Application of Software Tools for Predicting the Corrosion-Erosion Rate to Ensure Integrity of Equipment and Piping of Power Units at Nuclear Power Stations

Abstract

Basic principles are examined of the application of software tools (ST) for predicting the erosion-corrosion (EC) rate to ensure the integrity of equipment and piping of nuclear power station (NPS) power units. Methods for solving the erosion-corrosion problems encountered in NPS power units have been determined. Software tools that are used most widely throughout the world to solve erosion-corrosion problems in the nuclear power industry are reviewed. The specifics in the application abroad and in Russia are highlighted. Attention is given to the successful foreign experience in improving the corrosion-erosion resistance of piping and equipment based on the solution implemented in designing NPS power units. Information is presented on the development of Russian software tools and the results of their application to render the integrity of piping and equipment of NPS power units with a VVER reactor or fast breeder reactor due to numerical prediction and early detection of the maximum allowable erosion-corrosion metal thinning. The feasibility is substantiated of using the software tools in designing new NPS power units with a VVER-1200 reactor, assessing the residual service life, and prolonging the operation of existing NPSs. Examples are given of the ways for reduction in the erosion-corrosion rate of equipment components and piping of nuclear power units, for example, by controlling the intensity of the hydrodynamic component of erosion-corrosion and proper selection of the metal. It is demonstrated that the cost of power units with a VVER-1200 reactor (including export deliveries) can be reduced by a change-over to less erosion-corrosion resistant but relatively inexpensive steels. The prospects are noted on application in practice of STs to assess the carry over of iron-rich corrosion-erosion products into the working fluid of an NPS with a VVER-reactor. It is pointed out that, when changing over to operation of NPS power units at a super-rated power, this factor should be estimated using STs, and its effect on the wear rate and location of the zones wherein is the highest rate of thinning of the pipeline walls and equipment must be considered.