Reversing an earlier assessment, the Nuclear and Industrial Safety Agency admitted an active and dangerous fault may be lurking directly beneath one of the two reactors of the Tsuruga nuclear plant in Fukui Prefecture.
The surprising judgement by NISA, announced Tuesday night, would force Japan Atomic Power Co. to decommission the plant's reactor 2 if the fault is confirmed as active.
NISA would also find it difficult to restart reactor 1. Both reactors were shut down for regular checks, but have not been restarted in light of the meltdown crisis that hit the Fukushima No. 1 plant in March 2011. In light of the Fukushima crisis, all reactors are subject to stress tests to gauge their disaster survivability.