03/30/2016 05:35 EDT | Updated 03/31/2017 01:12 EDT

Japan regulators OK costly ice wall at Fukushima plant

TOKYO — Japanese regulators on Wednesday approved the launch of an unprecedented refrigeration structure resembling giant popsicles that would form a huge underground frozen barrier around the wrecked Fukushima nuclear reactor buildings in a desperate bid to contain contaminated water.

The Nuclear Regulation Authority said the structure, whose construction was completed last month, can now be activated.

The plant's operator, Tokyo Electric Power Co., said it planned to turn on the ice wall Thursday, in an attempt to minimize the risk of contaminated water escaping into the water.

The nearly 800,000 tons of water already stored in 1,000 huge industrial tanks at the plant has been hampering the decontamination of the nuclear facility since the 2011 quake and tsunami.

The plan has been delayed for more than a year because of technical uncertainties. Some experts are still skeptical about the technology and question whether it's worth the huge costs.

The authority Chairman Shunichi Tanaka cautioned against high expectations because the project in part relies on the nature. "It would be best to think that the natural phenomenon doesn't work the way you would expect."

The 35 billion yen ($312 million) government-funded project comes with pipes dug 30 metres (100 feet) underground and designed to freeze soil around them like giant popsicles. They are supposed to form a 1.5-kilometre (0.9 mile) long wall around the reactor and turbine buildings to contain radioactive water in the area and keep out groundwater.

Similar methods have been used to block water from parts of tunnels and subways, but the structure that huge surrounding 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.

A test using part of the ice wall has effectively frozen the ground around it, and officials hope that the ice wall would be successfully formed within several months, according to Shinichi Nakakuki, a spokesman for the utility known as TEPCO.

TEPCO officials say they hope the ice wall would effectively cut down the groundwater inflow into the area to about one-eighth of what it used to be and eventually dry up the turbine basements by 2020, confining the contamination only to the three melted reactors.

Mari Yamaguchi, The Associated Press