Validation Results of the AERCONT Aerosol Module of the TITAN-2/V1.0 Integrated Computer Code in Regard of Fission Product Aerosol Deposition Models

Safe operation of nuclear reactors depends in many respects on the insight into and prediction accuracy of the processes through which the fission product aerosols are generated, transferred, and deposited in the course of possible accidents. Aerosols are finely dispersed particles produced as a result of destruction of nuclear fuel and structural materials in the reactor core. They may be transferred with a gas and vapor flow; they can deposit on various surfaces and cause radioactive contamination of equipment and rooms. The article presents the results from verification and validation of the aerosol particle deposition model in the AERCONT aerosol module in the composition of the TITAN-2/V1.0 integrated computer code developed for calculating the behavior of gases, vapors, and fission product aerosols in the gas–vapor coolant in the primary circuit and rooms of the containment of an NPP with a reactor based on the VVER technology. The deposition of fission product aerosols determines the occurrence and accumulation of radioactive deposits on the walls of the process circuit and rooms. Therefore, validation of models for calculating this process is necessary and is of practical interest from the viewpoint of radiation safety. The article presents a brief description of the model simulating the behavior of multicomponent and polydispersed fission product aerosols, methods for numerically solving the system of differential equations, and a comparison of the model with similar approaches. The results of validating the particle deposition model against experimental data are given. Particle sizes, temperature gradients, and flow regime have an effect on the deposition rate, which are of crucial importance for assessing the contamination sources and elaborating efficient strategies for mitigating the consequence during the evolvement of accidents at NPPs.