This special issue contains contributions from the 3rd Interdisciplinary Research Symposium on the Safety of Nuclear Disposal Practices (safeND), held in Berlin, Germany, on 17–19 September 2025. The papers, representing a wide variety of disciplines, focus on the topic of the conference: "Time as a safety factor: opportunities and challenges of timely nuclear waste disposal". Among other topics, the special issue addresses some of the socio-technical challenges of nuclear waste management, recent developments in engineering as well as research on different host rocks and repository safety.