Tokyo Electric Power Company (TEPCO), the operator of Japan's crippled Fukushima nuclear power plant, has discovered that a coolant solution used to create an ice wall halting groundwater seepage into the reactor buildings has leaked from two storage tanks, Reuters reported on Sunday.
The company claims that there has been no impact on the wall or the environment, according to the report.
Still, it underscores the unpredictable challenges in the clean-up of the site, nearly 11 years after an earthquake and tsunami ravaged Japan's northeastern coast, causing the world's worst nuclear disaster since the Chernobyl accident in 1986.
On Sunday, TEPCO spokesperson Tsuyoshi Shiraishi said about four tonnes of a calcium chloride solution used to maintain the ice wall had leaked for the eighth time.
In the last such accident in December 2019, 16 tonnes spilled, likely due to metal fatigue resulting from vibrations caused by construction vehicles, Shiraishi said, adding that TEPCO is "now confirming the reason."
There was no immediate impact on the wall's function as it takes several months for the wall to thaw in the absence of coolant, he said.
Work on the underground frozen wall around unit 1-4 began in June 2014 to block the flow of groundwater into the plant's basements, according to China Media Group.
The 1.5-kilometer wall, which became operational in 2017, is made up of 1,568 pipes filled with a refrigerant and inserted 30 meters underground, turning the soil into a solid mass.
Only last year, Japan's government approved the release of over 1 million tonnes of irradiated water from the site after treatment, starting around spring 2023. TEPCO last month said it would build a tunnel reaching into the sea for the operation.
Separately, a group of six men and women is set to file on January 27 a lawsuit against TEPCO claiming they developed thyroid cancer due to exposure to radiation from the Fukushima disaster, the Mainichi newspaper reported.
(With input from Reuters)