The Tomari Nuclear Power Plant is the only nuclear power plant in Hokkaidō, Japan. It is located in the town of Tomari in the Furuu District and managed by the Hokkaido Electric Power Company. All of the reactors are Mitsubishi designs. The Tomari Nuclear Power Plant was originally going to be located on an island and be named the Kyowa-Tomari NPP, but there was a change in plans and the location and name was changed.

Reactors on Tomari Nuclear Power Plant

Unit Type Commission date Electric Power
Tomari - 1 PWR June 22, 1989 579 MW
Tomari - 2 PWR April 12, 1991 579 MW
Tomari - 3 PWR December 22, 2009 912 MW


  • In 2000, a worker fell into a sump tank in the chemical control system of the plant. The worker received a high radiation dose and died in the hospital later.
  • In September 2003, there was a leak in the steam generator causing about 140 liters of primary coolant to leak.
  • In May 2005, there was a trespassing event where someone crossed the fence into the property. Some people had apparently been gathering bamboo sticks as a part of a part time job and when discovered, 24 arrests were made. There were all questioned due to strong concerns about terrorism at the plant.
  • Also in 2005, company sensitive information was leaked from a worker's computer by a virus.
  • In July 2007, there were three separate fires related to the new unit that was under construction. Electrical wiring had apparently been cut and foul play was expected. Coming just days after a more serious earthquake caused events at the Kashiwazaki-Kariwa plant, it dealt a further blow to Japan's nuclear power industry.
  • On September 29, 2007, Kazutoshi Michinaka reported that there was no radiation leakage, and no one was hurt in the small fire at the half-built third reactor at Tomari Nuclear Power Plant, Hokkaidō, Japan At least 7 arson cases have been reported at the construction site this year.
Tomari Nuclear Power Plant
Country Japan
Construction began April 18, 1985 (1985-04-18)
Commission date June 22, 1989 (1989-06-22)
Operator(s) Hokkaido Electric Power Company

Reactor information
Reactors operational 2 x 579 MW
1 x 912 MW

Power generation information
Annual generation 8,554 GW·h
Net generation 138,706 GW·h

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