Use of a Model for the Final Stage of Transient Swelling to Predict the Radiation-Induced Porosity in Kh18N9 Steel during Operation in the BN-600 Reactor Internals

A model is developed to describe the final stage of transient swelling of austenitic steels, at which vacancy pores do not form. The evolution of an ensemble of radiation pores is determined by the following two processes: the growth of vacancy pores due to an unbalanced vacancy influx and the coalescence of growing pores. The evolution of an ensemble of pores during long-term operation is estimated using the model and the results of transmission electron microscopy studies of irradiated Kh18N9 steel samples, which are made of the BN-600 reactor internals having operated for 22 and 33 years. Time dependences of the average size, the concentration, the integral surface of pores and the swelling during operation for up to 50 years are plotted.