579 / 2019-01-18 15:43:23

Numerical simulation of aerosol resuspension in nuclear power plants

nuclear power plant,aerosol resuspension,GASFLOW,severe accident,STORM

全体主题 > 数值模拟、建模与CFD

In nuclear power plants,nuclear fission products and activated structural materials are released and migrated in the form of gas,steam and aerosol under severe accident conditions. Among them,aerosols are suspended in the form of solid or liquid particles in the atmosphere space,which is one of the main sources of radioactivity released into the environment. In the early stages of a severe accident,aerosols are deposited on the wall and structures of the reactor vessel and primary circuits by different natural deposition mechanisms,for example,gravitational settling,thermophoresis,diffusiophoresis and then remain in the containment.In the late stages,the deposited aerosols can be resuspended into the atmosphere inside the containment due to special phenomena such as hydrogen burning or other highly turbulent gas flows and significantly increase the amount of radioactive materials,which play a key role in the radioactive source released into the environment.In order to get a more comprehensive understanding of aerosol behaviour during severe accident,it is quite necessary to study the aerosol resuspension effect deeply.GASFLOW developed by Karlsruher Institut f黵 Technologie (KIT) in German is used to calculate the aerosol resuspension rate in the containment.Unlike the lumped parameter codes such as MELCOR and MAAP,GASFLOW is a three dimensional (3D) computational fluid dynamics (CFD) code used to calculate aerosol transport, deposition, resuspension and other processes.The resuspension model developed by authors using Lagrangian discrete particle model is used in this paper.The GASFLOW aerosol models comprises a particle transport model,a stochastic turbulent diffusion model,a particle deposition model and a particle resuspension model.These models incorporate the physics of particle behavior and clouds of particles in nuclear systems.The analogy argument among mass,momentum and heat transfer is adopted in GASFLOW to analysis mass,momentum and energy transfer between structure surface and fluid. The calculation results are compared with the Simplified Test Of Resuspension Mechanism(STORM) series tests at the Joint Research Center (JRC),Ispra.The simulation result shows basic agreement with experimental data in STORM tests.Further improvement of aerosol resuspension model in GASFLOW is necessary to achieve a better prediction of the source term for large-scale advanced pressurized water reactors.