Nuclear power is a significant source of energy in many industrialized nations and currently supplies nearly 20% of the world's electricity. Due to high capital costs and nuclear safety, proliferation, and waste issues, nuclear power has not grown to be the major source of energy once envisioned. With a few exceptions, nuclear power is on the path of decline in most countries of the world. However, potential climate change from greenhouse gas emissions and global energy security concerns have heightened a reinvestigation of the role of nuclear power as a non-carbon emitting source of energy. In this study, we have investigated the role of advanced nuclear reactor and fuel system technologies in the context of the global energy system and climate change issues. We have developed long-term scenarios of the future energy system with various nuclear technology pathways to identify and understand key issues where nuclear power plays a growing and major role in the global energy system.