Radiation measurements have been conducted more than 2,200 times in eight prefectures including Fukushima Prefecture. As a result, ¹³⁴Cs was detected at one spot, and ¹³⁷Cs was detected at two spots in Fukushima Prefecture in 2011. But the observed concentration was in the order of detection limit of the radiation detector (1 Bq/L). Since 2012, radioactive cesium has not been detected in any spots.

Fig.1　Groundwater quality monitoring points in Fukushima Prefecture

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Reference

1. Ministry of Environment, Results for Monitoring of Radioactive Materials in Environmental Water(June-August, 2015)
2. Ministry of Environment, Results for Monitoring of Radioactive Materials in Environmental Water(February,2018)