Methodology of using megavolt electrons for investigation of the functionality of thin polymer films of polycyanurates (PCN) is described. The relevance of research is determined by the prospects of using films as a functional basis for improvement of track-etched technologies of nanoporous nuclear filters, where ionizing radiation is used in most of technological stages of their production. Functionality control is the main criterion for the qualification of films on the suitability for production of nuclear filters on their base. Development of megavolt electrons radiation methods is promising for monitoring the functionality of filters. Radiation technologies are universal and able to provide maximum information content on investigations of the characteristics of materials to qualify them for suitability of practical use. To control the functionality of the films, the methodology for research and testing of thin polymer films using powerful electron beams of 1-2 MeV has been developed. The features of these methods and the results of their application at the control of functionality and for the qualification of the films based on crosslinked polycyanurates, synthesized by in situ polycyclotrimerization of dicyanate ester of bisphenol E in the presence of dimethylphthalate (DMPh) of the composition PCN/DMPh=70/30 wt.%, on the suitability for production of nanoporous track membranes are discussed. Key words: electron beams, nuclear membranes, thermostable polycyanurates, radiation stability, functional testing.