Numerical Study of the Deposition of Radioactive Nuclide (Aerosol) in Pressurized Water Reactor Steam Generator

Abstract

This research presents a numerical study of deposition efficiency and decontamination factor of the radioactive nuclide in steam generator tubes of a typical 325 MWel pressurized water reactor (PWR). To find out the deposition of aerosol, the discrete phase model (DPM) has been used. The flow has been characterized as compressible, adiabatic, turbulent and wall-bounded. When steam generator tube gets ruptured, the radioactive nuclides can escape from primary side and create a radioactive field on the secondary side. This can be harmful at the personnel working at the plant. Therefore, in order to ensure the safety of the plant and personnel, it is important to study the particles deposition on the wall of steam generator tubes. In the present study, a computational fluid dynamics (CFD) methodology has been first developed and validated with the published results. After methodology validation, it has been applied to the U-tube of a typical PWR steam generator. It has been observed that due to the action of centrifugal force near the bent, the velocity magnitude is high toward the inner wall and the flow separates at the bent entrance. Furthermore, the flow inside the tube is rotational with vortices throughout the domain due to the presence of the bent. Finally, the deposition efficiency and decontamination factor have been calculated and it has been observed that both increase with the increase in particle size due to inertial effects.