Unpacking public support for nuclear energy: A twin conjoint experiment on innovative nuclear fusion and next-generation fission technologies

The transition to sustainable energy systems is a critical priority for European countries. Among the most debated solutions are nuclear technologies, including innovative fusion and next-generation fission power plants. However, public support for these technologies is complex and influenced by a range of factors, including economic considerations, environmental concerns, and perceived social impacts; yet the majority of the studies conducted on these technologies are observational and mono-dimensional. To address this gap, we conduct the first-ever twin conjoint experiment designed to assess public support for both fission and fusion nuclear energy development plans. The conjoint fielded among a highly representative sample of the French, German, Italian, British, Spanish and Polish populations in May 2025. Our results reveal that public preferences for nuclear energy development plans, whether for innovative fusion or next-generation fission technologies, are shaped by place (topos), governance (nomos) and effectiveness (logos) oriented considerations. Respondents slightly favored fusion rather than fission development plans. • People slightly prefer fusion plans over fission plans across six European countries. • Distance, size, and local jobs strongly shape support for nuclear energy projects. • Governance matters: EU or domestic fuel sourcing increases public support. • Low electricity prices are the strongest driver of support for nuclear plans.