Yomiuri Shimbun file photo
Tomari nuclear power plant
16:24 JST, November 29, 2025
SAPPORO — The process to restart the No. 3 reactor at Hokkaido Electric Power Co.’s Tomari nuclear power plant in Tomari, Hokkaido, is beginning to move more quickly.
While the four nearby municipalities, including the village of Tomari, where the plant is located, have shown their understanding for the restart, Hokkaido Gov. Naomichi Suzuki also announced his support for the restart at the prefectural assembly.
With the demand for electricity likely to increase in Hokkaido, expectations are high for a stable power supply and a reduction in electricity prices, which are currently the most expensive in Japan.
Diversifying power sources
“Securing sources of carbon-free power generation will contribute to Hokkaido’s economic growth and greenhouse gas reduction,” Suzuki said at the prefectural assembly.
One of the reasons for the approval is the anticipated surge in power demand in Hokkaido.
Rapidus Corp., a Tokyo-based semiconductor manufacturing plant, started operating in Chitose in the prefecture and has received substantial support from the central government. Meanwhile, Tokyo-based SoftBank Corp.’s plan to construct a large data center in Tomakomai is also underway.
Furthermore, HEPCO has shown its plan to reduce electricity fees by about 11% for households and about 7% for businesses after the restart of the Tomari plant. This will also provide favorable conditions for revitalizing the regional economy.
HEPCO has wanted to restart the plant for many years. The No. 3 reactor was shut down in May 2012. While all the three reactors at the plant have been shut down, HEPCO has been heavily relying on thermal power generation, which now accounts for about 80% of its power source.
However, the Hokkaido Eastern Iburi Earthquake in September 2018 damaged the Tomato-Atsuma thermal power station, HEPCO’s main plant in Atsuma, causing a large-scale blackout that affected 2.95 million households.
Diversifying its power sources has become a major challenge for the company.
With the restart of the No. 3 reactor, about 40% of the power generated is expected to come from nuclear power and about 40% is expected to come from thermal power.
The No. 3 reactor passed a safety screening by the Nuclear Regulation Authority in July.
“We have steadily gone through the steps,” a senior HEPCO official said, after the governor expressed his support for the restart. “We need to move forward with the remaining procedures required by the NRA and the construction of a seawall to protect the Tomari plant from a tsunami.”
With the reactor now one step closer to restarting, local business circles also have high expectations.
“Although Hokkaido has a lot of business opportunities, including with the operation of a cutting-edge semiconductor manufacturing plant and the planned construction of a data center, high electricity prices are burdening local businesses,” said Keigo Iwata, chairman of the Federation of Hokkaido Chamber of Commerce and Industry. “We appreciate the governor’s policy.”
Lack of experience
Thirteen years have passed since the nuclear plant stopped operations, and now, half of HEPCO’s nuclear power division staff have no experience operation nuclear reactors.
Although HEPCO has temporarily loaned its employees to Kansai Electric Power Co. and Shikoku Electric Power Co. to learn about the technology, the lack of experience is undeniable.
While HEPCO has created an evacuation plan in the event of a nuclear disaster, it is still working on securing bus drivers to evacuate residents.
Within Hokkaido, the first phase of selecting a final disposal site for high-level radioactive waste generated by nuclear power plants is underway in the town of Suttsu and the village of Kamoenai.
However, Suzuki has been opposed to moving on to the second phase. While benefitting from the restart, Hokkaido is also facing a problem regarding the disposal of nuclear waste.
“Gov. Suzuki supports the restart but has opposed approving a final disposal site for nuclear waste, so his lack of consistency on the topic will likely be questioned,” said Kentaro Yamamoto, a professor of political science at Kokugakuin University.
Even after obtaining the consent of local residents, which is essentially required before restarting, the prefecture and HEPCO must “respond meticulously regarding ensuring the effectiveness of safety measures and evacuation plans,” Yamamoto added.
AloJapan.com