![Section cartouche combustible UNGG Bugey](https://upload.wikimedia.org/wikipedia/commons/5/51/Section_cartouche_combustible_UNGG_Bugey.png)
The UNGG (''Uranium Naturel Graphite Gaz'') is an obsolete
nuclear power reactor
A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat from ...
design developed in France. It was
graphite
Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large ...
moderated
Moderation is the process of eliminating or lessening extremes. It is used to ensure normality throughout the medium on which it is being conducted. Common uses of moderation include:
*Ensuring consistency and accuracy in the marking of stud ...
, cooled by
carbon dioxide
Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
, and fueled with
natural uranium
Natural uranium (NU or Unat) refers to uranium with the same isotopic ratio as found in nature. It contains 0.711% uranium-235, 99.284% uranium-238, and a trace of uranium-234 by weight (0.0055%). Approximately 2.2% of its radioactivity comes fr ...
metal. The first generation of French nuclear power stations were UNGGs, as was
Vandellos unit 1 in Spain. Of the ten units built, all were shut down by the end of 1994, most for economic reasons due to staffing costs.
The UNGG and the
Magnox
Magnox is a type of nuclear power/production reactor that was designed to run on natural uranium with graphite as the moderator and carbon dioxide gas as the heat exchange coolant. It belongs to the wider class of gas-cooled reactors. The n ...
are the two main types of
gas cooled reactor
A gas-cooled reactor (GCR) is a nuclear reactor that uses graphite as a neutron moderator and a gas (carbon dioxide or helium in extant designs) as coolant. Although there are many other types of reactor cooled by gas, the terms ''GCR'' and to a l ...
(GCR). A UNGG reactor is often referred to simply as a ''GCR'' in English documents, or sometimes loosely as a ''Magnox''. It was developed independently of and in parallel to the British Magnox design, and to meet similar requirements of simultaneous production of electric power and plutonium. The first UNGG reactors at
Marcoule
Marcoule Nuclear Site (french: Site nucléaire de Marcoule) is a nuclear facility in the Chusclan and Codolet communes, near Bagnols-sur-Cèze in the Gard department of France, which is in the tourist, wine and agricultural Côtes-du-Rhône r ...
used horizontal fuel channels and a concrete containment structure.
Chinon
Chinon () is a commune in the Indre-et-Loire department, Centre-Val de Loire, France.
The traditional province around Chinon, Touraine, became a favorite resort of French kings and their nobles beginning in the late 15th and early 16th centuri ...
A1 used vertical fuel channels, as did the British Magnox reactors, and a steel pressure-vessel.
[
The fuel cladding material was a ]magnesium
Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...
-zirconium
Zirconium is a chemical element with the symbol Zr and atomic number 40. The name ''zirconium'' is taken from the name of the mineral zircon, the most important source of zirconium. The word is related to Persian '' zargun'' (zircon; ''zar-gun'', ...
alloy in the UNGG, as opposed to magnesium-aluminium in Magnox. As both claddings react with water, they can be stored in a spent fuel pool
Spent fuel pools (SFP) are storage pools (or "ponds" in the United Kingdom) for spent fuel from nuclear reactors. They are typically 40 or more feet (12 m) deep, with the bottom 14 feet (4.3 m) equipped with storage racks designed to hold f ...
only for short periods of time, making short-term reprocessing of fuel essential, which requires heavily shielded facilities.
The programe was a succession of units, with changes to the design increasing power output. In the experimental phase they were built by the Commissariat à l'Énergie Atomique
The French Alternative Energies and Atomic Energy Commission or CEA (French language, French: :fr:Commissariat à l'énergie atomique et aux énergies alternatives, Commissariat à l'énergie atomique et aux énergies alternatives), is a French pub ...
(CEA), and later by Électricité de France
Électricité de France S.A. (literally ''Electricity of France''), commonly known as EDF, is a French multinational electric utility company, largely owned by the French state. Headquartered in Paris, with €71.2 billion in revenues in 2 ...
(EDF). The largest UNGG reactor built was Bugey 1 with a net electrical output of 540 MW.
Units
* G1, G2 and G3 at Marcoule
Marcoule Nuclear Site (french: Site nucléaire de Marcoule) is a nuclear facility in the Chusclan and Codolet communes, near Bagnols-sur-Cèze in the Gard department of France, which is in the tourist, wine and agricultural Côtes-du-Rhône r ...
. G1 was the first UNGG to go critical, in 1956.
* Chinon Nuclear Power Plant
The Chinon Nuclear Power Plant (french: Centrale nucléaire de Chinon) is near the town of Avoine in the Indre et Loire ''département'', on the river Loire (approximately 10 km from the town of Chinon) in central France. The power station ...
A1, A2, and A3 in Indre-et-Loire
Indre-et-Loire () is a department in west-central France named after the Indre River and Loire River
The Loire (, also ; ; oc, Léger, ; la, Liger) is the longest river in France and the 171st longest in the world. With a length of , it ...
.
* Saint-Laurent Nuclear Power Plant
The Saint-Laurent Nuclear Power Station is located in the commune of Saint-Laurent-Nouan in Loir-et-Cher on the Loire – 28 km upstream from Blois and 30 km downstream from Orléans.
The site includes two operating pressurized ...
A1 and A2 in Loir-et-Cher
Loir-et-Cher (, ) is a department in the Centre-Val de Loire region of France. Its name is originated from two rivers which cross it, the Loir in its northern part and the Cher in its southern part. Its prefecture is Blois. The INSEE and La P ...
, operated from 1969 and 1971 to April 1990 and June 1992.
* Reactor 1 at Bugey Nuclear Power Plant
The Bugey Nuclear Power Plant is located in Bugey in the Saint-Vulbas commune (Ain), about 75 km from the Swiss border. The site occupies 100 hectares. It is on the edge of the Rhône River, from where it gets its cooling water, and is a ...
in Ain
Ain (, ; frp, En) is a department in the Auvergne-Rhône-Alpes region in Eastern France. Named after the Ain river, it is bordered by the Saône and Rhône rivers. Ain is located on the country's eastern edge, on the Swiss border, where ...
, the last UNGG built in France, first criticality 1972, closed in May 1994.
* Vandellòs Nuclear Power Plant
The Vandellòs Nuclear Power Plant is a nuclear power plant in Vandellòs located close to the Coll de Balaguer pass (Baix Camp comarca) in Catalonia, Spain.
Unit one was a 508 MWe carbon dioxide gas cooled reactor modeled on the UNGG reactor ...
Unit 1 in Spain, the only UNGG built outside France, closed in July 1990.
The earlier units, at Chinon and Marcoule, had heat exchangers outside the main pressure vessel; Later units (Saint-Laurent, Bugey and Vandellos) moved these heat exchangers to inside the pressure vessel.
See also
* Nuclear power in France
Since the mid 1980s, the largest source of electricity in France is Nuclear power, with a generation of 379.5 TWh in 2019 and a total electricity production of . In 2018, the nuclear share was 71.67%, the highest percentage in the world.
Since ...
* Vandellòs I Nuclear Accident * Vandellòs town
*Vandellòs i l'Hospitalet de l'Infant municipality
*Vandellòs Nuclear Power Plant
The Vandellòs Nuclear Power Plant is a nuclear power plant in Vandellòs located close to the Coll de Balaguer pass (Baix Camp comarca) in Ca ...
References
French activities on gas cooled reactors
D Bastien, IAEA-TECDOC—899, pp:51-53, 30 Oct - 2 Nov 1995
Twenty-nine years of French experience in operating gas-cooled reactors
D Bastien, IWGGCR—19, pp:113-119 21-23 Sep 1988
{{Nuclear power in France
Graphite moderated reactors
Nuclear power reactor types