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

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

The influence of -rays from natural nuclides (particularly the radon progenies, Pb and Bi) must be excluded from aerial radiation monitoring (ARM) data to accurately estimate the deposition amount of artificial radionuclides. A method for discriminating the influence of Pb and Bi in air from the ARM data was developed. The influence of the radon progenies in air was excluded using the relation between the count rates of six NaI (Tl) detectors and a LaBr detector. The discrimination method was applied to the ARM data obtained from around the Sendai Nuclear Power Station. To verify the validity of the discrimination method, the dose rate estimated from the ARM data was compared with the dose rate measured using a NaI survey meter at a height of 1 m above the ground. The application of the discrimination method improved the dose rate estimation, showing the validity of the discrimination method.