Nuclear energy startups are competing in a $900 billion battle to be the future of energy in the United States. The resurgence of nuclear energy is seen as a serious option for abundant, carbon-free power, following a period of declining enthusiasm due to accidents at Three Mile Island, Chernobyl, and Fukushima. Companies like Kairos Power, TerraPower, X-Energy, and TerraPower are developing new types of nuclear reactors designed to be safer, more cost-effective, and faster to build than anything previously. These companies also incorporate fourth-generation nuclear technology, which is said to be more sustainable, more reliable, and economically viable to operate than their predecessors. Kairos is building its Hermes demonstration reactors in Oak Ridge, Tennessee, and has received up to $303 million in grant funding through the DOE's Advanced Reactor Demonstration Program.