| 2025 №03 (01) |
DOI of Article 10.37434/tdnk2025.03.02 |
2025 №03 (03) |
"Tekhnichna Diahnostyka ta Neruinivnyi Kontrol" (Technical Diagnostics and Non-Destructive Testing) #3, 2025, pp.15-23
Features of the stress state of welded absorber rods in the control and protection system of WWER-1000 during assembly and subsequent operation
O.S. Milenin, O.A. Velykoivanenko, G.P. Rozynka, O.O. Makhnenko
E.O. Paton Electric Welding Institute of the NAS of Ukraine 11 Kazymyr Malevych Str., 03150, Kyiv, Ukraine. E-mail: asmilenin@ukr.netThe rod control cluster assemblies with absorber rods (AR) plays a key role in the stable and safe operation of WWER-1000 reactor, ensuring power regulation and emergency shutdown. The reliability of AR directly depends on the integrity of the AR shell components, which are subjected to both welding stresses during assembly and to operational loads. A critical reliability factor for such structures is the stress-strain state at various stages of assembly and operation. This study focuses on the analysis of the stress-strain state in the AR shell components caused by the technological phase of installation welding and operational loading. Numerical modelling of thermo-mechanical processes shows that the geometric characteristics of the structure fundamentally affect the stress distribution: a biaxial stressed state forms in the area where the cone is welded to the AR shell, and a triaxial stressed state develops in the zone where the tip is joined to the shell. It is shown that during reactor emergency shutdown and cooling to room temperature, there is a significant drop in the external coolant pressure and a sharp increase in the maximum stresses within the AR shell wall, indicating an increased risk of integrity loss. 15 Ref., 1 Tabl., 8 Fig.
Keywords: nuclear reactor, WWER-1000, rod control cluster assemblies, absorber rods, welded shells, stressed state, modelling
Received in revised form: 10.06.25
Received in revised form: 24.07.25
Accepted: 29.08.25
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