October 28, 2021
As a countermeasure to reduce the amount of contaminated water from the Fukushima Daiichi Nuclear Power Plant, it was found that the temperature of the ground in some parts of the “frozen soil wall”, which freezes the ground around the buildings to prevent the inflow of underground water, has been rising above 0 degrees Celsius since the middle of last month, reaching a maximum of 10 degrees Celsius. The Tokyo Electric Power Company (TEPCO) is investigating the cause of the problem, saying that it does not affect the function of the wall to prevent the inflow of underground water.
The “frozen earth wall” is one of the measures to reduce the amount of contaminated water. Pipes are embedded around the buildings of the Fukushima Daiichi Nuclear Power Plant, and liquid at 30 degrees below zero is poured into the pipes and frozen, forming an “ice wall” that prevents groundwater from flowing into the buildings.
The Tokyo Electric Power Company (TEPCO) has installed thermometers in the “frozen earth wall” to measure the underground temperature, and in some areas located on the mountain side of the No. 4 reactor at the Fukushima Daiichi Nuclear Power Plant, the temperature, which is usually below freezing, has been rising and has been above zero since the middle of last month.
The temperature in the area where the increase was confirmed was between 1 meter and 4 meters deep, and the temperature exceeded 10 degrees Celsius on some days.
The freezing wall is about 10 meters thick, and TEPCO has stated that there is no significant difference in the water level between the inside and outside of the wall, so there is no impact on its ability to control the inflow of groundwater.
It is possible that water leaked from cracks in the drainage channel that intersects the frozen soil wall and seeped into the frozen area, causing the temperature to rise.