Superphénix
| Company type | Prototype nuclear power plant |
|---|---|
| Industry | Nuclear power |
| Founded | 1976 |
| Defunct | 1997 |
| Fate | Permanently shut down |
| Headquarters | Creys-Malville , France |
Area served | France |
| Products | Electricity generation |
Superphénix (; , SPX) was a prototype fast breeder nuclear power plant with a capacity of 1,242 MWe, situated on the Rhône river near Creys-Malville, France, close to the Swiss frontier. Its primary objective was to economically generate electricity while reprocessing nuclear fuel from France’s traditional reactors. It remains the largest breeder reactor ever constructed to date.
Construction commenced in 1976, with the reactor reaching criticality in 1985 and connecting to the electrical grid in 1986. The project encountered significant delays, budget overruns, and strong public opposition. Its operational performance was limited, with an overall capacity factor of only 14.4%, mainly due to regulatory constraints despite being technically ready for continuous operation. Technical difficulties were ultimately resolved, leading to an availability rate of 95% by 1996.
Although the facility was taken offline for maintenance in December 1996, it remained inactive due to ongoing legal disputes. In June 1997, Prime Minister Lionel Jospin declared its permanent shutdown, which was formally ratified by ministerial decree in December 1998.
Background
Following World War II, France began producing plutonium using graphite-moderated reactors cooled by air or water and fueled with natural uranium, such as the UNGG design. These reactors were not highly efficient for power generation but were effective in producing plutonium for chemical extraction.
An alternative approach uses liquid sodium metal as a coolant instead of graphite moderation. This design removes the need for a moderator by employing fuel that is sensitive to fast neutrons, typically composed of highly enriched uranium or plutonium. Liquid sodium acts as an excellent coolant with minimal neutron absorption, allowing a more compact reactor core.
The core is encased in a blanket of fertile material—such as natural uranium or nuclear waste—that facilitates breeding reactions from materials that would otherwise remain unused. A breeding ratio exceeding 1 indicates the reactor generates more fissile material than it consumes.
Key benefits include:
- Accelerated breeding cycles enabling faster fuel production
- Capability to utilize various fertile materials
- Production of substantial thermal energy for electricity generation
The primary drawback is the initial requirement for enriched fuel to start the reaction, although the fissile material produced can be recycled.
Earlier work and Phénix
France’s development of fast reactors began with Rapsodie in 1958 and advanced toward a larger 1 GWe model by 1964. Construction of Rapsodie started in 1962; it achieved criticality in 1967 and produced 22 MWth (approximately 8 MWe). Core configuration experiments were carried out at Masurca from 1966 onwards, supporting the design of power-generating fast reactors.
During the nuclear expansion era of the 1960s, France faced limited uranium supplies and sought to employ breeder reactors both to supply fuel for its conventional light water reactor fleet and to recycle their spent fuel, thereby reducing nuclear waste disposal demands. Plans included deploying around 20 breeder reactors to support approximately 200 light water reactors.
The demonstration reactor Phénix began construction in 1968. It was fueled with 931 kg of reactor-grade plutonium (77% Pu-239) and operated on two-month fuel cycles that required shutdowns for refueling, resulting in a relatively low capacity factor (~65%). As a prototype facility, maximizing availability was not a priority.
Phénix achieved a breeding ratio of 1.16—producing 16% more fissile material than consumed—and delivered 233 MWe during routine operation. It operated reliably through the 1970s and 1980s but experienced four power transient events between 1989 and 1990 that triggered automatic shutdowns. Renovation efforts commenced in 1993, and it resumed operation in 2003 at a reduced output level of 130 MWe.
Superphénix
During 1971 and 1972, France, Germany, and Italy reached an agreement to collaboratively build full-scale breeder reactors located in France and Germany. The 1973 oil crisis intensified worries about energy supply security, which led to France’s Messmer Plan emphasizing nuclear power as a primary source for electricity production. This initiative gave rise to the Superphénix breeder reactor, engineered for continuous operation with a high capacity factor and designed to be economically viable even when functioning independently.
Between 9 October and 8 November 1974, a public inquiry encountered immediate opposition. In November of that year, 80 physicists from the Lyon Physics Institute expressed concerns regarding the risks associated with breeder technology; by February 1975, approximately 400 scientists had signed a similar statement. In contrast, André Giraud from the CEA supported continuing the project to prevent "catastrophic consequences" for uranium conservation. Despite the opposition, construction commenced in 1976 and received official authorization the following year.
Construction
The design phase began in 1968 alongside the smaller LMFBR Phénix, following the decision to abandon graphite-gas reactors. The fast breeder reactor was chosen amid fears of disruptions in fuel supply; the concept of a "plutonium economy" appeared promising should oil prices remain elevated and uranium reserves diminish. Approval for construction came in 1972, with building activities spanning from 1974 to 1981; however, electricity generation did not start until 1985. Throughout this period, costs increased considerably. The facility was managed by NERSA, a consortium comprising EDF with a 51% stake, ENEL holding 33%, and SBK (Schneller Brüter Kernkraftwerksgesellschaft) owning 16%.
Protest
The building of Superphénix triggered significant public demonstrations. A large protest in July 1977 attracted around 60,000 participants, including members of the anarchist Fédération Anarchiste, which escalated into violent confrontations with protesters deploying molotov cocktails. The CRS intervened to disperse the crowd, resulting in the death of Vital Michalon and more than one hundred serious injuries as law enforcement used batons and tear gas.
Rocket attack
Amid persistent protests and acts of sabotage, on January 18, 1982, an attack involving an RPG-7 rocket-propelled grenade targeted the still incomplete facility. Five rockets were launched across the Rhône River towards the unfinished containment building; two struck and caused minor damage to the reinforced concrete outer structure but missed the reactor’s empty core. No group immediately claimed responsibility for this assault.
On May 8, 2003, Chaïm Nissim, who was elected to the Grand Council of Geneva in 1985 representing the Swiss Green Party, confessed to carrying out this attack. He revealed that the weapons had been acquired from Carlos the Jackal through the Belgian terrorist organization Cellules Communistes Combattantes.
Operation
Although the facility was engineered to deliver an electrical output of 1.20 GW, its annual operational availability fluctuated between zero and 33%. Challenges arose from corrosion and leakage issues within the liquid sodium cooling system, which impeded performance until these problems were rectified by December 1996, at which point the plant achieved 90% of its intended power capacity.
In December 1990, substantial snowfall inflicted damage on the turbine hall structure, resulting in a production halt that lasted until authorization for recommencement was granted in 1992. The plant was integrated into the EDF grid on January 14, 1986, and over a period of ten months leading up to 1994, it generated 4,300 GWh—equivalent to roughly one billion francs in 1995 currency value. In 1996, during an eight-month operational span, output reached 3,400 GWh with an estimated worth near 850 million francs.
The facility ceased operations in September 1998 following three incidents earlier that year which triggered automatic shutdown protocols. Throughout its eleven years of operation, the plant functioned normally for a total of 53 months—primarily at reduced power levels—underwent technical outages spanning 25 months, and remained offline for approximately 66 months due to political and administrative constraints.
Closure
Superphénix encountered intense resistance from anti-nuclear activists, notably the French Green Party (Les Verts) and the national coalition Sortir du nucléaire, which brought together numerous local committees and environmental organizations.
Production was halted in December 1996 for maintenance purposes. Nevertheless, on February 28, 1997, the Conseil d'État annulled a decree from 1994 that had authorized the plant’s restart. Subsequently, in June 1997, Prime Minister Lionel Jospin declared the plant’s closure citing prohibitive operational costs.
A report issued in 1996 by the French Accounting Office highlighted persistently low availability rates—under 10%—while acknowledging progress made that year. It projected that maintaining availability above 46% would have justified continued operation until at least 2001. Overall expenditures amounted to about 60 billion francs (9.1 billion euros).
An inquiry commission report from 1998 disclosed that the decision to close Superphénix aligned with Jospin’s political agenda and was part of an accord between the Socialist and Green parties. The assessment recognized significant technical achievements despite obstacles but concluded the shutdown was driven more by symbolic considerations than by technical deficiencies.
The final removal of all 650 fuel rods occurred on March 18, 2003; these were subsequently stored in spent fuel pools. In April 2004, a public consultation reviewed proposals to immobilize the approximately 5,500 tonnes of sodium coolant within around 70,000 tonnes of concrete—a technique akin to that employed following the closure of the Dounreay Fast Reactor in the United Kingdom.
See also
External links
- Superphénix News
- Creys-Malville Super Phénix (drawing)