Development of a method for discriminating the influence of the radon progenies in air from aerial radiation monitoring data

Hirouchi, Jun ; Nishizawa, Yukiyasu*; Urabe, Yoshimi*; Shimada, Kazumasa ; Sanada, Yukihisa   ; Munakata, Masahiro 

After the Fukushima Dai-ichi Nuclear Power Station (NPS) accident, a series of aerial radiation monitoring (ARM) was conducted as a national project to map the ground surface distribution of radiocesium. The influence of -rays from natural nuclides, especially the radon progenies (Pb-214 and Bi-214) should be excluded from the ARM measurement data to accurately estimate deposition of artificial radionuclides. Therefore, the aim of this study is to develop a method for discriminating the influence of the radon progenies in air from the measurement data. The discrimination method was applied to the ARM data around Sendai NPS and we compared the dose rate at a height of 1 m above the ground measured by NaI survey meter with the ARM data. The coefficient of determination (R2) and normalized mean square error (NMSE) were improved by applying the method, showing that the validity of the method was confirmed.