Japan is a signatory of the nuclear Non-Proliferation Treaty (NPT) and has signed and ratified the Comprehensive Test Ban Treaty (CTBT), being one of the 44 listed countries needed to sign and ratify for the CTBT to enter into force.

Japan has 55 reactors in operation, three under construction with a further 12 planned.

In 2004 Japan's Atomic Industrial Forum released a report on the future prospects for nuclear power in the country. It brought together a number of considerations including 60% reduction in carbon dioxide emissions and 20% population reduction but with constant Gross Domestic Product (GDP). Nuclear generating capacity for 2050 is seen as 90 GWe. This means doubling both nuclear generating capacity and nuclear share to about 60% of total power produced. In addition, some 20 GW (thermal) of nuclear heat will be utilised for hydrogen production. Hydrogen is expected to supply 10% of consumed energy and 70% of this will come from nuclear plants.

In mid 2005 the Nuclear Energy Policy Planning Division of the Agency for Natural Resources and Energy instigated a 2 year feasibility study on development of next-generation Light water Reactors (LWR's). The new designs, based on ABWR and APWR, are to lead to a 20% reduction in construction and generation costs and a 20% reduction in spent fuel quantity, with improved safety, 3 year construction and 60 year life. Projected sizes range from 800 to 1700 Mwe.

In May 2006 the ruling Liberal Democratic Party urged the government to accelerate development of fast breeder reactors (FBR's), calling this "a basic national technology". It proposed increased budget, better coordination in moving from research & development to verification and implementation, plus international cooperation. Japan is already playing a leading role in the Generation IV initiative, with focus on sodium-cooled FBR's, though the 280 MWe Monju prototype FBR remains shut down.

In April 2007 the government selected Mitsubishi Heavy Industries (MHI) as the core company to develop a new generation of FBR's.

Japan has been progressively developing a complete domestic nuclear fuel cycle industry based on imported uranium. Japan's Atomic Energy Agency operates a small uranium refining and conversion plant, as well as a small centrifuge enrichment demonstration plant, at Ningyo Toge, Okayama prefecture.

Japan Nuclear Fuel Ltd (JNFL) operates a commercial enrichment plant at Rokkasho. Japan has a further 6,400 tonnes of uranium recovered from reprocessing and stored in France and the UK, where the reprocessing was carried out. In 2007 it was agreed that Russia's Atomenergoprom would enrich this for the Japanese utilities who own it.

At Tokai-mura, in Ibaraki prefecture north of Tokyo, Mitsubishi Nuclear Fuel Co Ltd operates a major fuel fabrication facility, which started up in 1972. Further fuel fabrication plants are operated by Nuclear Fuel Industries (NFI) in Tokai and Kumatori, and JAEA has some experimental mixed oxide (MOX) fuel facilities at Tokai for both the Fugen ATR and the FBR program.

Reprocessing of spent fuel was largely undertaken in Europe by British Nuclear Fuels Ltd and Cogema, with vitrified high-level wastes and plutonium being returned to Japan. This finished in 2005, and full-scale operation of JNFL's reprocessing plant at Rokkasho-mura was scheduled to start in 2007. Used fuel has been accumulating there since 1999 in anticipation of its operation. The new Rokkasho plant will treat 14,000 tonnes of used fuel stockpiled there to end of 2005 plus 18,000 tonnes of used fuel arising from 2006, over some 40 years. It will produce about 4 tonnes of fissile plutonium per year.

Japan's plutonium stocks continue to increase - at the end of 2004 there was 41 tonnes of separated reactor-grade plutonium stored and awaiting use in Mixed-Oxide (MOX) fuel. Some 4 tonnes was in Japan and the rest in Europe, mostly France.

In April 2005 the Aomori prefecture approved construction of a US$1.2 billion MOX plant at Rokkasho, adjacent to the reprocessing plant. JNFL has applied for a licence to build and operate the 130 t/yr MOX plant. Construction of the plant was expected to begin in 2007 with operation about 2012.

Read the profile on Japan from the Model Nuclear Inventory (pdf), produced by the Reaching Critical Will project of the Women's International League for Peace and Freedom.