Seams not checked for 25 years at Shika
Seams beneath the Shika nuclear plant were judged safe 25 years ago, and have not been reassessed since.

Hokuriku Electric, the operator of the Shika plant, applied for government permission to build the plant's No.1 reactor in January 1987.

The utility decided the seven underground breaches, including the one at issue, in the area were not a hazard, and the industry ministry agreed based on its own safety assessment. The ministry is in charge of nuclear power plants.
[link to www3.nhk.or.jp]
.