FUKUI – Wooden boxes containing 800 kg of power transmission insulators fell Tuesday from a helicopter flying over the town of Mihama, Fukui Prefecture, Kansai Electric Power Co. said.
No one was injured in the accident, the utility said.
Recognizing it as a potentially serious incident, the Land, Infrastructure, Transport and Tourism Ministry let Japan Transport Safety Board inspectors launch an on-site investigation.
According to Kepco, 18 of 36 wooden boxes with power line tower insulators dropped from the helicopter operated by Tokyo-based Aero Asahi Corp. in the mountains about 700 meters from the heliport in the town at 10:10 a.m. (1:10 a.m. GMT). The boxes were hung in two bundles with ropes from the helicopter, which was headed for a tower construction site some 2.1 km from the heliport.
The power supplier for the Kansai region has been installing transmission lines between its Mihama nuclear power plant and a substation in the same town since 2013.
In a separate power line construction work by Kansai Electric last October, an empty box fell from a helicopter operated by Nakanihon Air Service Co., based in Aichi Prefecture, in the courtyard of the utility’s training center for nuclear plant workers in the Fukui town of Takahama.
Tuesday’s accident followed the automatic shutdown of the restarted reactor 4 at Kansai Electric’s Takahama nuclear power plant the previous day and the cooling water leakage at unit 4 on Feb. 20 before the restart on Friday.