Radiation internal exposure measurements archiving system (REMAS)

Development of a method of evaluating PuO2 particle diameters using an alpha-particle imaging detector

It is very important to evaluate the diameters (activity median aerodynamic diameter) of plutonium dioxide (PuO2) particles for internal exposure dose evaluation. In this study, a method of evaluating PuO2 particle diameters using an alpha-particle imaging detector was developed. PuO2 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 239PuO2 and the case of PuO2 (including isotopic composition of Pu). Multiple regression analysis was performed to determine the PuO2 particle diameter from the obtained parameters. The simulated diameters and the diameters obtained with the regression model were in good agreement. The advantage of using the alpha-particle imaging detector is to measure the alpha energy spectrum for individual particle, and this allows accurate measurement of particle diameter distribution.

Evaluation of in vivo and in vitro dose detection limits for different radionuclides and measurement techniques

Personal monitoring programs for workers handling radioactive materials are influenced by numerous factors as the measurements of radioactivity in tissues or/and in excreta can be carried out using different techniques. This paper summaries the basic procedures needed for accurate and fast measurement of different radionuclides like (235)U, (234)U, (238)U, (226)Ra, (210)Po, (131)I, (99m)Tc, (134)Cs, (137)Cs, (57)Co, (58)Co, and (60)Co. Overviews of in vitro and in vivo monitoring methods are provided as well as methods used to calculate detection limits and internal radiation dose. For the radionuclides of interest, in vivo and in vitro detection limits were converted into committed effective doses to evaluate the applicability and limitations of the systems used at the laboratory. The results proved that the systems' sensitivity is suitable for use in routine monitoring of workers subject to risk of internal exposure from such radionuclides. Consequently, monitoring programs suggested by the Syrian internal dosimetry laboratory are suitable to detect committed effective doses even below 1mSv in most cases.