Photo: Contaminated water storage tanks lined up in Fukushima nuclear plant area (1.2016) [Link]
It was found out Tepco has repeatedly been emphasizing the safety of contaminated water by using dosimeters that cannot detect the radioactive tritium and that do not react to cesium unless the concentration level is extremely high.
Nature of the water to be discharged to the Pacific is the filtered highly-concentrated contaminated water generated by cooling the nuclear fuel that has melted down into the reactor at least twice, and is announced to contain only tritium. Tritium cannot be removed even with decontamination equipment.
However During the demonstration to the press, a dosimeter that detects only extremely high levels of gamma rays was applied to a bottle containing the contaminated water, which showed no detection. Since July 2020. TEPCO has been repeating this performance to about 1,300 groups and 15,000 people.