Haomin Sun

Abstract: Because a pool scrubbing is important for reducing radioactive aerosols to the environment for a nuclear reactor in a severe accident situation, many researches have been performed. However, decontamination factor (DF) dependence on aerosol concentration was seldom considered in an aerosol number concentration with limited aerosol coagulation. To investigate an existence of DF dependence on the concentration, DF in a pool scrubbing with 2.4 m water submergence was derived from aerosol measurements by light scattering aerosol spectrometers. It was observed that DF increased monotonically with decreasing particle number concentration in a constant thermohydraulic condition: a gradual increase from 10 to 32 in the range of 1.3×1011 - 8.0×1011/m3 at the inlet and a significant increase from 32 to 77 in the range of 3.6×1010 - 1.3×1011/m3. Two validation experiments were conducted in the range with the gradual DF increase to confirm whether the DF dependence is a real pool scrubbing phenomenon. In addition, characteristics of the DF dependence in different water submergences were investigated experimentally. It was found that the DF dependence became more significant in higher water submergence. Significant DF dependence was observed in the condition of the water submergence higher than 1.6 m and the inlet particle number concentration less than around 1×1011 /m3. It is recommended to perform further analysis for the DF dependence mainly in such condition since it could make a difference to both experiment and model of the pool scrubbing.

TL;DR: Pool scrubbing is one of the promising means for mitigating radioactive aerosol release into the environment in nuclear severe accident scenarios as discussed by the authors, however, the influence of operational conditions on its percolation is unknown.

TL;DR: In this paper, the authors performed a pool scrubbing experiment with different aerosol number concentrations under the same boundary conditions, and the results indicated that DF dependence on the aerosol concentration was not because of our experimental system error including measurement instruments but a real phenomenon of the pool cleaning.

TL;DR: In this paper, a double sensor void probe was applied to bubble flow to measure the bubble interface velocity, and the measurement error due to the meniscus formation around the sensor was investigated and the error in measurement of the interface velocity was evaluated.

TL;DR: In this paper, the decontamination factor (DF) evaluation by an aerosol measurement and a detailed two-phase flow structure measurement is conducted by using a transparent pipe with the inner diameter of 0.2 m and length of about 4.5 m.