The Mainichi Shimbun answers some common questions that readers may have about the treated water from the Fukushima Daiichi Nuclear Power Station.
Answer: On May 18, a committee of experts examining the safety of nuclear power plants approved a plan to release treated water into the ocean, which has been accumulating at the Tokyo Electric Power Company Holdings Inc.'s TEPCO Fukushima nuclear plant since the March 2011 disaster.
Water is still being used to cool the fuel debris that was melted down in the 2011 accident, inside the building where the crippled nuclear reactor is located. When water mixes with groundwater that continues to flow into the building, it becomes contaminated with radioactive materials. The concentration of radioactive materials is lowered using special equipment, and the result is treated water. A radioactive substance called tritium can't be removed technically.
More than 1,000 tanks are lined up at the site because the amount of treated water continues to increase. TEPCO will not be able to store any more water because there is no more available space left.
A: TEPCO had stated that the tanks would be full in the spring of 2023, but in April it announced that they would be full by the summer or fall of 2023.
A: The amount of contaminated water generated was estimated to be about 150 cubic meters per day, equivalent to 750 oil drums in fiscal 2021, but in fiscal 2021 it decreased to about 130 cubic meters, leaving more room in the storage capacity of the tanks.
Q: Is the treated water released directly into the ocean?
If necessary, specialized equipment will be used to reduce the concentration of radioactive materials to below the national standard. Even so, the water will still contain tritium, so a large amount of seawater is added to dilute the tritium to less than 1 40 of the national standard before it is released. TEPCO says that the concentration will be lower than the World Health Organization standard for drinking water.