Civilian HEU: United States

June 28, 2019

Overview

The United States is a party to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) as a nuclear weapons state (NWS). Although the United States has declared its total Highly Enriched Uranium (HEU) stockpile (civil and military HEU), it does not voluntarily declare its civilian HEU holdings to the IAEA as part of its annual declaration of plutonium stocks (INFCIRC/549). [1] The most recent publicly available figures on the US HEU stockpile, from 2013, estimate it at 439 tons, of which 93 tons are designated for civil uses, 86 tons are available for downblending or are in spent fuel, and approximately 260 tons are for military use. [2] As the United States is active in HEU export, repatriation, and downblending, the current size of the stockpile is unknown.

The United States has focused significant diplomatic and financial efforts on minimizing civil HEU worldwide, through conversion or shutdown of research reactors at home and abroad, fuel repatriation, and movement toward HEU-free medical isotope production.

Production, Use, and Commerce

Production and Use

The United States ended Highly Enriched Uranium (HEU) production in 1992, but continues to use HEU for military and civilian purposes, and to engage in HEU commerce. The United States has eight remaining reactors that utilize civil HEU, including two advanced Test Reactors (ATR and ATR-C); the TREAT Reactor at Idaho National Laboratory; GE-NTR in Sunol California; the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory; the MIT Reactor-II (MITR) at the Massachusetts Institute of Technology; the Missouri University Research Reactor (MURR) at the University of Missouri in Columbia; and the National Bureau of Standards Reactor (NBSR) at the National Institute of Standards and Technology. [3]

The National Aeronautics and Space Administration (NASA) is developing a nuclear reactor for space exploration that will be fueled by HEU. The Kilowatt Reactor Using Stirling Technology (KRUSTY) underwent testing with a depleted uranium core in May 2018 and will soon undergo tests with an HEU core. [4]

Commerce

Under the 1953 Atoms for Peace initiative, the United States promoted nuclear science and the peaceful use of nuclear technology worldwide. A 1954 amendment to the Atomic Energy Act allowed for bilateral nuclear agreements with friends and allies. [5] These agreements initially only envisioned the export of LEU fuel. Soon, however, new high-powered research and test reactors that required low-density uranium fuels enriched to 90-93% were constructed abroad. As a result, in the mid-1960s the United States began to export HEU fuel for their use. [6]

Concerns about the proliferation potential of US HEU exports subsequently emerged, and in 1978 the United States created the Reduced Enrichment for Research and Test Reactors (RERTR) Program, to design and qualify appropriate LEU fuel substitutes. The program assists in the conversion of research and test reactors in the United States and abroad from HEU to LEU fuel, so that these facilities will no longer require US-origin HEU fuel. [7]

In 1992, Congress focused its efforts on further restricting US exports of HEU through the passage of the Schumer Amendment to the Energy Policy Act. This legislation conditioned exports of US-origin HEU on the following criteria: (1) that there was no existing alternative LEU fuel for the reactor in question; (2) that the facility agreed to convert to LEU fuel as soon as it became available; and (3) that the United States was actively developing an alternative LEU fuel suitable for that facility. [8]

According to a 1996 Department of Energy HEU Report, the United States exported approximately 25.6 metric tons of HEU primarily to the Euratom countries, Canada, and Japan. [9] With the passage of the Schumer Amendment, HEU exports declined until 1996, after which no HEU was exported. [10]

In 2005, this decline was reversed when the Burr Amendment to the National Energy Policy Act allowed the United States to license the export of HEU to several countries without requiring them to convert their research reactors to an LEU-based production process. One reason for this policy change was to ensure the continued supply of the critical medical radioisotope molybdenum-99 (Mo-99). [11] Mo-99 has an extremely short shelf-life, and at the time, there were few global producers, making unanticipated shutdowns of research reactors for maintenance result in global Mo-99 shortages. [12]

US policy has aimed to level the economic playing field for new LEU-based producers, who otherwise find it difficult to compete with established HEU-based producers. [13] In 2010, the NNSA announced that a consortium of producers from South Africa and Australia would begin to supply LEU-based Mo-99 to the United States. This consortium has, at times, supplied as much as a third of the Mo-99 market for diagnostic procedures in the United States. [14] In addition, the NNSA has worked with the IAEA to develop small-scale regional production capabilities in Eastern Europe and Latin America, and has encouraged establishment of a domestic production capability. The Nuclear Regulatory Commission (NRC) authorized a construction permit in early 2016 for a Mo-99 facility to be built in Janesville, Wisconsin, and is expected to begin production in 2019. This facility will utilize an accelerator-driven subcritical assembly in place of a reactor, using LEU targets. [15]

At the final Nuclear Security Summit in 2016, the United States was party to a Joint Statement on EU-US HEU exchange. Euratom member states committed to transfer unirradiated, excess HEU to the US for down-blending in exchange for US-supplied HEU for research reactors and isotope production facilitates. This agreement seeks to address the continued reliance on HEU in some facilities, while maintaining a reliable supply of medical isotopes, and at the same time achieving HEU minimization goals. [16]

Efforts to Reduce and Eliminate Civilian Use HEU

Over the past several decades, the United States has led international initiatives to convert research and test reactors, repatriate HEU fuel worldwide, and develop HEU-free fuel for reactors and targets for Mo-99 production capabilities. Efforts such as the Nuclear Security Summits, initiated by then President Obama, have focused the world’s attention on nuclear security issues, with specific focus on the challenges posed by HEU in civilian applications.

In April 2016, the final Nuclear Security Summit was held in Washington, DC. The United States was party to several notable announcements and achievements in furthering the minimization and elimination of HEU in civil applications. [17] In addition, the US was signatory to a Joint Statement reaffirming the importance of continued cooperation on the development and testing of high-density LEU fuel, [18] as well as to 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. [19]

US programs focused on assisting other countries with minimization are extensively discussed in Past and Current Civilian HEU Reduction Efforts.

While the United States has not converted a reactor domestically since 2009, the NNSA is slowly making progress towards the conversion of five research reactors and one critical assembly in the US from HEU fuel to LEU fuel. Feasibility studies and preliminary safety reports were completed in 2017 and 2018 for these conversions, but irradiation testing and final safety reports need to be conducted before conversion begins, which may require many more years. [20] The National Academies of Science argued in 2016 that the US focus on monolithic fuels, as opposed to dispersion fuels, has inhibited conversion of some facilities to LEU which could be converted using dispersion fuel, and has potentially delayed the conversion process by 10 to 15 years. [21]

Despite the slow domestic conversion process of US HEU-fueled research reactors, the United States continues to assist in LEU conversion projects abroad through the RERTR program and other international agreements, and plays an important role in the reduction and elimination of civilian-use HEU.

Sources:
[1] Regarding military stockpile declarations, see: The International Panel on Fissile Materials, “Global Fissile Material Report 2013: Increasing Transparency of Nuclear Warhead and Fissile Material Stocks as a Step toward Disarmament,” 22 October 2013, pp. 6, 10, www.fissilematerials.org; Regarding the United States” Information Circular, see for instance: “Communication Received from the United States of America Concerning Its Policies Regarding the Management of Plutonium,” INFCIRC/549/Add.6-/20, 12 October 2017, www.iaea.org.
[2] “Fact Sheet: Transparency in the US Highly Enriched Uranium Inventory,” The White House, Office of the Press Secretary, 31 March 2016. The White House publicly released the United States’ total HEU holding, total HEU stocks declared excess to national security needs, and ongoing efforts to down-blend HEU to LEU. Total HEU stocks declared in 2013 were 585.6 tons. Out of this, 239 tons were declared as excess to national security needs and 86.2 tons remained for down blending or are in spent reactor fuel. Of the 239 tons of HEU declared as excess, approximately 146 tons have been down-blended to LEU, leaving about 93 tons for civil use. It is estimated then that approximately 260 tons remain in or are available for weapons. Out of the 86.2 tons mentioned, 41.6 are available for down blending, while the remaining 44.6 tons are in spent reactor fuel.
[3] “Reducing the Use of Highly Enriched Uranium in Civilian Research Reactors,” Committee on the Current Status of and Progress Toward Eliminating Highly Enriched Uranium Use in Fuel for Civilian Research and Test Reactors, The National Academies Press, 28 January 2016.
[4] Sean Potter, “Demonstration Proves Nuclear Fission System Can Provide Space Exploration,” Press Release, NASA, 2 May 2018, www.nasa.gov; Marc A. Gibson, Steven R. Oleson, David I. Poston, and Patrick McClure, “NASA’s Kilopower Reactor Development and the Path to Higher Power Missions,” Paper presented at the 2017 IEEE Aerospace Conference, Big Sky, MT, March 2017, ntrs.nasa.gov.
[5] Anya Loukianova and Cristina Hansell, “Leveraging US Policy for a Global Commitment to HEU Elimination,” The Nonproliferation Review, Vol. 15, No. 2, July 2008, p. 161.
[6] Anya Loukianova and Cristina Hansell, “Leveraging US Policy for a Global Commitment to HEU Elimination,” The Nonproliferation Review, Vol. 15, No. 2, July 2008, p. 161.
[7] Anya Loukianova and Cristina Hansell, “Leveraging US Policy for a Global Commitment to HEU Elimination,” The Nonproliferation Review, Vol. 15, No. 2, July 2008, p. 162.
[8] “Highly Enriched Uranium: Striking a Balance,” United States Department of Energy, National Nuclear Security Administration, Office of the Deputy Administrator for Defense Programs, January 2001, revision 1, p. 96, retrieved at: www.fas.org.
[9] “US Needs Stronger Export Controls on Highly Enriched Uranium,” Union of Concerned Scientists, 21 November 2008, www.ucsusa.org.
[10] Anya Loukianova and Cristina Hansell, “Leveraging US Policy for a Global Commitment to HEU Elimination,” The Nonproliferation Review, Vol. 15, No. 2, July 2008, p. 164.
[11] James Harvey, “Alternative Production of Mo99,” presentation given at the 2013 SNMMI Winter Meeting, New Orleans, USA., p. 3, www.snm.org; Cristina Hansell, “Nuclear Medicine’s Double Standard,” The Nonproliferation Review, Vol. 15, No. 2, July 2008.
[12] 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; Committee on Medical Isotope Production without Highly Enriched Uranium, National Research Council, “Medical Isotope Production without Highly Enriched Uranium,” National Academy of Sciences, 2009, pp. 1-15.
[13] 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.
[14] 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. It should be noted, however, that as of mid-2012, NECSA still supplied HEU-based Mo-99 to Europe because it is not yet licensed to supply LEU-based Mo-99 there.
[15] “NRC to issue licence for MO-99 facility,” World Nuclear News, 29 February 2016; Judy Newman, “SHINE Medical Wins NRC’s OK to Build Medical Isotope Plant,” Wisconsin State Journal, 26 February 2016, www.madison.com.
[16] “Joint Statement on EU-US HEU Exchange: Joint Statement on the Exchange of Highly Enriched Uranium Needed for Supply of European Research Reactors and Isotope Production Facilities,” Nuclear Security Summit 2016, 1 April 2016.
[17] These include the announcement of the removal of over 500kg of HEU and Plutonium from Japan, US assistance in clearing Argentina of HEU, and cooperation between Germany and the US in the repatriation of HEU to the US “Joint Statement on US – Japan Cooperation,” Nuclear Security Summit 2016, 1 April 2016; “Fact Sheet: Eliminating all Highly Enriched Uranium from Argentina,” The White House Office of the Press Secretary, 1 April 2016; “Fact Sheet: Nuclear Material Removal from Germany,” The White House: Office of the Press Secretary, 1 April 2016.
[18] The signatories are Belgium, France, Germany, Republic of Korea, and the US “Joint Statement on Multilateral Cooperation on High Density Low-Enriched Uranium Fuel Development for High-Performance Research Reactors,” Nuclear Security Summit 2016, April 2016.
[19] 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, and 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.
[20] E. H. Wilson, D. Jaluvka, A. Hebden, J. Stillman, and L. Jamison, “US High Performance Research Reactor Preliminary Design Milestone for Conversion to Low Enriched Uranium Fuel,” Abstract presented at the 39th RERTR 2018 International Meeting on Reduced Enrichment for Research and Test Reactors, Edinburgh, Scotland, November 2018.
[21] “Reducing the Use of Highly Enriched Uranium in Civilian Research Reactors,” Committee on the Current Status of and Progress Toward Eliminating Highly Enriched Uranium Use in Fuel for Civilian Research and Test Reactors, The National Academies Press, 28 January 2016.