Test operations have begun at Tomari 3, ahead of commercial operation in December this year.
Hokkaido Electric Power Company started building the pressurized water reactor in 2003. It will eventually produce 912 MWe alongside two 550 MWe models at the Tomari site, the only nuclear power plant on the northern island of Hokkaido.
The reactor reached criticality on 3 March, according to the Japan Atomic Industry Forum's Atoms in Japan publication, while World Nuclear News was told by a Hokkaido source that test operations followed on 20 March.
|Tomari (Image: Mugu-Shisai)
The three-loop Mitsubishi Heavy Industries unit is the last second-generation nuclear reactor to be built in Japan, with only later-design units planned for the future. An application has been made to the Ministry of Economy, Trade and Industry (Meti) for the unit to use up to 40 mixed-oxide (MOX) fuel assemblies.