2016 №04 (02) DOI of Article
2016 №04 (04)

Automatic Welding 2016 #04
Avtomaticheskaya Svarka (Automatic Welding), #4, 2016, pp. 35-41
Modelling of residual stresses, radiation swelling and stressed state of in-service WWER-1000 reactor baffle

O.V. Makhnenko, I.V. Mirzov and V.B. Porokhonko
E.O. Paton Electric Welding Institute, NASU 11 Kazimir Malevich Str., 03680, Kiev, Ukraine. E-mail: office@paton.kiev.ua
The question of effect of baffle residual welding stresses on radiation swelling value has appeared in course of works on life extension of WWER-1000 reactor internals at the second power generating unit of the South-Ukrainian NPP. The E.O. Paton Electric Welding Institute has developed and realized a mathematical model for determination of residual stress-strain state of WWER-1000 reactor baffle in electroslag welding with further heat treatment as well as a model for calculation of baffle radiation swelling taking into account radiation creep. It can be stated based on the results of mathematical modelling that the baffle stressed state after 60 years of operation, calculated taking into account residual welding stresses, is close to the results received using the model without welding. This work studies relaxation of residual welding stresses in the WWER-1000 baffle under effect of irradiation and works out their in-service value-to-time dependence. 15 Ref., 3 Tables, 11 Figures.
Keywords: WWER-1000, baffle, electroslag welding, residual welding stresses, heat treatment, radiation swelling, radiation creep, mathematical modelling
Received: 16.02.2015
Published: 02.06.2016
1. (2000) Irradiation effects on the evolution of the microstructure, properties and residual stresses in the heat affected zone of stainless steel welds: INTERWELD Project. FIKSCT-2000-00103.
2. Makhnenko, O.V., Velikoivanenko, E.A., Mirzov, I.V. (2014) Redistribution of residual welding stresses in in-vessel core barrel of WWER-1000 reactor during operation. The Paton Welding J., 11, 8–14. https://doi.org/10.15407/tpwj2014.11.02
3. (1980) Electroslag welding and surfacing. Ed. by B.E. Paton. Moscow: Mashinostroenie.
4. (1975) Main principles on welding and surfacing of assemblies and structures of nuclear power plants, pilot and research nuclear reactors and units. Moscow: Metallurgiya.
5. Lychko, I.I., Sushchuk-Slyusarenko, I.I., Yushchenko, K.A. (1999) Specifics of electroslag welding of thick-wall long butts of 18-8 type steel. Avtomatich. Svarka, 9, 61–65.
6. GOST 30482–97: Electroslag welding of steels. Requirements to technological process. Interstate Standard.
7. Sorokin, A.A., Margolin, B.Z., Kursevich, I.P. et al. (2011) Influence of neutron radiation on mechanical properties of internals materials of WWER type reactors. Voprosy Materialovenediya, 66(2), 131–151.
8. Margolin, B.Z., Murashova, A.I., Neustroev, V.S. (2012) Analysis of influence of stressed state type on radiation swelling and radiation creep of austenitic steels. Problemy Prochnosti, 3, 5–24.
9. Pishtora, V., Vandlik, S., Lauerova, D. et al. (2011) Secondary operations on evaluation of technical state of reactor elements of power unit 1 of Yuzhno-Ukrainskaya NPP (Phase 1): Report of IYaI.
10. Margolin, B., Fedorova, V., Sorokin, A. et al. (2012) The mechanisms of material degradation under neutron irradiation for WWER internals and methods for structural integrity assessment. In: Proc. of Int. Conf. on Structural Integrity and Life of NPP Equipment (1–5 Oct. 2012, Kiev, Ukraine).
11. Margolin, B.Z., Kursevich, I.P., Sorokin, A.A. et al. (2009) To problem of radiation swelling and radiation embrittlement of austenitic steels. Pt 2: Physical and mechanical principles of embrittlement. Voprosy Materialovedeniya, 58(2), 99–111.
12. Nejmark, B.E. (1967) Physical properties of steels and alloys used in heat-power engineering: Refer. Book. Moscow; Leningrad: Energiya.
13. PNAE G-7002–86: Codes of design on strength of equipment and pipelines of nuclear power units. Moscow: Energoatomizdat.
14. Rabotnov, Yu.N. (1966) Creep of structure elements. Moscow: GIFML. 15. Margolin, B.Z., Murashova, A.I., Neustroev, V.S. (2011) Effect of stresses on radiation swelling of austenitic steels. Voprosy Materialovedeniya, 68(4), 124–139.