Reevaluation of nasal swab method for dose estimation at nuclear emergency accident

ICRP Publication 66 human respiratory tract model has been used extensively over in exposure dose assessment. Two default aerosol sizes of 5µm in AMAD for the workers and 1µm in AMAD for the public are given as being representative in the ICRP model, but both sizes are not linked directly to the maximum dose. In this study, an applicability of nasal swab method in exposure accident of alpha emitter was investigated. A computer software, LUDEP, was used in the calculation of respiratory deposition. It showed that the effective dose per unit intake activity strongly depended on the inhaled aerosol size. In case of Pu-239 dioxide aerosols, it was confirmed that the maximum of dose conversion factor was observed around 0.01µm. It means that the size is the most hazardous at plutonium exposure accident. From analysis of the relationship between AI and ET1 deposition, it was found that the dose conversion factor from the activity deposited in ET1 region also was affected by the aerosol size. The usage of the ICRP\u27s default size in nasal swab method might cause obvious underestimation of the intake activity. Dose estimation based on nasal swab method is possible from safety side at nuclear emergency, and the availability in quantity should be re-evaluated for emergency medicine considering of chelating agent administration.IRPA1