Estimation of  -ray dose in air and soil from Fukushima Daiichi Power Plant accident

Abstract

Following the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident of 2011, which deposited radionuclides across Tohoku and northern Kanto, β-ray dose evaluation has been performed to estimate radiation exposure for small creatures like insects as well as human skin. Using the Monte Carlo radiation transport code MCNP-4C, we calculated the β-ray dose for 129mTe, 129Te, 131I, 132Te, 132I, 134Cs and 137Cs in air as a function of altitude and in soil. These calculations of β-dose rate for each radionuclide were conducted for the conditions following the FDNPP accident, with 137Cs deposition assumed to be 1000 kBq/m2. Beta-ray dose rate was found to be ∼10-fold (resp. 5-fold) higher than the γ-ray dose rate in the soil (resp. on the ground surface) at ∼20 days after deposition, and ∼4-fold (resp. 1.7-fold) higher after 6 months or more. For convenience, the height dependence of the ratio for 0, 10, 30, 90, 180 and 365 days after deposition was obtained by a fitting function. The cumulative 70 µm β-ray dose at 30, 60 and 90 days after deposition was estimated to be 35, 45 and 53 mGy for the ground surface, and 61, 79 and 92 mGy in the soil, respectively. These results can be used to estimate the external β-ray exposure for small creatures as well as for human skin.

Spatiotemporal abnormality dynamics of the pale grass blue butterfly: three years of monitoring (2011–2013) after the Fukushima nuclear accident

“…We believe that the impacts of the early, acute exposure to the fast-decaying radionuclides that existed immediately after the burst (e.g., 131 I and 129 Te) were most likely higher than the chronic exposure to the slow decaying radionuclides that remained for years [ 14 ]. Furthermore, because the pale grass blue butterfly lives on or near the ground surface, especially at the larval stage, this butterfly is likely to be severely affected not only by γ-rays but also by β-rays [ 19 ]. The importance of β-rays was implicated by a high count rate detected by a GM counter in the spring of 2011 in the present study.…”

The Pale Grass Blue Butterfly as an Indicator for the Biological Effect of the Fukushima Daiichi Nuclear Power Plant Accident

“…To evaluate the contribution of the initial exposures immediately after the FNPP accident to the biological impact quantitatively, it is important to calculate absorbed doses for the pale grass blue butterfly, considering both γ-and β-rays [25]. Such a dosimetric analysis necessarily involves mathematical simulations that introduce many assumptions.…”

Dose Estimation of External and Internal Exposure in Japanese Macaques After the Fukushima Nuclear Power Plant Accident

“…The γ-ray energies and emission rates for the radionuclides were obtained from the National Nuclear Data Center [14]. Beta-particle energy spectra were obtained from the literature [15,16], and the internal conversion electrons for each radionuclide were obtained from the website of the National Nuclear Data Center [14]. The energy deposition in the ellipsoids was calculated for each γ-ray and each electron source.…”