The Paton Welding Journal, 2021, #3, 9-15 pages
Mathematical modeling of residual stresses in WWER-1000 elements after heat treatment
O.V. Makhnenko1, S.M. Kandala1, N.R. Basystyuk1 and M.V. Cherkashin2
E.O. Paton Electric Welding Institute of the NAS of Ukraine
11 Kazymyr Malevych Str., 03150, Kyiv, Ukraine. E-mail: firstname.lastname@example.org
«UKRTNIITMASh» Company, 7a Vasylenka Str., 03124, Kyiv, Ukraine. E-mail: email@example.com
Determination of residual life and extension of safe operating life of WWER-1000 internals for a term of up to 60 years
beyond the design period is an important scientific and engineering objective for nuclear power industry of Ukraine.
During long-term operation the reactor internal elements: reflection shield and cavity are exposed to intensive impact
of damaging radiation dose that causes the processes of radiation embrittlement, swelling and creep in the material
(08Kh18N10T austenitic steel). Technological residual stresses after welding and subsequent heat treatment should
be taken into account at calculation-based substantiation of the safe operating life of reactor internal elements. In the
work, mathematical modeling was used to derive residual stress distributions in the volume of the reflection shield
and internal cavity after electroslag welding and their redistribution fields after the technological process of postweld
heat treatment by the austenitizing mode. It is determined that the residual welding stresses are largely relaxed during
austenitizing. In the reflection shield, however, which is of complex geometry with variable wall thickness and cooling
channels, high residual stresses develop, due to occurrence of a significant temperature gradient at cooling during
austenitizing. These stresses should be taken into account at determination of the residual life of WWER-1000 reactor
internals. 8 Ref., 8 Figures.
WWER-1000, reactor internals, reflection shield, internal cavity, electroslag welding, heat treatment,
austenitizing, residual stresses
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