Development of a method of evaluating PuO particle diameters using an alpha-particle imaging detector

Morishita, Yuki   ; Sagawa, Naoki; Takada, Chie ; Momose, Takumaro  ; Takasaki, Koji  

It is very important to evaluate the diameters (activity median aerodynamic diameter) of Plutonium diocide (PuO) particles for internal exposure dose evaluation. In this study, a method of evaluating PuO particle diameters using an alpha-particle imaging detector, which can measure the change of the shape of alpha-particle energy spectrum of an individual particle, was developed. PuO particles with different diameters were modeled by Monte Carlo simulation, and the change in the shape of the energy spectrum for each particle diameter was evaluated. Two different patterns were modeled, namely, the case of PuO and the case of PuO (including isotopic composition of Pu). Multiple regression analysis was performed to determine the PuO particle diameter from the obtained parameters. The simulated diameters and the diameters obtained with the regression model were in good agreement.