The Ōi Nuclear Power Plant , also known as Oi or Ohi, is a nuclear power plant located in the town of Ōi, Fukui Prefecture, managed by the Kansai Electric Power Company. The site is 1.88 square kilometers. Ōi Units 3 and 4 were taken offline in September 2013. In December 2017 Kansai Electric Power announced that it will decommission reactors no. 1 and 2 because of their age and the difficulty of making safety upgrades within their small containment vessels. Unit 3 was restarted on 14 March 2018, and unit 4 was restarted on 9 May 2018.

Ōi is a town located in Fukui Prefecture, Japan. As of 1 June 2018, the town had an estimated population of 8,102 and a population density of 63 persons per km2. The total area of the town was 212.19 square kilometres (81.93 sq mi). It is one of the few Hiragana towns in Japan.