On 11 August Japan restarted its first reactor under the post-Fukushima safety regime. The Sendai No. 1 reactor, in Kagoshima Prefecture, southwest Japan, will be given a one-month test and is expected to be in normal service in mid-September. The Sendai No. 2 reactor is expected to restart in mid-October.


Nuclear power plant at Ohi, Japan. (Flickr/IAEA.)

Prior to the March 2011 Fukushima crisis, nuclear power supplied around 30% of Japan's electricity. With over 50 reactors, Japan had the world's third-largest nuclear power program (behind the US and France). Following Fukushima, all of Japan's reactors were progressively taken off line for major safety reviews, and the nuclear regulatory system has been reformed.

Japan has made up the loss of nuclear power generation by increased use of fossil fuels, mainly coal and liquefied natural gas. Increased energy imports have resulted in higher electricity prices and a record trade deficit. CO2 emissions from the electricity sector have increased by some 40%. For the 2013 Warsaw Climate Change Conference, Japan announced it had to revise its CO2 emission target for 2020 from a 25% reduction relative to 1990 to a 3.1% increase.

In 2012 the Democratic Party of Japan (DPJ) Government suggested nuclear power could be totally phased out by the 2030s. Following the DPJ’s loss in the December 2012 election, however, the new Liberal Democratic Party Government, responding to increasing emissions and economic impacts, described nuclear power as an essential part of Japan’s energy mix and announced that reactors that could meet rigorous new safety standards would be permitted to restart.

Today Japan has 43 reactors that are operable and potentially could be brought back into service. Of these, 25 reactors, including the two Sendai units, are being considered for restart. For the oldest reactors, major safety upgrades are not considered cost-effective and these will remain shut down. Japan also has two new reactors under construction and nine planned.

The Government has announced a new energy plan for Japan, under which nuclear energy will account for 20-22% of power generation in 2030, with a similar share coming from renewables. Coal is expected to be 26%, and LNG 27%. Based on this plan, a new 2030 target for CO2 emissions has been announced which represents a 26% reduction from 2013 levels.

Most opinion polls suggest the public continues to lack confidence in the safety of nuclear power. Local residents and activists groups are opposing reactor restarts. On the other hand, the public is also concerned about climate change, costs and reliable electricity supply. Industry Minister Yoichi Miyazawa describes nuclear energy as 'indispensable', saying 'It would be impossible to achieve all these three things simultaneously: keep nuclear plants offline, while also trying to curb carbon dioxide and maintain the same electricity costs...I hope to gain the public's understanding of the situation.'

If all 25 proposed restarts and new reactors proceed, Japan's nuclear power sector will be significantly smaller than pre-2011, but still one of the world’s largest. Japan will be vying with Russia for fourth-largest, the number three spot expected to be taken by China's expanding program.