When groundwater flowing from the mountain side of the site toward the ocean enters the reactor buildings and becomes mixed with radioactive water accumulated in the buildings, etc., contaminated water increases. For the sake of stable control of groundwater, multilayer measures are being taken to deal with contaminated water, in line with the three fundamental policies of removing contamination sources, keeping water away from contamination sources, and not allowing contaminated water to leak.

A Treated Water Portal Site has been created as a central point for data and other information about treated water* (contaminated water after it has been treated).
Treated Water Portal Site


Note on “Water treated with multi-nuclide removal equipment, etc.” is notated. (revised in March, 2020)
Treated water for which the sum of concentration ratios required by law, with the exception of tritium, is less than 1 is notated as either, “water treated with multi-nuclide removal equipment, etc.” or “treated water”.
Treated water that has not been completely treated is notated as, “water treated with multi-nuclide removal equipment, etc. (for which the sum of concentration ratios required by law equals or exceeds 1)”.
When referring to both of the aforementioned types of treated water collectively, the notation, “treated water*” is used.

What Is Contaminated Water?

Contaminated water is water that has been injected into reactors for cooling, or groundwater flowing from the mountain side of the site into the reactor buildings, where it becomes contaminated by directly contacting melted fuel or becoming mixed with radioactive water accumulated in the buildings, etc. The contaminated water undergoes treatment to remove radioactive materials in stages, reducing its risk, before being stored in tanks on the site.

Status before and after measures are taken

Summary of the Three Fundamental Policies for Contaminated Water Measures

Effectiveness of Measures Taken to Date

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