Neutron diffraction study of structure and phase composition of fuel claddings made of cold-deformed steel ChS68 after normal operation in BN-600 reactor

Samples of fuel claddings after their operation life in the BN-600 reactor have been investigated. They were irradiated with fast neutrons with a damage dose from the range 1.5–81.4 dpa and at temperatures from 643 to 798 K. Using the FullProf program analysis, data on the microstructure, texture, and microdeformations were gained. From the anisotropic broadening of reflections estimated by the Williamson-Hall method, the density of dislocations and their type were calculated. A conclusion is made on a significant impact of the irradiation temperature on the dislocation density. It is shown that neutron diffraction is an attractive way of investigation of microstructure of massive samples subjected to such high irradiation doses without leading the staff into any radiation danger. •Massive samples of fuel claddings after their operation life in the BN-600 reactor have been investigated using neuron diffraction technique.•The microstructure of the irradiated samples of fuel claddings depends on the damage dose and irradiation temperature.•The density of dislocation changes, the number of edge dislocations increases, and microparticles of another phase precipitate.