Analysis On Critical Factors Of Marine Organism Impacts On Water Intake Safety At Nuclear Power Plants

The safety of cooling water intake in nuclear power plants (NPPs) has gradually become an important factor affecting the safety of NPPs. Marine flora and fauna outbreaks are one of the main types affecting the safety of cooling water intake in NPPs, and the driving mechanism is more complicated and difficult to predict. This paper mainly analyzes the main types and typical cases of marine organisms that cause cooling water intake blockage in NPPs, and analyzes the key factors such as hydrodynamic conditions, timing of organism's outbreak, characteristics of species, and design of the screen systems. The results show that strong hydrodynamic conditions or strong tides caused by special meteorological conditions are important factors. Considering the time of organism's outbreak, spring and summer (May-August, may change slightly according to different latitude) is key period because of the reproduction and growth of most marine organisms, according to the growth law of marine organisms. In terms of biological characteristics, it is sensible to focus on those species with fast growth, strong reproductive capacity, short life cycle, weak swimming ability, and cluster distribution. As to the design of screen systems, the blockage mainly occurs in revolving filter screens. The grid spacing of normal mechanical grille is too large to block the small marine organisms. It is necessary to add trash interception nets according to the type and size of the marine species. Finally, a case is used to confirm the factors needed to pay more attention.