Tokyo Electric Power Co. announced completion Monday of a 780-meter coastal wall along the heavily damaged reactor buildings of the Fukushima No. 1 nuclear power plant.

Tepco hopes the wall will significantly reduce the amount of contaminated water that has continued to flow into the Pacific more than four years after the 2011 meltdown crisis.

The gigantic wall, which the utility describes as impermeable, has an underground section that reaches as deep as 30 meters. It will reduce the amount of tainted water flowing into the sea from 400 tons to 10 tons a day, according to Tepco's estimate.