Specimens of reactor vessel internals (RVI) made of 18Cr–10Ni–Ti steel from the decommissioned VVER-440 unit after 45 years of operation were investigated. The aim was to assess the structure degradation degree responsible for the properties changes of RVI components. Radiation-induced structural elements of RVI baffle, former, and flux thimble specimens with the damaging dose 7.9–43.0 dpa and irradiation temperature 280–315 °C were studied using TEM, SEM, and APT methods. TEM-studies showed the negligible swelling under these conditions with a slight increase of radiation swelling due to the formation of the low-density large void population in case of higher temperature irradiation. APT-studies revealed the formation of the high-density Ni–Si-rich clusters (presumably G- and γ′- phase precursors) and an increase of its volume fraction with the temperature increase. The Orowan equation was used to assess the hardening contribution of different radiation-induced structural elements. The observed yield strength increase is insignificant under the studied conditions.

在运行45年后，对退役的VVER-440装置中由18Cr-10Ni-Ti钢制成的反应堆容器内部构件（RVI）进行了研究。目的是评估造成RVI组件性能变化的结构退化程度。使用TEM，SEM和APT方法研究了损伤剂量7.9–43.0 dpa和辐射温度280–315°C的RVI挡板，前者和通量套管样品的辐射诱导结构元素。TEM研究表明，在这些条件下的溶胀可以忽略不计，由于在高温照射下形成了低密度的大孔隙，所以辐射溶胀略有增加。APT研究表明，形成了高密度的富含Ni-Si的团簇（可能是G和γ'相前体），并且其体积分数随温度的升高而增加。Orowan方程用于评估不同辐射诱导的结构元素的硬化作用。在研究条件下，观察到的屈服强度增加不明显。