Research On Small Space Diffusion Transport Of Radioactive Aerosols

In the production of nuclear materials, processing, as well as the nucleus of the operation process of the plant and nuclear materials may be radioactive aerosol formation in the workplace small enclosed space range. Which contains over radioactive aerosol particles of uranium are radioactive, toxicity larger. Tritium droplet gas soluble particles is easy to be absorbed by the human body harm. Because the workplace is mostly similar to the operation, glove box or reactor hall even tank elements are a class of small enclosed space, air condition in the spaces tend to close to the static or low wind speed, due to element glove box is often radioactive element transport and processing operation, prone to radioactive contamination. For the safety of radiation protection of personnel security. So in this paper, we mainly study the radioactive aerosol particles in static and low speed similar radioactive components from the glove box the size of small enclosed space diffusion transport behavior, experiments with small enclosed space for 0.5m height of 0.5m wide 2.5m long. Because the research on workplace radioactive aerosol pollution is universal, therefore on radiation protection work has very realistic significance.Is reviewed in this paper at home and abroad of aerosol particle diffusion transport in the field of some research advances and achievements, and combining with the present condition and background knowledge, try on radioactive aerosol particles in a small confined space diffusion transport the transport behavior of the new study.Of radioactive aerosol particles in a small confined space diffusion transport behavior research, the main need related theory analysis and selection of appropriate materials is verified experimentally. The theoretical analysis, due to the radioactive aerosol particle diffusion transport transport behavior is affected by many factors, so it needs to the radioactive aerosol particles in certain circumstances diffusion lost in the various influence factors were analyzed, simplified, ignored less impact factors to facilitate model. Experimental verification, first of all, due to radioactive materials are difficult to obtain and inconvenience of radioactive decontamination, therefore, generally choose radioactive aerosol particle simulation is validated by the experiment. Among them, the elemental AG Powder density and super close to the density of uranium oxides aerosol particles, close to NaCl saline droplets aerosol particles and droplets containing tritium density of aerosol particles and NaCl droplet aerosol particle size stable monodisperse good, Pao lubricating oil droplets and aerosol particles are not easy to volatile and easy to produce. Therefore, we selected the three kinds of aerosol particles simulated radioactive aerosol particle diffusion transport experiments. Experimental verification and aerosol particle measurement problems, this study mainly selected by Grimm gas aerosol size spectrum instrument, using optical methods for measuring the gas aerosol grain size, to quickly get the measurement results to reduce the dynamic expanding Dispersion experiment aerosol particle coalescing interference on the experimental results. According to the experimental results, this paper analyzes the experimental data and theoretical results of different, and try to make a reasonable explanation.Through the theoretical and experimental results, this study obtained some valuable results:First, highly specific square in a small space of specific particle size of radioactive aerosol particles, and analyzes the actual radioactive workplace with similar situations of various influencing factors and factors of the impact on smaller were simplified to ignore, according to the simplified theoretical model, mainly analyzes the static Brown diffusion, static sedimentation diffusion, ventilation state section uniform mixing and diffusion, the section of ventilation state uneven mixing turbulent diffusion, again according to the actual situation is ventilation state section uneven mixing turbulent diffusion calibration factor expression that specific particle size of radioactive aerosol particles in a highly specific square space diffusion transport theoretical results. Thought experiment Provide a theoretical support for the diffusion analysis of similar radioactive aerosol particles in the workplace.Then, using an aerosol generating device of dust, respectively produce all sizes of NaCl droplet aerosol particles, Pao lubricating oil droplets and aerosol particles and elemental Ag powder aerosol particles. Simulation of radioactive aerosol particles, in particular experimental organic glass glove box for static and ventilation state of aerosol transport and diffusion experiments, using Grimm aerosol particle size spectrometer analysis of the glove box gas aerosol size spectrum changes with time. Some valuable results from the sorted:the proliferation of static transmission experiments, Brownian diffusion velocity is on the model fast, speculate the reasons is because the coagulation of aerosol particles Residual gravity sedimentation changed the original particle size distribution spectrum, aerosol particle size spectrometer can detect the Knudsen number in the free molecule region of small particle size of the aerosol particles have a faster diffusion speed, and the small size of the aerosol particle diffusion part will condense into aerosol particle size spectrometer can detect the larger particle size of the aerosol particles, for the same reason, small particle size of the aerosol particle coalescing into larger particle size of the aerosol particles, resulting in the analysis of aerosol particle size spectrometer can detect the larger particle size of the aerosol particles, aerosol particle concentration than the theoretical value, the ventilation state diffusion transport experiments along different party To ventilation experiment, different correction value, due to organic glass wall has not completely smooth, rough protuberance asymmetry makes airflow direction is different with different friction resistance coefficient; in addition, the ventilation state of NaCl droplet aerosol particles diffusion experiments, gravity sedimentation rate than the theoretical value is low, from aerosol particle size spectrometer situation. The reason is that state ventilation under supersaturated air NaCl saline droplets balance has smaller particle size.Through the results of the above simulations, it can be seen that the diffusion of radioactive aerosol particles:Although the literature research to the radioactive aerosol particle diffusion transport research mostly only to activity in a dynamic particle size of radioactive aerosol particles were studied, but due to the radioactive aerosol particles actually are polydisperse and small size of aerosol particles will coalesce to form larger aerosol particles through. Thus, the radioactive aerosol particles full activity in an aerodynamic particle size research is not comprehensive, such as static diffusion experimental measurements and analysis that, this will underestimate the extent of the spread of the radioactive pollution.Dynamic diffusion experiments results show that the ventilation state diffusive transport experiments, different directions tend to have different radioactive aerosol particle gravity deposition rate. This guidance workplace radiation protection work of pollution source and space arrangement.