Under the 1953 Atoms for Peace Program initiated by President Dwight D. Eisenhower, the United States exported research reactors and low enriched uranium (LEU) fuel to many other countries. However, the LEU fuel technology used in the 1950s soon reached its limits. In order to build more powerful reactors and improve the performance of existing reactors, research reactor designers turned to highly enriched uranium (HEU) fuel. Consequently, in the following decades, the United States, the Soviet Union, and other nuclear weapon states exported HEU-fueled research reactors and HEU fuel.
The 1974 "peaceful" nuclear test by India dramatically changed global views on the export of fissile materials and technologies. As a result of this test the United States and the Soviet Union launched programs to mitigate the threat of possible misuse of fissile materials, including HEU, at civilian installations.  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 exporters have required International Atomic Energy Agency (IAEA) full-scope safeguards for transfers of nuclear materials and technologies. The IAEA has also established guidelines for the physical protection of civilian sites and materials. 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.
Following the 11 September 2001 terrorist attacks, threat perceptions shifted to include greater emphasis on the threat posed by non-state actors. There are significant concerns that terrorists could exploit inadequate security over civilian-use HEU and HEU spent fuel to build and detonate nuclear or radiological weapons. This has resulted in numerous proposals from both national governments, as well as international organizations to secure, reduce and eliminate civil-use HEU. Programs to promote and assist in civil HEU minimization have become mainstays of U.S. nonproliferation policy. These efforts have received widespread international acceptance and support, particularly through the international Nuclear Security Summit process which took place between 2010–2016.
Efforts to Convert Reactors to LEU and to Remove HEU from Sites
Comprehensive reactor conversion efforts typically involve three steps: (1) the development of replacement LEU fuel; (2) the conversion of the HEU-fueled reactor to use the new LEU fuel; and (3) the removal of fresh and spent HEU from the reactor site and its associated facilities. The following programs are associated with reactor conversion efforts:
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 subsequently added to the program. 
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.  Since the program's inception, over 40 research reactors have been converted.  Additionally, 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. RERTR holds annual conferences in order to gauge international progress, and to share information regarding the progress of national and international programs to develop low-enriched uranium (LEU) fuels and conversion analysis studies. 
In 2004, the U.S. Department of Energy and the National Nuclear Security Administration (NNSA) launched the Global Threat Reduction Initiative (GTRI) priority to overseeing 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. GTRI encompasses many reduction and elimination programs, including: Reduced Enrichment for Research and Test Reactors (RERTR); 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. 
GTRI was recently converted into the Office of Materials Management and Minimization (M3), and continues the efforts of GTRI in supporting reactor conversions, fuel returns, and LEU fuel development. M3 has been divided into three subprograms: Conversion, Nuclear Materials Removal, and Material Disposition. 
Efforts by GTRI and M3 have received high-level endorsement, including a certain level of bi-partisan support, and enjoy consistent funding. GTRI has targeted 200 reactors in the United States and around the world for conversion or shutdown by 2020. In 2009, the United States announced increased support for GTRI in an effort to lock down all nuclear weapons-usable materials within four years. As of 2016, GTRI had verified the conversion or shutdown of 94 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 high density LEU fuel to convert the remaining U.S. high performance research reactors.  This high density fuel in development is a uranium-molybdenum (UMo, or U-moly) monolithic fuel, as opposed to UMo dispersion fuel.
For more information on HEU minimization in the United States and M3 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, as well as fresh fuels from U.S.-supplied research reactors. In total, approximately 5 metric tons of HEU and 15 metric tons of LEU are eligible to be shipped back to the United States. Since 1996, through participation with 41 countries, a total of nearly 11,600 fuel assemblies, accounting for nearly 1,200 kg of HEU, have been received. 
Removal of the spent fuel addresses security and nonproliferation concerns. However, in order for the United States to accept the spent fuel, reactor operators must commit to convert to LEU. Additionally, the enriched fuel must be U.S.-origin, the participating country must enter into a contract that details national responsibilities, and the reactor must meet a list of status specifications.  As such, U.S. removal of spent fuel is an economic and environmental incentive for countries to convert to LEU.
FRR SNF is scheduled to conclude in 2019, with shipments in the next five years expected from, Canada, Japan, Finland, Australia, and other states. Despite the program's conclusion in 2019, shipments are expected from Austria and Japan as late as 2029.
U.S.-Russia RERTR Program
The Soviet Union followed the launch of RERTR with a similar initiative in 1978.  However, this initiative faced economic difficulties in the 1980s. Following the breakup of the USSR, several former Soviet republics found themselves in possession of HEU-fueled research reactors.  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 that 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 occurred in August 2002. 
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 them 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 work on Soviet-supplied reactors began in 2005, and targeted reactors in Libya, Vietnam, Uzbekistan, Hungary, Ukraine, Belarus, the Czech Republic, and Poland. 
For more information on HEU minimization in Russia, see the Russian Civilian HEU page.
Ad Hoc Efforts to Repatriate Soviet-Origin HEU
The United States 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 weapons-grade HEU, including some 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. 
The second operation, Auburn Endeavor, was conducted cooperatively by the United States, Georgia, and the United Kingdom on 24 April 1998, and involved the removal of approximately 4.3 kg of weapons-grade HEU fuel (mostly fresh) and 9.5 kg fresh and spent LEU fuel from the Institute of Physics in Mtskheta, Georgia. The material was transported to the Dounreay Nuclear Complex in Scotland. 
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.  The Vinca operation was a breakthrough in the repatriation of Soviet-supplied HEU fuel to its country of origin. The Nuclear Threat Initiative (NTI) played a crucial role in convincing the Yugoslav government to part with the HEU.  The final shipment was concluded in December 2010. 
Russian Research Reactor Fuel Return Program (RRRFR)
Since 2002, Russia has accepted Soviet-origin fuel containing HEU under 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 to remove "nearly 2160 kilograms of former USSR-supplied HEU from 14 countries to Russia in 61 shipments." 
For more information on fuel returns to Russia, see the Russia Civilian HEU page.
Effort to Consolidate Stockpiles and to Blend-Down HEU
There have also been efforts to consolidate fresh and spent HEU fuel at a smaller number of relatively secure locations, or to blend-down excess HEU to LEU. Consolidation of HEU holdings is designed to economize 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, reduced excess Russian civilian HEU by blending it down into LEU. This program blended down more than 10 tons of HEU, and led to the removal of HEU from the Krylov Shipbuilding Research Institute. 
Eliminating the Use of HEU in Medical Isotope Production
The production of medical isotopes has required the use of HEU 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 U.S.-origin HEU fuel to commit to convert to LEU as quickly as possible, or otherwise be prohibited from purchasing U.S. HEU. 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. U.S. HEU exports reached an annual peak of nearly three tons in the late 1960s, but dropped to a few tens of kilograms or less by the early 1990s, resulting in a nearly 99% reduction.  In 2005, however, Canada sought to relax HEU export restrictions within the Schumer Amendment in order to avoid the high costs of building an LEU facility, and a possible shortage of medical isotope availability. This resulted in Congress passing the Burr Amendment, which relaxed HEU export restrictions allowing the United States to export to medical isotope producers in Europe and Canada, although not elsewhere, without requiring conversion to LEU.
Recent programs by the NNSA and the IAEA have supported the development of regional medical isotope production using LEU and other alternative technologies.  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. 
Establishing a reliable supply of HEU-free medical isotopes has, however, proven difficult. The production of Mo-99 with HEU is presently cheaper, and is claimed to produce less waste, 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. 
Recommendations by the Nuclear Energy Agency have prioritized the long-term stability and availability of medical isotopes. NEA recommends conversion to LEU targets, noting that this will increase the cost of production but will not decrease productive capacity. In order for conversion to be successful, governments will need to play a role in facilitating conversion, by ending current subsidies, in order to ensure continued long-term supply security.  To this end, 14 countries made a joint declaration to the OECD-NEA committing to take steps towards ending subsidies of production at facilities that are part of the global Mo-99 supply chain. 
International Politics of Civilian HEU Elimination
As awareness of the need to secure civil-use HEU has increased, the issue has increasingly been addressed in high profile international forums. These include the Nuclear Security Summit process, the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) Review Conference (RevCon), and the G8 Global Partnership.
Nuclear Security Summit
In 2009, President Obama announced his intention to secure all vulnerable nuclear materials around the world within four years, beginning with "a Global Summit on Nuclear Security."  In April 2010, the United States hosted the leaders of 47 nations at the inaugural Nuclear Security Summit (NSS). Those present endorsed the goal of securing vulnerable nuclear materials within the four-year timeframe. The Summit Communiqué called for, inter alia, "focused national efforts to improve security and accounting of nuclear materials and strengthen regulations - with a special focus on plutonium and [HEU]" and the "consolidation of stocks of [HEU] and plutonium and reduction in the use of" HEU. The Summit Work Plan called on states to convert "civilian facilities that use highly enriched uranium to non-weapons-usable materials." 
The second Nuclear Security Summit took place in Seoul in 2012, and was attended by 53 heads of state. Participants reported their progress and pledged to accelerate their HEU reduction efforts. The Summit Communiqué encouraged "states to take measures to minimize the use of HEU...where technically and economically feasible...and encourage States...to announce voluntary specific actions intended to minimize the use of HEU." It also encouraged states to "promote the use of LEU fuels and targets in commercial applications such as isotope production, and in this regard, "welcome[d] relevant international cooperation on high-density LEU fuel to support the conversion of research and test reactors." 
In March 2014 the 53 countries from the Seoul Summit, along with representatives from four international organizations, met for the third Nuclear Security Summit in The Hague, The Netherlands. The summit focused on strengthening the global nuclear security architecture, including reducing stockpiles of nuclear materials, improving the security of nuclear and radioactive sources, increasing coordination with the nuclear industry, and improving international cooperation.  One of the outcomes of the 2014 summit was a joint statement, also known as a "gift basket," by twelve nations marking the elimination of HEU within their borders. 
The NSS process convened a fourth and final Summit in March 2016, held in Washington DC with fifty-two countries and four international organizations represented.  The final Communiqué reaffirmed the threat of nuclear and radiological terrorism, and highlighted the importance of strengthening the global nuclear security architecture by securing nuclear and radiological materials and facilities.  Notable achievements in HEU minimization and elimination included a 'gift basket' signed by twenty-two countries that pledged to implement a comprehensive plan towards the minimization and ultimate elimination of HEU from civil use;  the announcement of the successful removal of over 500 kg of HEU and plutonium from Japan - fulfilling a commitment made at the previous Summit;  and a reaffirmation of the importance of continued cooperation on the development of high-density LEU fuel . In addition, it was announced that Argentina had been cleared of HEU, resulting in Latin America and the Caribbean being HEU-free. 
Looking to the future, the final NSS established a Nuclear Security Contact Group, "to address continuing and evolving nuclear security challenges." The group will meet annually at the General Conference at the IAEA to discuss commitments, progress, and nuclear security. 
The summits have focused high-level attention on the issue of fissile materials security, facilitated information sharing, and provided an incentive for states to follow through on their commitments. By the completion of the 2016 NSS, 29 countries plus Taiwan had been cleared of HEU. 
The Non-Proliferation Treaty Review Process
One venue for discussion of the elimination of civil-use HEU has been the NPT Review Conference (RevCon), which is held every five years. At the NPT RevCon in 1995, eight European countries drafted text to be included in the final document recommending "that no new civil reactors requiring highly-enriched uranium be constructed."  However, Germany fought against the language, which conflicted with German plans for a new HEU-fueled research reactor, the FRM-II. 
Countries such as Kyrgyzstan continued to press for more steps toward enhancing "the security of existing stockpiles of highly enriched uranium, while consolidating them, reducing their size, and moving toward the elimination of the use of highly enriched uranium in the civilian sector."  Building on momentum at the 2005 RevCon, former IAEA Director General Mohamed El-Baradei called on countries "to minimize, and eventually eliminate, the use of high enriched uranium in peaceful nuclear applications." 
The 2010 RevCon, however, saw states devote much less attention to HEU minimization than expected.  The Conference's Final Document settled for muted and irresolute language, "encouraging states concerned, on a voluntary basis, to further minimize [HEU] in civilian stocks and use, where technically and economically feasible."  Dissatisfied with the lack of practical progress since the 2010 RevCon, ten states (Australia, Canada, Chile, Japan, Germany, Mexico, the Netherlands, Poland, Turkey, and the United Arab Emirates) formed the "Friends of the Non-Proliferation Treaty" group. Meeting in April 2011, the group called for a prohibition on a global scale of weapon-usable nuclear material "to curb the risk of future nuclear arms races and reduce the danger of non-state actors getting such material into their hands." 
Although the 2015 NPT RevCon did not produce a consensus document, the final document demonstrated continued attention to the security of civilian-use HEU and other radioactive materials. In particular, it called for all states to, "achieve and maintain highly effective nuclear security, including physical protection,"  and to, "improve national capabilities to detect, deter, and disrupt illicit trafficking in nuclear materials." It also encouraged states to, "further minimize highly enriched uranium in civilian stocks and use." 
The G7/G8 Global Partnership
The Global Partnership Against the Spread of Weapons and Materials of Mass Destruction, established at the G8 Kananaskis Summit in 2002, committed the G8 (France, the United States, the United Kingdom, Germany, Japan, Italy, Canada, and Russia) "to prevent terrorists or those that harbor them from acquiring or developing....radiological or nuclear weapons..." To that end, the G8 subscribed to a six-point program including, "promoting multilateral treaties aimed at preventing the spread of weapons, materials and know how; and accounting for and securing these items so as to ensure against any state or group having access to it." 
The 2004 G8 Sea Island Summit Action Plan included support for projects "to eliminate over time the use of HEU fuel in research reactors worldwide, secure and remove fresh and spent HEU fuel, control and secure radiation sources, strengthen export control and border security."  The 2005 Annual Report noted the "cooperation of Russia and the United States to convert research reactors to LEU (low enriched) fuel" and the repatriation of Russian-origin HEU fuel "from a number of countries, most of which are not involved directly in the Global Partnership."  This language referred to a U.S.-Russian initiative to improve the security of nuclear weapons and fissile materials in Bratislava, Slovakia in 2005, whereby Russia pledged to remove Soviet-origin HEU from research reactors outside its territories.
In 2011, the Global Partnership's mandate was extended beyond the year 2012, and the group opened to new members.  Partner countries committed to working on four priority areas, including the security of nuclear and radiological materials, biosecurity, scientist engagement, and implementation of UNSCR 1540. 
On 24 March 2014, the leaders of all G8 nations except Russia met on the sidelines of the Nuclear Security Summit in The Hague, Netherlands. They decided to expel Russia from the G8 as a punitive measure for its annexation of Crimea. Not long after the initial suspension was declared, Russia announced that it did not intend to seek re-admittance into the partnership. 
For more information see: Global Partnership Against the Spread of Weapons and Materials of Mass Destruction.
International Atomic Energy Agency
The IAEA plays a vital role in the technical component of HEU minimization, but does not have a mandate to take a policy leadership role. The IAEA has contended with numerous disagreements among its member states on this issue,  but according to the Agency "the IAEA Office of Nuclear Security, if adequately funded, could usefully serve as the focal point for collecting information on the status of nuclear security activities launched under the NSS [Nuclear Security Summit] process." 
In cooperation with the IAEA, the European Nuclear Society holds an annual International Topical Meeting on Research Reactor Fuel Management. The main issue during these conferences continues to be "the development of very high density low-enriched uranium fuel, as well as the conversion of the most demanding high-flux research reactors (high performance research reactors) to use LEU instead of HEU."  In February 2006, the IAEA held a technical workshop to examine the options for expanding the IAEA database on research reactors to include the information needed for a global effort to reduce HEU, including broadening it to include all civilian HEU uses. As IAEA Director General Yukiya Amano stated in his speech at the 2010 Nuclear Security Summit, the IAEA has "helped to repatriate more than one ton of highly enriched uranium research reactor fuel to the countries which produced it." However, he also stressed that "responsibility for nuclear security rests with each sovereign state." 
As the Nuclear Security Summit process ends, the IAEA is committed to promoting continued discussion of HEU minimization. In June 2018, Norway will host the 3rd international symposium on highly enriched uranium (HEU) minimization, organized in cooperation with the IAEA. 
United Nations Security Council Resolutions 1540 and 1887
UNSCR 1540 mandates the development of effective national measures to account for and secure materials that could contribute to nuclear weapons. These include appropriate and effective physical protection measures and appropriate and effective border controls and law enforcement efforts to prevent illicit trafficking of weapons and related materials.  On 20 April 2011, the Security Council voted to extend the mandate of the 1540 Committee, which monitors the implementation of these efforts, for an additional 10 years. 
UNSCR 1887, adopted in September 2009, encourages states to share best practices for improving nuclear safety and security standards, in order to reduce the risk of nuclear terrorism. Crucially, the resolution calls on states to "minimize to the greatest extent that is technically and economically feasible the use of highly enriched uranium for civilian purposes, including by working to convert research reactors and radioisotope production processes to the use of low enriched uranium fuels and targets." 
The Way Forward
The initiatives discussed here, when taken together with national programs, provide the key elements that, given strong political leadership, could be used to eliminate and secure much of the worlds' civil-use HEU. However, continued political commitment, political will, and proper coordination amongst policymakers and the scientific community will be required to fully implement these initiatives. Despite positive trends, fully converting all existing research reactors and removing all fresh and spent HEU fuel in civilian use is a costly and time-consuming undertaking which has been underway for nearly three decades. In addition, these efforts continue to face a number of technical and political challenges. The latter includes resistance from some countries such as Belarus, which suspended HEU elimination talks with the United States in a tit-for-tat response to the imposition of U.S. sanctions, and South Africa, which sees its HEU stocks as economically valuable and as a bargaining chip in its push for nuclear disarmament. 
 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.
 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.
 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.
 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.
 "RERTR: Reduced Enrichment for Research and Test Reactors," Nuclear Engineering Division at Argonne National Laboratory, www.rertr.anl.gov.
 "RERTR-2015 International Meeting," RERTR-2015, International Meeting on Reduced Enrichment for Research and Test Reactors, RERTR Program, Nuclear Engineering Division at Argonne.
 Kurt Westerman, "Global Threat Reduction Initiative: Reducing the Threat of Nuclear & Radiological Terrorism," presented at USSOCOM CBRN Conference, Tampa, U.S.A., 6-8 December 2005, www.dtic.mil.
 "Material Management and Minimization," National Nuclear Security Administration, April 2016, https://nnsa.energy.gov.
 As announced by Brian Waud (NNSA) at RRFM/IGORR 2016 (European Research Reactor Conference), 14 March 2016, Berlin.
 National Nuclear Security Administration, "GTRI's Convert Program: Minimizing the Use of Highly Enriched Uranium," Fact Sheet, 29 May 2014, https://nnsa.energy.gov.
 U.S. Department of Energy, Acceptance and Disposition of Department of Energy Spent Nuclear Fuel, Briefing to the National Academy of Sciences, 3 December 2014, https://dels.nas.edu.
 "Return of Research Reactor Spent Fuel to the Country of Origin: Requirements for Technical and Administrative Preparations and National Experiences," Proceedings of a technical meeting held in Vienna, 28-31 August 2006.
 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.
 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.
 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, 23-27 October 2011, pp. 1-2.
 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.
 Center for Nonproliferation Studies, "Georgia: Operation Auburn Endeavor," Nuclear Threat Initiative, www.nti.org.
 "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," 7 November 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, 27 May 2004.
 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).
 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. 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, https://nnsa.energy.gov.
 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, https://nnsa.energy.gov.
 Tozser, Sander, Uzbekistan Becomes HEU-Free Following Shipment of Fuel to Russia, IAEA, 28 September 2015, www.iaea.org.
 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.
 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.
 National Nuclear Security Administration, "Record Levels of Non-HEU-Based Mo-99 Supplied to the United States," NNSA Press Release, 2 June 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.
 Cristina Hansell, "Nuclear Medicine's Double Standard," The Nonproliferation Review, Vol. 15, No. 2, July 2008, p. 165.
 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 23 May 2013, p. 9, www.iaea.org.
 "The Supply of Medical Isotopes: Market Impacts of Converting to Low-enriched Uranium Targets for Medical Isotope Production," Nuclear Energy Agency, Organization for Economic Co-operation and Development, 2012.
 "Joint Declaration on the Security of Supply of Medical Radioisotopes," OECD-NEA, 2015, www.oecd-nea.org.
 Office of the Press Secretary, "Remarks by President Barack Obama," White House, Hradčany Square: Prague, Czech Republic, 5 April 2009, www.whitehouse.gov.
 Office of the Press Secretary, "Key Facts about the Nuclear Security Summit," White House, 13 April 2010, www.whitehouse.gov.
 "Seoul Communiqué: 2012 Seoul Nuclear Security Summit," 26-27 March 2012, www.un.org.
 "Nuclear Security Summit at a Glance: Fact Sheets and Briefs," Kelsey Davenport, April 2014, www.armscontrol.org.
 "Joint Statement on Countries Free of Highly Enriched Uranium," Nuclear Security Summit, March 2014, www.state.gov.
 "Countries and International Organizations Attending NSS 2016," Nuclear Security Summit 2016, 1 April 2016.
 "Nuclear Security Summit 2016, Communiqué," Nuclear Security Summit 2016, 1 April 2016.
 These countries include Argentina, Armenia, Australia, Canada, Czech Republic, Chile, Denmark, Finland, Georgia, Indonesia, Mexico, Netherlands, Nigeria, Norway, Philippines, Poland, Republic of Korea, Romania, Singapore, Sweden, United Kingdom, United States. "NSS 2016: Gift Basket on Minimizing and Eliminating the Use of Highly Enriched Uranium in Civil Applications," Nuclear Security Summit 2016, April 2016.
 "Joint Statement on U.S. - Japan Cooperation," Nuclear Security Summit 2016, 1 April 2016.
 The signatories are Belgium, France, Germany, Republic of Korea, and the U.S. "Joint Statement on Multilateral Cooperation on High Density Low-Enriched Uranium Fuel Development for High-Performance Research Reactors," Nuclear Security Summit 2016, April 2016.
 "Fact Sheet: Eliminating all Highly Enriched Uranium from Argentina," The White House Office of the Press Secretary, 1 April 2016.
 "Joint Statement on Sustaining Action to Strengthen Global Nuclear Architecture," Nuclear Security Summit 2016, 4 April 2016.
 "Fact Sheet: HEU Minimization Activities since March 2014," The White House: Office of the Press Secretary, Nuclear Security Summit 2016, 1 April 2016.
 Austria, Denmark, Finland, Hungary, Ireland, the Netherlands, Norway, and Sweden, together with Australia, Canada, and New Zealand. (Cf. Document NPT/CONF.1995/MC.II/WP.8 (21 April 1995).
 Wolfgang Liebert, "New German Research Reactor Using Highly-Enriched Uranium (HEU) Raises Concern," International Network of Engineers and Scientists against Proliferation Briefing Paper No. 6, 1998, www.inesap.org.
 Statement by H.E. Nurbek Jeenbaev, Permanent Representative of the Kyrgyz Republic to the UN at the 2005 Review Conference of the Parties to the Treaty on the Nonproliferation of Nuclear Weapons, New York, United States, 3 May 2005, www.un.org.
 Director General Mohamed El-Baradei Statement, Treaty on the Non-Proliferation of Nuclear Weapons 2005 Review Conference, United Nations, New York, 2 May 2005, IAEA, www.iaea.org.
 William Potter, et al., "The 2010 NPT Review Conference: Deconstructing Consensus," The James Martin Center for Nonproliferation Studies, 17 June 2010, www.nonproliferation.org.
 United Nations, "2010 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons, Final Document: Volume 1," 2010, www.un.org.
 "10 States Call For More Action on Nonproliferation," Global Security Newswire, 2 May 2011, www.nti.org.
 2015 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons: Draft Final document, 2015, www.reachingcriticalwill.org.
 2015 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons: Draft Final document, 2015, www.reachingcriticalwill.org.
 The group earmarked $20 billion over ten years to fund a variety of nonproliferation and weapons reduction projects, including HEU reduction work. The United States pledged to provide $10 billion toward this end. This initiative earned the informal title of "10 plus 10 over 10," a reference to its implementation scheme.
 G8, "G8 Action Plan on Nonproliferation," Sea Island, 9 June 2004, retrieved at: https://dosfan.lib.uic.edu.
 G8 Global Partnership Annual Report, G8 Senior Group, June 2005, G8 Gleneagles Summit, p. 6, www.fco.gov.uk.
 Office of the Spokesperson, "The Philippines Joins G8 Global Partnership as 26th Member," U.S. Department of State Media Note, 17 June 2013, www.state.gov.
 Despite the extension, the final 2011 document offered few specifics regarding funding pledges or implementation timelines. In 2012, a specialized sub-group dedicated to nuclear and radiological security was established. International organizations were invited to the working group meetings for the first time that year in an effort to deepen integration and to facilitate expansion beyond the original member states. William C. Potter, "International Cooperation for Nuclear Security: Designing a New Architecture Based on Lessons from Prior Experiences," 2013, p. 7.
 Rapoza, Kenneth, “Russia Quits G8,” Forbes, 5 June 2017, Forbes.com.
 Indeed, the Non-Aligned Movement has expressed general concern that the main threat lies in nuclear weapons possession rather than material in the civilian sector, and that too much attention to the latter would the raise costs of peaceful nuclear uses and diminish international cooperation. William C. Potter, Gaukhar Mukhatzhanova, Nuclear Politics and the Non-Aligned Movement (Routledge: The International Institute for Strategic Studies, 2012), p. 125.
 William C. Potter, "International Cooperation for Nuclear Security: Designing a New Architecture Based on Lessons from Prior Experiences," 2013, p. 7.
 Staff Report, "Search for a Fuel Solution: Research Reactor Fuel Management Meeting in Vienna Focuses on Non-Proliferation," International Atomic Energy Agency, 24 March 2009, www.iaea.org; European Nuclear Society, International Topical Meeting on Research Reactor Fuel Management, 2010, www.euronuclear.org.
 Yukiya Amano statement, Nuclear Security Summit, Washington, DC, 13 April 2010, www.iaea.org.
 “Events Organized and/or Co-sponsored by the Agency’s Secretariat in Conjunction with the Conference’s Session,” IAEA, 14 September 2017.  United Nations Security Council, "Resolution 1540 (2004)," 4956th Meeting of the Security Council, 28 April 2004, www.un.org.
 Department of Public Information, "Security Council Extends Mandate of 1540 Committee for 10 Years, Unanimously Adopting Resolution 1977 (2011)," United Nations, 20 April 2011, www.un.org.
 United Nations Security Council, "Resolution 1887 (2009)," 6191st meeting of the Security Council, 24 September 2009, https://daccess-dds-ny.un.org; Office of the Press Secretary, "Fact Sheet on the United Nations Security Council Summit on Nuclear Nonproliferation and Nuclear Disarmament: UNSC Resolution 1887," White House, 24 September 2009, www.whitehouse.gov.
 Pavel Podvig, "Belarus Suspends HEU Removal Talks with the United States," International Panel on Fissile Materials, 19 August 2011, https://fissilematerials.org; Noel Stott, "Motivations and Capabilities to Acquire Nuclear, Biological, or Chemical Weapons and Missiles: South Africa?" in Over the Horizon Proliferation Threats, James J. Wirtz, Peter R. Lavoy, eds., (Stanford: Stanford University Press, 2012), pp. 73, 75-76; Abdul Samad Minty, "South African Perspectives on Highly Enriched Uranium (HEU)," presentation for the International Symposium on HEU Minimization, Vienna, Austria, June 2006, www.nrpa.no.