Tokyo Electric Power Co. started freezing soil at the Fukushima No. 1 nuclear plant in trial operations for an underground wall aimed at preventing groundwater from flowing into the damaged reactors and becoming radioactive.
Tokyo Electric Power Co. started freezing soil at the Fukushima No. 1 nuclear plant in trial operations for an underground wall aimed at preventing groundwater from flowing into the damaged reactors and becoming radioactive.
The work was conducted at 18 points around the No. 1 through No. 4 reactor buildings on April 30 for the first time since the project started last June.
TEPCO plans to eventually create a 1,500 meter-long frozen soil wall around the reactors by circulating liquid of minus 30 degrees inside pipes 30 meters deep at 1-meter intervals. Under the project, the wall will divert the clean groundwater away from the plant and into the ocean, thereby stemming the daily accumulation of radioactive water at the plant.
The company says it will start creating the complete frozen soil wall after the tests are completed at the 18 points, where surrounding piping and other factors will likely make it difficult to freeze the soil.
But it is unclear when TEPCO will be able to begin the full operations.
In the trial run, TEPCO will use 58 underground pipes to freeze soil over a 60-meter distance on the mountain side of the nuclear facility. The company will monitor changes in temperature and groundwater levels near the test sites.
The trial operations, which are expected to take weeks to complete, are intended to determine if the method can create frozen walls even in locations with nearby structures and large volumes of groundwater.
TEPCO originally planned to start the freezing process of the entire 1,500-meter frozen wall by the end of March. But delays in preparatory work near the ocean, as well as a suspension of operations associated with safety checks following a worker’s death in January, pushed back the scheduled date.
In addition, the Nuclear Regulation Authority has required the utility to carefully examine the effectiveness of the project, so TEPCO decided to conduct the test operations before fully introducing the underground wall.