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Ice wall plan to halt radiation leaks
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The Japanese government announced yesterday that it will spend US$470 million on a subterranean ice wall and other steps in a desperate bid to stop leaks of radioactive water from the crippled Fukushima nuclear station after repeated failures by the plant’s operator.
The Fukushima Dai-ichi plant has been leaking hundreds of tons of contaminated underground water into the sea since shortly after the 2011 earthquake and tsunami struck.
Leaks from tanks storing tainted 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,” said Prime Minister Shinzo Abe after adopting the outline.
The government plans to spend an estimated 47 billion yen (US$470 million) through the end of March 2015 on two projects — 32 billion yen on the ice wall and 15 billion yen on upgraded water treatment units supposed to remove all radioactive elements but water-soluble tritium — said energy agency official Tatsuya Shinkawa.
The government, however, is not paying for water tanks that TEPCO is using to stop leaks.
The ice wall would freeze the ground to a depth of up to 30 meters through an electrical system of thin pipes carrying a coolant as cold as minus 40 degrees Celsius. That would block contaminated water from escaping 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 is being tested by Japanese construction giant Kajima Corp. and set for completion by March 2015.
Similar methods have been used to block water from parts of tunnels and subways, but building a 1.4 kilometer wall that surrounds four reactor buildings and their related facilities is unprecedented.
Some experts are skeptical about the technology and say running costs would be huge.
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 not proven for long-term use. The decommissioning process is expected to take about 40 years.
“We need safety backups in case it fails,” Marui said.
TEPCO has been pumping water into the reactors to keep cool nuclear fuel that melted when the March 2011 earthquake and tsunami knocked out its power and cooling system.
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.
Some 15 billion yen will go to producing a water treatment unit that can treat the contaminated water more thoroughly and by a larger volume.
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