Application of the ICRP Database for Calculation of the Dose Coefficient for Aerosol Having Multimodal Particle Size Distribution

Purpose: Development of a method for calculating radioactive aerosol dose coefficient when the aerosol particle size measurements resulted in a multimodal radionuclide activity distribution by particle diameters. Material and methods: The physical prerequisite for the proposed method is that the multimodal distribution may be caused by the presence of several sources of aerosols with different particle sizes. In the ICRP database to each value of the aerosol dose coefficient there corresponds one of ten functions of log-normal (unimodal) distribution with specified parameters. In the developed method the result of the aerosol particle size measurement is approximated by the sum of said standard functions with weight factors of each of the functions defined such that the best least squares approximation is obtained. Then the dose coefficient of the aerosol under study is calculated based on the dose value additivity property, i.e. each weight factor is multiplied by a respective value of the dose coefficient from the ICRP database, and the obtained products are added up. Results: There was carried out a series of numerical experiments, in each of which “experimental” points were simply plotted on a graph of a certain cumulative distribution function. Coordinates of the points are used as input for the programme implementing the developed algorithm. The calculated dose coefficient value is compared with the true value and/or the value obtained with the linear interpolation method using the AMAD. Conclusion: Physical prerequisites and results of numerical experiments confirm the validity of the developed method.