Influence of the heat transfer coefficient on the level of residual stress after heat treatment of the VVER-1000 reactor baffle
Keywords:VVER-1000 reactor, internals, baffle, welding, heat treatment, austenitization, residual stresses, mathematical modeling
Background. Improvement of the methodology for the computational analysis of residual stresses in the structural elements of the reactor is an integral part of the work when extending the service life of NPP power units.
Objective. Determine the value of residual technological stress arising in the baffle of a VVER-1000 reactor during welding and postweld heat treatment according to the austenitizing mode. To evaluate the effect of considering the dependence of the heat transfer coefficient on the temperature of the baffle surface at cooling in air during heat treatment.
Methods. Numerical modeling of the stress-strain state of the baffle during welding and postweld heat treatment was carried out using the finite element method.
Results. It was determined that in the process of heat treatment according to the austenitizing mode, the residual welding stress in the baffle are almost completely relaxed. Due to the high temperature gradient during rapid cooling in air after heating in the process of austenitization, new rather high residual stresses are formed in the zones of the baffle with the greatest metal thickness.
Conclusions. Based on the results of the investigation, a high level of residual technological stress was determined, which should be considered when calculating the justification for extending the service life of the VVER-1000 reactor baffle.
A.Y. Chirkov and V.V. Kharchenko, “Special features of computational assessment of the change in shape of WWER-1000 reactor core baffle in view of irradiation-induced swelling,” Strength of Materials, Vol. 52, pp. 339–352, 2020.
A.S. Kalchenko, and V.V. Bryk, “Prediction of radiation swelling of the VVER-1000 reactor baffle for an operation period of 30–60 years,” Problems of Atomic Science and Technology, pp. 69–78, 2011.
O.V. Makhnenko, and I.V. Mirzov, “Modeling of residual welding stresses, radiation swelling and stress state of a VVER-1000 reactor baffle during operation,” Automatic Welding, pp. 35–41, 2016. https://doi.org/10.15407/as2016.04.03
“Welding and surfacing of equipment and pipelines of nuclear power plants with VVER reactors,” NAEK "ENERGOATOM" Standard SOU NAEK 159: 2020.
V.I. Makhnenko, Calculation methods for ibvestigation the kinetics of welding stresses and deformations. Kiev, Ukraine: Nau-kova Dumka, 1976.
Y.N. Rabotnov, Creep of structural elements. Moscow, Russia: Nauka, 1966.
“Heat treatment of corrosion-resistant steels and iron-nickel-based alloys in chemical engineering,” JSC "NIIKHIMMASH" Standard STP 26.260.484-2004, 2004.
B.Z. Margolin, and A.G. Gulenko, “Modeling for fracture in materials under long-term static creep loading and neutron irradia-tion. Part 2. Prediction of creep rupture strength for austenitic materials”, Strength of Materials, Vol. 38, pp. 449–457, 2006. https://doi.org/10.1007/s11223-006-0064-z
A.L. Nemchinsky, Thermal calculations of heat treatment. Leningrad: State Publishing house shipbuilding literature, 1953.
M.V. Maisuradze et al., “Methodology for determining the cooling capacity of hardening media,” Innovations in materials sci-ence and metallurgy: materials of the 4th International interactive scientific and practical conference, Yekaterinburg, Russia, 2015, pp. 114–117.
O.V. Makhnenko, and S.M. Kandala, “Mathematical modeling of residual stresses in WWER-1000 elements after heat treat-ment,” Automatic Welding, pp. 10–16, 2021. https://doi.org/10.37434/as2021.03.02
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Copyright (c) 2021 Олег Махненко, Степан Кандала, Назар Басистюк
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