Understanding Nuclear Reactors provides a non-mathematical understanding of how nuclear reactors operate. It describes the components, the Pressure Vessel, the Pressuriser to control the pressure in a Pressurised Water Reactor (PWR), and the Steam Generator and it also explains how the chain reaction is controlled in the day-to-day operations in the Control Room. What goes on elsewhere in the nuclear fuel cycle, mining, enrichment, fuel manufacturer, spent fuel management, and reprocessing are also covered in detail. The book tells a set of historical stories about the development of the physics behind reactors and the discovery of fission and explains the hopes for the development of Generation IV reactors. Special attention is given to the safety of reactors and the lessons to be learned from the incidents at Three Mile Island, Browns Ferry, Chernobyl, and Fukushima. Hooton uses a set of stories to explain the invisible hazard of radiation on the human body. Global warming was the motivation for the book, so Hooton offers a detailed account of alternative energy sources to fossil fuel, solar panels, wind turbines, geothermal, as well as nuclear. He gives a detailed account of all the current developments in nuclear fusion as a future prospect for the production of electricity. The hydrogen strategy is emerging, and may become a revolution, but it is a very subtle partner in the quest for net zero, so he includes a detailed account of how it fits into the plan to defeat Global warming.