[en] The understanding of processes happening in fuel element materials under irradiation is connected with application of the modern instruments and techniques providing the largest body of information on changes of chemical and isotopic composition, crystalline structure, micro- and macrodefects, phase composition and distribution. It is the practice study by sampling techniques providing the representativity of the results obtained. Last years at the FSC RIAR hot laboratory the technique of integrated analysis is extensively used for grain a large information body by the same sample. It is achieved due to application of mutually co-ordinated instruments providing for examination of irradiated specimens of the same shape and dimension, quick fulfillment of transport operations between the instruments, specimen surface being without contact with the air in certain cases. The detailed non-destructive and traditional destructive techniques make it possible to choose the most representative and informative part of an irradiated fuel element for sampling and examinations. As an example of the WWER fuel, fuel element cladding investigations it was shown the main advantage of the integrated microscopy application, Auger-spectroscopy of X-ray microanalysis for examination of fuel element cladding materials and corrosion effects observed in fuel and coolant, secondary ionic and X-ray microanalysis for study of fuel composition. (author). 5 figs, 1 tab