Status and trends of the nuclear fuel cycle research in France

Bernard Boullis and Philippe Brossard
Radiochemistry and Processes Department, CEA Rhône Valley Center
Nuclear Energy Division of CEA

 

 

 

Mr. Chairman, Ladies and Gentlemen

 

I first like to express my thanks to the organizing committee for giving me opportunity to present French Research & Development in the field of nuclear fuel recycling.

 

As you are certainly aware of, nuclear fuel recycling is at the heart of the French energy policy.  Several reasons can be given to explain that situation but I do believe that the main one comes back in the 70fs.  France was relying almost entirely on oil and gas imports.  The two successive oil crisis deeply affected the perception of people about the energy supply and the price you must pay for it.  Although the language was not common by those days, insuring a sustainable development independent from international turmoil became a largely shared opinion and has been a strong incentive to launch our nuclear program.  That strategy proved to be good when one examines the evolution of the French energy balance (slide 1).  A huge effort was made in R&D in the field of reprocessing which ultimately led to the choice of the PUREX process and the construction and operation of the La Hague plants (slide 2 : throughput of COGEMA civilian plants).  The start up of these plants did not stop the R&D effort.  In fact, research is continuously performed in support of the operating plants to meet several needs :

˜         Increasing of the overall throughput (slide 3);

˜         Seeking more flexibility for the reprocessing of tomorrow's fuels: more highly irradiated fuels, MOX fuels, etc.

˜         Improving the process, not by further improving its global separation performance, which is already excellent, but by attaining equivalent performance at lower cost and with an even smaller volume of waste produced (slide 4), by decreasing the effluents discharged (slide 5) and by reducing the workers exposure even though it is by far lower than international standards (slide 6). There are many approaches, ranging from the use of totally destructible reagents to simplifications of the process that would make it possible to increase the unit performance of each elementary operation.

I must mention that this R&D effort is still going on.  For example, treatment in a single extraction / back‑extraction cycle is under consideration.

The situation may look smooth and quite but opposition came about the management of highly radioactive waste.  The issue has to be tackled and, in December 1991, the French parliament passed an act requesting that all the French entities involved (CEA, COGEMA , EDF, ANDRA, c) work together in order to propose, by 2006, several assessed technical solutions among which the political authorities may choose.  Three area of investigations were defined :

q       Separation/transmutation of long-lived radionuclides ;

q       Reversible or irreversible repository in a deep geological formation ;

q       Conditioning and long-term interim storage options, pending the development of management routes based on the research engaged under the first two topics.

The first one finds its justification in the potential radiotoxicity of waste : After a few centuries, almost all the radiotoxicity comes from the actinides (slide 7).  Therefore, not leaving these elements in the final waste to be disposed and burning them in a specific nuclear device reduces significantly the disposal hazards (slide 8).  Thus CEA launched an R&D program to study the separation of long-lived radionuclides (along with their transmutation which I wonft talk about here).

After some years of basic studies, it is now possible to propose a scheme fully compatible with La Hague plants, that separate the target elements with a yield greater than 99.9 % (slide 9).  The scientific feasibility of these processes have been demonstrated (here I mean that all the basic chemistry that support the separation concepts is defined and well understood and that each elementary step have been successfully tested with genuine material).  In the forthcoming years, we intend to run experiments integrating all the elementary steps and using devices which industrial scaled equivalents exist.  Success of these experiments will demonstrate what we call the gtechnical feasibilityh of the separation scheme.  To that purpose, we are currently fitting out a new hot cell line in the Atalante facility in Marcoule (slide 10).  Let me said here that, to succeed in such a short time by nuclear standards, this program was run in close collaborations : in France with universities and the CNRS (Centre National pour la Recherche Scientifique), within the European Community with several Research Institutes but also abroad.  It is a unique occasion, before this audience, to say that this success story did benefit from our collaboration with Japanese Institutes.

One has to mention also that we are also looking at other processes, like pyrochemistry.  Several scenarios are proposed for the transmutation of the minor actinides.  Oppose to once-through transmutation, there is the recycling of targets or dedicated fuels.  In that case, processing the irradiated material to recover the actinides is necessary.  For such processing hydrometallurgy may not be adequate because of the high activity and specific nature of the material.  Pyrochemistry on the other hand is a good candidate.  However, we have conducted a detailed bibliographical survey of many pyroprocesses studied in the past or at present in several countries.  We found that no demonstration has be done of the ability to quantitatively recover all of the actinides even at a level of 99 %.  This is a strong requirements for multirecycling scenarios.  Thus we currently concentrate our efforts on this matter.  Having chosen several possible media, techniques and potential transmutation materials (slide 11), we study the basic chemistry of actinides separation in molten salt in order to answer that simple question : is it possible to find the right combination - media & technique - that allows a quantitative recovery ?  If the answer is yes (and I believe it will) we may then start a more comprehensive development program.

 

Now, let us turn to the mid and long-term studies.

 

First, for the mid-term, a strong concern is the management of plutonium.  One must say that, in France, plutonium is not considered as a waste, having a considerable energetic value.  However, build up of the stockpile must be managed.  Recycling as a MOX fuel in PWR is only a first step and CEA has proposed to study new type of fuels that will greatly enhance the Pu consumption (CORAIL concept) or even make possible the decrease of the stockpile (APA concept) (Slide 12).  These fuels are designed mainly for new generation of PWR reactors like the EPR reactor.  The idea is to keep maximum compatibility with today technologies (slide 13) but allowing the multirecycling of the plutonium.  This has also to be the case for reprocessing technologies and we are working on possible specific adaptations of the PUREX process to take into account these new type of fuels.  The objective is, if these fuels are deployed, to be able to reprocess them with only slight modifications to the La Hague plant.

 

For the long-term, the previous speaker already gave an insight of the propose research.  France is indeed fully involved in the Generation IV International Forum. Assuming that nuclear energy will still be needed, very probably on a larger scale than presently, reprocessing will more than ever be necessary for both economy of resources and waste management. The idea for the future is to develop an integrated approach based on recycling of all the actinides in such a way that the actual waste to be definitely disposed will only be the unavoidable fission products, the amount of which is directly related to the energy production. Another improvement will be to limit as much as possible transportation of radioactive materials. An objective could be to have reprocessing and fuel fabrication on the same site and not too far from the reactors (slide 14).  For that purpose, technical solutions must be developed, either by improving existing technologies or by developments of new ones such as, for instance, dry processing or pyroprocessing.  In that domain too, we strongly believe that R&D must be shared with the international communities.

 

Well, Mr. Chairman, to summarize my talk and to conclude, I like to emphasize that CEA is still working hard on fuel processing, not only to improve competitiveness of today technologies but also to prepare the future.  But we must not count on ourselves.  I deeply believe that international collaboration  is essential to be prepared for coming challenges.