Japan’s Oldest Reactor Reaches Criticality Once Again

Following the Japanese earthquake in 2011, and the resultant Fukushima Daiichi nuclear accident, the country shuttered its reactors for inspection. 

At the time of the accident, Japan had 54 nuclear power reactors, including the six located at Fukushima Daiichi. Nuclear power accounted for 30 percent of the country’s electricity supply. At that time, the Japanese energy strategy expected the country’s nuclear output to grow to 40 percent of its electricity supply by 2017.

In the wake of the accident, the reactors were shuttered for safety checks with plans to slowly bring those deemed safe back online. 

Now, reading pre-2011 books and papers on global energy, it’s always striking to come across lines about the future of nuclear power in Japan. The country’s island geography makes energy independence a difficulty, and energy density essential. Japan imports 90 percent of its energy needs. Because of this, nuclear power is especially useful to the Japanese energy economy. 

21 reactors in Japan have been decommissioned since 2011 including all six reactors at Fukushima Daiichi, and all four reactors at Fukushima Daini, the nearby facility that was able to avoid a similar accident to that experienced at Daiichi through quick operator accident, but which was still significantly impacted by the Tsunami. 

But the rest of Japan’s reactors, 33 in total, are classified as operable, those that are operating currently or could safely be restarted. Of those reactors, 11 have now been restarted. 

The most recent of these is Takahama Unit 1, which is now the oldest operating unit in Japan. The reactor has reached criticality, and will be brought back into full operation on August 28th after a comprehensive load performance test. Takahama Unit 2 is expected to follow in September. 

The facility’s other two units, Takahama 3 and 4 recommenced operations in 2016 and 2017 respectively. In April, an application was filed with the Nuclear Regulation Authority (NRA) to extend the operating lives of Units 3 and 4 by an additional 20 years, which would allow them to operate until 2045. 

Although the restarted reactors are nowhere near the capacity that nuclear power used to constitute in Japan, it’s good to see more units coming back online after a hiatus of more than a decade, and new reactors will continue to be brought back online in the coming years. 17 reactors, including the 11 now in operation, have completed the NRA’s review to return, with another 14 at various stages of the approvals process. 

Bringing these facilities back online will help Japan to diversify its energy mix, and become less reliant on imports of LNG that are subject to global events out of its control like the war in Ukraine that had a major impact on the country’s power supplies. Japan was long the world’s largest importer of the resource, and is now second only to China. Energy independence is unlikely in a nation not endowed with natural energy resources, but that doesn’t mean work can’t be done to protect the country’s energy reliability from outside forces.