Abstract

Significance As a typical and important technical form of the new generation of advanced nuclear power technology， advanced pressurized water reactors （APWRs） have been widely promoted and applied in nuclear power engineering. Nevertheless， safety prevention and control under severe accident conditions remain a core concern restricting the further improvement of nuclear power safety margins， and it is also a key aspect in ensuring the long-term stable and safe operation of nuclear power plants. Under extreme severe accident conditions of APWRs， radioactive aerosols act as the main carriers of radioactive fission products and constitute a critical radioactive source term for nuclear accident releases. The migration， deposition， resuspension and other dynamic evolution behaviors of aerosol particles in the large and enclosed containment space directly determine the spatial diffusion range， temporal evolution patterns， and total release amount of radioactive substances. An accurate understanding of aerosol evolution characteristics is of great significance for reactor severe accident safety analysis， quantitative assessment of accident consequences， and targeted formulation of radioactive pollution prevention and control measures. This paper systematically reviews the research progress and relevant findings on aerosol transport behavior in APWRs under severe accident conditions.

Progress In general， current research on nuclear aerosol evolution still has obvious deficiencies in theoretical mechanisms and numerical simulations. In terms of mechanism research， most existing studies only focus on a single aspect of aerosol dynamic behaviors， such as deposition or resuspension， under specific accident conditions， lacking systematic， comprehensive， and hierarchical analysis and summary of multi-behavior coupling patterns. In addition， most research remains at the macroscopic statistical level， lacking a complete multi-scale research perspective that covers microscopic particle force evolution and macroscopic spatial migration. Consequently， it is difficult to reveal the essential evolution mechanism of aerosol groups under complex accident conditions. In terms of calculation models， traditional research mainly relies on classic lumped parameter programs， which can only obtain average parameters and cannot accurately characterize the three-dimensional spatially non-uniform distribution of aerosols. However， the containment has a large space and complex internal structure， and the thermal parameters and structural characteristics of different regions vary significantly， leading to considerable differences in aerosol dynamic mechanisms. Therefore， it is urgent to develop a multi-dimensional aerosol evolution calculation model that couples three-dimensional complex structural environments with time-varying accident parameters.

Conclusions and Prospects Conducting in-depth research on the multi-scale evolution mechanism of behaviors such as migration， deposition， and resuspension of aerosol particles in large space and complex structures， developing high-precision three-dimensional spatial unsteady numerical calculation models and programs， and realizing efficient coupled calculation and quantitative analysis of multiple aerosol dynamic processes are key research directions that need to be urgently advanced in the field of nuclear severe accident safety research.

Keywords：severe accident； advanced reactor； aerosol； particle motion； multi-scale coupling