In March 2015, the Association for the monitoring of radioactivity in the West (ACRO) published a file "Fukushima: the insurmountable challenges" that provided an overview on several aspects of the consequences of the accident at the Fukushima nuclear power plant in 2011.
Among this information, in the chapter dealing with the dosimetry of populations encouraged to return, IRSN has noted that the representativeness of measures given by individual dosimeters supplied by Chiyoda Technol is called into question, as well as IRSN, which distributes in France dosimeters of the same type for the radiological surveillance of workers.This information is scientifically inaccurate.
The value provided by the ambient dosimeter being higher by about 40% compared to the individual dosimeter, the document implicitly considers that the first value is correct, and that therefore the use of passive individual dosimeters is to the detriment of the protection of persons.
However, in this case, and despite all appearances, the reverse is true: the individual dosimeters give a correct estimate of the effective dose representative of the actual exposure of people, and the ambient dosimeters overestimate substantially the effective dose.
Download IRSN’s detailed explanatory note of March 24, 2015 (pdf)