Estimation of crack progration dynamics in WWER-1000 core barrel taking into account combined effect of high temperature, static loading and neutron irradiation [in Ukrainian].
Journal Title: Вісник Тернопільського національного технічного університету - Year 2015, Vol 80, Issue 4
Abstract
Reactor in-core components is subjected to high radiation doses that results in change of form and swelling during operation. Inside pressure of baffle on core barrel in zone of contact in WWER-type reactors creates additional stresses. Residual welding stresses can also significantly effect a level of stressed state of core barrel wall. High stresses combined with in-core temperature can cause growing of initial micro defects which can lead to rapid crack growth. That should be considered in estimation of working capacity of vessel internals for extension of WWER-1000 reactor service life. It is also important to take into account influence of neutron irradiation on material properties which can increase cracking rate. Aim of present work is to build general mathematical model of creep cracking which includes neutron irradiation influence, and apply it to reactor core barrel to see what happens with macro crack which is formed during service life of reactor. Base model for predicting crack growth of loaded cracked plate under influence of high temperature and neutron irradiation was build using second thermodynamics law modification for cracked body. It has been suggested that main mechanism of cracking is high-temperature creep crack growth. Neutron damage only increase creep rate which was shown in experimental investigations [5]. According to that we use creep law, and describe crack tip opening displacement rate like function of neutron damage. That function was used to describe one cycle of stepwise slow cracking process. All components were rewritten in terms of crack tip opening displacement. Adding initial and final condition equations to energy rate balance function extended for all time period forms finished model for predicting crack growth dynamics and estimating residual life in cracked plate under aforementioned conditions. Base model was further developed for case of plane crack in spatial body, and applied to reactor core barrel with initial longitudinal crack. It was shown than neutron irradiation significantly effect the creep crack growth level in the core barrel wall, that should be considered in estimation of working capacity of vessel internals at extension of service life of WWER-1000 reactor.
Authors and Affiliations
Oleksandr Andreykiv, Volodymyr Kukhar, Iryna Dolinska
Keywords
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