The integration of mobile robots in nuclear scenarios presents different challenges and opportunities, requiring specialized design, locomotion, sensing, and mission strategies. This chapter explores their classification, operational scenarios, and key applications, focusing on inspection, maintenance, and emergency response. The role of advanced sensing technologies, including radiation detection and traditional sensors used in mobile robotics, is examined in enabling reliable navigation and decision-making. Radioactivity fingerprint is introduced as a key feature for localization, navigation and mapping. Broader challenges, cross-disciplinary applications, and future directions for enhancing autonomous robotic systems in hazardous scenarios are also addressed, drawing inspiration from advancements achieved in nuclear scenarios.