Civilian HEU: Japan

July 1, 2019

Overview

Japan is a party to the Treaty on the Nonproliferation of Nuclear Weapons (NPT) as a Non-Nuclear Weapons State (NNWS). Amongst the NNWS, Japan has the largest holding of civil use highly enriched uranium (HEU), estimated at nearly 1,800 kg. [1] Unlike France, Germany, and the United Kingdom, Japan does not voluntarily declare its HEU holdings as part of its annual INFCIRC 549 plutonium report to the International Atomic Energy Agency (IAEA). [2] However, in an effort to enhance transparency, the Japan Atomic Energy Commission has requested relevant Japanese agencies to disclose the amounts of their HEU holdings. [3]

Japan was one of the earliest countries to participate in Atoms for Peace, and has utilized research reactors and critical assemblies powered by HEU since the 1960s. However, the country became an early participant in civil HEU minimization efforts. 1978 marked the first meeting of the special "Five Agency Committee on HEU," which directed Japan’s cooperation with the U.S. Reduced Enrichment for Research and Test Reactors (RERTR) program.

HEU Production, Use, and Commerce

Since 1992, Japan Nuclear Fuel Ltd. has produced low-enriched uranium (LEU) at Rokkasho for Japan’s extensive nuclear power program. However, Japan does not produce HEU.

Currently, one Japanese research reactor (UTR KINKI owned by Kinki University) and two critical assemblies (KUCA, wet and dry cores, owned by Kyoto University Research Reactor Institute (KURRI)), are still HEU-powered. [4]

HEU used at Japanese research facilities was supplied by the United States and the United Kingdom. [5] Approximately 500 kg of HEU at Japan's FCA critical assembly, which started up in 1967, are of UK origin. [6] Between 1957 and 1994, the United States supplied 1,000 kg of U-235 to Japan contained in 2,054 kg of uranium. [7]

Japan has partnered with the United States to begin to return U.S.-origin spent fuel, approximately 656 kg of HEU since 1997. [8] In 2014, the Foreign Research Reactor Spent Nuclear Fuel (FRR SNF) Acceptance Program was extended. Although the FRR SNF program is set to end in 2019, an exception has been made with Japan, and work is expected to conclude by 2029. [9]

Efforts to Reduce and Eliminate Civilian Use HEU

Japan’s two largest owners of HEU-fueled facilities, Kyoto University and JAERI, began to work with the RERTR program in 1978 and 1979, respectively. [10] The Five Agency Committee directed the RERTR program in Japan. The committee was active until 2000, but has not met since 2001 because the LEU conversion activities of the reactors under the RERTR program in Japan are in their closing phase. [11]

At the 2014 Nuclear Security Summit, Japanese and U.S. leaders agreed to remove and dispose of all highly enriched uranium and weapons-grade plutonium from the Fast Critical Assembly (FCA) at the Japan Atomic Energy Agency (JAEA) in Tokai Mura, Ibaraki Prefecture in Japan. [12] At the final NSS in 2016 it was announced that with U.S. assistance, the removal of all HEU and Plutonium from the FCA had been completed. [13] According to Japanese public documents, the amount of plutonium removed is estimated to be approximately 700 pounds, or 320 kilograms. [14] The amount of HEU removed is estimated to be about 214.5 kilograms, or 450 pounds of weapons-grade HEU. [15] Using the IAEA Significant Quantities definition, this is enough material for approximately 48 nuclear weapons. The United States will downblend the HEU to low enriched uranium (LEU), and the plutonium will be prepared for final disposition. [16] The FCA is designed to test the criticality of fast-neutron-reactor cores, purposes for which it was considered to be technically difficult to use LEU instead of HEU. [17] The decision to eliminate all of the plutonium and HEU at the FCA is therefore a significant milestone in minimization efforts.

Japan is in the final stages of conversion and shutdown of most HEU-powered facilities. Since 1990, Japan has converted four operational research reactors, the JRR-3M, JRR-4, JMTR, and KUR (converted in 1990, 1998, 1994, and 2010, respectively). [18] The Japan Material Testing Reactor Critical Assembly (JMTRC) and the JRR-2 reactor were shut down in 1995 and 1996. Also shut down were the Toshiba Training Reactor (TTR) (2001), the Rikkyo TRIGA (2002), and the Musashi MuITR (2004). [19] Decommissioning of the Very High Temperature Reactor Critical (VHTRC) Assembly was completed in 2009, and the DCA (Deuterium Critical Assembly) decommissioning process will be completed by 2023. Both facilities are located at JAEA's Oarai Research and Development Center. [20]

All new research reactors in Japan have been designed to use LEU fuel. In February 1991, the Japanese government cancelled the HEU-powered Kyoto University High Flux Reactor (KUHFR) Project. However, the U.S.-origin HEU fuel intended for use in this reactor was used in the Kyoto University Research Reactor (KUR) until February 2006, following U.S. approval in April 1994. The United States has been repatriating the fuel at Kyoto University; the full core conversion from HEU to LEU of the KUR was successfully completed in March 2010. [21]

Two HEU-powered facilities, the Kyoto University Critical Assembly (KUCA), operated by Kyoto University’s Research Reactor Institute, and the UTR KINKI research reactor, operated by Kinki University, are currently undergoing conversion feasibility studies. The aim is to initiate conversion of these reactors to LEU within the foreseeable future. [22] Since 2008, Kyoto University and the U.S. Department of Energy’s Argonne National Laboratory have been conducting joint feasibility studies for KUCA with the aim of substituting LEU-based fuel for the existing HEU. [23] In March 2012, the United States and Japan also agreed to launch joint feasibility studies on how to operate the UTR KINKI research reactor using LEU instead of HEU. [24] The YAYOI reactor operated by Tokyo University had employed HEU, but was permanently shut down at the end of March 2011 after 40 years' operation. It was decided that the spent HEU fuel from the reactor would be transferred to the JAEA. [25] In August 2018, the U.S. and Japan jointly committed to remove the HEU from the YAYOI reactor and to repatriate the HEU from KUCA by March 2022. [26]

As part of Japan's efforts to minimize civilian use of HEU, the JAEA has developed technology to generate the medical isotope Molybdenum 99 without HEU. This new technology is expected to produce between one-fifth and one-fourth of the quantity required for Japan's domestic market. As a next step, the JAEA has to conduct technology demonstration tests at its JMTRC. [27]

As an active participant in HEU minimization efforts since their inception, Japan has made important contributions to minimizing the use of this material. However, Japan's policy on how to handle its HEU materials has been less clear, and there are simultaneous and interlinked concerns regarding Japan's policy on plutonium. [28] There have been some shipments of HEU spent fuel to the United States, but other HEU spent fuel remains in Japan. Japan has considered storing spent HEU fuel domestically, repatriating it to the United States, or sending it abroad to France or the United Kingdom for reprocessing. [29] In June 2016 a shipment of HEU from JAEA’s FCA reactor arrived safely at the Y-12 complex for downblending into LEU. The arrival of the material fulfills the commitment to remove the FCA material that Japan and the United States announced at the 2014 and 2016 Nuclear Security Summits. [30] Furthermore, while the JAEA and Kyoto University reportedly paid for spent fuel shipping, storage, and handling expenses related to repatriation operations, the Japanese government does not appear to have contributed money or manpower for this purpose. [31] Some Japanese institute officials have suggested that the Japanese government consider deeper engagement in repatriation operations. [32]

Sources:
[1] David Albright and Serena Kelleher-Vergantini, "Plutonium and Highly Enriched Uranium, 2015," Institute for Science and International Security, 2015. Kazakhstan, however, has the most HEU in secure spent fuel storage, amounting to nearly 10 tons. Japan has the most HEU in current R&D purposes.
[2] International Atomic Energy Agency, "Communication Received from Japan Concerning Its Policies Regarding the Management of Plutonium," INFCIRC/549/Add.1/16, 23 September 2013, www.iaea.org.
[3] Personal communication with the authors.
[4] "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.
[5] Approximately 500 kg of HEU at Japan's FCA critical assembly are of UK origin. David Albright and Kimberly Kramer, "Civil HEU Watch: Tracking Inventories of Civil Highly Enriched Uranium," Global Stocks of Nuclear Explosive Materials, Institute for Science and International Security Chapter III, https://isis-online.org.
[6] David Albright and Kimberly Kramer, "Civil HEU Watch: Tracking Inventories of Civil Highly Enriched Uranium," Global Stocks of Nuclear Explosive Materials, Institute for Science and International Security Chapter III, https://isis-online.org.
[7] Of this total, 507 kg U-235 were contained in 1,523 kg of uranium enriched up to 90%, while the remaining 493 kg of U-235 were contained in fuel enriched to over 90% U-235. Highly Enriched Uranium: Striking a Balance, Department of Energy, released January 2001, p. 100, www.fas.org.
[8] David Albright and Serena Kelleher-Vergantini, "Civil HEU Watch: Tracking inventories of Civil Highly Enriched Uranium," 7 October 2014.
[9] Hitesh Nigam. "Department of Energy Spent Nuclear Fuel – Update," U.S. Department of Energy, Office of Environmental Management, Institute of Nuclear Materials Management, 12 January 2016, www.inmm.org.
[10] Yukiya Amano, "Reducing the Enrichment Level of Uranium Fuel: Japan's Experience," presented at the Minimization of Highly Enriched Uranium in the Civilian Sector Symposium, Oslo, Norway, 19 June 2006, www.nrpa.no.
[11] Keiichi Ohki et al., "Status of Reduced Enrichment Program for Research Reactors in Japan," paper presented at the 2010 RERTR International Meeting, October 2010, Lisbon, Portugal, www.rertr.anl.gov.
[12] Joint Statement by the Leaders of Japan and the United States on Contributions to Global Minimization of Nuclear Material, Ministry of Foreign Affairs of Japan, 24 March 2014, www.mofa.go.jp.
[13] "Joint Statement on U.S.-Japan Cooperation: U.S.-Japan Joint Statement on Nuclear Security Cooperation," Nuclear Security Summit 2016, 1 April 2016.
[14] "The Current Situation of Plutonium Management in Japan," Japan Atomic Energy Commission, 11 September 2013, www.aec.go.jp.
[15] Matthew Bunn, "Eliminating Potential Bomb Material from Japan's Fast Critical Assembly,"Nuclear Security Matters, 24 March 2014, https://nuclearsecuritymatters.belfercenter.org.
[16] Joint Statement by the Leaders of Japan and the United States on Contributions to Global Minimization of Nuclear Material, Ministry of Foreign Affairs of Japan, 24 March 2014, www.mofa.go.jp.
[17] "Kakufukakusan ni kansuru Nihon no Koremadeno Torimumi to sono Bunseki [Japan's Efforts for Nuclear Nonproliferation and Its Analysis]" JAEA Website, August 2010, www.jaea.go.jp.
[18] Keiichi Ohki et al., "Status of Reduced Enrichment Program for Research Reactors in Japan," paper presented at the 2010 RERTR International Meeting, October 2010, Lisbon, Portugal, www.rertr.anl.gov. The JMTR was initially converted from 93% HEU fuel to 45% enriched fuel in 1991, and then to the current 19.8% enriched fuel in 1994. Masataka Miyazawa, Masao Watanabe, Makoto Yokokawa, Hiroshi Sato, and Haruhiko Ito, "Present Status of JMTR Spent Fuel Shipment," RERTR-2002, www.rertr.anl.gov.
[19] Keiichi Ohki et al., "Status of Reduced Enrichment Program for Research Reactors in Japan," paper presented at the 2010 RERTR International Meeting, October 2010, Lisbon, Portugal, www.rertr.anl.gov.
[20] The critical assembly decommissioning is scheduled to be completed by 2023 and the entire demolition of the building is scheduled to be completed by 2028; "Haishisochi wo Shuuryou Shita Shisetsu, [Facilities That have Completed their Decommission Procedures]," Japan Atomic Energy Agency, www.jaea.go.jp; "Juusuirinkaijikkensouchi no Haishisochikeikaku no Shinchokujoukyou Houkokusho (Heisei 24 nendo Dai-ni shihanki) no Teishutsu ni tsuite [Report of Decommissioning Process of the Very High Temperature Reactor Critical Assembly (Quarterly Report of Second Quarter of Fiscal Year 2012) Nuclear Regulation Authority Website, 6 November 2012, www.nsr.go.jp; Kenji Morita, Makoto Morimoto, Masaki Hisada, and Yasutaka Fukui, “Deuterium Critical Assembly (DCA) Decommissioning work in 2013,” JAEA-Technology 2015-037 (Tokai: Japan Atomic Energy Agency, 1 January 2016), p. ii, 6.
[21] Toshinobu Ohba, Takeshi Inoue, and Hironobu Unesaki, "Status of Reduced Enrichment Program for Research Reactors in Japan," paper presented at the 2008 RERTR International Meeting, October 2008, Washington, DC, United States, www.rertr.anl.gov.
[22] Jeff Chamberlin, "Research Reactor Conversion Program," U.S. National Academies – Russian Academies of Science, presentation given at the Symposium on Research Reactor Conversion, 29 November 2010, https://dels.nas.edu; Hironobu Unesaki, Tsuyoshi Misawa, Tadafumi Sano, Ken Nakajima, Jordi Roglans-Ribas, "On the Feasibility Study for Utilization of Low Enriched Uranium Fuel at Kyoto University Critical Assembly (KUCA)," paper presented at RERTR, 23-27 October 2011, Santiago, Chile, pp. 1-2, www.rertr.anl.gov; G. Wakabayashi, T. Itoh, K. Hashimoto, S. Ito, H. Yamanishi, W. Sugiyama, T. Horiguchi, S. Hohara, "History and Present Situation of Kinki University Reactor (UTR-KINKI)," paper presented at RERTR, 14-17 October 2012, Warsaw, Poland, www.rertr.anl.gov.
[23] Hironobu Unesaki, Tsuyoshi Misawa, Cheol-Ho Pyeon, Tadafumi Sano, Yoshiyuki Takahashi and Ken Nakajima, "Neutronic Analysis for Utilization of Low Enriched Uranium Fuel At Light Water Moderated/Reflected Core of Kyoto University Critical Assembly (KUCA)" paper presented at the 2012 RERTR International Meeting, October 2012, Warsaw, Poland, www.rertr.anl.gov.
[24] "U.S., Japan to Research Uranium Fuel Swaps," The Japan Times, 26 March 2012, www.japantimes.co.jp.
[25] The University of Tokyo's Yayoi Reactor Website, www.tokai.t.u-tokyo.ac.jp; Japan Atomic Energy Commission website, 21 March 2012, www.aec.go.jp.
[26] Bilateral Commission, “Joint Statement: The Fifth Meeting of the U.S.-Japan Bilateral Commission on Civil Nuclear Cooperation,” Ministry of Foreign Affairs of Japan, 8 August 2018, www.mofa.go.jp.
[27] "Japan Devises HEU-Free Medical Isotope Production Method," Global Security Newswire, 28 November 2012, www.nti.org.
[28] For discussion of policy issues regarding Japan's plutonium stockpile, see: Tadahiro Katsuta and Tatsujiro Suzuki, "Japan's Spent Fuel and Plutonium Management Challenges," International Panel on Fissile Materials Research Report #2, September 2006. For a discussion of other nuclear-related policy issues, see Emma Chanlett-Avery and Mary Beth Nikitin, "Japan's Nuclear Future: Policy Debate, Prospects, and U.S. Interests," Congressional Research Service Report RL34487, 19 February 2009, retrieved at: www.fas.org. Also see: Masako Toki and Miles Pomper, "Time to Stop Reprocessing in Japan," Arms Control Today, January/February 2013, www.armscontrol.org.
[29] Ann MachLachlan, "Kyoto Reactor Institute Mulls Extension of HEU operation," NuclearFuel, 17 April 2000, p. 15.
[30] National Nuclear Security Administration, “NNSA Announces Arrival of Plutonium and Uranium from Japan’s Fast Critical Assembly at Savannah River Site and Y-12 National Secuirty Complex,” 6 June 2016, https://nnsa.energy.gov.
[31] "Uranium for 20 Nukes Repatriated from Japan in Special U.S. Operation,"Japan Economic Newswire, Kyodo, 27 December 2008, hosted on the Professional Reactor Operator Society website, 28 December 2008, www.nucpros.com.
[32] "Uranium for 20 Nukes Repatriated from Japan in Special U.S. Operation," Japan Economic Newswire, Kyodo, 27 December 2008, hosted on the Professional Reactor Operator Society website, 28 December 2008, www.nucpros.com.