Construction has begun on the "ice wall" at the shattered Fukushima Daiichi nuclear power plant, TEPCO announced today. This underground wall of frozen soil is intended to prevent groundwater from flowing into the reactor buildings, where it mixes with radioactive materials. Every day, about 400 tons of groundwater flows into the reactor basements.
Since the meltdowns of March 2011, TEPCO has been trying to capture this contaminated water, store it safely, and treat it to remove the radioactive materials. It's an understatement to say that the company has had some trouble with this process. Storage tanks have leaked, and it took a long time to get the water treatment systems working properly.
Stopping the contamination of groundwater is an important step in Fukushima Daiichi's 40-year decommissioning process. Right now, TEPCO is constantly building tanks to store the ever-accumulating water. Once the groundwater is kept out of the reactor buildings, TEPCO can focus on the radioactive water that's leaking out of the perforated reactors themselves.
In the video below, TEPCO explains that the ice wall technology is similar to that used in ice skating rinks. Pipes of coolant are inserted into the ground, which freeze the soil around them all the way down to the bedrock. The ice wall will redirect the groundwater around the damaged reactor buildings, letting it flow harmlessly to the sea. TEPCO plans to begin freezing the soil in March 2015.