Background to preparations for the discharge of treated water from the Fukushima Daiichi nuclear power plant

On 22 August 2023, the Japanese government asked Tokyo Electric Power Company (Tepco) to begin preparations for discharging treated water into the ocean. The water has so far been stored at the site of the damaged Fukushima Daiichi nuclear power plant. The discharge of treated water from the Fukushima Daiichi nuclear power plant began on 24 August 2023.

At the Fukushima Daiichi plant, contaminated water, some of which is used to cool the melted nuclear fuel, is treated using the ALPS (Advanced Liquid Processing System). The system removes most radioactive substances, with the exception of tritium. This treated water is now stored in more than 1,000 tanks at the plant site. The tanks have a total capacity of approximately 1.37 million cubic metres, and are expected to be full by the end of 2023 or early 2024.

Water discharge plan

In April 2021, Japan announced plans to gradually discharge the treated water stored at the site into the sea over a period of around 30 years. At a meeting of the interministerial council on Tuesday, the government announced that it had decided to begin discharging water treated by the ALPS system into the sea.