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It will take until March 2015 to build, cost $320 million and use enough power each day to run 3300 Japanese households. Yet the country’s government this week decided a wall of ice is the best solution to stem the flow of radioactive water leaking from Fukushima Daiichi’s four stricken nuclear reactors.

The wall is the centrepiece of a $470 million drive to stop 400 tonnes of groundwater being contaminated every day. It is currently being stored in an ever-increasing number of huge tanks.

Kajima Corporation will build the 1.4-kilometre wall by sinking pipes carrying freezing fluids into the ground, gradually freezing it to form a barrier of permafrost 30 metres deep, down to the bedrock. This will force the water to drain into the sea instead.

, in projects to secure mine shafts and contain contamination, for example. The cost of the project includes $150 million to reduce contamination of the stored water so it can be dumped at sea, a strategy backed by the International Atomic Energy Agency.

This article will appear in print under the headline “Icing Fukushima”