A government-commissioned group of experts concluded Wednesday that a costly underground ice wall is only partially effective in reducing the ever-growing amount of contaminated water at Japan's destroyed Fukushima nuclear plant. The plant's operator, Tokyo Electric Power Co., says the ice wall has helped reduce the radioactive water by half. The plant also pumps out several times as much groundwater before it reaches the reactors via a conventional drainage system using dozens of wells dug around the area, per the AP. The groundwater mixes with radioactive water leaking from the damaged reactors. Contaminated water also results from rainwater that comes in contact with tainted soil and structures at the plant, which suffered meltdowns of three reactors after a March 2011 earthquake and tsunami.
The 1-mile, coolant-filled underground structure was installed around the wrecked reactor buildings to create a frozen soil barrier and keep groundwater from flowing into the heavily radioactive area. The ice wall has been activated in phases since 2016. On Wednesday, TEPCO said the amount of contaminated water that collects inside the reactor buildings was reduced to 95 tons per day with the ice wall, compared to nearly 200 tons without one. The panel agrees the ice wall helps, but members suggest additional measures be taken to minimize the inflow of rainwater and groundwater, such as repairing roofs and other damaged parts of buildings. Results from the recent dry season were positive, but members say heavy rainfalls caused spikes in the amount of contaminated water—an important thing to note ahead of typhoon season.