Takahama plant’s No. 3 reactor reaches criticality


The No. 3 reactor at the Takahama nuclear plant in Fukui Prefecture reached criticality Saturday morning following its reactivation the previous afternoon, Kansai Electric Power Co. said.

The self-sustained fission reaction started at 6 a.m., according to Kepco, which serves western Japan. The reboot followed a hiatus of three years and 11 months prompted by the Fukushima disaster caused by the 2011 Great East Japan Earthquake and tsunami.

The company began removing the control rods, which are used to contain nuclear fission, from the 870,000-kilowatt reactor at 5 p.m. on Friday.

There are 157 fuel assemblies in the reactor, including 24 units of mixed oxide, or MOX, fuel, a blend of uranium and plutonium extracted from spent nuclear fuel.

The Takahama No. 3 unit is the first reactor in Japan to conduct so-called pluthermal power generation using MOX under new nuclear safety standards that were introduced by the government in July 2013.

The reactor is slated to start power generation and transmission on Monday. Kepco will raise the reactor’s output in stages while maintaining a close eye on the situation.

It is the third reactor operating under the new safety standards compiled based on lessons from the triple reactor meltdown at Tokyo Electric Power Co.’s Fukushima No. 1 nuclear power plant, which was heavily damaged by the 2011 earthquake and tsunami.

In August 2015, the No. 1 reactor at Kyushu Electric Power Co.’s Sendai nuclear power plant in Kagoshima Prefecture was brought back online to become the first to go operational under the stricter standards. The Sendai No. 2 reactor was reactivated in October the same year.

Kepco plans to start loading fuel into the No. 4 reactor at the Takahama plant on Sunday, hoping to restart it late next month.

On Friday, the utility said it expects to swing into a group net profit for the first time in five years in the fiscal year through March, helped by the reactor restart at Takahama.

At a news conference in Osaka, Kansai Electric President Makoto Yagi said the company aims to reduce electricity prices early in the new year beginning in April.

The utility expects to post a net profit of ¥150 billion for the current year, compared with a loss of ¥148.3 billion the previous year.

Kansai Electric’s earnings are expected to improve by ¥5 billion per reactor each month. It is also benefiting from falling fuel prices.

Kepco’s dependency on nuclear power was the highest of all Japanese power companies with nuclear plants before the Fukushima disaster.