A 1,200-MW nuclear reactor, commissioned in January 1986 at Creys-Malville in Isère, would only have operated at full power for 53 months during its first eleven years of operation. The rest of the time? Outages, lengthy administrative procedures, and a three-and-a-half-year shutdown. Superphénix, the largest fast breeder reactor ever built, spent more time idle than producing electricity.
À retenir
- A reactor designed to produce more energy than it consumes, yet hampered by unprecedented technological challenges
- Three and a half years of outage following a leak in 1990, followed by a legal battle that eclipsed the technical issues
- A bill of nine billion euros for electricity production that was six times lower than forecast
A Project Begun in the Midst of the Energy Cold War
The project kicked off in 1976 on a site alongside the Rhône, about fifty kilometres from Lyon. The ambition was colossal: to build a fast-neutron reactor cooled by liquid sodium, able to breed more fuel than it consumes. A breeding dream carried by three European electricity companies gathered under the NERSA umbrella, led by EDF with 51% of the shares, alongside Italian Enel and a German-Belgian-Dutch consortium. The construction was far from smooth: in 1982 a rocket attack targeted the plant still under construction. Superphénix, however, came into service in 1986, following a disagreement settled in 1985. January 1, 1986 marked the true start of the industrial venture.
The cooling with molten sodium at 550°C is no trivial technical detail. This metal ignites on contact with air and explodes on contact with water, an engineering challenge that largely explains why this prototype would accumulate incidents in the years that followed.
Eleven Years of Operation, Four and a Half Years of Actual Production
The official tally, drawn up by the Court of Audit and echoed in a Senate report, is unequivocal. From January 1, 1986 to December 31, 1996, time was distributed as follows: for 53 months—nearly four and a half years in total—the plant operated normally. The rest split into two almost symmetrical blocks: for twenty-five months it was unable to function due to various interventions to correct observed incidents, and for fifty-four months, while technically capable of running, administrative and judicial proceedings kept it shut down.
The most emblematic episode remains 1990. Since December 1986, the operation of the Superphénix reactor has been marked by incidents of fuel-transfer can leakage in April 1987 and contamination of the primary sodium in June 1990, leading to the reactor’s shutdown on July 3, 1990. Three and a half years. That is how long it took to restart, in September 1995, after a legal and political battle that ended up eclipsing purely technical questions. In 1996, the facility experienced a year of operation deemed satisfactory. Too late: after a good year in 1996, it was shut down again in 1997, and under pressure from the Greens, Lionel Jospin, who had become prime minister, announced in 1997 the definitive closure of Superphénix, which was formalized by a ministerial order in December 1998.
A Bill Measured in Billions
Cost estimates occupied several successive public reports. According to a 1997 Court of Auditors report, the construction of the Superphénix reactor cost 9.1 billion euros, with operating costs of about 1 billion per year whether the reactor produced electricity or remained idle. A previous report by the same auditors, dating from 1996, gave a near-identical figure for the entire life cycle of the installation, from initial investment to complete decommissioning, around 9.15 billion euros for the total cost of the plant.
As for revenues, the shortfall was spectacular. Electricity production should have yielded 12 billion francs, but delivered only 2 billion, one-sixth of what was expected. A National Assembly and a Senate divided on what to do next noted at the time that the financial equation was not simple to resolve: delaying the shutdown of the plant until the end of the partners’ convention in NERSA, i.e., by end-2000, would probably have had a neutral financial impact, according to the assumptions EDF itself used.
A Decommissioning Process Already Longer Than the Operating Period
Since 1999, Creys-Malville is no longer a power plant: it has become a demolition site. And an exceptional one, since Superphénix is the largest reactor in the world undergoing dismantling. Every day, 300 workers carry out dismantling activities, with a substantial annual budget: on average, EDF invests 50 million euros each year for the site’s operation and maintenance.
The phases stretch over decades. After removing the fuel and draining the sodium, completed in the 2010s, teams are now tackling the reactor core itself: the vessel internals and the large rotating head are to be treated from 2020 to 2025, then the reactor vessel from 2025 to 2028, while dismantling of the steam generators is planned from 2022 to 2027. Robots now intervene on the most sensitive operations, notably to extract the final plugs from the vessel. The entire project is not expected to conclude before 2030, with the final step being the decontamination of concrete structures. As for the cost of this decommissioning, estimates have varied over time: the Court of Auditors valued it at 955 million euros in its January 2012 report, but independent experts and more recent work now point to a figure closer to 2 billion euros at completion.
The site has not remained frozen in its nuclear past, however. Since 2023, part of the terrain hosts a 22,000-panel photovoltaic plant, built in parallel with the dismantling work. A spent-fuel storage facility also remains in operation on the site, with an operating horizon set for 2035. From the most complex fission ever attempted in France to solar panels laid on an industrial brownfield: Creys-Malville has seen, in half a century, two radically opposed faces of electricity production.
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Sources : revolution-energetique.com | senat.fr | techniques-ingenieur.fr
