[en] In order to operate in reliable and safe conditions a Sodium Fast Reactor, it is necessary to master the quality of the coolant. The chemical control of sodium is performed versus the different chemical compounds : oxygen (corrosion control), hydrogen (detection of the sodium-water reaction), and to a less degree carbon (carburization, decarburization phenomena). Moreover, other detrimental effects could be avoided: plugging of narrow sections, loss of heat transfer efficiency in heat exchangers, contamination and dosimetry,...Oxygen and moisture are introduced mainly during handling operations; hydrogen is due to aqueous corrosion of the Steam Generator Unit and thermal decomposition of hydrazine, used to control the oxygen content in the water. The purification of oxygen and hydrogen is performed satisfactorily thanks to cold traps and mainly because of the fact that the solubilities are nearly nil for temperatures close to the fusion point, i.e. 97.8^oC. This paper deals with the developments of the purification systems for the primary and intermediate circuits of a SFR. Basis studies were carried out to understand the basic mechanisms of crystallization of sodium oxide and sodium hydride and to establish their respective nucleation and growth kinetics. Then, new concepts were developed for Phenix, Superphenix and EFR in order to provide high efficiency, large filling rate and reliability in operation. The methodology of development, based on calculations, tests on mock-up, will be addressed. Thanks to these developments, sodium purification was never considered as a key issue during steady state operation and purification campaigns necessary to deal with the main pollutions ie sodium-water reaction or air ingress. The sodium purification always allowed to fulfil the operational requirements. (author)

[en] The Sodium Fast Reactor is a very promising candidate for the development of Fast Neutron Reactors. It is well known owing to its wide development since the 1950's, throughout all countries involved in the development of nuclear power plants. The development of Sodium-cooled fast neutron reactors is possible due to its very attractive sodium, nuclear, physical and even some of its chemical properties. Nevertheless, the operational feedback has shown that the concept has several drawbacks: difficulties for In-Service Inspection and Repair operations due to the sodium opacity and possible detrimental effects of its reactivity with air and water when the heat conversion is performed with a conventional Rankine cycle. Moreover, the various design projects have shown some difficulties in enhancing its competitiveness with regards to existing NPPs without any new innovative options, i.e. the possibility of suppressing the intermediate circuits and/or the development of an optimized energy conversion system. The Supercritical CO₂ Brayton Cycle option for the energy conversion has been widely suggested because of its high thermodynamic efficiency (over 40%), its potential compactness of the Balance Of Plant equipment due to the small-sized turbo machinery system, and for its applicability to both Direct or Indirect Cycle (Na, PbBi, He) assuming the hypothesis that the Supercritical CO₂-Na interaction has less serious potential consequences than sodium-water consequences in the conventional Rankine cycle. Within the framework of the SMFR (Small Modular Fast Reactor) project, developed jointly by Argonne National Laboratory (ANL-USA), the 'Commissariat a l'Energie Atomique' (CEA) and Japan Atomic Energy Agency (JAEA, formerly Japan Nuclear Cycle development), this option has been selected and investigated. This paper deals with the study of the interaction between Na and CO₂, based on a literature review: the result of this study will allow the definition of R and D tracks for the complementary experimental study and the appraisal of the potential consequences will contribute to weighing both the advantages and drawbacks of this innovative option, in comparison to the conventional Rankine cycle. The paper has the following contents: Introduction; 1. Literature review; 2. Interaction Na-CO₂; 3. The Na-CO Interaction; 4. Interaction Na - Na₂CO₃; 5. Carbon solubility in sodium; 6. Discussion; 7. Conclusion

[en] This paper provides a description of the French Sodium and liquid Metal School (ESML) created in 1975 and located in France (at the CEA Cadarache Research Centre) and of the Fast Reactor Operation and Safety School (FROSS) created in 2005 at the Phenix plant. It presents their recent developments and the current collaborations throughout the world with some other nuclear organizations and industrial companies. The very recent courses implemented within the frame of INSTN, (French Nuclear Teaching Institute), in collaboration with the Sodium and liquid Metal School (ESML) to answer to the future needs of Generation IV SFR concept and design are also presented. The sum of courses provided by CEA through its Sodium school and FROSS organizations is an unique valuable amount of knowledge on Sodium Fast reactor design, technology, safety and operation experience, decommissioning aspects and practical exercises. It is provided for the national demand and, since the last ten years, extensively opened to foreign countries. Over more than 30 years, this organisation has demonstrated its flexibility in adapting its courses to the changing demand in the Sodium Fast reactor field, and in association with the PHENIX and SUPERPHENIX plants, can adapt its teaching techniques using specific theoretical and practical courses and lectures. This paper is an up-to-date of the paper presented in 2007 in CONTE conference. (author)

[en] Since several years, there has been a new growing interest in the international nuclear community for Sodium Fast Reactor design. In France, a new objective has been defined to build a GENERATION IV prototype reactor by 2020, called ASTRID. This decision has motivated an important and rapid increase of R&D work, orientated toward design and concept evaluations. To answer to this demand, three new sessions were prepared successively since 2007, and launched, within the frame of INSTN (French National Institute for Nuclear Science and Technology): - SFR: History, main options, design and operational feedback - SFR: Functional analysis and design - SFR: Safety and operation This paper provides a description of these Education & Training activities, dedicated to the students, researchers, designers and operators involved in the development of Sodium Fast Reactors and related experimental facilities. The duration of each Session is one week. They are dedicated to the orientations of the Generation IV forum, the main design options, operational feedback experience, circuit and plant operation with emphasis on transients, safety and commissioning aspects, and finally visit of the PHENIX reactor. These complementary sessions will be described, including the pedagogical approach and the tools. In addition, European Sessions dedicated to Sodium Fast Reactors, have been organized within the frame of INSTN and the European Commission DG12, (CP-ESFR 7^th Framework Project) in partnership with the Sodium School and PHENIX. This Education and Training strategy is a key element for the future of the development of Sodium Fast Reactors, and more particularly the ASTRID project. CEA is ready to share training experience and to collaborate with other foreign Education and Training Entities. (author)

[en] Hydrogen permeation through nickel dense membrane applied to Sodium cooled Fast Reactors has been studied theoretically and experimentally. In order to investigate the coupling of nickel membrane with external gas and sodium flows, an analytical model based on mass transfer resistances is developed. A sensitivity analysis showed that, for enough thick membranes and high sodium velocities, the nickel resistance has the most important effect. A permeator prototype constituted of four Ni201 tubular membranes, has been designed: experimental tests at pilot-scale are carried out at different temperatures, gas pressures and flowrates, both in gas-vacuum and gas-sodium configuration. Results for permeation against vacuum demonstrate that hydrogen diffusion within the membrane is the limiting step, in accordance with previous literature results obtained for pure nickel permeation experiments. (author)

[en] This paper provides a description of the education and training activities related to sodium fast reactors, carried out respectively in the French Sodium and Liquid Metal School (ESML) created in 1975 and located in France (at the CEA Cadarache Research Centre), in the Fast Reactor Operation and Safety School (FROSS) created in 2005 at the Phenix plant, and in the Institut National des Sciences et Techniques Nucleaires (INSTN). It presents their recent developments and the current collaborations throughout the world with some other nuclear organizations and industrial companies. Owing to these three entities, CEA provides education and training sessions for students, researchers, and operators involved in the operation or development of sodium fast reactors and related experimental facilities. The sum of courses provided by CEA through its sodium school, FROSS, and INSTN organizations is a unique valuable amount of knowledge on sodium fast reactor design, technology, safety and operation experience, decommissioning aspects and practical exercises. It is provided for the national demand and, since the last ten years, it is extensively opened to foreign countries. Over more than 35 years, the ESML, FROSS, and INSTN have demonstrated their flexibility in adapting their courses to the changing demand in the sodium fast reactor field, operation of PHENIX and SUPERPHENIX plants, and decommissioning and dismantling operations. The results of this ambitious and constant strategy are first sharing of knowledge obtained from experimental studies carried out in research laboratories and operational feedback from reactors, secondly standardized information on safety, and finally the creation of a 'sodium community' that debates, shares the knowledge, and suggests new tracks for a better definition of design and operating rules. (author)

[en] In order to operate a Sodium Fast Reactor in reliable and safe conditions, the quality of the coolant must be mastered. The chemical control of sodium is performed versus the different chemical compounds: oxygen (corrosion control), hydrogen (detection of the sodium-water reaction) and to a lesser degree, carbon (carburization, decarburization phenomena).Furthermore, other detrimental effects could be avoided: plugging of narrow sections, loss of heat transfer efficiency in heat exchangers, contamination and dosimetry,... Oxygen and moisture are introduced mainly during handling operations; hydrogen is due to aqueous corrosion of the Steam Generator Unit and thermal decomposition of hydrazine, used to control the oxygen content in the water. The purification of oxygen and hydrogen is adequately performed thanks to cold traps and mainly due to the fact that the solubilities are nearly nil for temperatures close to the fusion point, i.e. 97.8 deg. C. This paper deals with the development of purification systems for the primary and intermediate circuits of an SFR. Based on previous studies related to the basic mechanisms of Na₂O and NaH crystallization and on operational feedback from French Reactors, new concepts of cold traps were developed for Superphenix and EFR. In order to design new cold traps, a new computer tool has been developed, predicting the location and the amount of impurities deposited on cold walls for NaH and on wire mesh packing for NaH and Na₂O. This model helps the engineer developing a preconceptual design and assists the operator in following the filling rate of the cold trap, thereby avoiding long experimental tests in sodium facilities and reducing the cost of cold trap qualification strategies. (authors)

[en] The MEGAPIE project aimed to design, build and operate a liquid metal spallation neutron target of 1 MW beam power in the SINQ facility at the Paul Scherrer Institut (Villigen, Switzerland). The project is an important step in the road-map towards the demonstration of the Accelerator Driven System (ADS) concept and high power liquid metal targets in general. Following the design phase, an experimental program was defined to provide a complete characterization of the facility by performing a 'mapping' of the neutron flux at different points, from the center of the target to the beam lines. The neutronic performance of the target was studied using different experimental techniques with the goals of validating the Monte Carlo codes used in the design of the target; additionally, the performance was compared with the solid lead targets used before and after the MEGAPIE experiment. (authors)

[en] Development of a technico-economic optimization strategy of cogeneration systems of electricity/hydrogen, consists in finding an optimal efficiency of the generating cycle and heat delivery system, maximizing the energy production and minimizing the production costs. The first part of the paper is related to the development of a multiobjective optimization library (MULTIGEN) to tackle all types of problems arising from cogeneration. After a literature review for identifying the most efficient methods, the MULTIGEN library is described, and the innovative points are listed. A new stopping criterion, based on the stagnation of the Pareto front, may lead to significant decrease of computational times, particularly in the case of problems involving only integer variables. Two practical examples are presented in the last section. The former is devoted to a bicriteria optimization of both exergy destruction and total cost of the plant, for a generating cycle coupled with a Very High Temperature Reactor (VHTR). The second example consists in designing the heat exchanger of the generating turbomachine. Three criteria are optimized: the exchange surface, the exergy destruction and the number of exchange modules.

[en] Within the framework of the dismantling of Sodium cooled fast neutron reactors (SFR) in France (PHENIX, SUPERPHENIX, RAPSODIE), several processes are under investigation regarding sodium disposal. One of them, called ELA (radioactive sodium waste treatment process), is based on the implementation of the sodium-water reaction, in a controlled and progressive way, to remove residual sodium mainly from the sodium purification systems called cold traps. This system contains, after draining, residual sodium and trapped impurities such as sodium oxide (Na₂O), sodium hydride (NaH) with traces of tritium (NaT). The hydrolysis of these various chemical species leads to the production of a liquid effluent, mainly composed of an aqueous solution of sodium hydroxide, and a gaseous effluent, mainly composed of an inert gas, hydrogen and steam. The tritium is present in both effluents. Within the gaseous effluent, it is expected to be released as HT form only. But, according to some experimental data gathered from tritiated sodium hydrolysis operations performed at the CEA in France, a non-negligible amount of tritium is released in the off-gas as HTO form (up to more than 90 % of the tritium found in the gaseous effluent). HTO being 10,000 times more radiotoxic than HT, a precise knowledge of the mechanisms governing the phase distribution of tritium is necessary to estimate the tritium distribution. Indeed, it will help designing the process needed to optimize the treatment of the offgas before its release into the environment. In order to develop a numerical model able to predict the chemical composition of each effluent, a phenomenological description of the hydrolysis of residual sodium performed in the conditions of ELA has been proposed and is described in this paper. To validate some of the hypotheses made in this phenomenological description, and with the aim to validate the model that will be based on this scenario, a series of experiments has been performed in a laboratory-scale hydrolysis process designed at the CEA Cadarache, France. The experimental device consists of a 2-liter cylindrical glass reactor into which small quantities of sodium containing tritium were hydrolyzed by water injected drop by drop. A chemical characterization of the effluents generated by the process will allow us to study the influence of several parameters on the tritium distribution. An analysis of the experimental results obtained during this study is provided in this paper. (authors)