Japan’s nuclear power industry is preparing for a highly significant re-launch following the government’s recent dramatic change of energy policy. Reliant on imports for most of its energy needs, soaring global energy prices and worrying threats of domestic power shortages are among the issues pressuring Japan to revive its once-important nuclear power sector.

Anti-nuclear power public sentiment following the Fukushima Daiichi nuclear plant earthquake and tsunami disaster in 2011 caused the government to shut all nuclear power stations pending completion of safety inspections, a slow and complicated process that until now has allowed only a handful of reactors to restart.

Recent events, however, including the destabilising impact of the war in Ukraine on global fuel prices and global energy supply stability, together with a pressing need to achieve the nation’s ambitious carbon neutral emission reduction targets, have prompted Japan’s energy policymakers to alter their stance on nuclear power – something almost unthinkable just a few years ago.

Prime Minister Fumio Kishida set the ball rolling in August, announcing plans to restart mothballed nuclear plants that have remained idle since the Fukushima disaster due to the long, laborious nuclear reactor safety inspection process created to satisfy strong anti-nuclear public feelings that developed as the extent of the disaster became apparent.

Kishida’s announcement came in an online speech on Japan’s green transformation, highlighting the importance the government is attaching to reviving the nuclear power industry in promoting decarbonisation.

In addition to clearly stating the government’s intention to play a leading role in promoting the restart of idle reactors, the Prime Minister’s speech touched on closely related topics including extending nuclear plants’ working life and the development of next generation nuclear reactors.

Restarting nuclear 
Nuclear power plants generated 30% of Japan’s electricity supplies before the Fukushima earthquake and tsunami disaster struck in March 2011. As noted, following the disaster all nuclear plants were ordered to close until they passed safety checks administered by Japan’s nuclear industry regulator. Only a handful of reactors have restarted and still remain in service since then.

The government’s medium-term nuclear revival target calls for an increase in the number of restarted reactors countrywide to generate at least 20–22% of total electricity supply, which is calculated to enable Japan to achieve its goal of cutting greenhouse gas emissions in 2030 by 46% compared with emissions in 2013.

For the immediate future, Kishida has pledged his government’s leadership to restart 17 nuclear plants initially, the first time a numerical target for restarting Japan’s out of service nuclear plants has been stated.

Nuclear units due to restart by summer 2023 or later include seven reactors that have been awarded Reactor Installment Licences and have permission to restart, in addition to 10 reactors that were subject to earlier restarts. The latter group includes six operational reactors totalling 5,546 MW that, as of September, were generating 6.4% of Japan’s electricity supply.

In addition to stating the government’s intention to play a leading role in promoting the restart of idle reactors, the Prime Minister’s speech touched on extending nuclear plants’ working life and development of next generation nuclear reactors.

Plans to cut LNG use 
With most of its nuclear reactors remaining idle, and reliant on imports for about 90% of energy supplies, Japan has been badly hit by soaring global energy prices that have followed the start of war in Ukraine.

Apart from boosting Japan’s energy security, the nuclear power industry’s planned relaunch is also aimed at reducing expensive LNG and coal power station fuel imports, which grew after the Fukushima disaster to fill the loss of nuclear energy supplies. 

Japan’s plans to use nuclear power to reduce LNG imports and increase domestic energy security will additionally help Europe’s energy crisis by increasing available LNG supplies. Commenting in September in Tokyo, International Energy Agency Executive Director Fatih Birol said: ‘Restarting nuclear is good news for Japan and a big help for Europe in winter.’

Japan’s LNG imports currently total about 101bn m³/y, slightly less than Europe’s 108bn m³ import total. According to Kishida, each restarted nuclear reactor will free up 1mn tonnes of LNG to add to the global LNG market for European countries or others to buy.

In a published commentary, Ken Koyama, Chief Economist and Managing Director of The Institute of Energy Economics, Japan (IEEJ), notes that the government’s nuclear revival policy gives priority to using existing nuclear plants as the key option to simultaneously achieve the so-called ‘3Es’ – energy security, environmental protection and economic efficiency – by reducing CO₂ emissions, securing a stable energy supply and cutting energy costs.

Lifetime extensions 
Koyama also highlights the importance of Kishida stating that the government will consider extending the working life of existing nuclear units to ensure the efficient utilisation of existing nuclear plant facilities. Under the current regulations, Japan’s nuclear plants have a 40-year initial lifetime that can be extended for a further 20 years with approval from the Nuclear Regulation Authority, allowing nuclear plants to be operated for up to six decades.

Due to their present age, if the 40-year lifetime rule were to be applied Japan’s nuclear power plants will begin closing one after another from the 2020s onward, says Koyama. Extending the current generation of nuclear plants’ lifetime by 20 years to 60 years will delay the start of a rapid fall in Japan’s nuclear power capacity to the 2040s, allowing power companies more time to plan and build new nuclear reactors.

According to the World Nuclear Association, Japan has 33 operable nuclear plants, including 10 that have received approval from the nuclear safety regulator to restart, among which six are in service. Applications to restart a further 15 nuclear plants have also been submitted for approval.

IEEJ estimates that about 30 reactors may have to be restarted and receive lifetime extension approval for Japan to meet its 2030 carbon emission reduction target.

Whether all 30 nuclear plants are restarted in practice remains to be seen. Although Japanese newspaper surveys suggest public opinion is more favourable to nuclear energy than immediately after the Fukushima disaster, local opinion on restarting nearby plants will be tested at the ballot box over coming years as local government elections are held around the country.

Koyama notes that the US already has extended the lifetime for some nuclear reactors to 80 years, something that Kishida may have considered before making his August statement.

Staffing and population issues 
Staffing will be another issue. More nuclear engineers will be needed to operate the nuclear plants as they are restarted, and to replace senior staff that have retired without being replaced during the past decade while most of Japan’s nuclear reactors lay idle. Nuclear power also is expected to play an important contribution to achieving Japan’s 2050 carbon neutral target, for which a new generation of nuclear engineers needs to be recruited and trained.

Nuclear energy will need to develop a modern, positive image if young Japanese graduates are to be persuaded that nuclear power is an exciting career choice.

For demographic reasons, Japan’s nuclear revival will coincide with lower overall energy demand. Unlike many other countries in Asia with growing populations and energy needs, Japan’s population already is in decline. This will cause a gradual reduction in energy consumption in future. According to government forecasts, the population is expected to decline by about 20% from 127mn in 2021 to slightly more than 100mn in 2050.

Electricity generation is forecast to reduce at a similar rate to the population decline, falling to about 850 TWh in 2050, down from about 1,000 TWh annually at present.

Under its new policy the government is looking to restart idle nuclear reactors within the current decade, while most growth in renewable energy is expected in the 2030s due to slow progress in launching renewable generation schemes until now. The LNG and coal-fired share of the generation fuel mix will decline as fossil fuels are replaced by nuclear and renewable energy under present plans for Japan to meet its carbon-neutral target.

New reactors? 
Kishida’s announcement contained news that the government will promote the construction of new generation nuclear power plants, prompting a swift response from Japan’s nuclear plant construction industry and regional power companies. Japan’s stock market responded well, with share prices for Tokyo Electric Power Company (Tepco) and several other regional power companies climbing immediately in response to Kishida’s announcements, as well as stock values for some nuclear plant equipment manufacturers.

Hitachi has announced it will work with GE Nuclear to develop an advanced reactor with enhanced safety features, while Mitsubishi Heavy Industries (MHI) announced it will develop a next generation nuclear reactor with four of its existing Japanese utility customers – Kansai Electric Power Company, Kyushu Electric Power Company, Shikoku Electric Power Company and Hokkaido Electric Power Company.

Fukushima’s owner Tokyo Electric Power Company’s headquarters building (with red and white tower) in Tokyo  
Photo: David Hayes

MHI said the five partners will develop a new type of pressurised water reactor (PWR), called an advanced light-water reactor, for which the conceptual design already is prepared and that will be ready to enter service in the mid-2030s.

Learning lessons from the Fukushima disaster, the new reactor – called the SRZ-1200, with a power output of about 1,200 MW – will have design features to protect the plant from natural disasters including earthquakes and tsunamis, from terrorist attacks and ‘unforeseen events’.

Nuclear power safety concerns are strong in Japan following the 2011 East Japan earthquake and tsunami disaster which caused reactor core meltdowns at Fukushima Daiichi (No 1) nuclear plant.

According to MHI, which has been involved in the construction and maintenance of all 24 of Japan’s PWR nuclear plants, the SRZ-1200 reactor design will include new safety mechanisms to comply with the more rigorous safety standards that Japan’s nuclear power regulators have introduced. These include advanced equipment to seal off melted nuclear fuel in a containment vessel and systems that prevent or limit radiation leaks in the event of an accident.

Another feature of the SRZ-1200 will be its operational flexibility, intended to improve its electric power delivery as part of a variable electricity generation fuel mix that will include a growing share of renewable energy sources in the future. ‘The ability to adapt the SRZ-1200 for hydrogen production also will be studied to ensure that all potential uses of energy generated from this plant are efficiently and proactively applied for all of societal needs,’ according to MHI.

Offshore wind 
Meanwhile, Japan’s plans to develop renewable energy are attracting local and overseas interest. Government targets include installing up to 10 GW of offshore wind capacity by 2030, and 30–45 GW by 2040. Progress with offshore wind projects has been slow until now due to various issues, including ownership of offshore seabed zones.

Most recently, Japan’s Ministry of Economy, Trade and Industry (METI) announced in September the designation of three ‘promotion areas’ for developing offshore wind farms while also selecting five ‘promising areas’ and 11 ‘potentially suitable areas’. The new promotion areas lie offshore Sakai, near Nagasaki, in Kyushu, south-west Japan, and in northern Japan, offshore Murakami in Niigata Prefecture and offshore Oga in Akita.

Auctions to select wind farm operators for the offshore projects are due to be held once METI revises bidding rules for the selection process after several bidders complained about a lack of clarity in bidding rules for three offshore wind projects awarded to Mitsubishi-led consortiums last year. In December 2021, three consortia, all led by Mitsubishi Corporation, were selected to operate three offshore wind power projects in Akita, northern Japan, and Chiba, near Tokyo, totalling 1,689 MW. The wind farms are due to start up from 2028–2030.

Wind power, mostly offshore, together with Japan’s other major renewable energy resource, solar energy, is due to make an important contribution towards achieving the country’s 2050 zero-carbon targets. However, due to the lengthy time frame currently required to approve and implement renewable power projects in Japan at present, wind and solar power are not expected to make a significant contribution to the country’s carbon neutral status until the early 2030s.

Restarting Japan’s out-of-service nuclear power plants may achieve a speedier reduction in greenhouse gas emission levels needed to achieve its committed zero carbon target. Japan’s progress in reviving its nuclear power industry will no doubt be watched with interest by many other countries.