The purpose of this study is to determine the metaphors that the candidate teachers develop about the nuclear power plants in a socio-scientific issues-based environmental education class and the justification of these metaphors. The study was constructed on the basis of a qualitative research model and phenomenological (phenomenology) pattern was used. The study was conducted during an academic semester in the environmental education course. The researcher presented to the classroom teacher candidates the positive and negative effects of the socio-scientific situations on environment, human development, economy, and health. It was ensured that teacher candidates were able to relate these issues to the subjects of environmental education course, assess the difficulties and discuss them with large group studies. A study for building the metaphors was conducted in the activity carried out for nuclear power plants as the last activity of the implementation process. The research was conducted with 197 classroom teacher candidates and the data were collected through a metaphor questionnaire prepared in a semi-structured form and the content analysis method was used in data analysis.