Work has begun in Japan on a huge underground ice wall to prevent the contamination of water at the wrecked nuclear reactors at Fukushima.
The plant experienced several leaks of radioactive water since being crippled by an earthquake and tsunami in 2011, and the wall is intended to stop nearby groundwater from seeping into the plant and mixing with contaminated water inside.
The 1.5km wall will be made by inserting 1550 pipes into the ground. Coolant circulating in the pipes will freeze the surrounding soil.
Some experts, including an American adviser assisting Japan with Fukushima clean-up efforts, have expressed doubts over whether the project will work.
Nothing on this scale has been tried before, and keeping the ground frozen in an area with summer temperatures close to 40 degrees celsius may be very hard, the BBC reports.
The 2011 disaster knocked out cooling systems to the nuclear plant's reactors, three of which melted down.
Water is now being pumped in to cool the reactors, but storing the resultant large quantities of radioactive water has proved a challenge for plant operator Tepco.
Last month, Tepco began releasing groundwater into the sea after checking its radiation levels.