Background: The recent Fukushima Nuclear Power Plant accident was one of more than 200 serious nuclear/radiation incidents (accidents and disasters) that occurred worldwide since 1945. The current Fukushima disaster is in the recovery phase with the decreasing levels of radiation in the environment. However, fears and stigma related to the perceived risk of radiation exposure persist among the general population. Introduction: To improve on students’ preparedness for social and public health challenges after a radiation incidence, radiation education was provided for undergraduate public health nursing students. Aim: This case study reports the development and implementation of the first class of radiation education in public health nursing, as well as students’ reflections on their class experience. Methods: We included a 90-min radiation class in an undergraduate public health nursing course in Tokyo, Japan. Lectures/discussion on technical and environmental aspects provided the minimally essential content for basic radiation knowledge. After class, all the 65 students were invited to freely write their reflections on the class. With their consent, 61 students’ anonymous written accounts were qualitatively analysed. Results: Five themes emerged: awareness of ignorance about radiation, problems produced by the mass media, becoming knowledgeable about radiation, public health nurses’ role, and trustful and enjoyable lecture. Discussion: The class inspired students to consider social, psychological and relational aspects of knowing and not knowing about radiation and their future professional role. Conclusion and implications for nursing: Once radiation is taught at school, nursing students will emerge as professionals with the belief that radiation is within their professional purview. Education is key to disaster prevention, preparation, response and recovery. Given the ubiquitous nature of health challenges after a radiation incident, radiation education is indispensable for nursing students worldwide.