Development of a semiempirical model for the aerosol scrubbing in a sodium pool

In sodium cooled fast reactors, failure of fuel rods may result in the release of radioactive fission products into the coolant pool. Radionuclides may be transported to the cover gas area through bubble entrainment, thereby affecting the normal operation of the reactor system. Therefore, the calculation of the scrubbing mechanism of radioactive fission product aerosols in the rising bubbles of the sodium pool is crucial to ensure the safe operation of fast reactor. In this study, we intend to propose a new sodium pool scrubbing model to evaluate the retention capacity of sodium pools for fission products. The model includes two modules: bubble dynamics module to calculate bubble size, eccentricity, and rising speed; aerosol pool scrubbing module considering four aerosol removal mechanisms: Brownian diffusion, gravitational sedimentation, inertial deposition, and vapor condensation. The model was firstly validated by two transient scenarios, PLOF+ and UTOP+. Moreover, SRT (Simplified Radionuclide Transport) experiments were utilized to validate the model. To further improve the accuracy of the model, we modified the model by introducing a correlation factor to correct the inertial deposition effect. In addition, the influence of various key parameters on the efficiency of pool scrubbing was discussed. The results show that larger bubble diameters and deeper depths have a promoting effect on the pool scrubbing efficiency; The influence of particle diameter is nonmonotonic; The pool temperature has no significant impact.