Equivalent Axisymmetric 2D Modeling of Three-Dimensional Stress State
Main Article Content
Abstract
The study addresses the urgent problem of rapid structural integrity assessment for VVER-1000 reactor pressure vessels (RPVs) under pressurized thermal shock conditions during lifetime extension. Given the high computational complexity of three-dimensional finite element modeling, the authors propose a fast computational scheme based on 2D axisymmetric models. The paper analyzes the effect of stiffness mismatch between the simplified models and the actual geometry of nozzle zones, and proposes a combined model that merges the exact vertical profile of the nozzle with the corresponding RPV shell segment. The proposed technique enables the transformation of stresses from the 2D formulation into complete profiles across the entire wall thickness, ensuring the accuracy of stress intensity factor calculations at the level of full-scale 3D models while significantly reducing computational time.
Article Details
Issue
Section
This work is licensed under a Creative Commons Attribution 4.0 International License.
References
[1] SE "NNEGC "Energoatom", Calculations on strength and lifetime of equipment components and pipelines of nuclear power plants. General requirements, SOU 177:2023, Kyiv, 2023.
[2] M. Brumovsky, O. Martin, VERLIFE Guidelines for integrity and lifetime assessment of components and piping in WWER nuclear power plants, Publications Office of the European Union, Luxembourg, 2024, pp. 256.
[3] API, ASME, API 579-1/ASME FFS-1: Fitness-For-Service, American Petroleum Institute; American Society of Mechanical Engineers, Washington, D.C., 2016.
[4] ASME, ASME Boiler and Pressure Vessel Code, Section XI: Rules for Inservice Inspection of Nuclear Power Plant Components, American Society of Mechanical Engineers, New York, 2023.
[5] A. Boz, O. Demir, Fracture analysis for nozzle cracks in nuclear reactor pressure vessel using FCPAS, Nuclear Engineering and Technology. 56 (2024) 2292–2306. https://doi.org/10.1016/j.net.2024.01.040.
[6] M.-D. Xue, Q.-H. Du, K.-C. Hwang, Z.-H. Xiang, An analytical method for cylindrical shells with nozzles due to internal pressure and external loads. Part I: Theoretical foundation, Journal of Pressure Vessel Technology. 132 (2010) 031206. https://doi.org/10.1115/1.4001199.
[7] C. Oh, S. Lee, M.J. Jhung, Analytical method to estimate cross-section stress profiles for reactor vessel nozzle corners under internal pressure, Nuclear Engineering and Technology. 54 (2022) 401-413. https://doi.org/10.1016/j.net.2021.08.001
[8] C. Oh, S. Lee, M.J. Jhung, N.S. Huh, Analytical approach to estimate the thermal stress distribution of reactor pressure vessel nozzle corners with a constant cooldown rate, International Journal of Pressure Vessels and Piping. 197 (2022) 104608. https://doi.org/10.1016/j.ijpvp.2022.104608
[9] O. Yasniy, V. Brevus, V. Yasniy, Assessment of thermal power plant superheater collector limiting state, Ternopil Branch of Shevchenko Scientific Society, Aston, Ternopil, 2014, pp. 85-92.
[10] O.Ye. Andreykiv, V.V. Kukhar, I.R. Dolinska, Estimation of crack propagation dynamics in VVER-1000 core barrel taking into account combined effect of high temperature, static loading and neutron irradiation, Scientific Journal of the Ternopil National Technical University. 80 (2015) 20 – 27.
[11] M.C. Walter, D.V. Sommerville, Nozzle Blend Radius Peak Stress Correction Factors for 2-D Axisymmetric Finite Element Models, Proceedings of the ASME 2010 Pressure Vessels and Piping Division / K-PVP Conference (PVP2010), Bellevue, Washington, USA, 2010, pp. 317–325. https://doi.org/10.1115/PVP2010-25104 .
[12] D. Sommerville, M. Walter, An investigation into the effects of modelling cylindrical nozzle to cylindrical vessel intersections using 2D axisymmetric finite element models and a proposed method for correcting the results, Proceedings of the ASME 2011 Pressure Vessels & Piping Division Conference (PVP2011), 2011, Paper No. PVP2011-57571.
[13] M. Walter, S. Yin, G.L. Stevens, D. Sommerville, N. Palm, C. Heinecke, Additional stress and fracture mechanics analyses of pressurized water reactor pressure vessel nozzles, Proceedings of the ASME 2012 Pressure Vessels & Piping Division Conference (PVP2012), 2012, Paper No. PVP2012-78411.
[14] M. Walter, S. Yin, G.L. Stevens, D. Sommerville, N. Palm, C. Heinnecke, Supplemental Stress and Fracture Mechanics Analyses of Pressurized Water Reactor Pressure Vessel Nozzles, Proceedings of the ASME 2012 Pressure Vessels and Piping Division Conference (PVP2012), Toronto, Ontario, Canada, 2012, pp. 737–747. https://doi.org/10.1115/PVP2012-78119.
[15] ANSYS, Inc., ANSYS Academic Research Mechanical, Release 18.0, Help System, ANSYS, Inc., Canonsburg, PA, 2017.