Although the concentration of radioactive materials in the seawater outside of the harbor is lower than radioactivity limits set in a public notice, the concentration of radioactive materials in part of area inside the harbor in front of inlet channels of Units 1-4 exceeds the radioactivity limits and is not declining even though cesium in the seawater is continuously removed (*). (See Figure3-1 for data of water measured in front of inlet channels of Units 1-4.)
Also, since radioactive materials (tritium, strontium) have been detected in groundwater near a revetment on the east side of the turbine buildings of Units 1 and 2, soil improvement work is being implemented as quickly as possible and an impervious wall on the sea side is being built to prevent further contamination through groundwater.
(*) Current cesium removal measures: Fabric absorbents of cesium have been installed in the sea and their effects are being examined.
Water data inside the harbor
(1)Removal of radioactive cesium and strontium inside the sea
- Radioactive cesium and strontium in the sea inside the harbor need to be removed, which is to
say, their concentrations need to be decreased dramatically.
- Upon removal of above mentioned materials, the decrease in efficiency of removal due to
absorption of materials other than targeted materials, such as magnesium and calcium should
- The amount of wastes produced due to cesium and strontium absorption should be limited.
- The removal systems should be a simple structure.
(2)Installation of a silt fence that absorbs radioactive materials