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The Fukushima Dai-ichi nuclear accident led to massive atmospheric deposition of radioactive substances onto the land surfaces. The spatial distribution of deposits has been estimated by Japanese authorities for gamma-emitting radionuclides through either airborne monitoring surveys (since April 2011) or in situ gamma-ray spectrometry of bare soil areas (since summer 2011). We demonstrate that significant differences exist between the two surveys for radiocaesium isotopes and that these differences can be related to dry deposits through the use of physically based relationships involving aerosol deposition velocities. The methodology, which has been applied to cesium-134 and cesium-137 deposits within 80-km of the nuclear site, provides reasonable spatial estimations of dry and wet deposits that are discussed and compared to atmospheric numerical simulations from the Japanese Atomic Energy Agency and the French Institute of Radioprotection and Nuclear Safety. As a complementary approach to numerical simulations, this field-based analysis has the possibility to contribute information that can be applied to the understanding and assessment of dose impacts to human populations and the environment around Fukushima.

A case study was conducted in the village of Komarin in Belarus at the edge of the Chernobyl exclusion zone, with the aim of evaluating the spatial and temporal variability in external and internal post-accidental radiation exposure. A database containing the radioactive measurements of foodstuffs made in Komarin over a 1990–2016 period makes it possible to estimate retrospectively the internal exposure. External exposure was prospectively studied through a citizen science approach involving a group of high school students and used two radioactive monitoring approaches, the D-shuttle© dosimeter and the OpenRadiation® system. Results showed that contamination level in food products varied over 2 to 4 orders of magnitude, underlining the usefulness of continuous monitoring of locally produced foodstuffs even more than 30 years after the Chernobyl accident. The study of external exposures showed that the current dose rates were similar to those usually observed elsewhere in the world, without any notable variations. More detailed analysis of these results will be conducted in future studies. This paper focuses on the methods used for the acquisition of data about both external exposure and foodstuff contamination and how it resulted in the strong involvement of high school students which in turn triggered a renewed interest in the practical radiological protection culture within the population of the village.

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