Each Member State independently decides on its own energy mix and use of nuclear energy. However, there are common rules and standards on nuclear energy, the basis for which is the Treaty on the European Atomic Energy Community (Euratom Treaty) signed in 1957. All current EU Member States are party to it and it has remained largely unchanged throughout the years.
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See the paper publication behind this podcast:
https://www.europarl.europa.eu/thinktank/en/document/EPRS_BRI(2023)751456