Tokyo Electric Power Co. said Thursday it has started freezing soil around damaged nuclear reactor buildings at the disaster-hit Fukushima plant, aiming to reduce the flow of groundwater into the highly contaminated facilities.

The Nuclear Regulation Authority on Wednesday gave Tepco permission to create a coolant-filled ice wall and start freezing soil on the east sea-facing side of the plant followed by 95 percent of the west side facing the mountains.

The work is expected to take more than three months to complete.