The operator of the damaged Fukushima Daiichi nuclear plant has begun the fifth round of the release of treated and diluted water into the ocean.
Tokyo Electric Power Company began the discharge shortly after 11:00 a.m. on Friday.
It plans to release about 7,800 tons of water through early May.
The Fukushima Daiichi plant suffered a triple meltdown in the 2011 earthquake and tsunami.
Water used to cool molten fuel has been mixing with rain and groundwater seeping into the crippled reactor buildings.
The accumulated water is being treated to remove most radioactive substances, but still contains tritium. The treated water is being stored in more than 1,000 tanks at the plant.
Before releasing the treated water into the ocean, the utility dilutes it to reduce the tritium levels to about one-seventh of the World Health Organization's guidance level for drinking water.
TEPCO began the first round of the water discharge in August last year. A total of 31,145 tons of treated and diluted water was released in four rounds through March.
These past four rounds were completed without major problems, and tritium levels in seawater sampled from around the plant have remained far below the mark at which TEPCO will voluntarily decide to stop the outflow.
For fiscal 2024, which began in April, the utility plans to conduct a total of seven releases, with six from April to October and one from February to March, totaling roughly 54,600 tons of water.