Photo/Illutration Kansai Electric Power Co.’s existing Mihama nuclear power plant (Asahi Shimbun file photo)

Kansai Electric Power Co. will build a new nuclear power plant in Mihama, Fukui Prefecture, the company announced on July 22.

The new plant will have a next-generation advanced light water reactor, an improved version of a conventional light water reactor, KEPCO President Nozomu Mori said at a news conference. 

The company said it has decided to embark on the first step: a geological survey of its existing Mihama nuclear power plant and the land nearby.

KEPCO was expected to notify the governments of Fukui Prefecture and Mihama town, where the current plant is located, by the end of the day.

This is the first concrete move by a major electricity utility to build a nuclear power plant since the 2011 triple meltdowns at the Tokyo Electric Power Co.'s Fukushima No. 1 nuclear power plant.

Mass evacuations and the difficult clean-up led to a surge of anti-nuclear sentiment, but under Prime Minister Fumio Kishida the government shifted toward allowing the construction of new nuclear power plants on a conditional basis.

In February this year the government revised its basic energy plan, deleting a line that vowed to “reduce dependence on nuclear power as much as possible.” That phrase was added after the Fukushima accident.

Moreover, utilities have now secured a range of government support measures for the construction of nuclear power plants.

Mori said the company sees strategic value in this.

“In resource-poor Japan, it is important that nuclear power continue to play its role in the future from the perspective of S plus 3E,” Mori told reporters at the company’s headquarters in Osaka.

The term “S plus 3E” refers to safety, energy security, economic efficiency and the environment.

“We have come to the conclusion that we need to resume our voluntary site survey,” he said.

The Mihama plant was KEPCO’s first nuclear power plant. Its No. 1 reactor began operation in 1970, feeding some of its output to the Osaka Expo that year.

By 2010, the No. 1 reactor was aging. KEPCO began a survey looking at the viability of rebuilding it but the survey was suspended a year later in the wake of the Fukushima disaster.

In 2015, the reactor’s fate was sealed when the decision was taken to decommission it.

At the time, KEPCO said that the geology and topography at the Mihama plant would be examined in a study that would take about a year to complete.

However, the Fukushima accident led to the creation of the Nuclear Regulation Authority and new safety standards. The regulations have become stricter, so the content and duration of the survey will be examined “on a zero basis,” a source said.

Construction of a new nuclear power plant is estimated to take 15 to 20 years. It will cost more than 1 trillion yen ($6.8 billion) per unit, including preliminary environmental impact studies.

When the operating period and subsequent decommissioning work are factored in, the time horizon on such a project is about 100 years.

As for reactor type, Mori said it will be an advanced light water reactor.

In September 2022, KEPCO teamed with Mitsubishi Heavy Industries Ltd. and three major electric power companies to jointly develop an advanced light water reactor called the SRZ-1200, with the aim of commercializing it in the mid-2030s.

Based on lessons learned from the Fukushima accident, the reactor will be equipped with a device called a core catcher, which would contain and cool the fuel in the event of a meltdown.

Meanwhile, the nuclear power sector is also watching the plans of Kyushu Electric Power Co., which owns the Genkai and Sendai nuclear power plants.

In May, the company included “consideration of the development and installation of next-generation advanced reactors” in its management vision for the period to 2035.

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