Justification for applying of guide thimbles with hydraulic brake made from E635 alloy for fuel assembly from light water reactors

The guide tube (GT), being an element of the bearing frame of the fuel assembly, must be highly resistant to form change and corrosion during the whole operating life.
The aim of this work was to determine reasons for formation and influence of radial orientation of hydrides in the area of dashpot of GT on their performance characteristics and assessment on this basis the possibility of using such tubes in TVSA-T for the VVER-1000 reactor.
The report presents results of research into the structure, texture, creep resistance, and corrosion of GT tubes with dashpot, and of the analysis of operation results of GT tubes made of the E635 alloy. On the basis of the investigations, GT tubes with dashpot were recommended for use in TVSA-T of the VVER-1000 reactor.