Korean nuclear energy regulatory policies are noted to have changed from earlier exclusive technocracy into open dialogues since the late 1980s after the nation’s political democratization. However, technocratic policies still co-exists with new regulatory terms such as openness, transparency and mutual learning between the lay and the expert knowledge. This paper analyzes Korean nuclear regulatory policies since roughly 2005 as a blend of old and new governance. The paper does not aim to decide whether the governance is genuinely new and participatory; rather, it explores how the Korean history of nuclear energy development and social assumptions of its public interact with changing policy environments. The case of Korean nuclear policies serves as a site to analyze how certain forms of the ‘public’ and ‘public participation’ are produced and reproduced through continued boundary work between science and society with new science and technology governance.