Aerosol is one of the main forms of fission products in nuclear reactor accidents, which are derived from direct leakage of solid fission products and homogeneous and heterogeneous nucleation of gaseous fission products. Pool scrubbing may reduce the leakage of radioactive aerosol, and it is vital for the prediction of radioactivity to accurately grasp the retention efficiency. In this paper, experimental research on aerosol retention characteristics in jet regime was carried out. Titanium dioxide and cesium iodide were used to simulate radioactive aerosols with different hydrophilicity, and the retention efficiency under different inlet pressure and aerosol size was obtained. The results show that the retention efficiency of aerosol increases significantly while the inlet pressure increases from 43 kPa to 110 kPa. While the inlet pressure is higher than 110 kPa, the retention efficiency still increases with the increase of inlet pressure, although the increasing trend is not obvious. The most easily permeable range of cesium iodide aerosol is smaller than that of titania aerosol, and the retention efficiency of cesium iodide aerosol is always higher than that of titania aerosol, which may be caused by hydrophilicity. However, with the increase of stokes number, the difference of retention efficiency between the two aerosols gradually decreases. The difference between different aerosols was analyzed in this paper and it was found that the influence of hydrophilicity was negatively correlated with stokes number. The results of this research can be used to assist the validation of pool scrubbing model.

As an important part of the ventilation system of nuclear facilities, the performance of filter is of great significance to the environment and personnel safety. With the operation of the filter, the filtration mode will change from depth filtration to surface filtration. In this paper, a numerical simulation method is developed for the unsteady deposition characteristics of particles in the surface filtration. The parcel injection model is applied to accelerate the formation and growth process of dust cake on the surface of fiber filter. A series of subroutines running in FLUENT environment are developed to enhance the capabilities of computational fluid dynamics code in ANSYS. The Brownian force is added to the DPM model to calculate the particle trajectory more accurately. The function that aerosol particles are intercepted and deposited on the surface of fiber filter to form dust cake is added. The porous media model is used to simulate the fiber filter and dust cake. The porosity and resistance coefficient change with the unsteady deposition of particles. Combined with the subroutine with FLUENT software, a numerical simulation method which can be used to predict the unsteady deposition characteristics of particles in the surface filtration is formed. The numerical simulation results are compared with the experimental results, and they are basically consistent. So the developed numerical simulation method can be used to predict the unsteady deposition characteristics of particles in the surface filtration, and can also provide a theoretical basis for the structural design of pleated filter.

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As a new filter material, metal fiber has good high-temperature resistance, moisture resistance, and radiation resistance. To explore the influence of the fiber’s primary structural parameters on the fiber’s performance, this paper experimentally studied the relationship between the flow resistance, filtration efficiency, and dust holding capacity of the metal fiber filter material and the thickness and solid volume fraction (SVF). Under the condition of ensuring uniform deposition of NaCl aerosol, we found that the deposition law of NaCl polydisperse aerosol is the same as that of monodisperse aerosol. The results show that for the same fiber diameter, increasing the fiber’s thickness and SVF will increase the flow resistance of the fiber under the same dust holding capacity; that is, reducing the dust holding capacity of the fiber. In the depth filtration, the efficiency increases rapidly due to the aerosol deposition in the fiber, while the efficiency changes gently when the filter cake is covered on the filtration surface. At the same time, for each high filtration efficiency fiber, the variation characteristics of resistance with dust holding capacity in the deep filtration stage are the same. After the filter cake is completely covered on the filter surface, the growth trend of resistance is the same, independent of the fiber’s structural parameters.