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The Japanese government will spend $470 million on a subterranean ice wall and other steps in a bid to stop leaks of radioactive water from the crippled Fukushima nuclear plant after repeated failures by the plant’s operator.

The decision is an attempt to show the nuclear accident won’t be a safety concern just days before the International Olympic Committee chooses among Tokyo, Istanbul and Madrid as the host of the 2020 Olympics.

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The Fukushima Dai-ichi plant has been leaking hundreds of tons of contaminated underground water into the sea since shortly after a massive 2011 earthquake and tsunami damaged the complex. Several leaks from tanks storing radioactive water in recent weeks have heightened the sense of crisis that the plant’s owner, Tokyo Electric Power Co. (Tepco), isn’t able to contain the problem.

“Instead of leaving this up to Tepco, the government will step forward and take charge,” Prime Minister Shinzo Abe said after adopting the outline. “The world is watching if we can properly handle the contaminated water but also the entire decommissioning of the plant.”

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The government plans to spend an estimated $470 million through the end of March 2015 on two projects — $320 million on the ice wall and $150 million on an upgraded water treatment unit that should remove all radioactive elements except water-soluble tritium — according to energy agency official Tatsuya Shinkawa.

The government, however, is not paying for urgently needed water tanks and other equipment that Tepco is using to contain leaks. Shinkawa said the funding is for “technologically challenging projects” but the government is open to additional help when needed.

The ice wall would freeze the ground to a depth of up to 30 meters (100 feet) through a system of pipes carrying a coolant as cold as minus 40 degrees Celsius (minus 40 Fahrenheit). That would block contaminated water from escaping from the facility’s immediate surroundings, as well as keep underground water from entering the reactor and turbine buildings, where much of the radioactive water has collected.

The project, which Tepco and the government proposed in May, is now in the testing phase for feasibility by Japanese construction giant Kajima Corp. and, if feasible, set for completion by March 2015.

Similar methods have blocked water from parts of tunnels and subways, but building a 0.9-mile wall that surrounds four reactor buildings and their related facilities remains unprecedented.

An underground ice wall isolated radioactive waste at the U.S. Department of Energy’s former site of the Oak Ridge National Laboratory in Tennessee that produced plutonium, but only for six years, according to the MIT Technology Review magazine.

Some experts are still skeptical about the technology and say the running costs would be a huge burden.

Atsunao Marui, an underground water expert at the National Institute of Advanced Industrial Science and Technology, said a frozen wall could be water-tight but is normally for use for a few years and has never been a long-term solution. The decommissioning process will take about 40 years.

“We still need a few layers of safety backups in case it fails,” Marui said. “Plus the frozen wall won’t be ready for another two years, which means contaminated water would continue to leak out.”

Marui said there should be additional measures to stop contaminated water from traveling under the seabed during that time and leaking further out at sea.

Tepco has been pumping water into the wrecked reactors to cool nuclear fuel that melted when the March 2011 earthquake and tsunami knocked out the plant’s power and cooling systems. The utility has built more than 1,000 tanks holding 335,000 tons of contaminated water at the plant, and the amount grows by 400 tons daily. Some tanks have sprung leaks, spilling contaminated water onto the ground.

After spending on the ice wall, the remainder of the public funding will go to the development and production of a water treatment unit that can treat larger amounts of contaminated water more thoroughly than an existing machine, which is under repair after workers found corrosion during a test run.

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