The Czech Republic is one of the leading states on the road to joining the European Union (EU). The Temelín nuclear power plant, situated near the Czech-Austrian border, has been under construction since 1968. Its impending commercial operation has not only been a focus of domestic debate, but also has become an international issue during negotiations with the EU with safety issues being raised by opponents because of its unique integration of Russian and Western technology. This case study traces the development of the Temelin nuclear power plant and the interactions between states, including how Temelín's proximity to Austria serves as the basis for Austrian threats to veto Czech accession. The analysis that follows highlights the unusual role the EU played as mediator in this controversy and the role of nuclear power in the mix of energy resources as an issue in the accession negotiations.