The Japanese Nuclear Regulation Authority deemed Tsuruga-2 in Fukui Prefecture unfit for a restart citing the risk of a fault moving directly below the reactor, NHK broadcaster reported.
The reactor was mothballed in March 2011 in response to a powerful earthquake that triggered a tsunami that caused a meltdown at the now defunct Fukushima power plant.
The nuclear safety authority determined that the findings provided by Tsuruga's operator lacked scientific proof, indicating that there remained a possibility of the rupture being dragged into activity by some other seismic event in the future.