The underground ice wall defending Fukushima’s nuclear power plant

The maze-like industrial landscape inside Fukushima Daiichi is complex and disorienting. 

Among the scattered debris, buildings overgrown with weeds and abandoned equipment, our bus pulls up alongside an intricate network of small metal pipes and scaffolding that blends into the cluttered landscape.

This is the Ice Wall — the critical front-line defense against Fukushima Daiichi's radioactivity spreading around the world.

Coolant running through the network of pipes freezes the soil into an impermeable ice wall that's nearly 100 feet deep and a mile long, encircling the reactors.

The crumbling structure of the Unit 2 reactor at Fukushima Daiichi Nuclear Power Center, where radiation is still extremely high.

The groundwater flowing toward the sea from the mountains to the west was entering Fukushima Daiichi and mixing with the toxic water leaking out of the Unit 1, 2 and 3 reactors. 

By freezing the ground with the ice wall, the clean groundwater is kept from mixing with the contaminated water leaking from the reactors.  

Outside of Unit 3, we walk along the Ice Wall, inside the perimeter where the ground has been frozen to prevent further contamination.

The coolant filled pipes forming the frozen-soil barrier that keeps the fresh groundwater running toward the sea from mixing with the contaminated water from the damaged, leaking reactors.

The $300 million structure uses a coolant to freeze the soil down to minus 30 degrees Celsius, blocking the groundwater flowing toward the coast.

The coolant-filled pipes form the frozen-soil barrier that keeps the fresh groundwater running toward the sea from mixing with the contaminated water from the damaged, leaking reactors.

A hole dug on the outside of the Ice Wall perimeter shows the high groundwater table. A similar hole on the inside of the perimeter illustrates the lower water level and thus the effectiveness of the Ice Wall's intent.

Water leaking from the damaged reactors has to be stored on site at Fukushima Daiichi. 

The fuel rods in the three damaged radioactive units need to be continuously cooled with fresh water, but Tepco must collect and store the leaking (and now contaminated) water.

In the eight years since the accident, that has meant Tepco has collected more than 1.1 million tons of leaking, contaminated water.

Where does it all go? There are currently 900 huge silos on site and counting. Tepco estimates it has enough space in the 37.7-million-square-foot facility to house an additional 270,000 tons of water, which means it will run out space to store any more water sometime in 2020.

The Ice Wall is part of the solution to this problem. Less ground water mixing with contaminated water means then less contaminated water to store in the finite amount of space available.

Workers among the maze of valves and pipes inside the water purification facility at Fukushima Daiichi handle decontamination of radioactive water.

Tepco's on-site purification process at the Advanced Liquid Processing System is able to remove 62 radioactive elements from the contaminated water used in the cooling Fukushima Daiichi's reactors. Remaining in the water is tritium, a lesser radioactive element that is more complicated to remove from water in purification processes. 

A technician monitors the Ice Wall operations from a building at the Fukushima Daiichi facility.

From an ultra-clean environment in the water treatment analysis center, glass beakers containing sea water and groundwater and water from the Advanced Liquid Processing System facilities.