Good structural performance of the fuel assembly during irradiation is an indispensable requirement. Extension of licensed burnups demands continuous improvements, and more precisely on the design and processing of components made of zirconium alloys. Experience feedback on the assembly behaviour is necessary and continuous surveillance of the assemblies’ performance is maintained through on site inspections and post irradiation examinations (PIE). For that purpose, two research programs have recently been performed which included PIE on selected pressurised water reactor (PWR) assembly components made of ZIRLO. In the first program, a 15 by 15 fuel assembly irradiated for four annual cycles in Ringhals 2 NPP was selected for PIE. Samples extracted from grid strap vanes, guide thimble, and guide thimble end to top nozzle joints were subjected to visual examinations and characterizations such as oxide layer thickness, orientation, and distribution of hydride precipitates and hydrogen content. In the second program, as extension of the irradiated material evaluation of 17 by 17 lead test assemblies (LTA) irradiated in Vandellós II NPP, outer grid strap vanes were removed from a normal operation three-cycle assembly and from a four-cycle LTA and sent to the hot cell laboratory for destructive examinations. One objective of this work was to analyse the behaviour of skeleton key parts at the end of their irradiation life. Special attention was paid to the performance of the guide thimble end to top nozzle joint. Another objective was to study the effect of an additional irradiation cycle on the oxide thickness, hydride precipitates distribution, hydrogen concentration, and hydrogen pickup fraction of ZIRLO grids. Furthermore, an analysis of the oxidation and hydrogen uptake contribution on ZIRLO grids growth was performed. The hot cell examination results are presented and evaluated in the paper.