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Status of Contaminated Water Measures
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.
Regarding Contaminated Water Treatment
For treatment of contaminated water, measurement and analysis results for contaminated water treatment etc., please see the following pages:
Treatement of Contaminated Water
Measurement and Analysis Results for Contaminated Water Treatment
“Plan for the Stabilization and Treatment of Waste generated by Contaminated Water Purification and Treatment Facilities”
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
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Remove
Water is being treated to remove contamination, reducing risk.
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Keep away
Initiatives are being carried out to prevent water from becoming contaminated through contact with contamination sources.
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Prevent leakage
Initiatives are being carried out to prevent contaminated water from leaking and having an adverse impact on the environment.
Remove
- (1) Treatment of contaminated water in the Multi-nuclide Removal Facility (ALPS) Completed treatment of most of the high-level contaminated water in May 2015
- (2) Removal of contaminated water from trenchCompleted in March 2017
- (3) Treatment of accumulated water in the buildings with cesium filtering equipment Operation started in June 2011
Keep away
- (4) Pumping up groundwater from groundwater bypass pumping wellsStarted drainage in May 2014
- (5) Pumping up groundwater from subdrain system around buildingsStarted drainage in September 2015
- (6) Installation of land-side impermeable wall (frozen soil wall)Largely completed in March 2018
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(7) Laying of ground pavement (facing) to minimize rainwater infiltration in soilCompleted in March 2016
Prevent leakage
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(8) Soil improvement using water glassCompleted in March 2016 except for the area around the reactor buildings, etc.
- (9) Installation of a ocean-side impermeable wallInstallation completed October 2015
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(10) Addition of tanks (including replacement of flange tanks with welded tanks)Transfer to reliable welded tanks completed in March 2019
- (11) Pumping up groundwater from groundwater drainStarted drainage in September 2015
Effectiveness of Measures Taken to Date
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Results of removal measures
■しかくWith some exceptions, treatment of high-level contaminated water was completed in May 2015, reducing risk.
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Results of “keeping away” measures
■しかくThe amount of contaminated water resulting from rainwater and groundwater was reduced from approximately 490m3/day (average for the period from December 2015 to February 2016) to around 110m3/day (average for the period from December 2017 to February 2018).
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Results of “prevent leaking” measures
■しかくRadiation levels in the bay have been reduced to 1/millionth (Cesium) the level right after the accident.