Assessing the economic viability of nuclear power requires a comprehensive evaluation of cost metrics and systemic factors. The levelized cost of electricity metric is widely used to compare energy generation technologies, yet it overlooks crucial aspects such as flexibility, waste management, and system integration costs. This chapter critically examines the discrepancies between reported, projected, and actual cost data for light-water reactors and so-called new reactor concepts in OECD countries, highlighting challenges in cost estimation and system modeling. While some energy system models anticipate increased nuclear capacity, cost-optimizing analyses suggest a stronger reliance on renewables. Additionally, this study explores the role of nuclear power in hybrid systems and discusses key economic and market integration constraints. The flexibility potential as well as the system transformation dynamics are determining factors in a renewable-dominated energy landscape and show that renewable and nuclear technology profiles are competitive rather than complementary.