France’s Superphénix, a fast breeder nuclear reactor located in Creys-Malville, Isère, was connected to the national electricity grid in January 1986, after a decade of construction. It was part of a joint project between France’s Électricité de France (EDF), Italy’s Enel, and Germany’s SBK, under the umbrella organization NERSA. The reactor was initially conceived in 1974 as a response to the global oil crisis, aiming to generate more fissile material—such as plutonium—than it consumed, a process known as "breeding." Construction began in 1976, and the reactor achieved criticality—meaning it sustained a nuclear chain reaction—in 1985. At the time, it was the most powerful reactor in the world, but it operated for only four and a half years during its 11-year lifespan, producing 7.9 billion kWh of electricity—enough to power Paris for an entire year. The reactor was shut down in 1997, not because of technical issues but due to a political decision. A parliamentary report noted that shutting it down immediately was more expensive than continuing to operate it. The closure followed the cancellation of a decree by the Conseil d'État, France’s highest administrative court, on February 28, 1997, which had blocked changes to the reactor’s core design. Despite a productive year in 1996, when its performance outpaced other EDF reactors, the reactor was legally prevented from operating and eventually shut down. This decision was influenced by the multi-party left coalition led by Prime Minister Lionel Jospin, which included the Green Party, who demanded the reactor's closure as a condition for supporting the government. The financial burden of the project was immense. According to the Cour des comptes, France’s audit court, the construction cost was 9.1 billion euros, with an annual operating cost of 1 billion euros. By 2010, the total cost of the project—excluding the dismantling process—was estimated at 12 billion euros. The decommissioning process, which began in 1999, has already exceeded the reactor’s original lifespan. Today, around 350 people are working on-site, with 80 directly employed by EDF. Their tasks include complex operations like draining liquid sodium, a coolant used in fast reactors, and cutting the reactor vessel. The technical knowledge gained from the project is now recognized globally, with EDF offering support to Japan’s Monju reactor project. The decommissioning is expected to continue until the mid- to late-2020s.