Radioactive Nuclide Concentrations in Contaminated Water Below Standard... Tritium Concentration at 206 Bq per Liter

IAEA "Tritium Levels Below 1/40th of Japan's Standard"

As of the 25th, safety evaluation data, including the concentration of radioactive nuclides in the contaminated water to be discharged into the sea from the Fukushima Daiichi Nuclear Power Plant, were found to be within normal ranges and below the standard limits.

As of 11 a.m. on the 25th, the current status of discharge data published on the International Atomic Energy Agency (IAEA) webpage
[Image source=Yonhap News]

Japan is discharging contaminated water stored in tanks at the Fukushima Daiichi Nuclear Power Plant after processing it through a treatment system called ALPS (Advanced Liquid Processing System) to remove multiple radionuclides and then diluting it with seawater. Even after the ALPS treatment process, tritium, one of the radioactive nuclides, remains in the contaminated water, but Japan plans to dilute it with seawater to meet international safety standards.

Therefore, the tritium concentration in the diluted contaminated water immediately before discharge is a key indicator for evaluating the safety of the discharge. According to the webpage established by the International Atomic Energy Agency (IAEA) to disclose discharge data and safety evaluation details, as of 6 p.m. Korean time on the same day, the tritium concentration in the diluted contaminated water was measured at 206 becquerels (Bq) per liter.

The IAEA evaluated the tritium concentration of 206 Bq measured in the diluted water on that day as "less than 1/40th of Japan’s operational discharge limit." This is even lower than 1/40th of 1500 Bq/L, which Japan considers the regulatory concentration limit for discharged contaminated water. Compared to other international safety standards, this concentration is significantly low. The World Health Organization (WHO) sets the tritium concentration guideline for drinking water quality at 10,000 Bq/L.

At the same time, the radiation dose of the diluted water measured along the vertical axis was 5.1 CPS, the radiation dose of the ALPS-treated contaminated water was 5.2 CPS, and the radiation dose of the seawater used for dilution was 7.8 CPS. CPS is a unit measuring radiation intensity per second, and the IAEA reported that the radiation doses of the diluted water along the vertical axis, the treated contaminated water, and the seawater used for dilution are all within normal ranges and not at unexpected levels.

Additionally, the hourly inflow volume of seawater used for dilution was 15,223 cubic meters, and the flow rate of treated contaminated water was 19.03 cubic meters per hour, which the IAEA assessed as normal. The IAEA displayed green lights indicating normal levels for all six data points, including tritium concentration. If measurements are not conducted, a gray light is shown, and if abnormal values are detected, a red light is displayed.

This content was produced with the assistance of AI translation services.