The Nuclear Regulation Authority (NRA) approved Hokkaido Electric Power’s Tomari Nuclear Power Plant Unit 3 under post-Fukushima regulatory standards on July 30, 2025, bringing Japan’s most recently commissioned reactor closer to restarting.
In its statement, Hokkaido EPCO said it plans to return the unit to commercial operation “as soon as possible in 2027.” Prior to the restart, the company will need to complete a new seawall that has been under construction since March 2024 and is expected to be finished in early 2027. It will also need to complete detailed engineering and construction plans for the safety upgrades and update its safety regulations.
Separately, it will need to secure local consent and resolve a lawsuit filed in 2011 claiming that Tomari’s countermeasures against natural disasters were insufficient. The court issued an injunction against the power plant’s operation and the appeal process is currently underway.
The Fukushima disaster led to Tomari’s shutdown in May 2012, less than three years after Unit 3’s December 2009 commissioning. Hokkaido EPCO applied for the reactor’s review under the new regulatory standards in July 2013. The process took significantly longer than for Kansai Electric Power’s Takahama Units 3 and 4 and Kyushu Electric Power’s Sendai Units 1 and 2, which applied around the same time and returned to commercial operation between 2015 and 2017.
Restarting Tomari, as well as other power plants that are still offline, is seen as critical to Japan having a chance of achieving the nuclear generation target outlined in the country’s 7th Basic Energy Plan. It is also key to securing enough capacity in the Hokkaido TSO area to meet an expected increase in demand due to the construction of new data centers and semiconductor manufacturing facilities.
Hokkaido EPCO also plans to return into service the older 579MW Units 1 and 2, which were commissioned in 1989 and 1991, respectively. According to its “2035 Management Vision,” it is currently targeting restarting them in the early 2030s.
