![]() ![]() In Europe, almost 80% of reactors are PWRs (Pressurized Water Reactors), by far the most common design worldwide. There are two types of second generation reactors that are based on enriched uranium: those that use boiling water and those using pressurized water. Today’s reactors, however, can use ordinary water both to slow the neutrons down and to serve as a coolant. Older reactors of first generation, which used unenriched uranium, had to have heavy water or graphite to slow the neutrons down. Nuclear energy is mainly released by conventional reactors of the so-called ‘second generation’, which use natural uranium (enriched with 3-4% of uranium 235) as a fuel source. SUPERPHENIX, the breeder reactor at Creys-Malville have been closed in 1997, but its predecessor PHENIX at Marcoule still runs for researches and development. Eleven units (Bugey, Chinon, Saint-Laurent-des-Eaux, Marcoule et Chooz), belonging to the first generation of graphite-gaz reactors using natural uranium (UNCC) have been definitively closed. Overall, 59 units (or tranches) of pressurized water Reactors were in activity in 2005. This map shows the implantation of the French nuclear plants in 1998. Asia is home to the two countries currently most heavily reliant on nuclear energy for their development: Korea and China. Outside Europe, the resource-rich United States have little need for nuclear energy, but in Japan, a country comparatively poor in natural energy sources, 33% of the energy is supplied by nuclear reactors. Italy’s four power plants were shut down after Chernobyl, and the country currently obtains 0% of its energy from nuclear processes. In Europe, for instance, France and Belgium are both heavily reliant on nuclear energy (in France, nuclear energy makes up 75% of the total supply), whereas England (35%) and Germany (33%) use far less. The part that nuclear energy plays, however, differs from country to country. They have a combined output of 350 GW, producing 17% of the world’s energy supply. Many modern reactors have an electrical power of 1 gigawatt each. In 2014, there was over 437 nuclear reactors in activity worldwide, all distant descendants of Fermi’s atomic pile and the nuclear reactors of Hanford. Symbol of the French atomic effort after the Second World War, Zoé, the first nuclear reactor in France, can still be visited today. The first sustained chain reactions at the Zoé reactor of Fort Châtillon (south of Paris) took place on December 1948. Developed as part of President Eisenhower’s Atoms for Peace program (1953), they are heirs to the naval propulsion reactor prototypes. It was not until the 1950s that reactors were designed for civil purposes to produce electricity. Onboard reactors for submarine propulsion were then put into service with the launch in 1954 of the world’s first nuclear submarine, NAUTILUS. Over the following years, several reactors were built in Washington State – in the desert environment of Hanford – with the aim of producing enough plutonium to build the first atomic bombs. This atomic pile, designed by a team of physicists led by the Nobel Laureate Enrico Fermi, diverged (chain reactions occurred) on December 2, 1942. Graphite served as a moderator, uranium as nuclear fuel. Under these stands was built, in the greatest secrecy, an edifice made of graphite and natural uranium which was given the name of atomic pile, because it was a real pile of graphite bars, some of which hollow containing uranium. The world’s first nuclear reactor was completed in 1942, and housed under the stands of the Chicago University stadium. ![]()
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