TOKYO — Japanese regulators on Wednesday approved the use of a giant refrigeration system to create an unprecedented underground frozen barrier around buildings at the wrecked Fukushima nuclear plant in an attempt to contain leaking radioactive water.
The Nuclear Regulation Authority said the structure, which was completed last month, can now be activated.
The plant’s operator, Tokyo Electric Power Co., said it plans to turn on the ice wall on Thursday, starting with the portion near the sea to prevent more contaminated water from escaping into the Pacific Ocean. The system will be started up in phases to allow close monitoring and adjustment.
Nearly 800,000 tons of radioactive water that is already being stored in 1,000 industrial tanks at the plant has been hampering the decontamination and decommissioning of the nuclear facility, which was damaged by a massive earthquake and tsunami in 2011.
The success of the ice wall is believed to be key to resolving the plant’s water woes.
The $312 million government-funded project, proposed by construction giant Kajima Corp., is more than a year behind schedule because of technical uncertainties. Some experts are still skeptical of the technology and question whether it’s worth the huge cost.
The project consists of refrigeration pipes dug 100 feet underground that are designed to freeze the soil around them. They are supposed to form a 0.9-mile wall around the reactor and turbine buildings to contain radioactive water and keep out groundwater.
At a meeting Wednesday of the nuclear agency, Chairman Shunichi Tanaka cautioned against high expectations because the success of the project depends in part on nature. “It would be best to think that natural phenomena don’t work the way you would expect,” he later told reporters.
Similar methods have been used to block water from parts of tunnels and subways, but a structure large enough to surround four buildings and related facilities is untested. A smaller wall was used to isolate radioactive waste at an U.S. Department of Energy laboratory in Tennessee but only for six years. The decommissioning of the Fukushima plant is expected to take decades.
TEPCO officials say they hope the ice wall will stop most of the flow of groundwater into the area and allow the turbine basements to be dried by 2020, confining the contamination to the three melted reactors.