Governments regulate risky industrial systems such as nuclear power plants in hopes of making them less risky, and a variety of formal and informal warning systems can help society avoid catastrophe. Governments, businesses, and citizens respond when disaster occurs. But recent history is rife with major disasters accompanied by failed regulation, ignored warnings, inept disaster response, and commonplace human error. Furthermore, despite the best attempts to forestall them, "normal" accidents will inevitably occur in the complex, tightly coupled systems of modern society, resulting in the kind of unpredictable, cascading disaster seen at the Fukushima Daiichi Nuclear Power Station. Government and business can always do more to prevent serious accidents through regulation, design, training, and mindfulness. Even so, some complex systems with catastrophic potential are just too dangerous to exist, because they cannot be made safe, regardless of human effort.