Tokyo Electric Power Co said Thursday it has started freezing soil around damaged nuclear reactor buildings at the disaster-hit Fukushima plant, aiming to reduce the flow of groundwater into the highly contaminated facilities.
The Nuclear Regulation Authority on Wednesday gave the utility, known as TEPCO, permission to create a coolant-filled ice wall and start freezing soil on the east side facing the sea first and then 95 percent of the west side facing the mountains.
The work is expected to take more than three months to complete.
TEPCO began installing equipment needed to establish the ice wall in June 2014 around the Nos. 1 to 4 reactors at the plant, crippled by a massive earthquake and tsunami in 2011, and completed the work last month. The government provided about 35 billion yen ($309 million) for the project.
The power company plans to seek permission to extend the wall to cover the entire west side as well as the south and north sides after collecting data.
The 1.5-kilometer-long and 30-meter-deep wall is designed to stem a massive flow of groundwater from entering the basements of the reactor buildings and becoming mixed with leaked toxic water.
Freezing of a wall on an all sides of the plant is expected to take eight months if all goes smoothly.
Chief Cabinet Secretary Yoshihide Suga said the government “hopes the ice wall will stem the flowing of groundwater into the facilities at an early date.”
TEPCO and the government initially aimed to complete freezing the entire wall by the end of fiscal 2015 but the schedule was delayed due to prolonged discussions on safety measures.
The wall is expected to reduce the amount of groundwater flowing into the facilities every day to about 50 tons from the current more than 100 tons.
Still the effect of the ice wall, to become the world’s largest ground freezing project, remains unclear.
The NRA warned earlier that if the groundwater level within the wall is reduced excessively by stemming the flow from outside, highly contaminated water within the buildings could seep out as a result.
TEPCO said it will stop the freezing work or inject water into wells around the reactor buildings if the groundwater level inside the wall is likely to become too low.