Experts appointed by the Nuclear Regulation Authority started a field survey Saturday to check for active faults running directly beneath the two reactors of the Tsuruga nuclear plant in Fukui Prefecture.
The NRA fears that the major active Urazoko fault, which already has been confirmed to lie only 250 meters away from the reactor buildings, could trigger smaller faults underneath the two units if it were to shift.
Past investigations have suggested that several faults running underneath reactors 1 and 2 extend from the Urazoko fault, raising fears about another disaster on the scale of the Fukushima meltdowns. If the NRA decides the reactors were constructed above faults that could move in the future, Japan Atomic Power Co. would likely be prevented from ever restarting them and could be forced to decommission the two units.