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Yanagisawa, Kayo; Matsueda, Makoto; Furukawa, Makoto*; Hirata, Takafumi*; Takagai, Yoshitaka*
no journal, ,
Determinations of radioisotopes in fuel debris and radioactive wastes are important for decommissioning of Fukushima Daiichi Nuclear Power Plant. Difficult-to-measure radioisotopes such as Sr-90 have been measured by radiometric analysis and inductively coupled plasma-mass spectrometry (ICP-MS), the methods have not achieved the distribution of the radioisotopes on the sample's surface due to its digestion process of the samples before measurements. Laser ablation (LA)-ICP-MS can obtain the distribution information of radionuclides directly on the surface of solid samples. In contrast, the quantification with the method is difficult caused by the spectral interferences and matrix effects from samples. In this study, a quantification method was developed combined with LA-ICP-MS and isotope dilution method. The proposed method was applied for Sr-90 quantification.
Hayashi, Gaku*; Torii, Tatsuo*; Ishizuka, Akihiro; Okuyama, Shinichi; Kato, Shingo; Nozaki, Tatsuo; Yasuda, Nakahiro*
no journal, ,
no abstracts in English
Kawahara, Rika*; Ochi, Kotaro; Yamaguchi, Katsuhiko*; Torii, Tatsuo*
no journal, ,
Radiation distribution maps based on Compton cameras make it possible to identify hotspots where radioactive material has accumulated locally. However, the radiation distribution obtained is two-dimensional and the distance to the hotspot cannot be confirmed. In this study, a combination of a Compton camera and an optical camera was used to integrate the radiation distribution with optical images and to confirm the radiation source position and its spread, aiming at a detailed understanding of the radiation distribution. Field tests using a Compton camera (H3D, H420, USA) with a CZT (CdZnTe) semiconductor and an optical camera (GoPro) were carried out in the difficult-to-return zone, approximately 3.6 km away from the Fukushima Daiichi NPP. By taking images of the hotspot at different positions and angles, the location of the radiation source and its three-dimensional extent could be confirmed.