We have investigated the conceptual understandings of seventy-eight 16-year-old Australian high school students' and their knowledge about several issues related to nuclear energy. As a result of their study of the physics topic Nuclear Technology, the students learned more about applications of nuclear technology, had better though still inadequate conceptual resources for explaining the effect of radiation on human tissue, but retained their fears of the potential for nuclear energy to cause widespread damage or disaster. (Contains 3 figures and 4 tables.)