The International Information Center for Structural Engineers

Thursday, 05 June 2014 10:41cat

Japan Begins Building Ice Wall at Fukushima Nuclear Plant

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Workers perform testing on a small-scale ice wall Workers perform testing on a small-scale ice wall Reuters

Construction is underway on a 1.5-kilometer long ice wall surrounding the Fukushima Nuclear Plant in Japan. The ice wall will prevent ground water flowing from nearby hills from mixing with the polluted soil beneath the nuclear plant. It is estimated that 400 tons of groundwater passes underneath the reactor’s basement each day. The chemicals used to cool the reactor have seeped through cracks into the basement walls and pipes and have contaminated the soil. The project, which began on Monday, will be completed in March 2015. The Japanese government is funding the project, which is expected to cost $313 million to construct. The owner and operator of the plant, Tokyo Electric Power, will conduct several months of testing on the ice wall once it is completed to ensure that it is working properly.  Tokyo Electric Power plans to maintain the ice wall for over a hundred years.

Ice wall technology is used on many civil engineering projects, especially tunnel projects near waterways. The Fukushima ice wall will be the largest in the world once completed, and the technology has not been used before for the proposed length of time for the Fukushima cleanup. Officials were also worried that the frozen soil would cause the ground to shrink and affect the stability of the reactors. After small-scale testing was successfully performed, the project received approval to begin last week from Japan’s Nuclear Regulation Authority. 

Tokyo Electric Power will construct the ice wall by drilling 30-meter deep holes into the ground. Over 1500 pipes will be inserted into the holes and refrigerant will be pumped through the pipes. The refrigerant will cool the soil and make it impermeable. The 1.5-kilometer wall will surround reactors 1 and 4.

The Japanese government already has a system in place that diverts ground water around the reactor. This system reduces the amount of groundwater flowing underneath the nuclear plant to 300 tons per day. Another impermeable wall has been built between the reactors and the sea. Once the ice wall is completed and tested, Japan expects there to be no more ground water traveling below the nuclear plant.


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