The operator of the crippled Fukushima Daiichi nuclear power plant has begun a boring survey to build an undersea tunnel for releasing treated water from the facility.
The water, used to cool molten nuclear fuel, is treated to remove most radioactive materials, but still contains radioactive tritium and other radioactive materials.
Japan's government plans to release the water into the ocean around spring of 2023, after diluting it to below levels set in national regulations.
Ahead of the construction, Tokyo Electric Power Company, or TEPCO, began drilling the seabed on Tuesday afternoon 700 meters offshore from the plant.
TEPCO plans to conduct more boring surveys 400 meters and one kilometer offshore.
The firm plans to dig as much as 21 meters into the seabed at the deepest site and take samples of mud and rocks to examine their components and hardness.
The surveys are expected to take 5 to 10 days for each location. TEPCO plans to use the resulting data to determine the route of the tunnel.
Local communities and critics are voicing concerns that the planned discharge could cause spreading of misinformation about the safety of local marine products.
