Effect of radioactive cesium-rich microparticles on radioactive cesium concentration and distribution coefficient in rivers flowing through the watersheds with different contaminated condition in Fukushima

Tatsuno, Takahiro*; Waki, Hiromichi*; Kakuma, Minato*; Nihei, Naoto*; Takase, Tsugiko*; Wada, Toshihiro*; Yoshimura, Kazuya; Nakanishi, Takahiro; Ote, Nobuhito*

Journal of Environmental Management, 329, p.116983_1 - 116983_13, 2023/03

https://doi.org/10.1016/j.jenvman.2022.116983

Isotope ratio analysis of U and U nuclide using a microwave digestion associated with ICP-MS and the large areal soil survey related to Fukushima Daiichi Nuclear Disaster

Takagai, Yoshitaka*; Furukawa, Makoto*; Nagahashi, Yoshitaka*; Takase, Tsugiko*; Shikino, Osamu*; Kameo, Yutaka

Bunseki Kagaku, 60(12), p.947 - 957, 2011/12

https://doi.org/10.2116/bunsekikagaku.60.947

Isotope ratio analysis for U and U in soil samples using a microwave digestion procedure associated with ICP-MS was proposed and demonstrated. In the microwave digestion procedure, the dissolution of natural uranium in silicate (in rocks) was reduced by using a mixture of nitric acid and hydrogen peroxide (to measure the radioactive uranium from a disaster). Upon ICP-MS, the isotope ratio of the certificated geochemical reference material was realized to precisely correct the isotope ratio in real soil samples. In addition, cell-pass voltages can be available to make calibrations and/or to correct the mass bias in the mass-spectrometer. By these effects, the isotope ration of uranium can be measured with an accuracy of 0.37% without using a radioactive standard source. U and U were quantitatively determined, and those detection limits were both 0.010 g/kg. In the case of an emergency, like a nuclear hazard, the proposed method is useful to immediately gather a large amount of information in large area as compared with a common method such as a complete dissolution process associated with an -ray spectrometer or ICP-MS. In addition, the survey of how radioactive uranium spreads was conducted from 7 to 80 km around the Fukushima Daiichi Nuclear Power Plant (Fukushima-DNPP) (115 points in Fukushima prefecture). As a result, the values of the uranium isotope ratio for those soils were similar to the natural abundance, although the various concentrations of uranium were detected from sampling points.

Preparation of metal nanocolloid dispersion by pulverizer and encapsulation technique in micro liquid phase for easy TEM observation

Suzuki, Reika*; Nakagawa, Taichi; Matsueda, Makoto; Terashima, Motoki; Takase, Tsugiko*; Takagai, Yoshitaka*

no journal, , 

no abstracts in English

Extraction and condensation for nanocolloid of metal oxide and metal carbide based on the temperature-dependent phase separation phenomenon of zwitterionic surfactant

Suzuki, Reika*; Nakagawa, Taichi; Matsueda, Makoto; Terashima, Motoki; Takase, Tsugiko*; Takagai, Yoshitaka*

no journal, , 

no abstracts in English

Studies on the effective dose for public calculated by air dose rate

Endo, Yuya; Yamaguchi, Katsuhiko*; Takase, Tsugiko*; Uezu, Yasuhiro; Tsukada, Hirofumi*

no journal, , 

After the Fukushima Dai-ichi Nuclear Power Station accident, the Ministry of the Environment decided that the additional annual dose in a high exposure situation (less than 20 mSv/y) reduced to 1 mSv/y or less. The additional annual dose is calculated by ambient dose equivalent. However, the relationship among air kerma, ambient dose equivalent and effective dose seems to be identically by many people. In addition, conversion coefficients from air kerma and ambient dose equivalent to effective dose have been considered to change as time proceeds because the half-lives of Cs and Cs are different. Therefore, agricultural land in an evacuation zone was selected to evaluate relationship among them. Furthermore, the actual environment such as soil will be simulated by using a Monte Carlo radiation transport code PHITS. Finally, the relationship will be verified by comparing the results calculated by PHITS to ones obtained from actual environmental monitoring.