Reactor Chooz A, located beneath a hill in the Ardennes region of France, was one of the earliest pressurized water reactors built in the country. It started operating in 1967 and was decommissioned in 1991. With a power output of 305 megawatts, it was a joint venture between the French energy company EDF and a group of Belgian producers, who formed the Société d'énergie nucléaire des Ardennes (Séna). The reactor was housed in two underground caverns carved into the hillside, a design that offered natural containment and was unique in Europe at the time. During its 24 years of operation, Chooz A produced 38 billion kilowatt-hours of electricity, enough to power millions of homes over several years. However, its shutdown in 1991 did not immediately lead to its demolition. EDF spent several years preparing the site for a monitored closure, including removing spent nuclear fuel, draining pipelines, and disposing of operational waste. In 2001, EDF decided to dismantle the reactor, a process that required extensive regulatory work. After more than three years of preparation, the official approval for dismantling was granted in 2007. The conventional parts of the site, such as pipelines and machinery, had already begun to be dismantled since 1990. However, the nuclear components, particularly the reactor vessel and its concrete pit, required a slower and more cautious approach. The actual dismantling of the vessel, the last major stage, did not begin until 2017. In March 2025, EDF achieved a significant milestone by extracting the 190-ton reactor vessel, a first in France. However, the project faced a setback later in 2025 when the Nuclear Safety Authority requested an action plan due to an increase in radiation-related incidents. This led to two weeks of training sessions for workers on radiation safety. Despite these challenges, the site director, Arnaud Lebrun, emphasized that the project was not entirely halted, even though the vessel cutting had been suspended by late November 2025. The dismantling of Chooz A involves around 100 people, with 60% being subcontractors and 40% EDF employees. This project is not just a local effort; it serves as a full-scale model for the future dismantling of other pressurized water reactors in France, such as Fessenheim in Alsace. Lessons learned from Chooz A are being applied to adapt dismantling methods at other sites. For example, the steam generator at Fessenheim will be cut on-site rather than removed as a single unit, a decision influenced by experiences at Chooz. The broader question remains: if the first French reactor to be dismantled takes 25 years to decommission, how long will it take to dismantle the remaining 50 reactors in France’s nuclear fleet?