Dissertations and theses elaborated in the graduate program of the Nuclear and Energy Research Institute (IPEN) were used to obtain scientific thematic indicators. The covered period was from 1977 to 2009, and a total of 1670 items were considered. The theses were categorized according to the 33 metacategories of the Subject Categories and Scope Descriptions List. The use of dissertations and theses as the basis of the study proved to be appropriate for the elaboration of scientific indicators. The results permitted a correlation with historical and political facts. The thematic distribution confirmed the multidisciplinarity of the nuclear area and allied sciences. Through cluster analysis, it was possible to juxtapose areas with similar behavior, showing occurred research initiatives and allowing for a better visualization of the trends of each area.