The 43rd edition of Reference Data Series No. 1 contains estimates of energy, electricity, and nuclear power trends up to the year 2050. The publication considers the prospects of new capacity additions, retirements and long term operation of existing units. The 2022 capacity and production data is taken from Nuclear Power Reactors in the World, Reference Data Series No. 2, IAEA, Vienna (2023). RDS-1 is organized into world and regional subsections, with global and regional nuclear power projections presented as low and high cases, encompassing the uncertainties inherent in projecting trends. The low case assumes a continuation of current market and technology trends leading to a modest increase in in global nuclear capacity to 458 GWe by 2050. The high case assumes a more favourable context and leads to a more than doubling of global nuclear power capacity to 890 GWe by 2050. Despite the increasing recognition of nuclear power's role in climate change mitigation and energy security improvement, the current pace of nuclear power development shows that urgent actions would be needed to maintain the existing role of nuclear power in the energy mix, involving a broad range of actors including policy makers, the nuclear industry, the financing community, and international organizations, along with active engagement with the public.