TEPCO to use frozen contaminated soil to stop groundwater leakage

The Japanese central government has ordered Tokyo Electric Power Co (TEPCO) to freeze the contaminated soil that surrounds the damaged No.1 nuclear power station in Fukushima in an attempt to stop groundwater entering the reactor. The nuclear plant was damaged in the earthquake and tsunami of 2011 and has since suffered problems with groundwater becoming contaminated with radioactive substances when it enters the damaged reactor.

The decision came following a government committee proposal being submitted to Toshimitsu Motegi, industry minister. The committee had been discussing possible measures that could be implemented in an attempt to stop the groundwater problem. TEPCO was then ordered to carry out the plan as detailed in the proposal.

TEPCO has said that the measures described by the proposal will be technically difficult to implement, but that the company will carry out the orders from the government; along with other measures that were detailed in the proposal.

The Agency for Natural Resources and Energy has said that Kajima Corp was the company that suggested the procedure. The construction company came up the idea to use walls of frozen soil around the damaged plant to stop the flow of groundwater. If the groundwater can be directed elsewhere it will reduce contamination from radioactive materials.

The procedure will entail ducts of around 30 metres deep to be inserted into the ground surrounding the reactor buildings. The ducts will be placed at one metre intervals. Coolants will then be circulated through the ducts. The coolants will be at temperatures of around minus 50 degrees, which should freeze the surrounding soil and create the wall.

Creating a frozen underground wall should be able to successfully block more of the groundwater than a wall made of crushed stones or clay. Although these types of walls could be constructed more quickly and would be much cheaper, the government has selected the option of freezing the soil as it will work better in the long run.