclear Safeguards, Security and Nonproliferation: Achieving Security with Technology and Policy, James E. Doyle, ed., (Burlington: Butterworth-Heinemann, 2008), p. 361.
[3] For a historical overview, see Anya Loukianova and Cristina Hansell, "Leveraging U.S. Policy for a Global Commitment to HEU Elimination," The Nonproliferation Review, July 2008.
[4] Armando Travelli, R. Domagala, Jim Matos, J. Snelgrove, "Development and Transfer of Fuel Fabrication and Utilization Technology for Research Reactors," paper presented at International Conference on Nuclear Technology Transfer, Buenos Aires, on November 1, 1982. Several other countries, including Canada, France, Germany, and Japan, established similar programs in the 1970s, while the IAEA provided a forum for cooperative technical research. In the late 1970s, the Soviet Union began replacing very highly enriched uranium fuels in research reactors outside of the USSR with 36 percent enriched fuel.
[5] For an excellent summary of RERTR's impact on U.S. HEU exports, see, Alan J. Kuperman, "Codifying the Phase-Out of Bomb Grade Fuel for Research Reactors," in Paul Leventhal, Sharon Tanzer, and Steven Dolley, eds., Nuclear Power and the Spread of Nuclear Weapons (Washington, DC: Brassey's, 2002), pp. 251-260.
[6] Alan J. Kuperman, "Global HEU Phase-Out: Prospects and Challenges," Nuclear Terrorism and Global Security: The Challenge of Phasing out Highly Enriched Uranium, Alan J. Kuperman, ed., (New York: Routledge, 2013), p. 8; Alexander Glaser and Frank N. von Hippel, "Global Cleanout: Reducing the Threat of HEU-Fueled Nuclear Terrorism," Arms Control Today, January/February 2006, www.armscontrol.org.
[7] See, for example, Paul Leventhal and Alan Kuperman, "RERTR at the Crossroads: Success or Demise?" paper presented to the RERTR 1995 International Meeting, Paris, France, September 18, 1995.
[8] Kurt Westerman, "Global Threat Reduction Initiative: Reducing the Threat of Nuclear & Radiological Terrorism," presented at USSOCOM CBRN Conference, Tampa, U.S.A., December 6-8, 2005, www.dtic.mil.
[9] Jeff Chamberlain, "The Role of International Cooperation in International HEU Minimization," Second Symposium on HEU, January 24, 2012, www.nti.org.
[10] C.E. Messick and J.J. Galan, "Global Threat Reduction Initiative's U.S.-origin Nuclear Material Removal Program: 2012 Update," International Topical Meeting on Research Reactor Fuel Management (RRFM), Prague, Czech Republic, March 2012, www.euronuclear.org.
[11] Elena Sokova, Charles Streeper, "Elimination of Excess Fissile Material," in Nuclear Safeguards, Security and Nonproliferation: Achieving Security with Technology and Policy, James E. Doyle, ed., (Burlington: Butterworth-Heinemann, 2008), p. 361.
[12] S. Tozser, P. Adelfang, and E. Bradley, "Ten Years of IAEA Cooperation with the Russian Reactor Research Fuel Return Programme," paper presented at the 2012 RRFM conference in Prague, Czech Republic, March 2012, www.euronuclear.org.
[13] S. Tozser, P. Adelfang, E. Bradley, "Ten Years of IAEA Cooperation with the Russian Research Reactor Fuel Return Programme," presentation given at RERTR 2011- 33rd International Meeting on Reduced Enrichment for Research and Test Reactors, Santiago, Chile, October 23-27, 2011, pp. 1-2.
[14] William C. Potter, "Project Sapphire: U.S.-Kazakhstani Cooperation for Nonproliferation," in John M. Shields and William C. Potter, eds., Dismantling the Cold War: U.S. and NIS Perspectives on the Nunn- Lugar Cooperative Threat Reduction Program (Cambridge: MIT Press, 1997), pp. 345-362.
[15] Center for Nonproliferation Studies, "Georgia: Operation Auburn Endeavor," Nuclear Threat Initiative, www.nti.org.
[16] "Joint Statement of U.S. Secretary of Energy Spencer Abraham and Minister of the Russian Federation for Atomic Energy Aleksandr Rumyantsev on Cooperation to Transfer Russian-Origin High-Enriched Uranium Research Reactor Fuel to the Russian Federation," November 7, 2003, www.nti.org. Agreement between the Government of the United States of America and the Government of the Russian Federation Concerning Cooperation for the Transfer of Russian-Produced Research Reactor Nuclear Fuel to the Russian Federation, May 27, 2004.
[17] William C. Potter, Djuro Miljanic, and Ivo Slaus, "Tito's Nuclear Legacy," Bulletin of the Atomic Scientists, 56 (March/April 2000), pp. 63-70; Philipp C. Bleek, "Project Vinca: Lessons for Securing Civil Nuclear Material Stockpiles," The Nonproliferation Review 10 (Fall-Winter 2003).
[18] William C. Potter, Djuro Miljanic, and Ivo Slaus, "Tito's Nuclear Legacy," Bulletin of the Atomic Scientists, 56 (March/April 2000), pp. 63-70; Philipp C. Bleek, "Project Vinca: Lessons for Securing Civil Nuclear Material Stockpiles," The Nonproliferation Review 10 (Fall-Winter 2003).
[19] U.S. Department of Energy, National Nuclear Security Administration, "The Four-Year Effort: Contributions of the Global Threat Reduction Initiative to Secure the World's Most Vulnerable Nuclear Materials, by December 2013," 2013, http://nnsa.energy.gov.
[20] S. Tozser, P. Adelfang, and E. Bradley, "Ten Years of IAEA Cooperation with the Russian Reactor Research Fuel Return Programme," paper presented at the 2012 RRFM conference in Prague, Czech Republic, March 2012, www.euronuclear.org.
[21] Matthew Bunn, Securing the Bomb 2010 (Cambridge, MA and Washington, DC: Belfer Center for Science and International Affairs and the Nuclear Threat Initiative, November 2010), www.nti.org, p. 37.
[22] Matthew Bunn and Eben Harrell, "Consolidation: Thwarting Nuclear Theft," Project on Managing the Atom report, March 2012, p. 17.
[23] "Military Warheads as a Source of Nuclear Fuel," World Nuclear Association Report, 18 July 2012, www.world-nuclear.org; "На ЭХЗ завершена переработка «Мегатонн - в мегаватты»," Новости ЭХЗ, August 27, 2013, www.ecp.ru; Nancy Slater-Thompson, Doug Bonnar, "Megatons to Megawatts Program Will Conclude at the End of 2013," U.S. Energy Information Administration, September 24, 2013, www.eia.gov; "Megatons to Megawatts," the United States Enrichment Corporation website, accessed July 27, 2012, www.usec.com.
[24] For information on the U.S. program, see "Reducing Excess Stockpiles: U.S. Highly Enriched Uranium Disposition" Securing the Bomb 2005, www.nti.org.
[25] Alan J. Kuperman, "Civilian Highly Enriched Uranium and the Fissile Material Convention," in Paul L. Leventhal, ed., Nuclear Power and the Spread of Nuclear Weapons (Dulles: Brassey's Inc., 2002), pp. 249-260, as cited in Alan Kuperman, "Bomb-grade bazaar," Bulletin of the Atomic Scientists, March/April 2006, www.thebulletin.org.
[26] National Nuclear Security Administration, "Record Levels of Non-HEU-Based Mo-99 Supplied to the United States," NNSA Press Release, June 2, 2011, www.nnsa.energy.gov; Miles Pomper, ""HEU Minimization after the Seoul Nuclear Security Summit," paper presented at the International Nuclear Materials Management conference in Orlando, Florida, United States, July 2012.
[27] Cristina Hansell, "Nuclear Medicine's Double Standard," The Nonproliferation Review, Vol. 15, No. 2, July 2008, p. 165.
[28] Miles Pomper, ""HEU Minimization after the Seoul Nuclear Security Summit," paper presented at the International Nuclear Materials Management conference in Orlando, Florida, July 2012; Roy W. Brown, "An Update on the Conversion from Highly Enriched Uranium (HEU) to Low Enriched Uranium (LEU)," presentation given at the International Atomic Energy Agency (IAEA) Technical Meeting on Conversion Planning for Molybenum-99 (Mo-99) Production Facilities, slides dated May 23, 2013, p. 9, www.iaea.org.

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This material is produced independently for NTI by the James Martin Center for Nonproliferation Studies at the Monterey Institute of International Studies and does not necessarily reflect the opinions of and has not been independently verified by NTI or its directors, officers, employees, or agents.


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