The Nuclear Restart in Japan

On August 11, 2015 Japan restarted a nuclear reactor after two years of having zero nuclear electric power generation. The Sendai Nuclear Power Station’s Unit 1 resumed operation roughly four years after the March 2011 severe nuclear accident in Fukushima, which eventually led the country’s 50-plus reactor fleet to come offline. This "Critical Question" explains the background context for this reactor restart and discusses its implications for the role of nuclear in Japan.  While the first reactor restart is a significant milestone, many questions remain unanswered for the future of nuclear energy in Japan.

Q1:  Why was there no nuclear power generation for two years?

Following the nuclear accident at the Fukushima Dai-ichi Power Station in 2011, the Japanese public was skeptical of the status quo nuclear safety of existing nuclear fleets, and called for greater scrutiny of nuclear sector governance. As a result, in the period following Fukushima, after nuclear reactors were shut down for a routine maintenance period of one-two months, they would not receive what had been the typical routine approval to reopen until a fuller safety examination was conducted. Until the Sendai reactor in Kagoshima Prefecture came back online this week, Japan had no nuclear power generation since the two Ohi reactors went offline in September 2013.  

Q2:  What is significant about this Sendai restart? 

The nuclear restart signifies a major milestone in Japan’s journey to restoring the public confidence in nuclear safety, and could also have positive economic and energy security impacts. First, the restart and the safety review process leading up to it constitute a major accomplishment for the Nuclear Regulatory Authority (NRA) of Japan, which was established in July 2012, to address the mounting public concern over the effectiveness and transparency of the nation’s nuclear governance following the Fukushima accident. Previously, the nuclear regulatory function resided within the same ministry in charge of promoting nuclear energy. During the two year period of nuclear outage, roughly two dozen reactors owned by 11 companies lined up before the NRA, which introduced new safety criteria for restart in July 2013. The Sendai reactor was among the first to apply for the NRA safety review and the very first to clear all the required steps necessary for restart, including the local consent. 

Another possible impact from the restart is that it may improve the energy-related economic and security conditions for Japan. Pre-Fukushima, nuclear accounted for roughly one-third of Japan’s power supply. The nuclear outage left a 44.3 GW hole in the country’s power supply capacity and Japan turned to fossil fuels like liquefied natural gas and coal to fill the gap, incurring a record level of trade deficit, stemming from a spike in fossil fuel import expenditure. While the Sendai Unit 1 restart by itself will not alleviate this problem, the notion that more existing nuclear capacity will be brought back online over time may allow Japan to alleviate some of the economic burdens of the last several years, as well as provide greater diversity of power supply which is beneficial from an energy security perspective. Moreover, the anticipated rise in nuclear power generation, together with austere energy conservation, are considered to be essential if Japan is to achieve its climate commitment of reducing emissions by 26 percent below 2013 levels by 2030.

Q3:  Is nuclear fully coming back in Japan’s energy mix? 

While significant, this milestone does not signal the full restoration of nuclear power generation in Japan in the face of continued public concern over nuclear safety. Highly dependent on imported fossil fuels, Japan had turned heavily to nuclear energy in response to the oil supply disruptions of the 1970s. Until the Fukushima accident, nuclear energy was a cornerstone of Japan’s energy policy. For example, the 2007 government plan aimed at increasing the share of nuclear power in the total power generation from 27 percent (in 2009) to 40 percent by 2017 and to 50 percent by 2030. The Fukushima accident and subsequent public concern over nuclear safety and governance rendered the 2007 plan impossible. 

In April 2015, the Japanese government announced a new vision for the country’s 2030 energy mix. Under the new vision, nuclear would account for 20 to 22 percent of the Japanese electricity supply mix in 2030. While necessary, the nuclear restarts alone are not sufficient to achieve the new targets. There are currently 43 operable units left in Japan. A healthy share of the fleet would need to see their operational licenses renewed beyond 40 years, or nuclear energy would only account for about 15 percent in 2030 in the absence of new builds—a prospect of great uncertainty given the continued public concern over nuclear safety and governance.

Additionally, the future of nuclear energy in Japan will be significantly affected by developments in a range of related policy areas. For example, Japan’s nuclear fuel cycle policies, including the rationale for having indigenous reprocessing capability in light of nuclear power uncertainty as well as the technical and economic viability of its fast reactor program, are the subject of public scrutiny both at home and abroad.

Q4:  What to expect next?

By early next week, the Sendai reactor, restarted on August 11, is scheduled to begin generating electricity. A smooth, trouble-free restart is essential for the restart of not only the second unit at Sendai as early as mid-October, but also the two dozen other units that are under the NRA safety review. As these reactors have been long dormant, however, technical issues are likely to arise as shown by the experiences of 14 reactors around the world that resumed operations after being offline for at least four years. It is important for the public to recognize that such technical issues are inherent in nearly any engineered equipment/machinery long dormant and do not necessarily invalidate the efficacy of nuclear technology for electricity generation. 

As mentioned earlier, the prospect for new nuclear constriction remains highly uncertain in Japan. The three units that have been under construction since before the Fukushima accident are likely to come to completion given the scale of capital already sunk into the projects. However, the fate of nearly ten reactors in the preparatory stage for construction is another question. 

Lastly, with the power sector deregulation underway, the economics of building new reactors and maintaining the existing reactors will likely come under greater pressure as many utilities become uncertain about their market competitiveness in the liberalized landscape.

Jane Nakano is a senior fellow with the CSIS Energy and National Security Program.

Critical Questions is produced by the Center for Strategic and International Studies (CSIS), a private, tax-exempt institution focusing on international public policy issues. Its research is nonpartisan and nonproprietary. CSIS does not take specific policy positions. Accordingly, all views, positions, and conclusions expressed in this publication should be understood to be solely those of the author(s).

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