Calculation code to estimate admissible thickness of NPP equipment components under flow-accelerated corrosion
The paper presents a calculation code to estimate admissible wall thickness of NPP pipelines made of carbon steel to evaluate residual service life under flow-accelerated corrosion. The code is in full compliance with the industry-specific Regulatory Document RD EO 126.96.36.199.0571-2010. The key principles of development are reliability and conservatism of the code calculation, reliance on nuclear industry rules and regulations, estimation of the piping component characteristic size and analysis of working stresses. A data base on physical and chemical properties of metals was developed for algorithm realization. This makes it possible to calculate admissible thickness of different types of component sizes under real operating conditions. The data base includes all steel grades used in the nuclear industry and their physical and chemical properties. In addition, the possibility of increasing the metal nomenclature is realized. So far, calculation procedures have been realized for straight parts, bends and weld-adjacent zones. The results obtained are in full compliance with the Regulatory Document RD EO 188.8.131.52.0571-2010. The calculation code was tested on more than fifty components. Good agreement of the calculated parameters with the values in the Regulatory Document RD EO 184.108.40.206.0571-2010 has been achieved (error of less than 3%). The main advantage of the code presented is the possibility to perform calculations for any element size under any admissible conditions in accordance with the operating rules and regulations.
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