If a severe accident occurs in a nuclear power plant, radioactive aerosols and gaseous fission products are expected to release from the reactor containment to the environment.
Pool scrubber is a one of the filtering system which can achieve aerosol removal by injecting gas containing radioactive aerosol into the pool. Pool scrubbing code was developed to evaluate the efficiency of aerosol retention of pool scrubber in case of severe accident in nuclear power plant.
In order to evaluate the efficiency of aerosol retention, the pool was separated by two zones ? injection and rise zone ? according to hydrodynamics of bubbles such as initial steam condensation, inertial impaction, gravity settling and diffusive deposition.
Based on the current pool scrubbing models, some models such as bubble size distribution, shape and diameter were added in the code. The developed code has been also verified by analyzing LACE-Esapana and Kim’s experiment.
As comparing the code calculation with Kim’s experiment, the code can be estimated the experimental decontamination factors in the pool in the cases of small or large aerosol particles. However, the decontamination factors of middle sized aerosols were under-estimated by the code, it seems why the code was not considered a temporal aerosol coagulation effect through the inlet pipe.
As comparing the code calculation to LACE-Espana experiments, the calculation results agreed qualitatively with the experimental ones, that is, the steam faction and aerosol diameters were reasonably affected on the aerosol decontamination factors in the pool. However, the code was very sensitive according to the centrifugal velocity,
The decontamination factor in the ellipsoid bubble was higher than the spherical bubble because the aerosol removal by inertial impaction within bubble increases as bubble becomes flatter. If the various sized bubbles were considered in the pool, the decontamination factors increased compared with the single bubble assumption because some small bubbles with higher decontamination factors were considered.
To estimate the pool scrubbing phenomena precisely, some future works are suggested, that is, temporal aerosol coagulation, condensation on the hygroscopic aerosol, and vapor evaporation within the bubble. It is also required to measure temporal bubble diameter and shape in the pool to apply to newly development models as the hydrodynamic input data.