Tritium Concentration in Pacific Ocean Remains Negligibly Low Despite Fukushima Daiichi Nuclear Power Plant Releases

Scientists from the Institute of Industrial Science, The University of Tokyo, and Fukushima University have conducted a numerical modeling study to assess the impact of tritium-rich water releases from the Fukushima Daiichi Nuclear Power Plant (FDNPP) on the Pacific Ocean. The study, which simulated the discharge of Advanced Liquid Processing System (ALPS)-treated water, found that the concentration of tritium in the ocean remains very low and negligible. The researchers found that the simulated increase in tritium concentration in the Pacific Ocean due to the tritium originating from the ALPS-treated water is about 0.1% or less of the tritium background concentration of 0.03-0.2 Bq/L in the vicinity of the discharge site. This is far below the WHO international safety standard of 10,000 Bq/L and consistent with results of tritium concentration monitoring in seawater conducted in conjunction with the discharge of ALPS-treated water.

Key Takeaways:

The study simulated the discharge of ALPS-treated water from the FDNPP into the Pacific Ocean using a realistic discharge scenario and for a period long enough to consider long-term impacts.
The researchers found that the concentration of tritium in the ocean remains very low and negligible, with a simulated increase of about 0.1% or less of the tritium background concentration of 0.03-0.2 Bq/L.
The study's results are consistent with the WHO international safety standard of 10,000 Bq/L and the results of tritium concentration monitoring in seawater conducted in conjunction with the discharge of ALPS-treated water.
Climate change and eddies in the water currents speed up the tritium movement through the ocean, but the researchers found that the concentrations of tritium from ALPS-treated water discharge remain similar and very low.
The study's findings may help in building models to understand how tritium, as tritiated water molecule, moves through water vapor and ocean water, and can be used to trace the dynamics of the water cycle.
The researchers from the Institute of Industrial Science, The University of Tokyo, and Fukushima University, including Alexandre Cauquoin and Maksym Gusyev, contributed to this study.

Statistics:

The FDNPP has been pumping water to cool nuclear reactors since the accident in 2011 and treating this cooling water with ALPS, a state-of-the-art purification system that removes radioactive materials, except tritium.
The tritium radionuclide has a half-life of 12.32 years and is very costly and difficult to remove.
The ALPS-treated water is being discharged into the ocean via a one-kilometre long tunnel, with planned releases beginning in August 2023 and set to be completed by 2050.
The simulated increase in tritium concentration in the Pacific Ocean due to the tritium originating from the ALPS-treated water is about 0.1% or less of the tritium background concentration of 0.03-0.2 Bq/L.
The WHO international safety standard for tritium concentration is 10,000 Bq/L.

Sources:

"Tritium concentration in Pacific Ocean remains negligibly low despite Fukushima Daiichi Nuclear Power Plant releases" by News Reporter-Staff News Editor, Global Warming Focus, Tokyo, Japan, 2025 JUL 14.