Abstract
In a postulated accident of fuel pin failure of sodium cooled fast reactor, a fission product cesium will be released from the failed pin as an aerosol such as cesium iodide and/or cesium oxide together with a fission product noble gas such as xenon and krypton. As the result, the xenon and krypton released with cesium aerosol into the sodium coolant as bubbles have an influence on the removal of cesium aerosol by the sodium pool in a period of bubble rising to the pool surface. In this study, cesium aerosol removal behavior due to inertial deposition, sedimentation and diffusion from a noble gas bubble rising through liquid sodium pool was analyzed by constructing a computer program which deals with the expansion and the deformation of the bubble together with the aerosol absorption. In the analysis, initial bubble diameter, sodium pool depth and temperature, aerosol particle diameter and density, initial aerosol concentration in the bubble were changed as parameter, and the sensitivities of these parameters on decontamination factor (DF) of cesium aerosol were investigated. From the results, it was concluded that the initial bubble diameter was most sensitive parameter to the DF of cesium aerosol in the rising bubble due to the inertial deposition. It was found that the sodium pool depth, the aerosol particle diameter and density have also important effect on the DF of cesium aerosol, but the sodium temperature has a marginal effect on the DF.
To meet these results, the experiments for the investigation of cesium aerosol absorption behavior from rising noble gas bubble through sodium pool are under planning to validate the results for the sensitivities of above-mentioned parameters on the DF of cesium aerosol in the analysis.
