AbstractNuclear power has remained a hugely controversial energy technology since the 1970s and became particularly so after the 2011 Fukushima nuclear accident. Engaging citizens in making energy decisions have thus become an increasingly important governing approach to post‐Fukushima energy transitions in many countries. Deliberative participatory processes and learning through social interactions have been increasingly regarded as critical elements of effective public engagement. Yet, little is known about who learns what, how they learn, and what impacts learning has on nuclear governance. Even less is known about the contextual factors influencing social learning. Advancing the literature on nuclear governance, deliberative participation, and social learning, this paper proposes a learning‐oriented framework to evaluate the outcomes of deliberative participation in the context of nuclear governance. We apply this framework in a case study of a national deliberative poll (DP) on energy conducted in Japan in 2012. We critically examine the extent to which and how social learning occurs under the influence of pre‐existing government‐industry‐society relations as a key contextual factor. Mainly based on a qualitative analysis of transcribed materials from a two‐day deliberation over the DP involving 285 citizens, this study has three main findings. First, participating citizens of the DP were able to acquire all of the three orders of social learning through deliberative processes in the DP process. Second, the provision of multiple sources of information, access to diverse perspectives, and the availability of plenty of dialogic processes are identified as factors that were found to facilitate advancement toward higher orders of learning. Third, the “nuclear iron triangle”—a pro‐nuclear coalition—appeared to constrain social learning impacts in the wider socio‐political systems of nuclear governance in Japan.