After Fukushima, nuclear preparedness and response have returned to center stage. The latest in a series of so-called “beyond design basis accidents”, the event, yet again, demonstrated a glaring lack of emergency response capability and expertise and revealed a precarious imbalance in the world’s nuclear infrastructure. Similar to severe nuclear accidents before, Fukushima triggered initiatives to ramp up emergency preparedness and response capabilities; arguably, it even shifted the nuclear industry’s hitherto exclusive focus on accident prevention. An enduring challenge, however, has been the anticipated non-use of these technologies: maintaining highly qualified experts and sophisticated hardware on alert for events that are not only highly undesirable, but also very unlikely is costly and demands new repertoires of justification. The challenge with technologies-not-in-use is that one needs to keep material, expertise, and process know-how current, and on hair-trigger alert, while knowing (and hoping) that this alert may never come. How long does it make sense to fund an expensive inventory of artifacts that may never be needed? How would one train emergency responders that will hopefully never actually need to use their skills? And how does “use” (or non-use) become part of a justification – for continued funding, diligent maintenance and upgrading, regular practice, etc.? This presentation is part of a multi-year project on “Globalizing Nuclear Emergency Response” and draws primarily on STS research on energy policy, expertise, and socio-technical imaginaries.