Tokyo Electric Power Company (Tepco) said the leak had no impact on the wall or the environment.
The ice wall, in operation since 2017, is really more like a barrier of frozen soil. Built by Kajima Corp, it cost 34.5 billion yen ($303m) in public funds.
Tepco spokesperson Tsuyoshi Shiraishi said about four tonnes of the calcium chloride solution used to maintain the ice wall had leaked. “We’re now confirming the reason,” he said, according to the Japan Times.
The leakage was discovered on 16 January. Tepco said there may be damage to the pipes that make up the wall and it will need to carry out repairs.
The ice wall is intended to block groundwater from flowing into the reactor buildings. Groundwater entering the reactor buildings had been coming into contact with melted nuclear fuel and other debris from the March 2011 accident, resulting in an increasing amount of contaminated water.
The project involved 1,568 pipes that were placed into the ground 30 meters deep around the four reactor buildings to circulate liquid at minus 30 degrees and freeze the soil around them.