The Japanese government and their domestic nuclear industry are facing a serious dilemma this winter. While geologists caution about the risk of active seismic faults beneath many of Japan’s nuclear reactors, the electric power industry is pressing the need to restart nuclear power plants in order to supply stable electricity, mainly for industrial consumption. This disagreement between the two communities of experts has, in turn, confused and frustrated the public, which now feels sceptical of both ‘uncertain seismology’ and ‘unreliable nuclear engineering’.

Can Japan’s new Prime Minister Shizo Abe address this crisis and secure the country’s long-term energy strategy? What is the future for nuclear technology in Japan and around the world?

Japan’s unprecedented earthquake of M.9.0 (on the Richter scale) of March 11, 2011, and the following Fukushima nuclear power plant accident, came as a shock not only to the Japanese public but also to many of the country’s geologists and seismologists. The scientists forced to question their hitherto-established standards for seismic risk control, agreeing that the risk of seismic faults must be re-evaluated at a basic level. The Japanese government also recently started a series of comprehensive assessments, collecting specific information about seismic faults surrounding major nuclear power plant sites. This, however, has resulted in a delay in the resumption of operation of nuclear plants in the country for at least several months and potentially for much longer – posing a substantial challenge and cost for power-hungry industry currently relying on expensive imported energy.

Nuclear Power meets Geo-science in Japan
In 1963, Japan started producing electricity from nuclear power plants, just ten years after the US policy Atom for Peace was announced by President Eisenhower in 1953. The majority of Japanese people welcomed this decision, due in great part to the loss of access to traditional sources of energy, such as petroleum, as a result of defeat in World War II. Since then, Japan has continued to import and further develop nuclear technology, and today there are 54 nuclear power plants in Japan, which, until 2010, were supplying about 30% of the electricity in the country.

The unprecedented earthquake and subsequent tsunami in 2011 severely hit the east coast of Japan, including the Fukushima Daiichi nuclear power plants operated by the Tokyo Electric Power Company (TEPCO). TEPCO successfully stopped all of the nuclear reactors following the earthquake, but the lack of continuous water supply needed to cool down the power plants resulted in the meltdown of nuclear fuel rods in the pressure vessel, while hydrogen gas explosions destroyed the reactor buildings. As a consequence 770,000 Tera Becquerel radioactive particles and compounds were scattered around the nuclear plants, corresponding to a radiation level 20 billion higher than the annual exposure limit in the US, and about 110,000 people who were living within 30 km distance from the plants were forced to evacuate.

After the Fukushima accident, fearing similar or knock-on events, all nuclear reactors in Japan were ordered to stop their operation. Operators were instructed to install additional infrastructure to protect the reactors against tsunami and a self-generating electric system to cope with the sudden loss of external electric supply. Currently only two reactors – out of the existing 54 in Japan – are operating at the Oi nuclear power plant of Kansai Electric Power Co. in Fukui prefecture. These reactors resumed operation in July 2012.

While the nuclear industry was assessing the impact of Fukushima and reacting to public pressure to reform, the scientific community was forced to respond to the crisis. Many geo-scientists in Japan suffered public criticism for naively describing the disaster as “beyond expectation.” Despite many years of research, and the large amount of resources that Japan had invested in seismic research, no geologists or seismologists had predicted that a M 9.0 earthquake could or would occur in Japan or its coastal regions. Aside from Alaska and South America, geo-scientists did not predict M.9.0 scale earthquakes anywhere in the world. In Japan itself, the maximum estimate was M.8.3. However, due to the exponential nature of the Richter scale, a M.9.0 earthquake actually indicates about 10 times greater energy than M.8.3.

The Japanese seismologists revised the definition of the term ‘active’, expanding the previous referential range to a much longer timespan. This meant, however, that virtually the entire Japanese archipelago was now classified as an active fault

The Seismological Society of Japan, the largest in the country, held a conference in May 2012 to discuss proposed new paradigms for seismological research. One major outcome was the revision of the definition of an active fault – this was vitally important as the Japanese government’s safety guidelines prohibit the construction of a nuclear plant directly above an active fault. Initially, in 1978, the guidelines determined that an active fault should show an evidence of seismic activity in the past 50,000 years, which was expanded to 120,000-130,000 years in 2006. At this conference, the Japanese seismologists revised the definition of the term ‘active’, expanding the previous referential range to a much longer timespan. This meant, however, that virtually the entire Japanese archipelago was now classified as an active fault.

In order to reassess possible earthquake risks at nuclear power plants in the country, the government launched the Nuclear Regulation Authority (NRA) in September 2012. The NRA’s task was to investigate any potentially active faults located near to nuclear power plants, and to draw up new safety standards that regulate the conditions for restarting nuclear power plants. For the NRA to officially agree on reactivation of any nuclear reactor there must be an assurance that no active fault is found underneath the nuclear facility.

Since the geological studies by NRA experts started in November 2012, there has been growing concern about a suspected active fault located directly under the site of the Oi nuclear power plant. Mitsuhisa Watanabe, Professor of Geomorphology at Toyo University and a member of the NRA’s expert panel, believes that the risk of active faults has been intentionally underestimated by the scientists supporting Japan’s nuclear industry. He insists that the Oi nuclear power plant should be suspended until the geological assessment of the NRA is complete.

It has been suggested, however, that related events abroad may have been influencing the Japanese scientists. Following the 2009 L’Aquila earthquake in Italy that killed 309 people, the prosecution of seven geo-scientists for manslaughter related to the underestimation of seismologic risks and superficial reassuring of the population of L’Aquila may have encouraged Japanese scientists’ post-Fukushima to ‘play safe’ in their assessment of risks.

New Nuclear Safety Regulations
Pressure on Japanese scientists continued to grow, and in December 2012, a mere two months after the Italian verdict, the seismologists at the Japanese Nuclear Regulation Authority substantially revised their definition of an active fault. According to the new definition, a fault is judged to be active if it has moved in the past 400,000 years. This revision resulted in a major shift in the nuclear safety regulations in Japan, severely limiting the areas that can accommodate nuclear power plants.

On December 10th, the Tsuruga nuclear power plant of Japan Atomic Power Co. (JAPC) in the Fukui prefecture was inspected by an expert panel of the NRA. There is a major active fault named Urazoko which lies about 250 meters from the nuclear reactor building. The panel focused on a fault fracture zone called ‘D-1’, which is located beneath the nuclear reactor building and is connected to the Urazoko fault. After inspecting test trenches and soil conditions for two days, the expert panel concluded that the D-1 fault is likely to be active or more accurately “cannot prove that the ‘D-1’ is inactive”. Consequently, Tsuruga, one of JAPC’s major nuclear reactors, cannot be reactivated and may have to be scrapped.

Following Tsuruga, the NRA expert panel investigated the Higashidori nuclear power plant of Tohoku Electric Power Co. in the Aomori prefecture. Sure enough, they pointed out other active faults on the site of the nuclear plant. The NRA is now planning to investigate a total of seven nuclear power plant sites, where there are suspicious faults. The presence of these newly recognized ‘active’ faults may lead to an extended, large-scale suspension of nuclear electric supply in Japan.

JAPC responded to the NRA’s decision on the Tsuruga nuclear plant stating that the NRA’s conclusion is “based on too much speculation and lacks support from sufficient empirical data, and is therefore unacceptable”, announcing that the company would independently investigate the site to prove the inactivity of the D-1 fault.

Japan’s Energy Future
Nuclear engineering requires the combined practices of many fields of science and technology such as civil engineering, earthquake engineering, architecture, and structural mechanics. Coordinating this effort, the Japanese Association for Earthquake Engineering (JAEE) has a membership of more than 1,000 researchers. However, not one expert from the JAEE was present on the NRA expert panel. In fact, following the ‘Fukushima Shock’ which drastically undermined public faith in the nuclear industry in Japan, researchers linked to the nuclear industry were distanced from the NRA. As a result, the expert panel became dominated by ‘pure’ geologists, lacking engineers with practical knowledge.

The prosecution of seven geo-scientists for manslaughter related to the underestimation of seismologic risks and superficial reassuring of the population of L’Aquila may have encouraged Japanese scientists’ post-Fukushima to ‘play safe’ in their assessment of risks

In response, however, the nuclear industry points to the uncertainty inherent in seismology, and argues that the estimated risk of the newly defined ‘active’ faults is poorly substantiated. Katsuichiro Hijikata of the Japan Nuclear Safety Institute explains: “Risk assessment for nuclear facilities should not only focus on the existence of active faults on the site, but should also incorporate the frequency of seismic activity and potential physical impact of ground motion to the facilities. We need to approach this issue from various angles and discuss it in a more interdisciplinary manner.”

Japan has quite limited domestic energy resources. Energy has been, and will always be, at the heart of Japan’s national security agenda. The country cannot afford to abandon its nuclear energy programme without addressing the challenges that accompany the alternatives, such as the potential increase in CO2 emissions and high cost of importing natural gas. While a comprehensive review and revitalization of national energy strategy is urgently needed, the lapse in communication between geoscientists and nuclear engineers is today’s most pressing roadblock.

However, a much-needed breakthrough may be possible. The new Prime Minister Shizo Abe and his cabinet are now aiming to bridge this divide and successfully communicate the uncertainty and risks of nuclear technology to the public. The short-term nuclear phase-out plan, which had been pushed through by the previous cabinet, is now likely to be replaced by a more realistic, long-term strategy to gradually introduce more sustainable energy options in place of nuclear energy such as the use of ‘smart grids’ that optimize efficiency by combining various sources of energy while monitoring and controlling the balance between the supply and consumption of electricity. Time will tell if Japan’s tsunami has nudged it on a new path away from nuclear.