Japan’s Nuclear Power Plants in 2026

Hamaoka Withdraws Restart Application

Due to expectations of increased electricity demand driven by the construction of generative AI data centers, the Japanese government’s February 2025 basic energy plan stated that it would make maximum use of the country’s existing nuclear power plants. In July 2026, it announced a policy to replace two to five nuclear reactors by the 2040s.

In January 2026, Tokyo Electric Power Company (TEPCO) restarted the number 6 reactor at its Kashiwazaki-Kariwa Nuclear Power Station in Niigata Prefecture for the first time in nearly 14 years, while Hokkaidō Electric Power is expected to bring its Tomari Nuclear Power Station back online in 2027.

Amid these developments, it came to light in January 2026 that Chūbu Electric Power had falsified data concerning earthquake resistance at its Hamaoka Nuclear Power Station in Shizuoka Prefecture. On September 14, the company announced the resignations of President Hayashi Kingo and Chairman Katsuno Satoru, as well as the withdrawal of its application for safety review to restart Hamaoka’s number 3 and number 4 reactors. In addition to making prospects for restarts uncertain, the scandal has rekindled public anxiety and distrust over nuclear power, in a setback to the government’s energy policy.

Nuclear Power Plants: Major Developments Since the Great East Japan Earthquake

September 2026  Chūbu Electric Power withdraws its application to restart reactors at its Hamaoka Nuclear Power Station in Shizuoka Prefecture.

July 2026  The Nuclear Regulation Authority announces that Chūbu Electric Power attempted to cover up evidence after the start of an investigation into seismic resistance tests at its Hamaoka Nuclear Power Station.

January 2026  TEPCO restarts the number 6 reactor at its Kashiwazaki-Kariwa Nuclear Power Station in Niigata Prefecture for the first time in 13 years and 10 months. This is the first restart for a reactor operated by TEPCO since the Great East Japan Earthquake in March 2011.

January 2026  Chūbū Electric Power announces that it may have underestimated expected seismic movement during safety reviews required for the restart of its Hamaoka Nuclear Power Station.

December 2025  Hokkaidō Governor Suzuki Naomichi approves the restart of Hokkaidō Electric Power’s Tomari Nuclear Power Station, with operations expected to resume in early 2027.

November 2025  Niigata Governor Hanazumi Hideyo approves the restart of TEPCO’s Kashiwazaki-Kariwa Nuclear Power Station, which is expected to resume operation within the fiscal year, at earliest. It will become the first active TEPCO nuclear plant since the 2011 Fukushima Daiichi nuclear accident.

February 2025  The government approves a new basic energy plan. This removes a phrase about minimizing dependence on nuclear power, which had been in the document since 2014, instead stating an intention to make the maximum use of existing plants.

December 2024  The number 2 reactor at Shimane Nuclear Power Station (Chūgoku Electric Power Company) resumes operation.

October 2024  The number 2 reactor at Onagawa Nuclear Power Station (Tōhoku Electric Power Company) resumes operation. It is the first plant in eastern Japan to restart after the 2011 Great Eastern Japan Earthquake.

October 2024  The Nuclear Regulation Authority approves Kansai Electric Power Company’s plans to continue operating Takahama Nuclear Power Station in Fukui Prefecture, Japan’s oldest nuclear plant, which will have been in use for 50 years in November 2024. It is the first time for a plant more than 50 years old to receive approval to operate under the present system.

September 2023  Restart of the number 2 reactor at Takahama Nuclear Power Station (Kansai Electric Power Company).

August 2023  Start of the release of treated water containing radioactive tritium that had accumulated at the number 1 reactor of Fukushima Daiichi Nuclear Power Station.

July 2023  The number 1 reactor at Takahama Nuclear Power Station resumes operation after a 12-year hiatus.

May 2023  The GX Decarbonization Power Supply bill is enacted. In order to ensure stable power supply and achieve decarbonization, significant changes are made to the safety regulations stipulating that the operating period for reactors is “40 years in principle and a maximum of 60 years,” making it possible for them to operate for periods of longer than 60 years.

June 2021  Mihama Nuclear Power Station (Kansai Electric Power Company) restarts operation for the first time since being shut down for routine inspection a decade before. At 44 years since it began operation, it is the first nuclear plant to restart despite being more than 40 years old.

July 2018  The cabinet approves the fifth energy basic plan, with the intention to have nuclear power account for 20%–22% of power generation in 2030.

March/June 2018  The number 3 and number 4 reactors at Genkai Nuclear Power Station (Kyūshū Electric Power Company) resume operation.

March/May 2018  The number 3 and number 4 reactors at Ōi Nuclear Power Station resume operation.

August 2016  The number 3 reactor at Ikata Nuclear Power Station (Shikoku Electric Power Company) resumes operation.

January/February 2016  The number 3 and number 4 reactors at Takahama Nuclear Power Station (Kansai Electric Power Company) resume operation.

August/October 2015  The number 1 and number 2 reactors at Sendai Nuclear Power Station (Kyūshū Electric Power Company) resume operation. These are the first restarts since the introduction of the new standards and follow almost two years without nuclear power in Japan.

April 2014  The cabinet approves the fourth energy basic plan, positioning nuclear power plants as an important base-load power source, while also pledging to reduce dependency on nuclear power as much as possible by introducing renewable energy.

July 2013  New regulatory standards relating to natural disasters and terrorist attacks introduced for nuclear power plants.

September 2012  Nuclear Regulation Authority established.

July 2012  The number 3 and number 4 reactors at Ōi Nuclear Power Station (Kansai Electric Power Company) resume operation, ending a 2-month period of no nuclear power generation in Japan.

June 2012  The operating period of nuclear power plants is limited to 40 years in principle.

May 2012  Tomari Nuclear Power Station (Hokkaidō Electric Power Company) suspends operation of its number 3 reactor. For the first time in 42 years there are no nuclear power plants operating within Japan.

March 2011  The Great East Japan Earthquake and TEPCO Fukushima Daiichi Nuclear Power Station accident take place.

Data Sources

• Data on Japan’s nuclear plants (Japanese) from the Federation of Electric Power Companies of Japan
• Data on Japan’s nuclear policy (Japanese) from the Agency for Natural Resources and Energy

(Translated from Japanese. Banner photo: Chūbu Electric Power’s Hamaoka Nuclear Power Station. © Jiji.)