Mapping project in Fukushima and related researches, 7; Dose estimation of artificial / natural radioisotopes by an analysis of photon energy spectrum

Tsuda, Shuichi  ; Tanigaki, Minoru*; Saito, Kimiaki  

A GPS-aided radiation monitoring system KURAMA and the KURAMA-II developed by Kyoto University has been utilized after the Fukushima Dai-ichi Nuclear Power Plant accident in a mapping project of radionuclides deposited in the environment and monitoring of dose rates in air. KURAMA-II has a function of precisely evaluating dose rates in air based on measured pulse-height spectra from the incorporated CsI(Tl) scintillation detector. In this study, to evaluate dose contribution of the radionuclides in the environment, photon energy spectra was estimated by an unfolding method, using the measured pulse-height spectra and the dataset of the calculated response functions of the CsI(Tl) scintillation detector in a simulative environment. The results of dose contributions of artificial and natural radionuclides based on the estimation method will be reported in the session, "Mapping project in Fukushima and related researches".