Iran Occupational Health

  Background and Aims : Many systems and processes can cause the introduction of radioactivity into the environment. Human activities in nuclear industry such as nuclear fuel cycle and reactor operation, lead to a significant production and release of radioactivity to the environment. Understanding the physical and chemical nature, including size, chemical composition and radioactivity of aerosol particles in the safety chamber of Tehran research reactor is indispensable for evaluation of exposure level and methods of prevention. The aim of this study was to measure the size distribution of aerosols and their activities, which was determined using an Anderson cascade Impactor (ACI) ACFM model and liquid scintillation respectively. The measurements were performed in three workstations in the safety chamber of Tehran research reactor.

  Methods: The identification of existing radio nuclides on suspended particles were carried out in the safety chamber by means of environmental sampler and mass size distribution of particles was measured using an Anderson cascade Impactor (ACI). To determine the type and amount of radio nuclides in the aerosol particles the γ-ray spectrometry with a high –purity germanium (HPGe) detector and ultra-low level liquid scintillation spectrometer were used respectively.

  Results : The results showed that the activities median aerodynamic diameter (AMAD) value for three selected workstations were 2.4, 3.1 and 3µm with geometric standard deviation of 2.3, 2.12 and 2 respectively. Furthermore, the results of particle activity size distribution showed that the most fraction of activity was related to nucleation and accumulation mode, especially particles with the aerodynamic diameter less than 0.4µm.

  Conclusion: The most activity was related to the number of particles in the accumulation and nucleation mode (fine particles). The origin of these particles can be the coagulation of particles in the nucleation mode. The accumulation mode also contains droplets formed by the chemical conversion of gases to vapors that condense.