The corrosion simulation model of the typical seawater piping system is established by using COMSOL, which is the multi-physical field coupling evaluation software, in order to research the corrosion mechanism and the anti-corrosion optimization of the marine B10 seawater piping system. According to the distribution of flow rate, streamline, pressure, oxygen concentration and corrosion rate, it is found that the flow rate has a great impact on the distribution of the oxygen concentration, resulting in the galvanic corrosion of oxygen concentration difference. Three anti-corrosion optimization methods are proposed in view of the weakness of the pipe corrosion in the simulation calculation, including the appropriately increase of the bending curvature of the elbow, the cathodic protection of the steel straight pipe section coupled with the B10 pipe, and the installation of steel bellows in front of the equipment. It provides solutions for the life extension of the marine B10 seawater piping system.

The Integrated Pressurized Water Reactor (IPWR) has great advantages in the development of small and medium reactors because of its compact structure and high inherent safety. The casing once-through steam generator (OTSG) has been widely adopted in IPWR. The heat transfer tubes are annular tubes, which adopt double-sided heat transfer, with strong hear transfer capacity. However, the heat transfer situation is complex as there are single phase regions, steam/liquid two-phase regions and superheated regions in the casing. It is therefore easy to generate two-phase flow instability during the start-up, shutdown or low power operation of the reactor. A lumped parameter analysis model for a casing OTSG of a land reactor is established by using the RELAP5 code, in order to investigate the influence of several parameter, such as system pressure, inlet subcooling and inlet throttling, on the flow instability. The calculation results show that the increase of the system pressure, the inlet subcooling and the inlet throttling under the certain conditions have a positive effect on the system stability. The study of the flow of the OTSG of the IPWR in this paper can also provide reference for the study of the OTSG for the marine IPWR.