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 Tepco permission to create a coolant-filled ice wall and start freezing soil on the east sea-facing side of the plant followed by 95 percent of the west side facing the mountains.
The work is expected to take more than three months to complete.
The plant was crippled by a massive earthquake and tsunami in March 2011.
In June 2014, Tepco installing equipment needed to establish the ice wall around the No. 1 to No. 4 reactors.
The work was completed in February, with the government funding some ¥35 billion ($309 million) of the project.
The utility plans to seek permission to extend the wall to cover the entire west side as well as the south and north sides of the plant 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 mixing with leaked toxic water.
The complete freezing 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 flow 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 more than 100 tons currently.
Still, the effectiveness of the ice wall, which would be 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.
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.
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