AI data center power demand has triggered a nuclear renaissance. As of April 2026, over 75 reactors are under construction worldwide (WNA), and the U.S. DOE has set a target of adding 200GW of new nuclear capacity by 2050. This article deconstructs the nuclear supply chain into 5 tiers (Fuel, Reactor Design, Components, EPC, Operations/Services) and scores 13 globally listed companies (4 Korean, 9 international) using the PhotonCap GVM framework. With 1-year returns ranging from +322% to -50% across the same supply chain, we map where alpha remains.