국내 석탄 연소 발전소 내 작업종사자의 입자 흡입에 따른 내부피폭 방사선량 평가 = Assessment of Internal Radiation Dose Due to Inhalation of Particles by Workers in Coal-Fired Power Plants in Korea

다국어 초록 (Multilingual Abstract)

Coal-fired power plants handle large quantities of coal, one of the most prominent NORM,and the coal ash produced after the coal is burned can be tens of times more radioactive than thecoal. Workers in these industries may be exposed to internal exposure by inhalation of particles whilehandling NORM. This study evaluated the size, concentration, particle shape and density, and radioactivityconcentrations of airborne suspended particles in the main processes of a coal-fired power plant. Finally,the internal radiation dose to workers from particle inhalation was evaluated. For this purpose, airborneparticles were collected by size using a multi-stage particle collector to determine the size, shape, andconcentration of particles. Samples of coal and coal ash were collected to measure the density andradioactivity of particles. The dose conversion factor and annual radionuclide inhalation amount werederived based on the characteristics of the particles. Finally, the internal radiation dose due to particleinhalation was evaluated. Overall, the internal radiation dose to workers in the main processes of coalfiredpower plants A and B ranged from 1.47×10-5~1.12×10-3 mSv y-1. Due to the effect of dust generatedduring loading operations, the internal radiation dose of fly ash loading processes in both coal-fired powerplants A and B was higher than that of other processes. In the case of workers in the coal storage yard atpower plants A and B, the characteristic values such as particle size, airborne concentration, and workingtime were the same, but due to the difference in radioactivity concentration and density depending onthe origin of the coal, the internal radiation dose by origin was different, and the highest was found wheninhaling coal imported from Australia among the five origins. In addition, the main nuclide contributingthe most to the internal radiation dose from the main processes in the coal-fired power plants wasthorium due to differences in dose conversion factors. However, considering the external radiation doseof workers in coal-fired power plants presented in overseas research cases, the annual effective dose ofworkers in the main processes of power plants A and B does not exceed 1 mSv y-1, which is the dose limitfor the general public notified by the Nuclear Safety Act. The results of this study can be utilized to identifythe internal exposure levels of workers in domestic coal-fired power plants and will contribute to theestablishment of a data base for a differential safety management system for NORM-handling industriesin the future.