Phase and structural transformations in VVER-440 RPV base metal after long-term operation and recovery annealing
Autor: | D. Yu. Erak, Z.V. Bukina, Evgenia Kuleshova, S.V. Fedotova, G.M. Zhuchkov, D.A. Maltsev, A.S. Frolov, D. A. Zhurko, D. V. Safonov, E. V. Krikun, M.A. Saltykov, B. A. Gurovich |
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Rok vydání: | 2018 |
Předmět: |
010302 applied physics
Nuclear and High Energy Physics Materials science Annealing (metallurgy) 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Lifetime extension Brittleness Nuclear Energy and Engineering 0103 physical sciences Hardening (metallurgy) General Materials Science Grain boundary VVER Composite material 0210 nano-technology Reactor pressure vessel Base metal |
Zdroj: | Journal of Nuclear Materials. 501:261-274 |
ISSN: | 0022-3115 |
Popis: | This study was carried out to evaluate the possibility of 1st generation VVER-440 reactors lifetime extension by recovery re-annealing with the respect to base metal (BM). Comprehensive studies of the structure and properties of BM templates (samples cut from the inner surface of the shells in beltline region) of operating VVER-440 reactor (after primary standard recovery annealing 475 °C/150 h and subsequent long-term re-irradiation within reactor pressure vessel (RPV)) were conducted. These templates were also subjected to laboratory re-annealing 475 °C/150 h. TEM, SEM and APT studies of BM after laboratory re-annealing revealed significant recovery of radiation-induced hardening elements (Cu-rich precipitates and dislocation loops). Simultaneously a process of strong phosphorus accumulation at grain boundaries occurs since annealing temperature corresponds to the maximum reversible temper brittleness development. The latter is not observed for VVER-440 weld metal (WM). Comparative assessment of the properties return level for the beltline BM templates after recovery re-annealing 475 °C/150 h showed that it does not reach the one typical for beltline WM after the same annealing. |
Databáze: | OpenAIRE |
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