This study reassesses the role of nuclear power in low-carbon electricity transitions under prevailing cost, finance, and system conditions. Using harmonised international data and observed 2024 operational metrics, we conduct a modelling-based stress test that evaluates how nuclear power performs when realistic construction, financial, and flexibility assumptions are applied. The results show that large nuclear power shares in prior modelling studies emerge primarily under optimistic conditions: Low overnight capital cost, reduced financing risk, or constrained renewable energy portfolios. When empirically validated inputs and full flexibility options are included, least-cost system pathways are consistently dominated by renewable energy-based portfolios complemented by storage, demand response, and existing dispatchable assets, while new nuclear power contributes only marginally. Empirical project evidence from recent builds corroborates the modelling results: prolonged construction duration and extended financing exposure significantly elevate effective project cost, irrespective of nominal levelised cost estimates. The Nordic region provides a natural comparative lens, revealing divergent governance models and public acceptance trajectories across Denmark, Sweden, Finland, and Norway, yet a shared economic constraint shaped by financing structure, risk allocation, and system alternatives. Overall, the findings indicate that under current techno-economic parameters and financing environments, renewable-centred energy portfolios form the cost-optimal foundation for power sector decarbonisation. Nuclear power remains a system- and policy-specific option that can contribute where governments assume substantial construction and financing risk and offer long-term capital recovery mechanisms. Transparent modelling assumptions and explicit financing terms are therefore essential for credible assessments of future nuclear deployment. • Nuclear competitiveness hinges on optimistic cost and financing assumptions. • Renewables plus flexibility dominate least-cost decarbonisation pathways. • New nuclear plays only marginal role under realistic system conditions. • Empirical data contradicts optimistic nuclear deployment scenarios. • Nordic case shows nuclear role shaped by policy and financing limits.
Weibezahn et al. (Sat,) studied this question.