Nuclear Power in Japan

(Updated 27 January 2015)

  • Japan needs to import about 84% of its energy requirements.
  • Its first commercial nuclear power reactor began operating in mid-1966, and nuclear energy has been a national strategic priority since 1973. This came under review following the 2011 Fukushima accident but has been confirmed.
  • The country's 50+ main reactors have provided some 30% of the country's electricity and this was expected to increase to at least 40% by 2017. The prospect now is for at least half of this, from a depleted fleet of no more than 48 reactors.
  • The process of regulatory clearance for restarting 48 reactors is under way, but slowly and expected to take some years.
  • Japan has a full fuel cycle set-up, including enrichment and reprocessing of used fuel for recycle.
  • Japan has been a leading country in nuclear R&D, notably with fast reactors.
  • Following the Fukushima accident its regulatory structure was completely overhauled.

Despite being the only country to have suffered the devastating effects of nuclear weapons in wartime, with over 100,000 deaths, Japan embraced the peaceful use of nuclear technology to provide a substantial portion of its electricity. However, following the tsunami which killed 19,000 people and which triggered the Fukushima nuclear accident (which killed no-one), public sentiment shifted markedly so that there were wide public protests calling for nuclear power to be abandoned. The balance between this populist sentiment and the continuation of reliable and affordable electricity supplies is being worked out politically.

Japan's energy situation and international dependence

Japan’s shortage of minerals and energy was a powerful influence on its politics and history in the 20th century. Today it depends on imports for over 90% of its primary energy needs. As it recovered from World War II and rapidly expanded its industrial base it was dependent on fossil fuel imports, particularly oil from the Middle East (oil fuelled 66% of the electricity in 1974). This geographical and commodity vulnerability became critical due to the oil shock in 1973. At this time, Japan already had a growing nuclear industry, with five operating reactors. Re-evaluation of domestic energy policy resulted in diversification and in particular, a major nuclear construction program. A high priority was given to reducing the country's dependence on oil imports. A closed fuel cycle was adopted to gain maximum benefit from imported uranium.

Nuclear power has been expected to play an even bigger role in Japan's future. In the context of the Ministry of Economy, Trade and Industry (METI) Cool Earth 50 energy innovative technology plan in 2008, the Japan Atomic Energy Agency (JAEA) modelled a 54% reduction in CO2 emissions (from 2000 levels) by 2050 leading on to a 90% reduction by 2100. This would lead to nuclear energy contributing about 60% of primary energy in 2100 (compared with 10% in 2008), 10% from renewables (from 5%) and 30% fossil fuels (from 85%). This would mean that nuclear contributed 51% of the emission reduction: 38% from power generation and 13% from hydrogen production and process heat.

In June 2010 METI resolved to increase energy self-sufficiency to 70% by 2030, for both energy security and CO2 emission reduction. It envisaged deepening strategic relationships with energy-producing countries. Nuclear power would play a big part in implementing the plan, and new reactors would be required as well as achieving 90% capacity factor across all plants.

However, following the Fukushima accident, in October 2011 the government sought to greatly reduce the role of nuclear power. This appears to have been a significant factor in them losing office in 2012 elections (see later section). The new government in 2014 adopted the 4th Basic (or Strategic) Energy Plan, with 20-year perspective and declaring that nuclear energy is a key base-load power source and would continue to be utilized safely to achieve stable and affordable energy supply and to combat global warming.

Early in 2011, nuclear energy accounted for almost 30% of the country's total electricity production (29% in 2009), from 47.5 GWe of capacity (net) to March 2011, and 44.6 GWe (net) from then. There were plans to increase this to 41% by 2017, and 50% by 2030.

IEA figures indicate that in 2013 Japan generated 1059 TWh gross, 338 TWh from coal, 408 TWh from gas (up from 300 TWh in 2010), 9 TWh from nuclear (cf 288 TWh in 2010), 161 TWh from oil (up from 94 TWh in 2010), and 84 TWh from hydro. The country’s nuclear capacity was progressively shut following the March 2011 Fukushima accident. Renewables contribution in 2013 was small: solar 10 TWh, wind 5 TWh, geothermal 2.6 TWh, biomass & waste 41 TWh. Final consumption in 2010 was about 1000 billion kWh, or about 7870 kWh per capita. This dropped to 923 TWh, or 7200 kWh/capita in 2012.

Capacity (IEA figures) at end of 2012 was 295 GWe, this being 46 GWe nuclear, 45 GWe hydro, 36 GWe coal, 47 GWe gas, 41 GWe oil, 16 GWe oil or coal, 50.6 GWe autoproducers’ ‘combustible fuels’, 6.6 GWe solar, 2.5 GWe wind and 0.5 GWe geothermal. In response to nuclear difficulties, coal capacity is planned to increase 21% to 47 GWe by early 2020s.

The electricity market is due to be deregulated in 2016, with legal separation in 2018 between generation, transmission, and distribution.

Other energy information for Japan can be found at

Development of nuclear program & policy 1950 to 2005

Japan started its nuclear research program in 1954, with ¥230 million being budgeted for nuclear energy. The Atomic Energy Basic Law, which strictly limits the use of nuclear technology to peaceful purposes, was passed in 1955. The law promoted three principles – democratic methods, independent management, and transparency – are the basis of nuclear research activities, as well as promoting international co-operation. Inauguration of the Atomic Energy Commission (AEC) in 1956 promoted nuclear power development and utilisation. Several other nuclear energy-related organisations were also established in 1956 under this law: the Nuclear Safety Commission (NSC), the Science & Technology Agency; Japan Atomic Energy Research Institute (JAERI) and the Atomic Fuel Corporation (renamed PNC in 1967 – see below).

The first reactor to produce electricity in Japan was a prototype boiling water reactor: the Japan Power Demonstration Reactor (JPDR) which ran from 1963 to 1976 and provided a large amount of information for later commercial reactors. It also later provided the test bed for reactor decommissioning.

Japan imported its first commercial nuclear power reactor from the UK, Tokai 1 – a 160 MWe gas-cooled (Magnox) reactor built by GEC. It began operating in July 1966 and continued until March 1998.

After this unit was completed, only light water reactors (LWRs) utilising enriched uranium – either boiling water reactors (BWRs) or pressurised water reactors (PWRs) – have been constructed. In 1970, the first three such reactors were completed and began commercial operation. There followed a period in which Japanese utilities purchased designs from US vendors and built them with the co-operation of Japanese companies, who would then receive a licence to build similar plants in Japan. Companies such as Hitachi Co Ltd, Toshiba Co Ltd and Mitsubishi Heavy Industry Co Ltd developed the capacity to design and construct LWRs by themselves. By the end of the 1970s the Japanese industry had largely established its own domestic nuclear power production capacity and today it exports to other east Asian countries and is involved in the development of new reactor designs likely to be used in Europe.

Due to reliability problems with the earliest reactors they required long maintenance outages, with the average capacity factor averaging 46% over 1975-77 (by 2001, the average capacity factor had reached 79%). In 1975, the LWR Improvement & Standardisation Program was launched by the Ministry of International Trade and Industry (MITI) and the nuclear power industry. This aimed, by 1985, to standardise LWR designs in three phases. In phases 1 and 2, the existing BWR and PWR designs were to be modified to improve their operation and maintenance. The third phase of the program involved increasing the reactor size to 1300-1400 MWe and making significant changes to the designs. These were to be the Advanced BWR (ABWR) and the Advanced PWR (APWR).

A major research and fuel cycle establishment through to the late 1990s was the Power Reactor and Nuclear Fuel Development Corporation, better known as PNC. Its activities ranged very widely, from uranium exploration in Australia to disposal of high-level wastes. After two accidents and PNC's unsatisfactory response to them the government in 1998 reconstituted PNC as the leaner Japan Nuclear Cycle Development Institute (JNC), whose brief was to focus on fast breeder reactor development, reprocessing high-burnup fuel, mixed-oxide (MOX) fuel fabrication and high-level waste disposal.

A merger of JNC and JAERI in 2005 created the Japan Atomic Energy Agency (JAEA) under the Ministry of Education, Culture, Sports, Science & Technology (MEXT). JAEA is now a major integrated nuclear R&D organization.

A peculiarity of Japan's electricity grids is that on the main island, Honshu, the northeastern half including Tokyo is 50 Hz, served by Tepco (and Tohoku), the southwestern half including Nagoya, Kyoto and Osaka is 60 Hz, served by Chubu (with Kansai & Hokuriku), and there is only 1 GWe of frequency converters connecting them. (Japc has plants in both areas, which are separated by the Itoigawa River.) This frequency difference arises from original equipment coming from Germany and USA respectively. The interconnection is being increased to 2.1 GWe, funded by the utilities. Early in 2013 it was announced that METI will establish a new body to balance electricity supply and demand in wide areas across Japan, as early as 2015. The new body will manage grid and transmission facilities, which are currently owned and managed by utility companies.

More recent energy policy 2002-2011: Focus on nuclear

Japan's energy policy has been driven by considerations of energy security and the need to minimise dependence on current imports. The main elements regarding nuclear power were:

  • continue to have nuclear power as a major element of electricity production.
  • recycle uranium and plutonium from used fuel, initially in LWRs, and have reprocessing domestically.
  • steadily develop fast breeder reactors in order to improve uranium utilisation dramatically.
  • promote nuclear energy to the public, emphasising safety and non-proliferation.

In March 2002 the Japanese government announced that it would rely heavily on nuclear energy to achieve greenhouse gas emission reduction goals set by the Kyoto Protocol. A 10-year energy plan, submitted in July 2001 to the Minister of Economy Trade & Industry (METI), was endorsed by cabinet. It called for an increase in nuclear power generation by about 30 percent (13,000 MWe), with the expectation that utilities would have up to 12 new nuclear plants operating by 2011. In fact only five (5358 MWe net) came on line in that decade.

In June 2002, a new Energy Policy Law set out the basic principles of energy security and stable supply, giving greater authority to the government in establishing the energy infrastructure for economic growth. It also promoted greater efficiency in consumption, a further move away from dependence on fossil fuels, and market liberalisation.*

* In November 2002, the Japanese government announced that it would introduce a tax on coal for the first time, alongside those on oil, gas and LPG in METI's special energy account, to give a total net tax increase of some JPY 10 billion from October 2003. At the same time METI would reduce its power-source development tax, including that applying to nuclear generation, by 15.7% – amounting to JPY 50 billion per year. While the taxes in the special energy account were originally designed to improve Japan's energy supply mix, the change was part of the first phase of addressing Kyoto goals by reducing carbon emissions. The second phase, planned for 2005-07, was to involve a more comprehensive environmental tax system, including a carbon tax.

These developments, despite some scandal in 2002 connected with records of equipment inspections at nuclear power plants, paved the way for an increased role for nuclear energy.

In 2004 Japan's Atomic Industrial Forum (JAIF) 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 GDP. Projected nuclear generating capacity in 2050 was 90 GWe. This would mean doubling both nuclear generating capacity and nuclear share to about 60% of total power produced. In addition, some 20 GW (thermal) of nuclear heat would be utilised for hydrogen production. Hydrogen is expected to supply 10% of consumed energy in 2050 and 70% of this would come from nuclear plants.

In July 2005 the Atomic Energy Commission reaffirmed policy directions for nuclear power in Japan, while confirming that the immediate focus would be on LWRs. The main elements were that a "30-40% share or more" should be the target for nuclear power in total generation after 2030, including replacement of current plants with advanced light water reactors. Fast breeder reactors would be introduced commercially, but not until about 2050. Used fuel would be reprocessed domestically to recover fissile material for use in MOX fuel. Disposal of high-level wastes would be addressed after 2010.

In May 2006 the ruling Liberal Democratic Party urged the government to accelerate development of fast breeder reactors (FBRs), calling this "a basic national technology".* It proposed increased budget, better coordination in moving from R&D to verification and implementation, plus international cooperation. Japan was already playing a leading role in the Generation IV initiative, with focus on sodium-cooled FBRs, though the 280 MWe (gross) Monju prototype FBR remained shut down until May 2010, and then shut down again a few months later, with prospective restart repeatedly postponed.

* In April 2007 the government selected Mitsubishi Heavy Industries (MHI) as the core company to develop a new generation of FBRs. This was backed by government ministries, the Japan Atomic Energy Agency (JAEA) and the Federation of Electric Power Companies of Japan. These were concerned to accelerate the development of a world-leading FBR by Japan. MHI has been actively engaged in FBR development since the 1960s as a significant part of its nuclear power business.

METI's 2010 electricity supply plan showed nuclear capacity growing by 12.94 GWe by 2019, and the share of supply growing from 2007's depressed 262 TWh (25.4%) to about 455 TWh (41%) in 2019. This is now unachievable. A regular AEC Policy Planning Council review ceased in 2011 and the Council was disbanded in 2012.

In March 2011 units 1-4 of the Fukushima Daiichi plant were seriously damaged in a major accident, hence written off for decommissioning, which removed 2719 MWe net from Tepco's – and the country's – system. In 2014 units 5&6 joined them in being decommissioned.

At present Japan has 48 reactors totalling 42,569 MWe (net) operational, with two (2756 MWe) under construction, one in indefinite shutdown (Monju), and 12 (16,532 MWe) planned. In the light of mid-2012 policy options Monju is considered more relevant to the R&D section of this paper. In 2010 the first of those power reactors then operating reached their 40-year mark (at which stage there was a presumption that some might close down). Some licence extensions have been approved, see subsection below tables.

Post-Fukushima energy policy changes, 2011 on

In July 2011 an Energy & Environment Council (Enecan or EEC) was set up by the Democratic Party of Japan (DPJ) cabinet office as part of the National Policy Unit to recommend on Japan's energy future to 2050.* It was chaired by the Minister for National Policy to focus on future dependence on nuclear power. Its initial review was to recommend that nuclear power's contribution to electricity be targeted at 0%, 15%, or 20-25% for the medium term – a 36% option was dropped.

* The Atomic Energy Commission (AEC) and Central Environment Council apparently came under Enecan in 2011, and in 2012 were restored to previous status.

Meanwhile major Japanese companies such as Mitsui and Mitsubishi started investing heavily in LNG production capacity from Australia and elsewhere eg a 15% stake in Woodside's Browse LNG project for $2 billion. METI estimated that power generation costs would rise by over JPY 3 trillion ($37 billion) per year, an equivalent of about 0.7 percent of gross domestic product, if utilities replaced nuclear energy with thermal power generation. In February 2012 METI's minister said that electricity costs would need to increase up to 15% while the nuclear plants remained shut.*

* Meanwhile, costs of nuclear power relative to alternatives were published. The Institute of Energy Economics of Japan in 2011 put the cost of nuclear electricity generation at ¥8.5 per kWh taking into account compensation of up to ¥10 trillion ($130 billion) for loss or damage from a nuclear accident. Later in the year a draft report for Enecan estimated nuclear generation costs for 2010 to be ¥8.9 per kWh (11.4 US cents). This included capital costs (¥2.5), operation and maintenance costs (¥3.1), and fuel cycle costs (¥1.4). In addition, the estimate included ¥0.2 for additional post-Fukushima safety measures, ¥1.1 in policy expenses and ¥0.5 for dealing with future nuclear risks. The ¥0.5 for future nuclear risks is a minimum: the cost would increase by ¥0.1 for each additional ¥1 trillion ($13 billion) of damage. The ¥8.9 figure was calculated based on a model nuclear power plant using average figures from four plants operating over the period since the 2004 estimate, with an output of 1200 MWe and construction costs of ¥420 billion ($5.4 billion). Costs were calculated assuming a discount rate of 3%, a capacity factor of 70% and a 40-year operating life. The 2010 costs for fossil fuel generation, including costs for CO2 measures, ranged from ¥9.5 for coal through to ¥10.7 for LNG to ¥36.0 for oil. Projecting forward to 2030 the nuclear cost remains stable but fossil fuels costs increase significantly.

In July 2012 feed-in tariffs (FiTs) were introduced for solar and wind power. The solar FiT was ¥42/kWh (41 cents US) for ten years, which was reduced in April 2013 to ¥38 for small systems, and to be reduced again in April 2014 to ¥37/kWh residential and ¥32/kWh for systems over 10 kW. The wind FiT in 2012 was ¥23.1/kWh for units above 20 kW, and ¥57.75 for smaller units (of which none had been approved).

Enecan's "Innovative Energy and Environment Strategy" was released in September 2012, recommending a phase-out of nuclear power by 2040. In the short term, reactors currently operable but shut down would be allowed to restart once they gained permission from the incoming Nuclear Regulation Authority (NRA), but a 40-year operating limit would be imposed. Reprocessing of used fuel would continue. Enecan promised a "green energy policy framework" is promised by the end of 2012, focused on burning imported gas (LNG) and coal, along with expanded use of intermittent renewables. This provoked a strong and wide reaction from industry, with a consensus that 20-25% nuclear was necessary to avoid very severe economic effects, not to mention high domestic electricity prices. In the past year increased fossil fuel imports had been a major contributor to Japan's record trade deficit of JPY 2.5 trillion ($31.78 billion) in the first half of 2012. The Keidanren (Japan Business Federation) said the Enecan phase-out policy was irresponsible, as did the leadership of the Liberal Democratic Party (LDP).

Four days after indicating general approval of the Enecan plan, the DPJ cabinet backed away from it, relegating it as "a reference document" and the prime minister explained that flexibility was important in considering energy policy. The timeline was dropped. Reprocessing used nuclear fuel would continue and there would be no impediment to continuing construction of two nuclear plants – Shimane 3 and Ohma 1. A new Basic Energy Plan would be decided after further deliberation and consultation, especially with municipalities hosting nuclear plants. 

However, at the end of 2012 the new Liberal Democratic Party (LDP) government promptly abolished Enecan, along with the National Policy Institute, so that METI’s Advisory Committee for National Resources and Energy became responsible for formulating energy plans, while MoE’s Central Environment Council focused on climate change matters. The new LDP prime minister ordered a ‘zero-based’ review of energy policies.

In December 2012, after a decisive victory in national elections for the Diet's lower house, with 294 out of 480 seats, the LDP took a more positive view of restarting idled nuclear power plants than its predecessor, which had seemed indifferent to electricity shortages and massive LNG and other fossil fuel import costs. (The DPJ won only 57 seats, down from 267)  The new government said it would take responsibility for allowing reactor restarts after the Nuclear Regulation Authority issued new safety standards and confirmed the safety of individual units. After abolishing Enecan it also said that abandoning reprocessing of used fuel was ruled out. Construction of Shimane 3 and Ohma 1 was to continue, and the construction of up to 12 further units could be approved.

In July 2013, elections for the Diet’s upper house gave the LDP 115 seats out of 242. Its coalition partner and another pro-nuclear party won 29 seats. This consolidated the LDP position and role in reviving the economy, including restoring power supplies. The DPJ with its policy of abandoning nuclear power by 2040 won only 59 seats. The LDP won a seat in every constituency with a nuclear power plant. In Fukushima prefecture the LDP candidate polled more than twice as many votes as the DPJ candidate. In Fukui prefecture, where Kansai Electric Power Co. has 11 units, Japan Atomic Power Co. has two units, and the government has the Monju prototype breeder reactor, an LDP candidate beat the DPJ contender, 237,000 votes to 56,000.

In December 2013 a draft of the new 4th Basic (or Strategic) Energy Plan* was issued, with 20-year perspective, and declaring the period to 2020 as a special stage to reform energy systems. It said that nuclear energy is a key base-load power source and would continue to be utilized safely to achieve stable and affordable energy supply and to combat global warming. However, the degree of dependence on it would be reduced as much as possible consistent with those goals and the maintenance of nuclear technology and expertise. Reactors will be restarted as their safety is confirmed by NRA. Used fuel will receive more attention, and the nuclear fuel cycle will be promoted, including R&D on fast reactors.

* updated every three years, under the Energy Policy law.

In February 2014 METI presented the proposed new 4th Basic Energy Plan to government, which adopted it in April. It lists nuclear as an important one of four base-load options. Two of the others – hydro and geothermal – are limited, and the other is coal, but though cheap, its pollution works against emissions goals and represents a geopolitical risk. Natural gas/LNG was designated as intermediate between low-cost base-load and peaking oil, and capable of complementing the intermittency of renewables. Renewables were given the most space and will be "accelerated to full introduction" though without targets: solar is seen as useful to supply power during peak demand; large-scale deployment of wind could produce significant power, but this would come from northern areas and would require balancing with as-yet undeveloped storage systems. Nuclear power is presented as a quasi-domestic source that gives stable power at low operational cost and with low greenhouse gas profile. Nuclear power is an "important power source that supports the stability of the energy supply and demand structure," it said. 

Later, in October 2014, at least seven of the ten major utilities limited the access of renewable energy to their grids due to potential overloads. The government is addressing the problem by reducing the 2012 high fixed-price feed-in tariffs (FITs).

In January 2015 the Institute of Energy Economics, Japan (IEEJ) released a report looking at four electricity scenarios in 2030 and their implications, for about 1150 TWh (less than 10% up on 2013). They ranged from zero nuclear up to 30% nuclear contribution, with power costs for zero being 42% higher than the 30% nuclear scenario (21.0 vs 14.8 JPY/kWh), and GDP being JPY 10 trillion less. The other metric of obvious significance is energy self-sufficiency, only 7% in 2013, and ranging from 19% in zero-nuclear scenario to 28% in the 30% nuclear one (considering nuclear as quasi-indigenous, as it has been). LNG imports in the zero nuclear scenario are almost as high as in 2013, but reduce 20% from 2013 level in the 30% nuclear one. Reliance on renewables is 35% in zero-nuclear but only 20% in high-nuclear scenario, compared with 13.5% in 2013.

2011-14 Electricity Supply Constraints and Changes and Power Plant Situation

The chairman of Japan's Federation of Electric Power Companies (FEPC) warned in May 2011 that the organization expected the supply-demand balance in summer 2011 would be very tight in the east coast areas served by Tokyo Electric Power Co (Tepco), Tohoku Electric Power Co (both 50 Hz) and Chubu Electric Power Co (60 Hz). He said that all the utilities on the west coast of Japan will cooperate to transfer electricity to the east coast, noting the significant role of nuclear energy in ensuring a stable power supply*. He stressed the importance of the government allowing those reactors currently shut down for mandated periodic inspections to be able to return to service as soon as possible. In particular, the government should help local authorities and residents understand the importance of restarting those reactors currently shut for periodic inspections.

* There is a supply constraint in that the northeastern half of Honshu including Tokyo is 50 Hz, served by Tepco and Tohoku, but the southwestern half including Nagoya, Kyoto and Osaka is 60 Hz, served by Chubu with Kansai & Hokuriku, and there is only 1 GWe of frequency converters connecting them. (Japc has plants in both areas, which are separated by the Itoigawa River.)

Under Japanese regulations, the default period between inspections at reactors is 13 months, but changes made in 2009 allow operators to apply to increase this to 18 months. Subject to approval, a five-year introductory period would follow, after which the limit could be raised to 24 months between inspections – more in line with international practices.

The median capacity factor for Japanese nuclear plants is about 70% – compared with over 90% for the best performers worldwide – with the country's inspection requirements a contributing factor to this difference. Most other countries conduct regulatory checks so that utilities can operate their power plants almost all of the time that refuelling or major maintenance is not taking place.

Decline in operating capacity

By mid-May 2011, only 17 out of Japan's 50 remaining nuclear power reactors (apart from Monju and written-off Fukushima Daiichi 1-4) were in operation. This represented 15,493 MWe, or 35%, of the total remaining nuclear generating capacity of 44,396 MWe. Twenty units, with a combined capacity of 17,705 MWe (40% of total nuclear capacity) were not operating as they had been shut for periodic inspections, while another two units (1700 MWe) had been shut for unplanned inspections or equipment replacement. Units 4&5 at Chubu Electric's Hamaoka plant were shut down at the government's request in May 2011 to increase their resistance to tsunamis.*

* Chubu was spending some JPY 140 billion ($1.7 billion) on seawall defences, which were expected to be complete by the end of 2013 (see following subsection). During the shutdown process for the unit 5 ABWR, a burst pipe in the condenser allowed seawater to enter the main cooling circuit and some 5000 litres reached the reactor itself, but disassembly and inspection to December 2012 revealed no serious corrosion damage to fuel assemblies or other components. It is expected to be ready to restart about mid-2014, subject to NRA clearance.

The other nine units – with a combined capacity of 8826 MWe (20% of total nuclear capacity) – were shut down during the 11 March earthquake and have not restarted. These nine reactors – units 1 and 3 of the Onagawa plant, unit 2 of the Tokai plant, all four units at the Fukushima Daini plant and units 5&6 of Fukushima Daiichi – are in cold shutdown and were progressively joined by others as maintenance outages came due. (Four units – Fukushima Daiichi units 1 to 4, total 2719 MWe – were written off and are to be decommissioned. Fukushima Daiichi units 5&6 have joined them in being decommissioned.)

After May 2011 the number of operating reactors steadily dwindled to zero.

In the summer of 2011 stringent energy conservation measures were applied leading to a 12% reduction in power consumption (relative to 2010) in August, and more significantly, a reduction in peak demand reaching 18%, exceeding the government target of 15%.

Tsunami defences

Chubu Electric Power Co is undertaking increased tsunami and flooding protection for the Hamaoka nuclear power plant, which was closed in response to an extraordinary request from the Japanese prime minister. The plant is in a region of high seismic activity, where a large undersea earthquake can be expected within the next 30 years. Behind a row of sand dunes measuring between 10 and 15 metres high above sea level, the company has erected a new 1.6 km breakwater wall reaching 22 metres above sea level. On the main plant site, measures will mitigate general serious flooding in case a tsunami overwhelms the breakwater. They include the waterproofing of diesel generator rooms and seawater pumps, as well as the installation of pumps in the building basements. Grid connections are to be doubled up, with another set of diesel generators complete with long-term fuel supply installed on ground behind the main plant buildings about 25 metres above sea level. Spare parts for seawater pumps will be kept in a hardened building and heavy earthmoving capability will be maintained.

Hokkaido is building a seawall 1.25 km long and up to 6.5 m high at its Tomari site, which is 10 m above sea level.

In April 2012 Kansai announced that it would spend more than JPY 200 billion ($2.5 billion) over four years on defences against earthquakes and tsunamis at its eleven reactors. Kansai submitted the plans to the government as a precondition for restarting its two Ohi reactors in western Japan.

Stress Tests 2011-12

Nuclear risk and safety reassessments – 'stress tests' – along the lines of those in Europe were carried out in 2011. After some confusion the government decided that these would be in two stages.

In the primary stage, plant operators assessed whether main safety systems could be damaged or disabled by natural disasters beyond the plant design basis. This identified the sheer magnitude of events that could cause damage to nuclear fuel, as well as any weak points in reactor design. The 'tests' started from an extreme plant condition, such as operating at full power while used fuel ponds are full. From there, a range of accident progressions such as earthquakes, tsunamis and loss of off-site power were computer simulated using event trees, addressing the effectiveness of available protective measures as problems developed. Stage 1 tests had to be approved before reactors are restarted.

In the second stage even more severe events were considered, with a focus on identifying 'cliff-edge effects' – points in a potential accident sequence beyond which it would be impossible to avoid a serious accident. This stage included the effects of simultaneous natural disasters. A particular focus was the fundamental safety systems that were disabled by the tsunami of 11 March, leading to the Fukushima accident: back-up diesel generators and seawater pumps that provide the ultimate heat sink for a power plant.

The stage 1 stress test results for individual plants were considered first by NISA and then by the Nuclear Safety Commission before being forwarded to the prime minister's office for final approval. Local government must then approve restart.* 

* Late in March 2012 NISA had received stage 1 assessments for 17 reactors – 12 PWRs and 5 BWRs. Three of these – Ohi 1&2 and Ikata 3 – had been approved by NISA and two confirmed by NSC. In September NISA finished reviewing those for six units: Hokkaido’s Tomari 1&2, Kansai’s Takahama 3&4 and Kyushu’s Sendai 1 & 2. Its findings and comments were forwarded to the new Nuclear Regulation Agency (NRA), which is now responsible for approving restarts. It appears that at least 12 stress test assessments then remained at the review stage, including Hokuriku’s Shika 1&2, Genkai 2, 3&4; Mihama 3; Tsuruga 2; Higashidori 1; Takahama 1; Kashiwazaki-Kariwa 1&7; Ohi 1 and Ikata 1.

In mid-April 2012, after a series of high-level meetings, the Japanese government approved the restart of Kansai Electric’s Ohi 3 & 4 reactors, and urged the Fukui governor and the Ohi mayor to endorse this decision. They restarted in July 2012 and ran through to September 2013, when they were shut down for routine maintenance.

Nuclear plant restarts

In October 2012 the new Nuclear Regulation Authority (NRA) which had taken over from the Nuclear & Industrial Safety Agency (NISA) and NSC announced that henceforth nuclear power plant restart reviews would comprise both a safety assessment by NRA and the briefing of affected local governments by the operators. The assessment would be based on safety guidelines formulated by NRA in July 2013 after public consultation. In rulemaking, the NRA commissioners referred to the guidelines of the IAEA, Finland, France and the USA, as well as the former NISA July 2011 stress test rules and provisional 30-point measures, issued in April 2012, that were applied to the restarts of Ohi 3&4.

In July 2013 four utilities applied for restart of 12 PWR reactors at six sites, two of which – Ohi 3&4 – were already running on interim basis. The units covered by the applications were Kansai's Takahama units 3&4 and Ohi units 3&4; Hokkaido's Tomari units 1-3; Shikoku's Ikata unit 3, and Kyushu's Sendai 1&2 and Genkai 3&4. Gross capacity is 11,200 MWe, almost a quarter of the nation’s total. These were all among the units well advanced in NISA’s stress test assessments in 2012. As of September 2013 the NRA was prioritising six PWR units: Tomari 3, Ikata 3, Sendai 1&2, Genkai 3&4 using four investigation teams with 80 staff. 

Tepco delayed its application for Kashiwazaki-Kariwa 6&7 ABWRs pending negotiation with local government, and lodged it in September 2013, lining up a further 2710 MWe gross. The Kashiwazaki-Kariwa 6&7 units were the first BWRs to be put forward for restart. Unlike the 12 PWRs referred to above, BWRs require a filtered containment venting (FCV) system. Under the general terms of a nuclear operator's agreement with local government, prefectural approval is required for these because any use during an emergency would mean releasing radioactivity in the course of avoiding the kind of hydrogen build-up which caused the explosions at Fukushima, destroying the superstructure of three units there.

In December 2013 Chugoku applied for assessment to restart its Shimane 2 reactor, and Tohoku applied for Onagawa 2, both also BWRs. Both companies had obtained local government approval for their applications. Chugoku also plans to apply for an assessment of the Shimane 3 ABWR, almost finished construction, once unit 2 is cleared to restart. J-Power in December 2014 applied for a safety assessment of its Ohma ABWR under construction. In February 2014 Chubu applied for approval to restart Hamaoka 4 BWR, following completion of a major sea wall. It intends to apply to restart unit 3 there in 2015, subject to completing work to conform with NRA regulations, local government agreement, and community acceptance. Unit 5 (1360 MWe ABWR) will also be ready to restart then. In May 2014 Japco applied to restart its Tokai 2 BWR, an older unit. In June Tohoku applied for restart of its relatively new Higashidori BWR, and in August Hokuriku applied for Shika 2 ABWR, the 8th BWR and 20th overall.

In March 2014 NRA said it would prioritise clearance of Kyushu’s Sendai 1&2 for restart, and in May it said this would be followed by Kansai’s Takahama 3&4. NRA has approved the review reports for these four units, which thus meet safety requirements for restart subject to final changes. Meanwhile a district court has ordered Kansai not to restart its Ohi 3&4 in Fukui prefecture due to public concerns. Kansai, with local government support, has appealed the ruling.

Status of restart applications and safety reviews

Type Utility Reactors Applied Final plan
PWR Kyushu Sendai 1&2 July 2013 Oct 2014 NRA approval,  making final checks
  Kansai Takahama 3&4 July 2013 Oct 2014 NRA approval, making final checks
  Kansai Ohi 3&4 July 2013   Quake & tsunami scenarios
  Hokkaido Tomari 1-3 July 2013   Quake scenarios pending
  Shikoku Ikata 3 July 2013   Quake & tsunami scenarios
  Kyushu Genkai 3&4 July 2013   Quake & tsunami scenarios
ABWR Tepco Kashiwazaki Kariwa 6&7 Sept 2013   NRA doing inspection
  J-Power Ohma 1 Dec 2014   NRA reviewing
BWR Chugoku Shimane 2 Dec 2013    
  Tohoku Onagawa 2 Dec 2013    
  Chubu Hamaoka 4 Feb 2014    
  J-Power Tokai 2 May 2014    
  Tohoku Higashidori 1 June 2014   Question re faults nearby
  Hokuriku Shika 2 August 2014    

The reactor restarts are facing significant implementation costs ranging from US$700 million to US$1 billion per unit, regardless of reactor size or age. To March 2014 the cost was put at $12.3 billion so far. The NRA is working to increase its relicensing staff to about 100 people, which could potentially shorten the currently envisaged six-month review timeline. Under a high case scenario developed by Itochu, about 10 reactors could be added every year for a total of up to 35 reactors back online within five years.

Media reports in January 2015 said that Kyushu’s Mihama 1&2, Japan Atomic Power's Tsuruga 1, Chugoku’s Shimane 1, and Kyushu’s Genkai 1 will be closed down permanently, subject to approval by prefecture authorities in Fukui, Shimane and Saga and approval by METI. All are relatively small (320 to 529 MWe net) and by October 2015 will be more than 40 years old, so that major expenditure on upgrades is hard to justify even though all of them already have life extension approvals. Two larger units, Kansai’s Takahama 1&2 also reach the 40-year mark in 2015 but these have had significant work done already and the costs of upgrading will be more readily recoverable, though Kansai is uncertain about their future. METI has approved draft provisions for cost recovery for decommissioning all seven units. Final approval for decommissioning and allocation of costs is expected by mid-2015.

Economic impact of shutdowns

JAIF has said that increased fuel imports are costing about ¥3.8 to 4.0 trillion ($40 billion) per year (METI puts total fossil fuel imports at ¥9 trillion in FY2013). The trade deficit in FY2012 was ¥6.9 trillion ($70 billion), and in 2013 ¥11.5 trillion ($112 billion), up 65% on 2012's figure. For fiscal 2013 the trade deficit was ¥13.75 trillion ($134 billion), 70% up on FY 2012, according to the Ministry of Finance. The total trade deficit from April 2011 to end of March 2014 was thus ¥23.25 trillion ($227 billion), compared with previous surpluses of at least ¥2.5 trillion per year (¥6.6 trillion in 2010). 

Generation cost was up 56% from ¥8.6/kWh to 13.5/kWh in FY 2012. Losses across the utilities are about ¥1 trillion per year. The Ministry of Economy Trade and Industry (MITI) said in April 2013 that Japanese power companies had spent an additional ¥9.2 trillion ($93 billion) to then on imported fossil fuels since the Fukushima accident. In FY 2012 the additional fuel costs to compensate for idled nuclear reactors was ¥3.6 trillion ($35.2 billion), mostly for oil and LNG. In 2013 Japan imported a record 109 million tonnes of coal, and plans to build almost 15 GWe of coal-fired generating capacity were reported.

At the end of 2013 the Japan Business Federation (Keidanren) said that “By stopping nuclear power plants, national wealth of ¥3.6 trillion ($34.9 billion) per year is flowing overseas” due to increased fossil fuel imports. The ongoing slump of trade balance into the negative could lead to deterioration of government credit and must be addressed “with a sense of crisis.” “There can be no new capital investment in domestic industry which is power-intensive.” Keidanren urged the government to recognise that economic growth depends on stable and affordable power, and nuclear needs to be part of that rather than continuing undue reliance on LNG. Also the current feed-in tariff to encourage renewables should be reviewed to reduce its burden on the economy.

In June 2014 three major business lobbies – the Japan Business Federation (Keidanren), the Japan Chamber of Commerce and Industry, and the Japan Association of Corporate Executives (Keizai Doyukai) – submitted a written proposal to the Industry Minister seeking an early restart of the nuclear reactors. “The top priority in energy policy is a quick return to inexpensive and stable supplies of electricity”, they said.

In early 2014 some 92 mostly very old oil-burning generation plants were running to full capacity, and these will be the first to shut down, due both to age and cost of running with imported oil.

Climate change effects

Carbon dioxide intensity from Japan's electricity industry climbed again in FY2012, reaching levels 39% greater than when the country's nuclear reactors were operating normally, and taking the sector far beyond climate targets. About 100 million tonnes per year more CO2 is being emitted than when the reactors were operating, adding 8% to the country’s emissions. Emissions from electricity generation accounted for 486 Mt CO2 (36.2%) of the country's total in fiscal 2012, compared with 377 Mt (30%) in 2010.

Up to March 2011 the CO2 intensity of Japan’s power generation was 350 g/kWh. Over the next year, with progressive reactor shut-downs, it rose to 487 g/kWh in FY 2012. In FY 2013 the country’s overall emissions rose to 1395 million tonnes of CO2 equivalent, the highest since records began in 1990. Among Japan's climate change goals was for the electricity sector to reduce carbon intensity by 20% from 1990 levels, to 334 g/kWh CO2 on average, over the five years from 2008 to 2012.

On the eve of the UN climate change meeting in Warsaw in November 2013, Japan’s Minister of the Environment announced that his country was changing its CO2 emission reduction target from 25% lower than 1990 levels by 2020 to a 3.1% increase from then, or 3.8% reduction from 2005 levels. He cited the shutdown of Japan’s 50 nuclear power reactors, some possibly for an extended period, as a prime reason for this, forcing reliance on old fossil fuel plant. In FY 2013 emissions were 1.3% up on 2005 levels.

Reactor development 1970 on

In the 1970s a prototype Advanced Thermal Reactor (ATR) was built at Fugen. This had heavy water moderator and light water cooling in pressure tubes and was designed for both uranium and plutonium fuel, but paticularly to demonstrate the use of plutonium. The 148 MWe unit, started up in 1978, was the first thermal reactor in the world to use a full mixed-oxide (MOX) core. It was operated by JNC until finally shut down in March 2003. Construction of a 600 MWe demonstration ATR was planned at Ohma, but in 1995 the decision was made not to proceed.

Since 1970, 30 BWRs (including four ABWRs) and 24 PWRs have been brought into operation. All the PWRs, comprising 2-, 3-, and 4-loop versions (600 to 1200 MWe classes) have been constructed by Mitsubishi.


The first ABWRs (of 1315 MWe) were Tokyo Electric Power Co's (Tepco's) Kashiwazaki-Kariwa units 6 & 7 which started up in 1996-97 and are now in commercial operation. These were built by a consortium of General Electric (USA), Toshiba and Hitachi. Four further ABWRs – Hamaoka 5, Shika 2, Shimane 3 and Ohma 1 – are in operation or under construction, and eight of the planned reactors in Japan are ABWR. These have modular construction. Hitachi-GE talks of its 1500 MWe class "global unified ABWR", and is developing a high-performance 1800 MWe class ABWR. Hitachi was also developing 600, 900 and 1700 MWe versions of the ABWR


The 1500 MWe class APWR design is a scale-up of the four-loop PWR and has been developed by four utilities with Mitsubishi and (earlier) Westinghouse. The APWR is in the process of being licensed in Japan with a view to the first 1538 MWe units being constructed at Tsuruga (units 3&4). Approval by Fukui prefecture was given in March 2004. It is simpler than present PWRs, combines active and passive cooling systems to greater effect, and has over 55 gigawatt days per tonne (GWd/t) burn-up. Design work continues and will be the basis for the next generation of Japanese PWRs. The APWR+ is 1750 MWe and has full-core MOX capability.

Mitsubishi Heavy Industries (MHI) is now marketing its 1700 MWe APWR in the USA and Europe, and lodged an application for US design certification in January 2008. The US-APWR has been selected by TXU (now Luminant) for Comanche Peak, Texas, and by Dominion for its North Anna plant. (MHI also participated in developing the Westinghouse AP1000 reactor, but now that Westinghouse has been sold to Toshiba, MHI will develop PWR technology independently.)

Next-generation LWR

In mid-2005 the Nuclear Energy Policy Planning Division of the Agency for Natural Resources and Energy instigated a two-year feasibility study on development of next-generation LWRs. 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 and three-year construction and longer life. They will have at least 5% enriched fuel and a design life of 80 years with 24-month operating cycle, and be deployed from about 2020. In 2008 the Nuclear Power Engineering Center was established within the Institute of Applied Energy to pursue this goal, involving METI, FEPC and manufacturers. The project is expected to cost JPY 60 billion over eight years, to develop one BWR and one PWR design, each of 1700-1800 MWe. The government, with companies including Toshiba and Hitachi-GE, will share the cost of these. The PWR is to have thermal efficiency of 40%. Basic designs are to be finished by 2015, with significant deployment internationally by 2030.

Power reactors operational in Japan

Reactor Type Net capacity Utility Commercial Operation Planned shutdown
Fukushima II-1
1067 MWe
April 1982
Fukushima II-2
1067 MWe
February 1984
Fukushima II-3
1067 MWe
June 1985
Fukushima II-4
1067 MWe
August 1987
Genkai 1
529 MWe
October 1975
Genkai 2
529 MWe
March 1981
Genkai 3
1127 MWe
March 1994
Genkai 4
1127 MWe
July 1997
Hamaoka 3
1056 MWe
August 1987
Hamaoka 4
1092 MWe
September 1993
Hamaoka 5
1325 MWe
January 2005
Higashidori 1 Tohoku
1067 MWe
December 2005
Ikata 1
538 MWe
September 1977
Ikata 2
538 MWe
March 1982
Ikata 3
846 MWe
December 1994
Kashiwazaki-Kariwa 1
1067 MWe
September 1985
Kashiwazaki-Kariwa 2
1067 MWe
September 1990
Kashiwazaki-Kariwa 3
1067 MWe
August 1993
Kashiwazaki-Kariwa 4
1067 MWe
August 1994
Kashiwazaki-Kariwa 5
1067 MWe
April 1990
Kashiwazaki-Kariwa 6
1315 MWe
November 1996
Kashiwazaki-Kariwa 7
1315 MWe
July 1997
Mihama 1
320 MWe
November 1970
2020, 2015
Mihama 2
470 MWe
July 1972
2020, 2015
Mihama 3
780 MWe
December 1976
Ohi 1
1120 MWe
March 1979
Ohi 2
1120 MWe
December 1979
Ohi 3
1127 MWe
December 1991
Ohi 4
1127 MWe
February 1993
Onagawa 1
498 MWe
June 1984
Onagawa 2
796 MWe
July 1995
Onagawa 3
796 MWe
January 2002
Sendai 1
846 MWe
July 1984
Sendai 2
846 MWe
November 1985
Shika 1
505 MWe
July 1993
Shika 2
1304 MWe
March 2006
Shimane 1
439 MWe
March 1974
Shimane 2
791 MWe
February 1989
Takahama 1
780 MWe
November 1974
Takahama 2
780 MWe
November 1975
Takahama 3
830 MWe
January 1985
Takahama 4
830 MWe
June 1985
Tokai 2
1060 MWe
November 1978
Tomari 1
550 MWe
June 1989
Tomari 2
550 MWe
April 1991
Tomari 3 PWR 866 MWe Hokkaido December 2009
Tsuruga 1
341 MWe
March 1970
2016, 2015
Tsuruga 2
1110 MWe
February 1987
Total: 48 reactors
42,569 MWe

Fukushima II = Fukushima Daini
The 2015 shutdown dates above are subject to METI approval in mid-2015. The later dates are NISA or NRA approved. 
In 2006 NISA ordered Hamaoka 5 and Shika 2 to be shut down due to problems with steam turbine blades. They were then restarted at lower power levels – 1212 and 1108 MWe net respectively. In 2011 Hamaoka 5 reverted to the above net power level.

Japanese reactors under construction

Reactor Type Gross capacity Utility Construction start Operation*
Monju** Prototype FNR
280 MWe
(246 net)
JAEA   Operated 1994-95, then May-Aug 2010
Shimane 3
1373 MWe
December 2005, suspended 2011
deferred, TBD
Ohma 1 ABWR 1383 MWe EPDC/ J-Power May 2010, suspended 3/11 to 10/12 start-up end 2020, comm operation early 2022
total (2 + Monju)
3036 MWe
* Latest announced commercial operation. TBD = to be determined.
** Monju operation is outlined in Fast Neutron Reactor section below. It is listed here in line with JAIF categorisation, and is under performance test process. JAEA rather than any utility is responsible for it and WNA may move it to the R&D section of this paper when its future is clearer. IAEA PRIS database lists it as ‘long-term shutdown’.

Japanese reactors planned and proposed

Reactor Type MWe gross
Utility start *
start *
Tsuruga 3
Tsuruga 4
Higashidori 1 Tepco
Kaminoseki 1
(deferred 3/11)
Sendai 3
(deferred 4/11)
Higashidori 2 Tepco
Hamaoka 6 ABWR 1380 Chubu 2016 or later TBD
Higashidori 2 Tohoku
Kaminoseki 2
(deferred 6/11)
Total Planned (9)  
12,947 MWe
Fukushima I-7
4/2012 (suspended)
Fukushima I-8
4/2012 (suspended)
Total proposed (3)
4145 MWe

* According to METI FY2010 plan, unless updated by company. TBD = to be determined.
Tsuruga 3&4 and Tepco's Higashidori 1 were undergoing final safety assessment by regulatory authorities. The units listed as Fukushima I-7&8 and Namie-Odaka will be built elsewhere if at all.

Japanese Nuclear Facilities

Life extension and 30-year reviews

Power reactors are licensed for 40 years and then require approval for life extension in 10-year increments. At 30 years, the regulator must review and approve the utility’s ageing management plan for each reactor. Following the Fukushima accident, the government tightened requirements for approving life extension beyond 40 years, which became the default limit. Operators can apply for up to 20-year licence extensions from 40 years, allowing possible 60 years as in the USA.

The Nuclear & Industrial Safety Agency (NISA) granted a 10-year licence extension for Fukushima Daiichi 1 in February 2011, after technical review and some modifications in 2010. However, this was destroyed in the 2011 accident.

In March 2010, local government approved life extension to 2016 for JAPC's Tsuruga 1, which started commercial operation in March 1970. A year earlier JAPC issued a technical evaluation of the reactor with a plan for its ongoing maintenance. METI approved this in September 2009. (JAPC then applied for life extension to 2016 in order to bridge the gap until units 3&4 at Tsuruga come on line. Construction of the two units was due to start later in 2010 and commissioning of the first was due in March 2016.)

Then Kansai applied for a 10-year licence extension from November 2010 for its Mihama 1 PWR. NISA approved Kansai's long-term maintenance and management plan for the unit and granted a life extension accordingly in June 2010, which was then agreed by local government. However, this effectively means simply that the reactor did not have to be decommissioned then, but may be upgraded according to new standards. Kansai in July 2011 applied for approval of its ageing management plan for Mihama 2, and NISA granted this in July 2012. In February 2014 the NRA approved Chugoku’s Shimane 1 BWR similarly, and in November 2014 they approved a 10-year life extension for Kansai’s Takahama 1 PWR. Subject to required upgrades to new safety standards, all these can now be licensed to 50 years. In October 2014 Kyushu applied for a ten-year extension for Genkai 1. Kansai has applied for ten-year cold shutdown of Takahama 2 to defer any decision on its future beyond its 40th anniversary in 2015.

In March 2012 NISA and METI approved Shikoku Electric's strategy for managing ageing and hence approved operation of its Ikata 2 PWR for 40 years, and in 2014 approved the same for Tepco’s Fukushima Daini 2 and Tohoku’s Onagawa 1 BWR. In June 2014 Kansai sought approval for Takahama 4, which joined Takahama 3 and Kyushu’s Sendai 1 in being reviewed at 30 years and approved for age-related degradation issues. In January 2015 the NRA approved these issues being handled together with engineering work involved with Kansai meeting safety requirements for restart of the two Takahama units. However, none of the reactors can be restarted until NRA assesses that they conform to its 2013 safety guidelines.

Particular plants: most under construction and planned

Chugoku's Shimane 3 was to enter commercial operation in December 2011, but this was delayed to March 2012 because control rod drives had to be returned to the manufacturer for modification and cleaning. The start-up date was then deferred until evaluation of the Fukushima accident could be undertaken. It was 94% complete when construction was suspended in March 2011. Chugoku finished building a 15 m high sea wall in January 2012, and then extended this to a total length of 1.5 km to also protect Shimane 1&2. Chugoku plans to apply for a safety assessment to clear the way for it to start, so that construction can be completed, once unit 2 is cleared to restart. Seismic rating of the unit is 1000 Gal.

The Electric Power Development Corp, now known as J-Power, is building its Ohma nuclear plant – 1383 MWe Advanced Boiling Water Reactor (ABWR) – in Aomori prefecture. Construction of unit 1 was due to start in August 2007 for commissioning in 2012, but was delayed by more stringent seismic criteria, then delayed again in 2008, and commenced in September 2009. Seismic criterion is now 650 Gal. Construction was suspended for 18 months after the Fukushima tsunami, with it 38% complete – JSW had completed manufacturing the major components. J-Power in mid-2012 affirmed its intention to complete and commission the unit, and announced resumption of work in October. In November 2014 J-Power said that it plans to complete construction by the end of 2020, and have it in commercial operation about 12 months later.  It applied to NRA for safety review in December 2014.

Apart from the Fugen experimental Advanced Thermal Reactor (ATR), this will be the first Japanese reactor built to run solely on mixed oxide (MOX) fuel incorporating recycled plutonium. It will be able to consume a quarter of all domestically-produced MOX fuel and hence make a major contribution to Japan's "pluthermal" policy of recycling plutonium recovered from used fuel.

Tepco struggled for two years with the loss of its Kashiwazaki-Kariwa capacity – nearly half of its nuclear total – following the mid 2007 earthquake. While the actual reactors were undamaged, some upgrading to improve earthquake resistance and also major civil engineering works were required before they resumed operation. Overall, the FY2007 (ending March 2008) impact of the earthquake was estimated at JPY 603.5 billion ($5.62 billion), three quarters of that being increased fuel costs to replace the 8000 MWe of lost capacity. The Nuclear & Industrial Safety Agency (NISA) approved the utility's new seismic estimates in November 2008, and conducted final safety reviews of the units as they were upgraded and then restarted, the first in May 2009. Tepco undertook seismic upgrades of units 1 and 5, the two oldest, restarting them in 2010.

Review of earthquake design criteria meant that construction of Tepco's Higashidori 1&2 and Fukushima Daiichi 7&8 were delayed, requiring investment in coal-fired (1.6 GWe) and gas plant (4.5 GWe of LNG) to fill the gap. However, METI approved Tepco's Higashidori 1 in December 2010 and NISA approved it in January 2011, allowing Tepco to begin work on the site. Work stopped after the Fukushima accident, though JSW started manufacturing major components in 2011 after the accident. Tepco before this had forecast its overall nuclear capacity increasing from 24% of total in FY2007 to 27% of total in 2017, and nuclear output increasing from 23% to 48% of total supply in the same period. It then announced suspension of plans to build ABWR units 7&8 at Fukushima Daiichi. In 2012 it was reported that it could not afford to proceed with Higashidori, and both are probably cancelled.

The three approved plants are to be allowed to complete construction, despite the government's plans for scaling back nuclear power by 2040, according to the trade minister in September 2012.

Tohoku's Higashidori 2 on the same site as Tepco's is scheduled for construction start in 2016, though the company has yet to decide whether to proceed. The site is in Higashidori-mura, on the Pacific coast, near Mutsu on the eastern side of the Shimokita Peninsula in Aomori Prefecture. The company is building a 2km seawall to protect the site.

Chubu's Hamaoka 1&2 reactors, closed in 2001 and 2004 respectively for safety-related upgrades, remained shut down following the mid 2007 earthquake. In December 2008 the company decided to write them off (JPY 155 billion, $1.7 billion) and build a new one there. Modifying the two 1970s units to current seismic standards would cost about double the above amount and be uneconomic. The 540 and 840 MWe units (515 & 806 MWe net), which started operation in 1976 & 1978, will be replaced by a single new one, Hamaoka 6, to start operating in 2020, though in April 2011 the company deferred construction start until 2016. Hamaoka is the company's only nuclear site, though it said that it recognizes that nuclear needs to be a priority for both "stable power supply" and environment. However, the shutdown of units 3-5 in May 2011 by government edict for modification has set back plans.

Japan Atomic Power Co first submitted plans for its Tsuruga units 3&4 to NISA in 2004, and after considerable delay due to siting problems, they were approved by the Fukui prefecture. JAPC then submitted a revised construction application based on new geological data to NISA in October 2009. The approval process, including safety checks by METI, was expected to take two years, but the process then passed to the new NRA. In December 2012 the NRA said that a fault zone directly beneath the existing Tsuruga unit 2 reactor (operating since 1987) was likely to be seismically active, and in May 2013 it endorsed an expert report saying that the reactor poses a risk in the event of a major earthquake. An international review group investigating the faults with a massive excavation concluded in 2014 that the faults were not active. The matter is likely to have implications for the planned units and also unit 1. 

JAPC would need to spend JPY 140 billion ($1.75 billion) on civil engineering for site preparation, including land reclamation and a breakwater before construction start for units 3 & 4. Construction – estimated at JPY 770 billion (US$ 7.4 billion) – was due to start in March 2012 with commercial operation in 2017-18. This would be the first Mitsubishi APWR plant, with each unit 1538 MWe. JAPC planned to continue operating Tsuruga 1 beyond its scheduled shutdown date of 2010 and obtained an extension of the licence to 2016, due to the delay with the new units. Some of the power will be supplied to Chubu.

Kyushu Electric Power Co. filed a draft environmental statement ith METI in October 2009 for its Sendai 3 plant, also an APWR, but 1590 MWe. The Ministry of Environment told METI that the project was "absolutely essential, not just for ensuring energy security and a stable supply of electricity... but also to reduce greenhouse gas emissions." Local government has given approval. In 2010 METI began the process of designating it a key power source development project. Subject to METI and NISA approval, Kyushu expects to start construction in March 2014, for commercial operation in December 2019.

Chugoku Electric Power Co plans to build two Kaminoseki ABWR nuclear power units on Nagashima Island on the Seto Inland Sea coast in Kaminoseki Town, Yamaguchi Prefecture. Some site works commenced but then halted after the Fukushima accident – 40% of the site is to be reclaimed land. The small island community of Iwaishima a few kilometres away has long opposed the plant. In October 2012 Chugoku confirmed its intention to proceed.

Tohoku Electric Power Co planned to build the Namie-Odaka BWR nuclear power plant from 2017 at Namie town in Minami Souma city in the Fukushima prefecture on the east coast, but indefinitely deferred this project early in 2013.

Further proposed plants

In September 2010 Tepco, Japan's biggest utility, said it planned to invest JPY 2.5 trillion ($30.5 billion) on low-carbon projects domestically by 2020 to generate more than half of its power free of carbon. Most of this capacity will be nuclear. Two ABWR plants for Tepco are listed as planned, and two as proposed.

Early in 2011 Chubu Electric Co announced that it intended to build a new 3000-4000 MWe nuclear plant by 2030, with site and type to be decided. Beyond the planned Hamoka 6 ABWR, this is listed as 3 x 1350 units proposed in WNA table.

Fast Neutron Reactors

The Joyo experimental fast breeder reactor (FBR has been operating successfully since it reached first criticality in 1977, and has accumulated a lot of technical data. It is 140 MWt, and has been shut down sine 2007 due to damage to some core components.

The 280 MWe Monju prototype FBR reactor started up in April 1994 and was connected to the grid in August 1995, but a sodium leakage in its secondary heat transfer system during performance tests in December 1995 meant that it was shut down after only 205 days actual operation, until May 2010.* It then operated for 45 days but late in August 2010 it shut down again, due to refuelling equipment falling into the reactor vessel. This was retrieved in June 2011 and replaced with a new one, allowing potential restart in 2012. It produced 246 MWe (net) when it was fully operating. Its oversight passed to JNC (now JAEA), and the Minister for Science & Technology has been eager to see it restarted. In September 2014 the NRA approved JAEA’s management reorganisation for Monju. Its restart is contingent upon NRA approval of a new maintenance program.

* A Supreme Court decision in May 2005 cleared the way for restarting it in 2008, but this was put back to May 2010. METI confirmed early in 2010 that Monju's seismic safety under new guidelines was adequate, and NSC approved its restart and operation for a three-year period, prior to "full operation" in 2014. In line with the Japan Atomic Industry Forum, Monju is listed as 'under construction' in the Table above and in WNA's Reactor Table. IAEA PRIS lists it as 'long-term shutdown'.

JAEA also undertakes FBR and related R&D at Oarai in Ibaraki prefecture, near Tokai-mura.

In mid-2012 the Education, Science & Technology Ministry, MEXT, outlined to the AEC some options for the future of Monju, for which it is responsible through JAEA. If Japan opts for direct underground disposal of used fuel, Monju would be terminated. If the closed fuel cycle with reprocessing is continued, Monju would continue with its original mission to prepare for commercial use of FBRs from 2050, with demonstration unit to operate from 2025. Monju is reported to have cost JPY 1 trillion ($12.5 billion) to build and operate, and its budget for 2012 was JPY 17.5 billion. Early in 2014 its maintenance was reported as costing JPY 50 million per day.

Originally in 1960s the concept was to use fast breeder reactors (FBR) burning MOX fuel, making Japan virtually independent regarding nuclear fuel. But FBRs proved uneconomic in an era of abundant low-cost uranium, so development slowed and the MOX program shifted to thermal LWR reactors.

From 1961 to 1994 there was a strong commitment to FBRs, with PNC as the main agency. In 1967 FBR development was put forward as the main goal of the Japanese nuclear program, along with the ATR. In 1994 the FBR commercial timeline was pushed out to 2030, and in 2005 commercial FBRs were envisaged by 2050. This remains the plan: a demonstration breeder reactor of 500-750 MWe by 2025, and commercial 1500 MWe units by 2050.

In 1999 JNC initiated a program to review promising concepts, define a development plan by 2005 and establish a system of FBR technology by 2015. The parameters were: passive safety, economic competitiveness with LWR, efficient utilisation of resources (burning transuranics and depleted U), reduced wastes, proliferation resistance and versatility (include hydrogen production). Utilities are also involved, with CREIPI and JAEA.

Phase 2 of the JNC study focused on four basic reactor designs: sodium-cooled with MOX and metal fuels, helium-cooled with nitride and MOX fuels, lead-bismuth eutectic-cooled with nitride and metal fuels, and supercritical water-cooled with MOX fuel. All involve closed fuel cycle, and three reprocessing routes were considered: advanced aqueous, oxide electrowinning and metal pyroprocessing (electrometallurgical refining). This work is linked with the Generation IV initiative, where Japan has been playing a leading role with sodium-cooled FBRs. The JAEA 2006 budget gave a significant boost to R&D on the fast breeder fuel cycle with an increase to JPY 34.6 billion.

Some work has been done by JAEA on reprocessing of used fuel from fast reactors, with higher plutonium levels. FEPC envisages aqueous reprocessing which recovers uranium, plutonium and neptunium together, and minor actinides being added to the MOX pellets for burning. JAEA is part of a project under the Generation IV International Forum investigating the use of actinide-laden fuel assemblies in fast reactors – The Global Actinide Cycle International Demonstration (GACID). See Generation IV paper .

In April 2007 the government selected Mitsubishi Heavy Industries (MHI) as the core company to develop a new generation of FBRs, notably the Japan Standard Fast Reactor (JSFR) concept, though with breeding ratio less than 1:1. This is a large unit which will burn actinides with uranium and plutonium in oxide fuel. It could be of any size from 500 to 1500 MWe. The demonstration FR model was due to be committed in 2015 and on line in 2025, and a 1500 MWe commercial FR was proposed by MHI for 2050. From July 2007 Mitsubishi FBR Systems (MFBR) has operated as a specialist company. It was responsible for a joint bid with Areva for work on the US Advanced Recycling Reactor project and is part of the Japanese involvement with the French Astrid project (see R&D section below).

Early in 2014 Monju remains shut down and its future is uncertain. One proposal is to focus it on nuclear waste reduction, in line with JAEA research.

Public Opinion

A number of public opinion polls were taken in April and May 2011 following the Fukushima accident. Those in April showed around 50% supported the use of nuclear power at present or increased levels, but as the crisis dragged on the May polls showed a reduction in support to around 40% and a growth in opinion to over 40% of those wanting to decrease it. A steady 15% or so through May- June 2011 wanted it abolished. In March 2013, the proportion opting for increase or status quo had dropped to 22%, while 53% wanted to decrease it and 20% wanted to abolish it.

Uranium supply

Japan has no indigenous uranium. Its 2011 requirements of 8195 tU will be met from Australia (about one third), Canada, Kazakhstan and elsewhere.

Increasingly, Japanese companies are taking equity in overseas uranium projects.

In Kazakhstan, Itochu agreed to purchase 3000 tU from Kazatomprom over ten years in 2006, and in connection with this Japanese finance contributed to developing the West Mynkuduk deposit in Kazakhstan (giving Sumitomo 25%, Kansai 10%). In 2007 Japanese interests led by Marubeni and Tepco bought 40% of the Kharasan mine project in Kazakhstan and will take 2000 tU/yr of its production. A further agreement on uranium supply and Japanese help in upgrading the Ulba fuel fabrication plant was signed in May 2008. In March 2009 three Japanese companies – Kansai, Sumitomo and Nuclear Fuel Industries – signed an agreement with Kazatomprom on uranium processing for Kansai plants.

In Uzbekistan, a Japan-Uzbek intergovernmental agreement in September 2006 was aimed at financing Uzbek uranium development and in October 2007 Itochu Corporation agreed with Navoi Mining & Metallurgy Combinat (NMMC) to develop technology to mine and mill the black shales, particularly the Rudnoye deposit, and to take about 300 tU/yr from 2007. Then in February 2011 Itochu signed a 10-year "large-scale" uranium purchase agreement with NMMC.

In Australia, Mitsui joined Uranium One's Honeymoon mine project in 2008 as a 49% joint venture partner. Then early in 2009, a 20% share in Uranium One Inc was taken by three Japanese companies, giving overall 59% Japanese equity in Honeymoon. In July 2008 Mitsubishi agreed to buy 30% of West Australia's Kintyre project for US$ 495 million, with Cameco (70%). In February 2009 Mega Uranium sold 35% of the Lake Maitland project to the Itochu Corporation (10% of Japanese share) and Japan Australia Uranium Resources Development Co. Ltd. (JAURD), acting on behalf of Kansai Electric Power Company (50%), Kyushu Electric Power Company (25%) and Shikoku Electric Power Company (15%) for US$ 49 million.

In Namibia, Itochu Corporatioon bought a 15% stake in Kalahari Minerals, in March 2010, for US$ 92 million. Kalahari owns 41% of Extract Resources, which is developing the Husab project. Then in July 2010 Itochu bought a 10.3% direct stake in Extract for US$ 153 million, mostly from Polo Resources, giving it 16.43% overall in the project.

Fuel cycle – front end

Japan has been progressively developing a complete domestic nuclear fuel cycle industry, based on imported uranium.

JAEA operated a small uranium refining and conversion plant, as well as a small centrifuge enrichment demonstration plant, at Ningyo Toge, Okayama prefecture, but these facilities are now decommissioned.

While most enrichment services are still imported, Japan Nuclear Fuel Ltd (JNFL) operates a commercial enrichment plant at Rokkasho – RE2A. This began operation in 1997 using indigenous technology and had seven cascades each of 150,000 SWU/yr, though only one had been operating. The plant is being equipped with a new centrifuge design, and 37,500 SWU/yr came fully on line in March 2012 after a 15-month break in operations. A further 37,500/yr SWU came on line in May 2013, and in mid 2014, 1.05 million SWU was operational. The design capacity of 1.5 million SWU/yr is expected to be reached about 2022. JNFL's main shareholders are the power utilities.

A new enrichment plant using Russian centrifuge technology is planned under an agreement between Rosatom and Toshiba, the location not announced.

Japan has 6400 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 Japanse utilities who own it.

At Tokai-mura, in Ibaraki prefecture north of Tokyo, Mitsubishi Nuclear Fuel Co Ltd operates a 440 tU/yr fuel fabrication facility, which started up in 1972 and has had majority shareholding by Mitsubishi Materials Corporation (MMC). In April 2009 this was restructured as a comprehensive nuclear fuel fabrication company to supply Japanese customers with uranium fuel assemblies for pressurized water reactors (PWR), boiling water reactors (BWR) and high-temperature gas-cooled reactors (HTR), as well as MOX fuel assemblies. It will also provide related services, including uranium reconversion from 2014. The new shareholdings are MHI 35%, MMC 30%, Areva 30% and Mitsubishi Corporation 5%, with capital of JPY 11.4 billion. In October it was announced that a new 600 t/yr plant using Areva's dry process technology would be built by the company. As part of the new partnership with Areva, MHI and Areva are preparing to build a dedicated nuclear fuel fabrication facility in the USA, with each having 50% equity.

At Kumatori and Tokai, Nuclear Fuel Industries (NFI) operates two fuel fabrication plants which have operated from 1976 and 1980 respectively. Kumatori (284 tU/yr) produces PWR and BWR fuel, Tokai (200 tU/yr capacity) is also set up to produce HTR and FNR fuel. NFI is also involved in a project to design MOX fuel for Areva to manufacture for Japanese power plants. In 2009 Westinghouse bought the 52% share of NFI owned by Furukawa and Sumitomo for $100 million.

JAEA has some experimental mixed oxide (MOX) fuel fabrication facilities at Tokai for both the Fugen ATR and the FBR program, with capacity about 10 t/yr for each. See also MOX section below.

Fuel Cycle – back end

For energy security reasons, and notwithstanding the low price of uranium for many years, Japanese policy since 1956 has been to maximise the utilisation of imported uranium, extracting an extra 25-30% of energy from nuclear fuel by recycling the unburned uranium and plutonium as mixed-oxide fuel (MOX). The AEC reaffirmed this in 2005.

At the end of 2013 Japan’s ten power companies were reported to have 55,610 used fuel assemblies, 13,236 tonnes, stored at 18 nuclear power plants. These occupied 55% of available pool storage space.

At Tokai, JNC (now JAEA) has operated a 90 t/yr pilot reprocessing plant using Purex technology which treated 1117 tonnes of used fuel* between 1977 and its final batch early in 2006. It processed 5401 used fuel assemblies, with a Pu-U mixed product as well as reprocessed uranium. Since 2006 the plant has focused on R&D, including reprocessing of MOX fuel from the Fugen ATR reactor. In the 2013 OECD Nuclear Energy Agency data publication it is listed as having 40 t/yr MOX reprocessing capacity. In September 2014 JAEA announced that it would close down the whole facility rather than spend JPY 100 billion ($915 million) to upgrade it to new safety standards.

* This comprised 88 tonnes of fuel from the Fugen ATR, 644 tonnes of boiling water reactor fuel, 376 tonnes of pressurized water reactor fuel and 9 tonnes of fuel from the Japan Power Demonstration Reactor (JPDR).

JAEA operates spent fuel storage facilities at Tokai containing 110 tonnes of fuel in 2014, and was proposing a further one. It has also operated a pilot high-level waste (HLW) vitrification plant at Tokai since 1995. Tokai is the main site of JAEA's R&D on HLW treatment and disposal.

Until a full-scale plant was ready in Japan, the reprocessing of used fuel has been largely undertaken in Europe by BNFL and AREVA (4200t and 2900t respectively), with vitrified high-level wastes being returned to Japan for disposal. Areva's reprocessing finished in 2005, and commercial operation of JNFL's reprocessing plant at Rokkasho-mura was scheduled to start in 2008 (now 2014). Used fuel has been accumulating there since 1999 in anticipation of its full-scale operation (shipments to Europe finished in 1998). Japan at the end of 2012 had a total of 14,460 tonnes of used fuel in storage, mostly at reactors. In May 2014 JNFL had 2951 tonnes of used fuel in storage at Rokkasho, with capacity of 3000 tonnes.

Reprocessing involves the conventional Purex process, but Toshiba is developing a hybrid technology using this as stage 1 to separate most uranium, followed by an electrometallurgical process to give two streams: actinides (plutonium and minor actinides) as fast reactor fuel, and fission products for disposal.

In April 2012 the government announced a full review of nuclear fuel cycle options, considering both economic and other criteria. The review committee started by considering technical options: one scenario involved direct disposal of used reactor fuel, two scenarios involved this being reprocessed and with fuel materials recycled as mixed-oxide fuel. Two more scenarios looked at the use of fast reactors and fast breeder reactors. A review of policy options baed on these then followed. Finally, these were combined with the addition of a time axis with mid-to-long term scenarios. This review quantifies the amount of plutonium and used fuel generated by each option as well as looking at broader impacts such as energy security, the international perspective, and the impacts of the changes resulting from each of the potential policies.

Meanwhile the AEC fuel cycle subcommittee has updated cost estimates for different used fuel options considering both 20% and 35% nuclear contributions to electricity in 2030. In each case reprocessing and recycle of used fuel is economically much better – by about 20% – than direct disposal.

In June 2012 the AEC brought all this together focused on three options to 2030, and sent them to the Energy & Environment Council (Enecan) along with a recommendation that any R&D on fast reactors should continue with international cooperation and as a means of waste treatment.

  • Option 1: if there is no new nuclear plant construction and nuclear share declines to zero by 2030, direct underground disposal of all used fuel is appropriate. Monju should be decommissioned.
  • Option 2: if reliance on nuclear power is reduced to 15% in 2030, both reprocessing and direct disposal are appropriate. Monju should be run for five years, but plans for a demonstration commercial FBR cancelled.
  • Option 3: if nuclear power retains a 20-25% share in 2030, Rokkasho plant should operate fully (and maybe be replicated) and there could be some direct disposal, while Monju runs for 5 or 10 years and paves the way for a successor.

Enecan in mid-September 2012 confirmed that reprocessing would continue. It was abolished later in the year, and METI’s Advisory Committee for National Resources and Energy became responsible for such energy plans.

Rokkasho complex – reprocessing and wastes

In 1984, the Federation of Electric Power Companies (FEPC) applied to the Rokkasho-mura village and Aomori prefecture for permission to construct a major complex including uranium enrichment plant, low-level waste (LLW) storage centre, HLW (used fuel) storage centre, and a reprocessing plant. Currently JNFL operates both LLW and HLW storage facilities there at the north end of Honshu (main island), while its 800 t/yr reprocessing plant is under construction and is being commissioned. The used fuel storage capacity is 20,400 tonnes.

In October 2004 the Atomic Energy Commission advisory group decided by a large majority (30 to 2) to proceed with the final commissioning and commercial operation of JNFL's 800 t/yr Rokkasho-mura reprocessing plant, costing some JPY 2.4 trillion (US$ 20 billion). The Commission rejected the alternative of moving to direct disposal of spent fuel, as in the USA. This was seen as a major confirmation of the joint industry-government formulation of nuclear policy for the next several decades.*

* A 2004 government study showed that projected over the next 60 years it would be significantly more expensive to reprocess – at 1.6 yen/kWh, compared with 0.9 - 1.1 yen for direct disposal. This translates to 5.2 yen/kWh overall generating cost compared with 4.5 - 4.7 yen, without considering the implications of sunk investment in the new plant, or apparently the increased price of uranium since 2004.

In November 2011 the AEC released results of a further study on the same matter. At the reference 3% discount rate, direct disposal after interim storage would cost about JPY 1 per kWh, while immediate reprocessing of all Japanese spent fuel would cost JPY 1.98 per kWh. Storage for 20 years followed by reprocessing would cost JPY 1.39 per kWh.

The Rokkasho-mura reprocessing plant was due to start commercial operation in November 2008, following a 28 month test phase plus some delay at the end of 13 years construction. The test phase treated 197 t in PWR fuel and 134 t in BWR fuel in four cycles to January 2008. Based on previous figures, this would have yielded about 1.8 tonnes of fissile plutonium (in reactor-grade material). The intended start date was then moved to October 2013, the five-year delay being due to problems in the locally-designed vitrification plant for HLW at the end of the line (see below). The main plant is based on Areva's La Hague technology, and in late 2007 the twenty-year cooperation agreement with Areva was extended and related specifically to Global Nuclear Energy partnership (GNEP) goals. The modified PUREX process now employed leaves some uranium with the plutonium product – it is a 50:50 mix, so there is no separated plutonium at any time, alleviating concerns about potential misuse.

Active testing at the new vitrification plant attached to the Rokkasho reprocessing plant commenced in November 2007, with separated high-level wastes being combined with borosilicate glass. The plant takes wastes after uranium and plutonium are recovered from used fuel for recycle, leaving 3% of the used fuel including minor actinides as high-level radioactive waste. However, the furnaces (developed at Tokai, rather than being part of the French technology) proved unable to cope with impurities in the wastes, and commissioning was repeatedly delayed. Finally in 2010 JNFL decided to redesign the unit to better control temperature of the molten glass. One of the two rebuilt furnaces was tested successfully in July 2012, producing ten batches of vitrified HLW, and a second test run successfully produced 33 canisters by mid January 2013, confirming its 70 litres/hour HLW rate. The other system was tested similarly by May 2013, producing 25 logs of vitrified HLW, each from 70 litres of liquid HLW. JNFL was ready to commission the plant in October 2013, but had to await NRA inspections, following new NRA fuel cycle facility regulations published in November 2013. NRA found no problem with the plant in respect to earthquake and tsunami issues, but its overall safety review is taking much longer than envisaged.

The new target start-up date was October 2014, and JNFL intended to process 282 BWR fuel assemblies and 73 PWR ones (48 t and 32 t respectively) by March 2015. From April 2015 to March 2016 (FY 2015) the target was 1129 BWR assemblies (192 t) and 291 PWR assemblies (128 t). However, in November 2014 JNFL announced that due to the slow NRA safety checks, the plant would not start operation until March 2016, and not reach full capacity until 2019.

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. Eventually at 800 t/yr it will produce about 4 tonnes of fissile plutonium per year, enough for about 80 tonnes of MOX fuel.

The Rokkasho facility has storage capacity for 2880 canisters of vitrified HLW. At the end of 2012 it had 1414 canisters, 1310 of these from La Hague.

In December 2013 new NRA regulations came into effect. JNFL filed requests in January 2014 for safety reviews of the reprocessing plant; the J-MOX fuel fabrication plant (annual capacity of 130 tonnes); a uranium enrichment plant (1,050 SWU/yr capacity); and for a waste storage facility – all at Rokkasho. The 2013 NRA regulations specified that interim storage of spent fuel should be in dry storage with convection cooling. This applies principally to Mutsu.

Mutsu storage

In 2010 Recyclable-Fuel Storage Co (Tepco 80%, Japco 20%) obtained approval to construct a facility at Mutsu in the northern Aomori prefecture to store used fuel from Tepco and Japco nuclear plants for some 50 years before reprocessing at the Japan Nuclear Fuel plant in that region. Initial capacity is 3000 tonnes, in dry casks, and a further stage after 10-15 years will add 2000 t capacity. NISA approved this in August 2010. Construction started but was suspended for a year in March 2011, then resumed in March 2012. It was completed in October 2013, but awaits full NRA review according to the new regulations and is expected to come into service in 2016. About 70% of the JPY 100 billion cost is reported to be the casks.

Mixed-oxide fuel (MOX)

The Federation of Electric Power Companies has said that nine member companies will use plutonium as mixed oxide (MOX) fuel in 16-18 reactors from 2015 under the "pluthermal" program. About 6 tonnes of fissile plutonium per year (in about 9 tonnes of reactor-grade Pu) is expected to be loaded into power reactors. Meanwhile MOX fuel fabricated in Europe from some 40 tonnes of separated reactor-grade plutonium (25.6t Puf) from Japanese used fuel can be used. However, local concerns about MOX fuel use has slowed implementation of the 1994 "pluthermal" program, and not until late 2009 was there a commercial Japanese reactor running with MOX.

By end of January 2010 the Nuclear & Industrial Safety Agency (NISA) on behalf of the Ministry (METI) had approved the use of MOX fuel in ten reactors, including: Takahama 3 & 4, Fukishima I-3, Kashiwazaki Kariwa 3, Genkai 3, Hamaoka 4, Onagawa 3 and Shimane-2. This was expected to occur progressively to 2012, after modifications to the reactors to take a one quarter or one third core of MOX. NRA permission for MOX use in Tomari 3 is pending.

Two prefectural governments – Fukushima and Niigata – moved to defer the use of MOX fuel at reactors within those prefectures, forcing TEPCO and Kansai to suspend or reschedule their planned use there. In 2008 the Shizuoka prefecture accepted Chubu's plans to use MOX in its Hamaoka-4 plant. Fukui prefecture accepted Kansai's planned use of MOX at Takahama 3 and 4 from 2010, and Hokkaido accepted Hokkaido Electric Power's use of MOX at Tomari-3, making a total of 11 reactors allowed to use it. Early in 2010 Fukushima prefecture agreed to MOX use in TEPCO's Fukushima I-3 reactor, and in July NISA confirmed this approval.

So far, Japan has received five shipments containing over two tonnes of its (reactor-grade) plutonium from Europe. The first shipment, in 1992, was simply plutonium oxide and earmarked for use in the Monju prototype FBR.

Subsequent shipments have been in the form of MOX fuel for light water reactors. The first MOX shipment was in 1999. Part of this shipment from BNFL and intended for use in Kansai Electric Power Co's Takahama plant was found to contain falsified quality control data, so that material was returned to the UK in 2002. The balance was for Tepco's Fukishima I-3. The second MOX shipment in 2001 consisted of fuel from BNFL for use in TEPCO's Kashiwazaki-Kariwa 3 reactor. The third MOX shipment was fuel for Chubu's Hamaoka BWR, Shikoku's Ikata PWR and Kyushu's Genkai PWR, and arrived from France in May 2009. The fourth MOX shipment in 2010 from France contained 12 assemblies for Kansai's Takahama 4 and 20 for the second load at Genkai 3. The shipment which arrived in June 2013 was for Kansai’s Takahama 3 plant.

In November 2009 Kyushu Electric Power started using MOX in its Genkai 3 reactor. During a scheduled refuelling outage the company replaced about one-third of the 193 PWR fuel assemblies, 16 of them comprising MOX fuel. Shikoku Electric Power Co started Ikata-3 with some MOX fuel in March 2010, and Tepco started up Fukishima-Daiichi 3 BWR with MOX fuel in September 2010. Kansai started using MOX in its Takahama 3 PWR in January 2011, but in mid 2011 deferred its use in unit 4.

For its new Ohma ABWR plant, designed to run on a full MOX core, J-Power has signed a contract with Areva to supply the first three years' fuel, fabricated from Japanese plutonium separated in France. Areva also has MOX fabrication contracts with Chubu, Kyushu, Shikoku and Kansai.

Meanwhile, Japan's plutonium stocks increase, with separated reactor-grade plutonium (about 65% fissile) stored and awaiting use in MOX fuel. At the end of 2013 there was 10.8 tonnes of plutonium stored domestically (7.3 t fissile), plus 36.3 t overseas (24.1 t fissile) – 45% in France and 55% in the UK. During 2009 1.345 t Pu was loaded into Japanese reactors in MOX fuel and 1.72 t was added to storage. It was estimated that 5.5 to 6.5 tonnes of Puf would be used each year from about 2012, though in 2011 only 640 kg was loaded.

J-MOX plant

In April 2005 the Aomori prefecture approved construction of the JNFL's J-MOX plant at Rokkasho, adjacent to the reprocessing plant. The Governor urged the Federation of Electric Power Companies "to step up their efforts towards realisation of the MOX-use program." The approval was seen as a significant step forward in closing the fuel cycle in Japan, and was strongly supported by the federal government, Atomic Energy Commission and utilities. JNFL has applied for two of the four licences needed to build and operate the 130 t/yr plant. Construction of the plant started in October 2010 after a three-year delay due to revision of seismic criteria. Operation of J-MOX is now expected about October 2017, and the cost has escalated to JPY 210 billion (US$ 2.05 billion). It will produce MOX with 4 to 9% plutonium.

In November 2006 Shikoku Electric Power contracted with Mitsubishi to manufacture 21 MOX fuel assemblies for its Ikata nuclear plant using 600 kg of reactor-grade plutonium. The plutonium had been recovered by Areva at La Hague from Shikoku's used fuel and the MOX was fabricated at Areva's Melox plant in France and shipped to Japan in March 2009.

With the delay in construction of the J-MOX plant, several other utilities have sought MOX fuel supplies from Areva in France.

Once MOX fuel is fully in routine use in Japan, it is expected that the Japanese stockpile of separated plutonium in Europe will be used up in about 15 years, with demand being about 6 tonnes per year of fissile plutonium and output from Rokkasho only 4 tonnes Puf.

METI approved construction a used fuel storage facility for Tepco and Japco in Mutsu, at the same time as approving J-MOX. Government approval for both followed in May

High-Level Wastes

In 1995, Japan's first high-level waste (HLW) interim storage facility opened in Rokkasho-mura – the Vitrified Waste Storage Centre. The first shipment of vitrified HLW from Europe (from the reprocessing of Japanese fuel) also arrived in that year. The last of twelve shipments from France was in 2007, making a total of 1310 canisters. Shipments from UK started in 2010, with 1850 canisters to go in about 11 shipments. These include an equivalent amount of HLW to avoid the need to transport greater amounts of low-level wastes (LLW). The first shipment from UK arrived in March 2010, the fourth in April 2014.

In 2005 Tepco and JAPC announced that a Recyclable Fuel Storage Centre would be established in Mutsu, with 5000 t capacity, to provide interim storage for up to 50 years before used fuel is reprocessed. See fuller description above.

In May 2000, the Japanese parliament (the Diet) passed the Law on Final Disposal of Specified Radioactive Waste (the "Final Disposal Law") which mandates deep geological disposal of high-level waste (defined as only vitrified waste from reprocessing spent reactor fuel). In line with this, the Nuclear Waste Management Organisation (NUMO) was set up in October 2000 by the private sector to progress plans for disposal, including site selection, demonstration of technology there, licensing, construction, operation, monitored retrievable storage for 50 years and closure of the repository. Some 40,000 canisters of vitrified HLW are envisaged by 2020, needing disposal – all the arisings from the Japanese nuclear plants until then.

NUMO began an open solicitation process to find a site, with a view to shortlisting those that were proffered and potentially suitable.* The promising ones would be subject to detailed investigation from 2012. A third phase to 2030 would end with site selection. However, the government decided to become more involved in the process, and in October 2013 METI’s Agency for Natural Resources and Energy (ANRE) established a working group to re-evaluate geological disposal technology and developments since 2000, taking account of NUMO’s work. It reported in April 2014 that potential repository sites were available across Japan. The minister said in 2013 that "The government will play an active role in choosing a permanent place. We will abandon the current system of waiting for volunteers to raise their hands." In April 2014, HLW disposal was part of the new Basic Energy Plan, which included facilitating construction and use of new intermediate and dry storage facilities.

* In mid-2007 a supplementary waste disposal bill was passed which said that final disposal is the most important issue in steadily carrying out nuclear policy. It called for the government to take the initiative in helping the public nationally to understand the matter by promoting safety and regional development, in order to get the final disposal site chosen with certainty and without delay. It also called for improvement in disposal technology in cooperation with other countries, revising the safety regulations as necessary, and making efforts to recover public trust by, for example, establishing a more effective inspection system to prevent the recurrence of data falsifications and cover-ups.

Repository operation is expected from about 2035, and the JPY 3500 billion (US$ 35 billion) cost of it will be met by funds accumulated at 0.2 yen/kWh from electricity utilities (and hence their customers) and paid to NUMO. This sum excludes any financial compensation paid by the government to local communities.

The technical aspects of Japan's HLW disposal concept is based on two decades' work under JAEA involving generic evaluation of repository requirements in Japan's geology. Since 2000 the Horonobe Underground Research Centre on Hokkaido has been investigating sedimentary rocks about 500m deep, and in November 2005 construction of the underground shafts and a 760-metre gallery was launched. This is a seismically stable area of Japan. JAEA runs the Tona Geoscience Centre at Toki, in Gifu prefecture, and is building a similar facility, the Mizunami Underground Research Laboratory (MIU) also in Gifu prefecture, in igneous rock about 1000m deep. By the end of 2012 two shafts were 500 m deep and the first research and access tunnels were dug.

The basic repository concept involves sealing about 20 HLW canisters in a massive steel cask or overpack and surrounding this by bentonite clay. NUMO has built design options on this including those allowing inspection and retrieval over long periods. In particular the Cavern Retrievable (CARE) concept has emerged, involving two distinct stages: ventilated underground caverns with the wastes in overpacks (hence shielded) fully accessible, followed by backfilling and sealing the caverns after 300 years or so. The initial institutional control period allows radiological decay of the wastes so that thermal load is much reduced by stage 2 and hence the concept allows a much higher density of wastes than other disposal concepts.

The CARE concept can be adapted for spent fuel, the cask then being similar to shipping casks for such except that a layer of shielding required due to higher thermal and radiation output could be removable before the cavern is backfilled and sealed. However, for spent fuel retrieval would be likely rather than merely possible, since it represents a significant potential fuel resource (via reprocessing), whereas vitrified HLW does not. Also spent fuel would require ease of access due to the need for safeguards inspections. Eventual backfill could include depleted uranium if that is then considered a waste.

In 2004 METI estimated the costs of reprocessing spent fuel, recycling its fissile material and management of all wastes over 80 years from 2005. METI's Electricity Industry Committee undertook the study, focused on reprocessing and MOX fuel fabrication including the decommissioning of those facilities (but excluding decommissioning of power reactors). Total costs over 80 years amount to some JPY 19 trillion, contributing almost one yen (US 0.9 cents) per kilowatt-hour at 3% discount rate. About one third of these costs would still be incurred in a once-through fuel cycle, along with increased high-level waste disposal costs and increased uranium fuel supply costs. Japan's policy however is based on energy security rather than purely economic criteria.

Funding arrangements for HLW were changed in October 2005 under the new Back-end Law which set up the Radioactive Waste Management Funding and Research Centre (RWMC) as the independent funds management body. All reserves held by utilities were to be transferred to it and companies then refunded as required for reprocessing.

Low- and Intermediate-level wastes

JNFL operates a large LLW storage facility at Rokkasho. METI, with JNFL and FEPC, is seeking permission from the Aomori prefecture to build further low-level waste storage capacity there, adjacent to the reprocessing plant. In particular this will be for LLW and what is internationally designated as ILW returned from France from 2013. NISA recommended approval early in 2012 to increase capacity to 2000 drums (200-litre).


The Japan Power Demonstration Reactor (JPDR) decommissioning program, following its closure in 1976, established the necessary techniques for the decommissioning of commercial power reactors by the Japan Atomic Energy Research Institute (JAERI). Phase I of the program started in 1981 to develop a set of techniques and Phase II was actual dismantling of JPDR over 1986-92.

The original Tokai 1 power station, a British Magnox reactor which started up at the end of 1965 and closed down in March 1998, is being decommissioned over 20 years, the first ten as "safe storage" to allow radioactivity to decay. Phase 1 (to 2006) comprised preliminary work, in Phase 2 (to 2011) the steam generators and turbines are being removed, and in Phase 3 (to 2018) the reactor will be dismantled, the buildings demolished and the site left ready for re-use. All radioactive wastes will be classified as low-level (LLW), albeit in three categories, and will be buried – the 1% of level I wastes 50-100 metres deep. The total cost is expected to be JPY 93 billion – JPY 35 billion for dismantling and JPY 58 billion for waste treatment including the graphite moderator (which escalates the cost significantly).

Fugen ATR (148 MWe, started up in 1978) closed in March 2003, and JAEA plans to decommission it and demolish to clear the site by 2029, at a total cost of about JPY 70 billion, including waste treatment and disposal. Plans for this were approved in February 2008.

Chubu's Hamaoka 1&2, earlier closed for safety-related upgrades, remained shut down following the 2007 earthquake, were written off, and are now being decommissioned.

In March 2011 units 1-4 of the Fukushima Daiichi plant (2719 MWe net) were seriously damaged in a major accident, and are written off to be decommissioned. Units 5&6 were basically undamaged, but are written off from January 2014 to appease public opinion. Tepco established an internal entity, the Fukushima Daiichi Decontamination & Decommissioning Engineering Company, to focus on measures for decommissioning units 1-6 and dealing with contaminated water. The company commenced operations in April 2014.

Japanese reactors being decommissioned

Reactor Type Net capacity MWe Utility Commercial operation
JPDR BWR 12 JAERI 2/65 - 3/76
Tokai 1 Magnox 137 Japco 7/66 - 3/98
Fugen ATR 148 JNC 3/79 - 3/03
Hamaoka 1 BWR 515 Chubu 3/76 - 2/09
Hamaoka 2 BWR 806 Chubu 11/78 - 2/09
Fukushima I-1 BWR 439 Tepco 3/71 - 3/11
Fukushima I-2 BWR 760 Tepco 7/74 - 3/11
Fukushima I-3 BWR 760 Tepco 3/76 - 3/11
Fukushima I-4 BWR 760 Tepco 10/78 - 3/11
Fukushima I-5 BWR 760 Tepco 4/78 - 3/11
Fukushima I-6 BWR 1067 Tepco 10/79 - 3/11

JAEA has been responsible for research on reactor decommissioning. However, in August 2013 an International Research Institute for Nuclear Decommissioning (IRID) was set up in Japan by JAEA, Japanese utilities and reactor vendors, with a focus on Fukushima 1-4.

In August 2014 the Nuclear Damage Compensation and Decommissioning Facilitation Corporation (NDF) was set up by government as a planning body with management support for R&D projects, taking over IRID’s planning role. It will work closely with IRID, whose focus now is on developing mid- and long-term decommissioning technologies. NDF will also work closely with Tepco Fukushima Daiichi D&D Engineering Co. which has responsibility for operating the actual decommissioning work there. The NDF will be the main body interacting with government (METI) to implement policy. 

Research & Development

The Japan Atomic Energy Research Institute (JAERI) and the Atomic Fuel Corporation were set up in 1956. The latter was renamed PNC in 1967 and reconstituted as Japan Nuclear Cycle Development Institute (JNC) in 1998. A merger of JNC and JAERI in 2005 created the Japan Atomic Energy Agency (JAEA) under the Ministry of Education, Culture, Sports, Science & Technology (MEXT). JAEA is now a major integrated nuclear R&D organization, with 4400 employees at ten facilities and annual budget of ¥161 billion (US$ 1.7 billion).

JAEA runs a number of research reactors including JRR-3, a 20 MW unit supporting neutron beam experiments, and JRR-4, a 3.5 MW reactor used for medical irradiation, activation analysis and training. The Nuclear Safety Research Reactor (NSRR) is used for that purpose.

JAEA's Japan Materials Testing Reactor (JMTR) at the Oarai R&D Centre was refurbished for 2011 resumption of operation, to produce some radioisotopes, notably Mo-99, as well as enable basic research on LWR fuel and materials, and other applications. The JMTR was initially converted from 93% HEU fuel to 45% enriched fuel in 1991, and then to 19.8% enriched fuel in 1994.


At the end of 1998 JAERI's (now JAEA's) small prototype gas cooled reactor, the 30 MWt High Temperature Engineering Test Reactor (HTTR) started up at the Oarai Nuclear Hydrogen and Heat Application Research Centre near Tokyo. This was Japan's first graphite-moderated and helium-cooled reactor. It runs at 850°C and in 2004 achieved 950°C, which will allow its application to chemical processes such as thermochemical production of hydrogen. Its fuel is ceramic-coated particles incorporated into hexagonal graphite prisms, giving it a high level of inherent safety. It is designed to establish a basis for the commercialisation of second-generation helium-cooled plants running at high temperatures for either industrial applications or to drive direct cycle gas turbines. By 2015 an iodine-sulfur plant producing 1000 m3/hr of hydrogen is expected to be linked to the HTTR to confirm the performance of an integrated production system. However, HTTR was shut down in February 2011 and remained closed pending new post-Fukushima regulations in July 2013. In November 2014 JAEA announced that it had applied to NRA for inspection prior to restart. It is expected to restart in 2015.

In 2014 the government included HTR research in its draft basic energy plan, and in May the Nuclear Science and Technology Committee of MEXT established a working group to evaluate the current R&D situation of HTRs and discuss their future direction, based on domestic and foreign needs.

JAEA has a major agreement with Kazakhstan’s National Nuclear Centre relating to the design, construction and operation of an HTR of about 50 MW at Kurchatov city. See also Kazakhstan paper. It also has HTR research agreements with South Korea and China.

JAEA is proposing to develop a 100 MW demonstration HTR at Abu Dhabi in the UAE, with Emirates Nuclear Energy Corp (ENEC), and expedited by the Japan Engineers Federation (JEF). 

Under a 2007 cooperation agreement with Indonesia’s National Atomic Energy Agency (BATAN), JAEA in 2014 agreed to include research and development of HTRs. Prior to the introduction of commercial reactors in Indonesia, BATAN plans to build a test and demonstration HTR of about 3-10 MWe.


The Reduced-Moderation Water Reactor (RMWR) being developed in Japan is a light water reactor, essentially as used today, with the fuel packed in more tightly to reduce the moderating effect of the water. Considering the BWR variant (resource-renewable BWR – RBWR), only the fuel assemblies and control rods are different. In particular, the fuel assemblies are much shorter, so that they can still be cooled adequately. Ideally they are hexagonal, with Y-shaped control rods. The reduced moderation means that more fissile plutonium is produced and the breeding ratio is around 1 (instead of about 0.6), and much more of the U-238 is converted to Pu-239 and then burned than in a conventional reactor. Burn-up is about 45 GWd/t, with a long cycle. Initial seed (all??) MOX fuel needs to have about 10% Pu. The void reactivity is negative, as in conventional LWR. A Hitachi RBWR design based on the ABWR-II has the central part of each fuel assembly (about 80% of it) with MOX fuel rods and the periphery uranium oxide. In the MOX part, minor actinides are burned as well as recycled plutonium. Power is quoted at 1346 MWe. Little has been heard of the project for several years.

The main rationale for RMWRs is extending the world's uranium resource and providing a bridge to widespread use of fast neutron reactors. Recycled plutonium should be used preferentially in RMWRs rather than as MOX in conventional LWRs, and multiple recycling of plutonium is possible. JAERI started the research on RMWRs in 1997 and then collaborated in the conceptual design study with the Japan Atomic Power Company (JAPCO) in 1998. Hitachi has also been closely involved.

A new reprocessing technology is part of the RMWR concept. This is the fluoride volatility process, developed in 1980s, and is coupled with solvent extraction for plutonium to give Hitachi's Fluorex process. In this, 90-92% of the uranium in the used fuel is volatalised as UF6, then purified for enrichment or storage. The residual is put through a Purex circuit which separates fission products and minor actinides as HLW, leaving the unseparated U-Pu mix (about 4:1) to be made into MOX fuel.


Among several critical assemblies, JAEA has operated the Fast Critical Assembly (FCA) at Tokai since 1967 to study the neutronic characteristics of fast reactors. It has been used for both Joyo and Monju development. In the course of this the facility has accumulated some hundreds of kilograms of separated plutonium (reported as being weapons-grade) and high-enriched uranium. In March 2014 it was agreed to send all of this to the USA for disposal or downblending and civil use respectively under the auspices of the Global Threat Reduction Initiative (GTRI) set up by the USA in 2004. The FCA itself will be converted to use low-enriched uranium and reassigned to transmutation and disposition of wastes.

In May 2014 Japan committed to support the development of the French Astrid fast reactor project, and in August 2014 JAEA, Mitsubishi Heavy Industries and Mitsubishi FBR Systems concluded an agreement with the French Atomic Energy Commission (CEA) and Areva to progress cooperation on Astrid. Astrid is envisaged as a 600 MWe prototype of a commercial series of 1500 MWe sodium-cooled fast reactors which is likely to be deployed from about 2050 to utilise the abundant depleted uranium available by then and also burn the plutonium in used MOX fuel. Astrid will have high fuel burnup, including minor actinides in the fuel elements, and great flexibility in breeding ratios. Astrid arises from a 2006 French government commission to the CEA to develop a fast neutron reactor which is essentially a Generation IV version of the sodium-cooled type which already has 45 reactor-years' operational experience in France. In mid-2009 Astrid (Advanced Sodium Technological Reactor for Industrial Demonstration), was given high priority in R&D on account of its actinide-burning potential. The CEA sought partnerships with Japan and China to develop it.

Thorium and MSRs

Japan's Research Institute for Applied Sciences based in Kyoto with Chubu Electric at Hamaoka are developing thorium-fueled molten salt reactor technology, from 2013.

Regulation and safety

The Atomic Energy Commission (AEC) was set up in 1956 under the Science & Technology Agency (STA) but has been part of the Cabinet Office since 2001. It was a senior policy body except for a period in 2011 to 2012, though in 2001 it was reduced to an advisory role. A government panel in 2013 recommended that it become simply a committee focused on such issues as the peaceful uses of nuclear energy, nuclear non-proliferation, and the treatment and disposal of radioactive waste. The panel said that it should no longer be involved with formulating nuclear policy or estimating funding requirements, but should remain within the Cabinet Office. In 2014 parliament reduced its role to the supervision of Japan’s plutonium and advising on radioactive wastes.

The former Nuclear & Industrial Safety Agency (NISA) within the Ministry of Economy Trade & Industry (METI, the successor of MITI) was responsible for nuclear power regulation, licensing and safety. It conducted regular inspections of safety-related aspects of all power plants.

In mid-2011, following the Fukushima accident, the government established a new and more independent Nuclear Regulation Authority (NRA) under the Environment Ministry. This commenced in September 2012 and combined the roles of NISA and NSC, and also the monitoring functions of the Education & Science Ministry (MEXT). The four commissioners and chairman were appointed in February 2013. It started with a staff of 473, nearly three quarters of whom were from NISA, and a budget of ¥50 billion/yr (about $600 million). It is modelled on the US Nuclear Regulatory Commission. The first task of the NRA is decide on reactor restarts (see earlier section). In July 2013 NRA published two sets of regulations with regard to detailed design of nuclear power plant systems and severe accident management procedures.

Regulations relating to the fuel cycle and research reactors including Monju took effect in mid-December 2013. The new regulations apply to two used fuel reprocessing plants – JNFL’s Rokkasho commercial plant and the older JAEA facility at Tokai (shut down since 2007); seven fuel fabrication facilities, including JNFL’s partially completed mixed-oxide fuel facility; Recyclable-Fuel Storage Co.’s partially completed interim spent fuel storage facility at Mutsu; four waste storage facilities; 22 research reactors; and 15 large and 196 small facilities using nuclear fuel for research. They require facility operators to assume stricter earthquake and tsunami standards in line with new safety guidelines for nuclear reactors implemented in July, and they require improved safety measures to prevent hydrogen explosions and criticalities during emergencies.

Also coming under the remit of the Ministry of the Environment is a new 5-member Nuclear Safety Investigation Commission (NSIC), which replaced the Nuclear Safety Commission (NSC) – a senior government body set up in 1978 under the Atomic Energy Basic Law and responsible for formulating policy, alongside the Atomic Energy Commission. NSIC will review the effectiveness of the NRA and be responsible for the investigation of nuclear accidents. The Environment Ministry already handles disposal of radiation-contaminated debris around the Fukushima Daiichi nuclear plant. The lower house of parliament (Diet) passed the enabling legislation in mid June 2012, with the support of all three main parties, and the upper house endorsed it a week later. The reform was implemented in September. Key issues will be addressed toward creating a stronger and more effective safety regulatory organization, with a plan to be issued by year end. As an expression of its determination to strengthen nuclear safety regulation Japan plans to receive an IAEA Integrated Regulatory Review Service mission later in 2012.

The Japan Nuclear Energy Safety Organisation (JNES) was set up in 2003 to inspect nuclear installations and nuclear reactor facilities and undertake safety analysis and evaluations of the design of nuclear installations and nuclear reactor facilities. It had 401 staff (as of October 2013, compared with 527 in NRA then) and functioned as technical support for NRA. The law that established NRA in September 2012 stipulated that JNES must be integrated into NRA, and in October 2013 NRA outlined provisions for the merger by March 2014, when 384 staff transferred. As well as the staff from both organisations, 81 will be added to boost capacity for inspections, making a total of over 1000. The merger substantially enhances the professional competence and experience base of NRA.

In December 2013 the NRA with its China and South Korean counterparts agreed to form a network to cooperate on nuclear safety and quickly exchange information in nuclear emergencies. In addition to exchanging information on nuclear accidents, the three countries will share standard information such as safety plans.

Following the Fukushima accident, the Energy and Environment Council Council (Enecan or EEC) was set up by the cabinet office in mid 2011 as the energy arm of the National Policy Unit, being chaired by that minister. The Atomic Energy Commission (AEC) and Central Environment Council apparently came under Enecan until it was abolished by the new government at the end of 2012.

The Science & Technology Agency was responsible for safety of test and research reactors, nuclear fuel facilities and radioactive waste management, as well as R&D, but its functions were taken over by NISA in 2001.

In June 2012 parliament amended the 1955 Atomic Energy Basic Law to stipulate that nuclear plant operators must prevent the release of radioactive materials at abnormal levels following severe accidents, and that the NRA is to formulate regulations to achieve this.

A new inspection system of nuclear facilities came into effect in 2009, following deliberations on the matter since November 2005. Under the new system, the number of nuclear power plants approved for operation over 40 years was expected to increase, starting with Tsuruga 1.

The Atomic Energy Society of Japan (AESJ) has a Committee for Investigation of Nuclear Safety.

Nuclear safeguards will remain with METI after the regulatory functions are removed.

Regulatory history

Well before the Fukushima accident, public support for nuclear power in Japan had been eroded since the 1990s due to a series of accidents and scandals. The accidents to 2011 were the 1996 sodium leak at the Monju FBR, a fire at the JNC waste bituminisation facility connected with its reprocessing plant at Tokai, and the 1999 criticality accident at a small fuel fabrication plant at Tokai. The criticality accident, which claimed two lives, happened as a result of workers following an unauthorised procedures manual. None of these accidents were in mainstream civil nuclear fuel cycle facilities. However, the 1999 accident did lead to safety improvements at nuclear power plants, notably the establishment of emergency off-site facilities (EOF) at all of them.

Following the 1999 Tokai criticality accident, electric power companies, along with enterprises involved with the nuclear industry established the Nuclear Safety Network (NSnet). The network's main activities were to enhance the safety culture of the nuclear industry, conduct peer reviews, and disseminate information about nuclear safety. In 2005 this was incorporated into the Japan Nuclear Technology Institute ( JANTI), as the Safety Culture Division. Peer reviews 'tailored to the corporate structure' are implemented periodically for members of NS net involve in the nuclear fuel cycle of Japan. JANTI's Operating Experience Analysis Division collects and analyses operating experience information that was previously handled by the Central Research Institute of Electric Power Industry (CRIEPI) Nuclear Information Center. The Safety Culture Division cooperates with US Institute of Nuclear Power Operations (INPO) and WANO.

Japan's former Nuclear Safety Commission (NSC) confirmed in April 2002 that using mixed oxide (MOX) fuel is safe, and that its use at up to 18 reactors by 2010 was supported. Senior members of the government have reaffirmed that the country's use of MOX "must happen", and that the government will initiate educational and information programs to win wider acceptance for it.

In 2002 a scandal erupted over the documentation of equipment inspections at Tepco's reactors, and extended to other plants. While the issues were not safety-related, the industry's reputation was sullied. Inspection of the shrouds and pumps around the core is the responsibility of the company, which in this case had contracted it out. In May 2002 questions emerged about data falsification and the significance of cracks in reactor shrouds (used to direct water flow in BWRs) and whether faults were reported to senior management. By May 2003 Tepco had shut down all its 17 reactors for inspections, and by the end of 2003 only seven had been restarted. Replacement power cost on average over 50% more than the 5.9 yen/kWh (5.5 cents US) nuclear generation cost. Tepco eventually had all its reactors back on line, with the whole fiasco costing it about JPY 200 billion (US$ 1.9 billion).

In 2007 NISA ordered reactor owners to check their records for incidents which should have been reported at the time but were not. This revealed a brief (15 minute) criticality incident during refuelling at Hokuriku's Shika 1 BWR in 1999. A series of deficiencies and errors contributed to the incident, and clearly more should have been learned from it to benefit other operators of boiling water reactors such as Chubu and Tohoku, which have also had control rod anomalies over the last 20 years. Tepco said that its Fukishima I-3 BWR may have experienced criticality over seven hours during an outage in 1978, when control rods slipped out of position. NISA ordered the Shika-1 reactor to be shut down for detailed checks.

Seismic concerns

Because of the frequency and magnitude of earthquakes in Japan, particular attention is paid to seismic issues in the siting, design and construction of nuclear power plants. In May 2007 revised seismic criteria were announced which increased the design basis criteria by a factor of about 1.5 and required utilities to undertake some reinforcement of older plants. See also paper on Nuclear Power Plants & Earthquakes.

In July 2007 the Niigata Chuetsu-Oki earthquake occurred on a fault very close to the Kashiwazaki-Kariwa nuclear power plant, and the ground acceleration exceeded the design parameters for the plant, ie it was more severe than the plant was required to be designed for. The operating reactors shut down safely and there was no damage to the main parts of the plant. The government (METI) then set up a 20-member Chuetsu Investigation and Countermeasures Committee to investigate the specific impact of this earthquake on the power station, and in the light of this to identify what government and utilities must address to ensure nuclear plant safety. It acknowledged that the government was responsible for approving construction of the first units in the 1970s very close to what is now perceived to be a geological fault line. It was also agreed that the International Atomic Energy Agency (IAEA) would join Japan's Nuclear Safety Commission in a review of the situation. The second IAEA team confirmed after inspecting key internal components that there was apparently "no significant damage to the integrity of the plant". Ground subsidence damaged much equipment around the seven reactors, but the main part of each plant is built on bedrock, which had entailed excavation in some places to 45 metres.

In October 2008 NISA presented to the NSC its evaluation of Tepco's report on Kashiwazaki Kariwa, assessing it as "appropriate". It contained the results of Tepco's inspections and assessments of equipment, buildings and other structures at the plant following the July 2007 earthquake. In 2009 the NSC endorsed NISA's recommendation that units 6 & 7 be restarted.

Tsunamis are also a feature of Japan and Kuril Islands. Since 1498 there have been 16 tsunamis with maximum amplitudes above 10 metres (some much more), these having arisen from earthquakes of magnitude 7.4 to 9.0, on average one every 30 years. The accident arising from the 11 March 2011 tsunami is described in the paper on the Fukushima Accident.

International outlook and exports

Apart from some active interest in uranium exploration and mine investment in Australia and Canada to help secure fuel supplies, for many years the Japanese nuclear industry was focused domestically, but in the 1990s it started to look at export possibilities and international collaboration.

Companies such as Hitachi, Mitsubishi Heavy Industries (MHI) and Toshiba formed important alliances internationally or took over major foreign nuclear companies. Their export initiatives are in collaboration with an operator such as Tepco and the Japan Bank for International Cooperation.

In heavy manufacturing, particularly of large forgings, Japan Steel Works (JSW) is generally regarded as the main company and world leader. Other enterprises are also active in export of major reactor components. JSW spent JPY 40 billion ($330 million) from 2007 to increase capacity in advance of orders expected from both China and the USA. It has production and research bases in Hiroshima, Yokohama and Muroran. The Muroran centre, in Hokkaido, hosts the heavy steel works and research laboratory relevant to power generation. Muroran manufactures reactor pressure vessels, steam generator components, generator & turbine rotor shafts, clad steel plates and turbine casings for nuclear power plants. JSW has been manufacturing forgings for nuclear plant components to US Nuclear Regulatory Commission standards since 1974, and around 130 JSW reactor pressure vessels are used around the world – more than one third of the total.

See also WNA paper on Heavy manufacturing of power plants.

At the government level, there were agreements with several governments including Kazakhstan. Then NISA set up the International Nuclear Power Safety Working Group in 2008 to cooperate in the field of nuclear safety with emerging countries, primarily in Asia, planning to introduce and expand their use of nuclear power.

This led in 2009 to an industry-based group, the JAIF International Cooperation Center (JICC), established with government backing to support countries planning to introduce nuclear power generation, and the International Nuclear Energy Cooperation Council, a forum for the relevant Japanese government authorities and private institutes to collaborate in international aid.

In October 2010 industry and government set up the International Nuclear Energy Development of Japan Co Ltd (JINED) to export nuclear goods and services collaboratively. The new company will solicit orders for nuclear power plants from countries such as Vietnam starting their own nuclear power programs, and advise on project and infrastructure development, bolstered by legislative and financing support from the Japanese Government. A separate company will be set up to act as engineering, procurement and construction (EPC) contractor. JINED is associated with JAIF and JICC, and is owned by the government (METI, through Innovation Network Corporation), nine utilities (Chubu, Kansai and Tepco being main shareholders), and three manufacturers (MHI, Toshiba and Hitachi).

For Vietnam's second nuclear power plant, Japan Atomic Power Co. and JINED in 2010 signed an agreement with Electricity of Vietnam (EVN) to undertake the Ninh Thuan II project. The government has appointed Mitsubishi to prepare a PWR proposal and Hitachi to prepare one using BWR technology. The project is seen as a METI initiative.

However, following the Fukushima accident reactor manufacturers are reported to be finding it difficult to do business abroad because Tepco, the main operator partner, is preoccupied with remediation at Fukushima. Establishment of its internal entity, the Fukushima Daiichi Decontamination & Decommissioning Engineering Company, to focus on measures for decommissioning units 1-6 and dealing with contaminated water, may ease this.

The only significant export deal in recent years is MHI’s involvement with Areva in contracting to build the Sinop nuclear plant in Turkey. Itochu is also involved. Here, GdF Suez is to be the operating partner. The deal is under a government-level nuclear energy cooperation agreement. In April 2014 the House of Representatives approved this agreement and the export of Japanese nuclear power plants to Turkey and also to the United Arab Emirates. The approval was backed by the ruling Liberal Democratic Party and junior partner New Komeito, as well as the opposition Democratic Party of Japan.

Another initiative which will lead to exports is Hitachi’s purchase of Horizon Nuclear Power PLC in the UK, which will lead to construction of four to six ABWR units at Wylfa and Oldbury. Hitachi plans to sell its interest in Horizon once the plants are operating.

In June 2008 an agreement on high-temperature gas-cooled reactor research was initialled by JAEA and the Kazakhstan Atomic Energy Committee, focused on small cogeneration plants.

Nuclear liability

Japan has not been party to any international liability convention but its law generally conforms to them. Two laws governing them have been revised about every ten years: the Law on Compensation for Nuclear Damage and Law on Contract for Liability Insurance for Nuclear Damage.

Plant operator liability is exclusive and absolute, and power plant operators must provide a financial security amount of JPY 120 billion (US$ 1.4 billion). The government may relieve the operator of liability if it determines that damage results from “a grave natural disaster of an exceptional character”, though it did not do this after the Fukushima accident in 2011, and in any case liability is unlimited. For the Fukushima accident the government set up a new state-backed institution to expedite payments to those affected.

In line with a 2013 undertaking by the Minister for Foreign Affairs and confirmed in the 4th Basic Energy Plan adopted in April 2014, a bill to ratify the IAEA’s Convention on Supplementary Compensation for Nuclear Damage (CSC) was passed by both houses of parliament in November 2014, along with amended domestic compensation laws. The Ministry of Foreign Affairs has now filed a formal document with the IAEA so that Japan became the sixth member country of the CSC, enabling it to enter force globally in mid-April 2015.


The Atomic Energy Basic law prohibits the military use of nuclear energy and successive governments have articulated principles reinforcing this. In 1976 Japan became a party to the Nuclear Non-Proliferation Treaty with its safeguards arrangements administered by the UN's International Atomic Energy Agency, and in 1999 it was one of the first countries to ratify the Additional Protocol with IAEA, accepting intrusive inspections.

Japan is noteworthy in being the only non-weapons state under the NPT with major fuel cycle facilities, which are thus under full safeguards. The Rokkasho reprocessing plant is the first such plant to be under full IAEA safeguards (others are under Euratom safeguards). Monitoring equipment funded by IAEA was built in to the plant, which was a novel challenge for both IAEA and JNFL.

Japan also has bilateral safeguards arrangements with its major nuclear supplier states and has long been a member of the Nuclear Suppliers Group which restricts export of nuclear equipment.

JAIF Atoms in Japan, various.
Tanaka, H 2006, Japan's nuclear power program, WNA Symposium 2006
JAIF summary of 4th Strategic Energy Plan April 2014