On behalf of all the engineers and technicians who worked on developing the sodium-cooled fast reactors and enabled them to reach the highest level worldwide.
The development of sodium-cooled fast breeders has been going in in France even before the early sixties under a step by step approach of research and conception which produced three different nuclear reactors. The first one was Rapsodie, a low thermal power reactor of 20 MWTh which was mainly used for fuel and sodium coolant testing and which reached a neutronic criticality in 1967. The dismantling of Rapsodie whose thermal power has been enhanced at 40 MWth under the name of Fortissimo has been undertaken in the nineties. It must be pointed out that in the early seventies an integrated team of Indian and French scientists has been set up and moved to India in order to design a sibling reactor of Fortissimo, the FBTR, which only achieved criticality in 1985 after that many problems occurred. Nevertheless, it demonstrated that an emergent country which is eager to reach a high level in science and technology and to deal with its growing energy consumption together with the supply of its own nuclear fuel like Thorium, has efficiently used the development of fast breeder for this purpose. Although the Indian fast breeder program has been largely inspired and helped as well by the French project, it must be emphasized that the brutal ending of Super Phénix had not impacted the course of the fast breeder development in India. As in Russia, which is now the leading country in this advanced nuclear reactor technology.
In the French program the second step was a prototypical reactor designed to deliver a nominal electrical power of 250 MWe, Phénix, which started producing electricity in 1974. It had been successfully operating tunill 2010 despite some gaps in its operating at nominal power, due to some problems which have been dealt with, such as sodium fires… but for a mystery surge of a neutronic anti reactivity. Which has never been fully understood. After that, it was dedicated to the tests for the transuranides and long-life fission products elimination process, with some interesting results.
The third step was quite significant. The Super Phenix was an industrial prototype of sodium cooled fast breeder. With an electrical power of 1200 MWe, it was even larger than that of the first French generation of PWR. A wiser choice would have been to select an electrical power between 600 and 800 MWe, a power level where all the technological and scientific challenges of the large reactor meet. This was the electrical power of the Russian BN600, in USSR. Such an approach was also the one behind the ASTRID project.
This story shows that todevelop advanced nuclear reactor, which applies also to the molten salt nuclear reactors for example, requires tens of years of research both in technology, dedicated facilities, components, fuel handling, control rods behaviour, fuel fabrication, even in experimental nuclear facilities, with regards neutronics studies, fuel and steel irradiations, safety experiments and in computer code developments in different fields such as thermal hydraulics, mechanics, neutronics… Various sets of data also needed to be acquired – neutron cross sections, mechanical properties of stainless steel under the irradiation of high energy neutron fluxes… Moreover, the overall project depends on the ability of the metallurgical industry to produce stainless steel with sufficient performances, to build vessels and components, to realize welding when altogether abiding to strict norms of construction.
One important setback of this long-lasting development and research process is that when the final industrial objectives are achieved, the team who initiated the project and have led the main studies is, on its entirety, retired – if not gone for ever. This also applies to thermonuclear fusion development.
The Fast breeder
Fuel breeding in a nuclear reactor has been identified as the main feature of the fourth generation of nuclear reactor. Sodium cooled fast breeders are evidently part of this 4th generation and are the most developed element of this type of nuclear reactor.
They use U-Pu mixed oxide fuel and the neutron capture breeding concerns U238 or Th232. For example, in the Indian fast breeder project Th232 can be part of a blanket shrouding the core of the reactor for U233 breeding.
Molten salt reactors are another example of this generation of nuclear reactors for the future. The main advantages of the sodium cooled fast breeder are known :
* An ability to better burn natural uranium – with a factor of 60 to 80 regarding thermal water reactor;
* Higher thermal to electrical power conversion rate;
* Elimination either by burning or transmutation of Pu and Transuranides;
* The release of radioactive elements by Super Phénix was 40 times lower than by a PWR electrical plant;
* The flexibility and reactivity of its operating process allows the Super Phénix to better adapt to the electrical consumption variations on the electrical grid;
* The most severe and highly hypothetical nuclear accident based on an accidental prompt neutronic excursion is a main part of the design assumptions. This most severe accident in Super Phénix has been studied for tens of years both by theoricaly and in experiments directly ran in a nuclear facility in order to estimate the maximum energy release in such an event. Also the most severe accidents in a Super Phénix would have been better contained in the nuclear facility – although it is a highly hypothetical scenario.
The brutal ending of Super Phénix
From an accountant perspective only, the required investments to develop Sodium cooled Fast breeder technology in France were evaluated at 60 milliards de Francs by a parliamentary commission. This is about 9 billion euros. In its last year oly the Super Phénix has been operated at full power, as a consequence in the losses one should be balanced by the potential gain issued by the MWh delivered to the electrical grid. In addition, the costs of the dismantling (billions of euros) were engaged without any capitalization.
All these investments and many other valuable ideas were criminally canned with the brutal stop put to the Super Phénix program.
The Super Phénix was not only stopped, but it was also sabotaged. Its primary vessel was wilfully damaged in order to impede its exhumation under a future government.
In the course of the twentieth century France has maintained a leading position in the world, which has now shifted from mainly military stances to technological and economic competition thanks to its skills in high technology and research. Efforts undertaken in nuclear research, nuclear reactor conception and building resulted in a world spearheading position in this field. It is very clear that access to nuclear technologies is viewed by all emergent countries as a key factor to their international status.
Considering the actual receding position of France in the world economy, it is very clear that this decline may be linked to the wreck of the fast breeder program and the quasi moratory on nuclear power plant projects, going from 1991 (Civeaux REP) to 2006 (EPR Flamanville and ASTRID).
This was the first main intrusion of politics – rather political swindling – in an advanced scientific and technical field.
As we have seen, in the very long course of development of advanced technology for nuclear reactor such as Fast breeder, there are strategical challenges: keeping the know-how and in transferring of the knowledge in research and design to new teams. The said moratory has also severed the transmission of the knowledge and the majority of the teams involved in these research and development project were retired or deceased by the beginning of the twenty-first century.
Meanwhile, many facilities dedicated to fast breeder technology, including nuclear facilities and experimental nuclear reactors also have been shut down. Today there is no fast neutron irradiation source, neither is there an experimental nuclear reactor to study the safety of fast breeders or to perform studies in neutronics (the questions of reactivity and anti-reactivity are very sensible ones regarding fast neutron cores). The Jules Horowitz reactor which was supposed to also deliver fast neutron fluxes for irradiation experiments (an objective that could not be seriously considered anyway). It took it years to only emerge from the ground. And finally, as shown by the current problems in the components manufacturing processes, the welding of pipes in the primary circuit of both the REP and Flamanville EPR, the nuclear industry also lost some of its ability and knowledge. Moreover, the mechanical and chemical properties of steels needed for the fast breeder reactors – cladding, vessels, pipes – rely on much higher standards.
In this nefarious context, ASTRID could have been more than an abandoned project, which admittedly was too referential in its initial design and drawings to Super Phénix. Although ASTRID still sadly was a fiction, a ghost if you will, it was killed under the political “ecology” ruling (In France Industry is now monitored by the “ecology” Ministry). So, even the ghost is gone. All the while, fast breeders are not dead. In fact, they are well alive in Eurasia (Among other things sanctions taken by the West against Russia sent the country further down that lane).
This post is also available in: FR (FR)
Merci Jean-Marie et Bravo pour ce brillant article