This document discusses the future of nuclear power after the Fukushima disaster. It provides background on nuclear fission and power, reviews past nuclear accidents, and models projections of global energy and emissions under scenarios with and without expanded nuclear power. Advanced reactor designs promise enhanced safety but are very expensive. Small modular reactors may have potential but likely cannot scale fast enough to replace fossil fuels at the necessary rate. Even before Fukushima, projected growth rates of nuclear power needed to mitigate climate change were extremely challenging and unrealistic.