This will be an important year for Japanese nuclear energy planning, as it will announce its domestic and foreign nuclear energy and plutonium policy. Japan, the only non-nuclear-weapon state (NNWS) with a civilian reprocessing capability, has faced some proliferation concerns. Despite this, Japan has consistently pledged their peaceful usage of their approximately 46.9 tons of separated plutonium, potentially enough to make over 5,000 nuclear weapons. Other East Asian countries have expressed worries about the storage of this much material. Big events for Japanese nuclear energy planning The “Strategic Energy Plan,” due to be released later this year, sets the fundamental direction of Japan’s energy policy. Japan’s Basic Energy Law mandates that the government release an energy plan every three years, and the current plan was the first to be released after the 2011 Fukushima accident. The U.S.-Japan peaceful nuclear cooperation agreement, commonly referred to as the U.S.-Japan 123 Agreement, is the key pact that allows Japan to have two critical technologies: reprocessing and enrichment. The plutonium separated through reprocessing can be recycled into MOX fuel (plutonium-uranium mixed oxide) for light-water reactors. Since Japan lacks natural resources, recycled spent fuel could help to reduce dependence on foreign energy sources. The 123 Agreement stipulated that by July 2018 the United States and Japan must have a new agreement in place or allow the existing one to remain in force. Japan and the United States decided to automatically renew this agreement on January 17, 2018. North Korean nuclear and missile tests have helped create dramatic changes in security environments in East Asia. In response to those changes, Japan should re-commit to reducing its plutonium stockpile. Japanese commitment to reduce plutonium Plutonium in spent fuel is not weapons-usable. Once this reactor-grade plutonium is separated from spent fuel through reprocessing, it is potentially nuclear weapons-usable. Japan owns approximately 9.8 tons of separated plutonium at home and 37.1 tons of separated plutonium at reprocessing plants in the United Kingdom and France. Over the past six years, the Nuclear Security Summits made progress to strengthen nuclear security and reduce the threat of nuclear terrorism. The 2014 Hague produced a communiqué that encouraged states to keep their stockpile of separated plutonium as low as possible. Additionally, Japanese Prime Minister Abe stated that Japan would not possess separated plutonium for which it did not already identify a specific use during the 2014 Hague summit. While Japan pledged to maintain their no-surplus plutonium policy, the disarray that continues to plague Japan’s nuclear industry—following the 2011 Fukushima nuclear accident, new regulations and delays in completing and opening the Rokkasho reprocessing plant, and decisions to close the MONJU fast breeder reactor—throws into question the credibility of Japan’s plutonium consumption plan. With approximately 46.9 tons of separated plutonium, Japan’s no-surplus plutonium policy looks hollow to date. Important steps for Japan and the international community On January 17, 2018, the U.S.-Japan peaceful nuclear cooperation agreement automatically renewed, which allows Japan to continue reprocessing spent nuclear fuel and uranium enrichment. Japan’s stockpile of separated plutonium, consumption plan, and advanced nuclear technology have raised proliferation concerns in East Asia. Despite several legal restrictions on Japan’s ability to develop nuclear weapons—the Nuclear Non-Proliferation Treaty, Article 9 of the Japanese constitution, the Atomic Energy Basic Law, and the Three Non-Nuclear Principles—North Korean nuclear and missile tests have raised questions among East Asian countries about whether Japan would develop nuclear weapons. To reduce this concern, Japan should clarify its policies on four issues. First, Japan should scale-down operations of its reprocessing plant. Rokkasho repossessing plant is designed to produce 8 tons of plutonium per year, but that is more than what Japan can plausibly use annually. So far, only two MOX reactors are operating in Japan, which means less than 2.0 tons of plutonium could be consumed annually. Since Japan already possess approximately 9.8 tons of separated plutonium at home, Japan should stop any further stockpiling. Second, Japan should build more dry cask storages. Potentially reprocessing plant and ongoing delays in opening the plant might require utilities to store spent fuels at reactors for longer than planned until they can be transported to the Rokkasho reprocessing plant. The plant was originally expected to be completed by 1997, but is now scheduled to open by 2021. Moreover, existing spent fuel storage is approaching its maximum capacity. Once plants run out of storage space, whether dry or wet, the utilities cannot continue to operate the plant. Third, Japan should revise its basic principles for the utilization of plutonium, perhaps to include a timeline describing methods, timing, purposes, and quantities of plutonium Japan will consume. These basic principles show transparency in the plutonium utilization plan and the purpose of use. After the Fukushima nuclear accident, the restarts have been slow: only four of Japan’s 54 original nuclear reactors came back online. To make up for the shortfall in nuclear output, Japan relied on fossil fuel imports. Moreover, this could help assuage concerns from other East Asian countries, who argue that what Japan says on peaceful usage is not enough without a clear pathway to using plutonium as a MOX fuel in the near future. Once the government clarifies a pathway, domestic and international communities could monitor plutonium supply and demand before reprocessing. Fourth, the Spent Nuclear Fuel Reprocessing Implementation Act should be revised for a nuclear fuel cycle option. Despite the 2014 Strategic Energy Plan mentioning that Japan has flexibility on disposal because its nuclear fuel cycle will not be resolved in short-term—but likely will be in the middle- to long-term—this act describes that the purpose is constant and efficient reprocessing operations. There has been an inconsistency between words and actions. Obviously, Japan needs more time to consume its stockpile of plutonium than originally planned, and the government should revise its actions accordingly.