Recommendations on Long-term Use of Nuclear Energy in a Carbon-Neutral Japan

About two years have passed since former Prime Minister Suga declared at the end of October 2020 that Japan would become carbon neutral by 2050, and in that time the global trend toward decarbonization has greatly accelerated. On the other hand, the invasion of Ukraine in February 2022 exposed the risk of dependence on authoritarian countries for energy, and achieving decarbonization and energy security simultaneously has become a trend in the energy sector. As an example of this balancing act, a decision was made in July to include nuclear and natural gas in the EU taxonomy¹ , suggesting the importance of having a variety of options for energy sources. Countries are also reviewing their energy policies, including the United Kingdom and France, which plan to build more nuclear power plants, and Germany, which plans to return to coal-fired power plants and to maintain in reserve some of its nuclear power plants that were to be decommissioned at the end of this year.

On November 4, 2022, we published the English version of our Social and Economic Impacts of Carbon Neutrality in 2050 report. The report defined four scenarios for Japan’s future through 2050 and proposed the direction that measures should take to achieve a smooth transition to a decarbonized society. This report states the importance of making clear that nuclear power will play a role in Japan’s long-term energy strategy. It elaborates on the need for Japan to maintain its nuclear-power related technologies and human resources, and innovate in nuclear power itself. The report speaks to the potential for using nuclear power in harmony with the large-scale uptake of renewable energy.

In Japan, where energy self-sufficiency is only about 10%, energy security is an important issue that will determine the fate of the nation. The power supply capacity in the eastern Japan area was greatly reduced by the Fukushima earthquake in March 2022, and demand for electricity increased significantly at the end of June due to unusually hot weather—both resulted in tight electricity supply. In addition, the invasion of Ukraine accelerated the rise of resource prices and exposed the risk of procuring energy supplies on the assumption of good relations with other countries, underscoring the importance of securing anew a diverse supply capacity. Electric power systems need to be flexible enough to handle rare events such as earthquakes and extreme weather. Japan’s own power system, which has been reliant upon renewable energy and thermal power sources in recent years, could have been more responsive if nuclear power, which features a different set of characteristics, had been in operation too. In light of these circumstances, at the GX Implementation Council² in August, Prime Minister Kishida ordered for studies to be undertaken, including on "…the development and construction of next-generation advanced reactors…"

We estimated nuclear energy requirements as of 2050 from three perspectives: (1) compensating for uncertainties in the development of decarbonization technologies such as hydrogen and CCS, (2) diverse supply capacities, and (3) maintaining the nuclear safety base of technology and human resources. (1) In particular, if the implementation of hydrogen, ammonia, and CCS technologies is delayed, up to 40 - 50% of the electricity generated must be supplied by established sources such as nuclear power to supplement renewable energy—in reference to discussion at the national council (Supplement 1). (2) According to our calculations, even assuming the deployment of variable renewable energy, such as solar and wind power, a large amount of storage batteries, and a significant increase in the number of interconnection lines, which greatly exceed the council's reference values mentioned above, it would be difficult to meet electricity supply and demand solely with variable renewable energy. It would be necessary to maintain at least 10 - 15% of power with base load sources, including nuclear power. (3) According to a commissioned study we conducted, the maintenance of technology, human resources, and supply chain is necessary for the safe operation of nuclear power generation until 2050. In particular, with regard to the maintenance of technology, human resources, and supply chain related to design and advanced equipment manufacturing, the construction of nuclear reactors will be important not only for operation and maintenance but also for the succession of unique technology related to design and construction. For this, about one reactor will need to be constructed every few years^{3, 4}. This, together with existing nuclear power plants, is equivalent to maintaining about 10 - 15% of the electricity. Taking into account (1) through (3) above, nuclear power will realistically have to cover at least 10 - 15% of the electricity generated in 2050.

Policy on the use of nuclear energy after 2050 needs to be reconsidered around 2040 in light of developments in other decarbonizing technologies, including further expansion of nuclear energy use itself if necessary, and the option of post-nuclear power, in other words stopping the use of nuclear power altogether. If a post-nuclear power scenario is a viable option around 2040, society will then be able to redefine how power plants in operation, under construction, or planned at the time should be used in order to make the option a reality.

As a power supply option beyond 2050, nuclear innovation technologies, along with other decarbonization technologies, could continue to make a significant contribution to carbon neutrality. In promoting the introduction of renewable energy to the maximum extent possible, it is important to consider the changing role of nuclear power and the timing of this change, assuming that it coexists with renewable energy, in order to promote the necessary development. For example, plans could be fleshed out such as the introduction of a small modular reactor with adjustable power for variable renewable energy around 2030, a high-temperature gas cooled reactor for large-scale domestic hydrogen production around 2040, and a fusion reactor for high safety and low environmental impact after 2050 with an eye toward replacing existing light water reactors.

According to the results of our own questionnaire survey of 30,000 people nationwide, the social acceptance of nuclear power is gradually increasing (Supplement 2), and nuclear power is seen as one of the energy sources that can be used to achieve both decarbonization and energy security, as well as a stable supply of electricity at present. However, there are inherent risks associated with the use of nuclear power, such as widespread environmental pollution that became apparent after the accident at the Fukushima Daiichi nuclear power plant. While we can say that safety has steadily improved due to the independence of regulatory bodies after the accident and the implementation of countermeasures to avoid severe accidents based on the new regulatory standards, we should never forget the feelings of those who were directly or indirectly affected by the accident. In light of the inherent risks of nuclear power, which will never reach zero, it is essential to continue to make efforts to improve safety and build trust, including improving the way operators approach nuclear power and addressing the risk of being targeted for attack in wartime.

It goes without saying that the accident at the Fukushima Daiichi nuclear power plant damaged the public's trust in the nuclear industry, including nuclear power operators, manufacturers, and the government.

Trust has three main aspects. The first is competence, such as the ability of the nuclear industry to use nuclear technology safely. The second is motivation, such as whether the nuclear power industry complies with regulations and conducts business activities fairly and honestly. The third is value similarity, such as whether organizations and individuals in the nuclear power industry view the world from the same point of view as the rest of society, and whether the industry responds to the needs and wishes of society. Our own questionnaire survey on trust, conducted separately with 4,700 people nationwide, revealed that value similarity had a particularly strong influence in cases such as trust in the nuclear industry (Supplement 3). In other words, whether or not the nuclear power industry can properly understand and respond to society's wishes from the same point of view as society is important in building trust. On the other hand, public opinion spans the full spectrum from prioritizing safety above all else, to requests for electricity that is both inexpensive and stable. In light of this, the nuclear industry should not focus on measures aimed at building trust just for show, but rather on steady efforts to understand the thoughts and values of society and to demonstrate a willingness to respond appropriately to each. In other words, perfunctory initiatives that do not involve internal or substantive changes in the nuclear industry, such as changing the organization without changing the mindset of following precedent, will not foster trust. It goes without saying that the industry must make voluntary, autonomous, and continuous efforts to improve safety based on incorporating the latest knowledge and technological developments. The first step toward building trust should be to continuously demonstrate that as an industry all are sincere in efforts to accurately understand and appropriately respond to the diverse thoughts and values of society.