The International Atomic Energy Agency's final report on the March 2011 triple meltdowns at Tokyo Electric Power Co.'s Fukushima No. 1 nuclear power plant puts the main blame on the then prevailing assumption that Japan's "nuclear power plants were so safe that an accident of this magnitude was simply unthinkable." Constant monitoring is needed to make sure the government, power companies and nuclear regulatory authorities aren't falling into the same "safety myth" as they push to reactivate idled reactors that meet what is now touted as the "world's most stringent" nuclear safety standards.

Last week, Kyushu Electric Power Co. began commercial operation of the No. 1 reactor of its Sendai nuclear power plant in Satsumasendai, Kagoshima Prefecture — a little over a month after it became the first reactor idled since 2011 to be reactivated on the basis of the safety standards that were tightened in response to the Fukushima disaster. The utility plans to restart the plant's No. 2 reactor as early as next month, and the Abe administration and the power industry are pushing to bring more idled plants back online once they have cleared the Nuclear Regulation Authority's screening.

The regulatory system for nuclear power generation has been reformed since the 2011 crisis. The old Nuclear and Industrial Safety Agency, which came under fire for the Fukushima debacle, has been replaced by the NRA, and new regulations introduced in 2013 require operators of nuclear power plants to beef up their defense against natural disasters such as major earthquakes and tsunamis. But while the NRA itself states that compliance with the new standards does not guarantee the plants' safety, the government says the plants are ready for restart because they meet the NRA criteria. No one appears ready to take final responsibility for the plants' safety.