To understand the importance for the EU of nuclear energy this chapter starts with a detailed analysis of the Euratom Treaty of 1958 (including legal aspects, safeguards and EU Supply Agency). This Treaty intended to achieve a rapid development, which because of the Chernobyl nuclear accident and later the Fukushima tsunami negatively impacted the development. These majors’ events are analysed for putting in perspective the ongoing development of nuclear energy both within the EU and worldwide. Regarding technologies both the uranium cycle and the characteristics of nuclear power plants will be analysed. Despite certain difficulties, including those relating to the disposal of spent fuel, we will note that nuclear energy is still very much alive and that new solutions are constantly under development. We will show that the greatest risk is that Western political pressure for shunning nuclear energy could put the nuclear technology issue exclusively into the lap of Russia, China and Japan. This chapter will conclude with a short explanation of the current developments in the field of nuclear fusion.