The Zoé reactor, or EL-1, was the first French atomic reactor. It was built in 1947 at the Fort de Châtillon in

Fontenay-aux-Roses Fontenay-aux-Roses () is a commune in the southwestern suburbs of Paris, France. It is located from the center of Paris. In 1880 a girls school École Normale Supérieure was opened in the town. It was one of the most prestigious of Paris and ...

, a suburb of

Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), ma ...

. Design work for the

heavy-water reactor A pressurized heavy-water reactor (PHWR) is a nuclear reactor that uses heavy water ( deuterium oxide D2O) as its coolant and neutron moderator. PHWRs frequently use natural uranium as fuel, but sometimes also use very low enriched uranium. T ...

was started in 1947 by

Frédéric Joliot-Curie Jean Frédéric Joliot-Curie (; ; 19 March 1900 – 14 August 1958) was a French physicist and husband of Irène Joliot-Curie, with whom he was jointly awarded the Nobel Prize in Chemistry in 1935 for their discovery of Induced radioactivity. T ...

, who was at the time director of the French Commission for Atomic Energy (''Commissariat à l'énergie atomique'' (CEA)). The project manager was

Lew Kowarski Lew Kowarski (10 February 1907, Saint Petersburg – 30 July 1979, Geneva) was a naturalized French physicist. He was a lesser-known but important contributor to nuclear science. Early life Lew Kowarski was born in Saint Petersburg to Nicholas K ...

, who had just returned from

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

, where he had supervised the construction of the Canadian

ZEEP The ZEEP (Zero Energy Experimental Pile) reactor was a nuclear reactor built at the Chalk River Laboratories near Chalk River, Ontario, Canada (which superseded the Montreal Laboratory for nuclear research in Canada). ZEEP first went critical a ...

heavy-water reactor. Zoé was activated on 15 December 1948, reaching a power of 150 kW by 1953. The nuclear fuel was provided by Bouchet of

Ballancourt-sur-Essonne Ballancourt-sur-Essonne (, literally ''Ballancourt on Essonne'') is a commune in the Essonne department in Île-de-France in northern France. Geography The Essonne forms the commune western border. Ballancourt-sur-Essonne is 37 kilometers south ...

, which reprocessed the irradiated fuel and extracted the first milligrams of French-produced

plutonium Plutonium is a radioactive chemical element with the symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibi ...

. The reactor was shut down in March 1976 and containment of the reactor was completed in 1977. The choice of moderator and fuel was dictated by the undeveloped state of the French nuclear industry at the time, which could not manufacture the corrosion-proof equipment needed for a more advanced unit. The reactor was a pool-type design, with five tons of heavy water moderator surrounded by a two-meter-thick concrete wall. The core, immersed in the pool, consisted of 60 aluminum-cased vertical rods containing three tons of uranium oxide pellets, controlled by

cadmium Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it demonstrates oxidation state +2 in most of ...

rods. The heavy water was purchased from

Norsk Hydro Norsk Hydro ASA (often referred to as just ''Hydro'') is a Norwegian aluminium and renewable energy company, headquartered in Oslo. It is one of the largest aluminium companies worldwide. It has operations in some 50 countries around the world a ...

. A cooling system was added after the reactor had operated for a time, allowing it to run at a heat release rate of 200 kilowatts. The name Zoé was an

acronym An acronym is a word or name formed from the initial components of a longer name or phrase. Acronyms are usually formed from the initial letters of words, as in ''NATO'' (''North Atlantic Treaty Organization''), but sometimes use syllables, as ...

, from ''Zéro de puissance'' (zero power, that is, very little capacity to produce electricity, which made it easier and faster to build); ''Oxyde d'uranium'' (uranium oxide), ''Eau lourde'' (heavy water).Pinault, Michel, Frédéric Joliot-Curie, Editions Odile Jacob, Paris (2000), pg. 359 The Châtillon site was superseded for later nuclear research by a new site at

Saclay Saclay () is a commune in the southwestern suburbs of Paris, France. It is located from the centre of Paris. It had a population of 3,067 in 2006. It is best known for the large scientific facility CEA Saclay, mostly dealing with nuclear and pa ...

. The reactor was also known as EL-1 (Eau Lourde); its successor at Saclay was EL-2. The building that formerly housed Zoé is now an exhibit space, the Museum of the Atom.

References

Bibliography

*Pinault, Michel, ''Frédéric Joliot-Curie'', Editions Odile Jacob, Paris, 2000. () {{DEFAULTSORT:Zoe Heavy water reactors Military nuclear reactors Nuclear power in France Nuclear technology in France