French Atomic Energy Commission Research Articles

The Specific Research and Development Contribution of Commissariat à I’Energie Atomique for the Disposal of Radioactive Waste Containing Long-Lived Elements

An overview is given of the research carried out by the French Atomic Energy Commission on the geological disposal of nuclear waste. Recalling the new legal framework of these studies, the specific methodology of this field, which relies on the association of laboratory and in situ experiments, natural analogues, and modeling is emphasized. Next are underlined the basic questions, which have to be reliably answered when one wants to predict the behavior of the repository and the fate of the most radio toxic nuclides, in particular over very long time spans: What parameters govern the hydrodynamics and the geochemistry of the system? What are the processes controlling the degradation of the different technological and natural barriers, as well as the release, migration, and retardation of radionuclides through the geosphere? For each of these issues, the current programs of research are described and indications are given about significant achievements.

Sensor research at the French Atomic Energy Commission

Highlights some of the projects being carried out by the Leti, a laboratory within the French Atomic Energy Commission. Specifically looks at the development of a miniature sensor to detect methane in coal mines; pressure sensors in the automotive industry; the development of a miniature sensor which triggers airbag inflation in vehicles; and a sensor to measure pressure at high temperatures for use within the aeronautics industry.

Ultrasonic defect characterization with a dynamic adaptive focusing system

In order to improve ultrasonic inspection, in terms of detection, sizing and characterization of defects, the French Atomic Energy Commission (CEA) has developed a dynamic adaptive focusing system called FAUST: Focusing Adaptive UltraSonic Tomography. This sytem is based on ultrasonic phased array transducers connected to a multi-channel acquisition system, which provides the delay and amplitude laws, allowing one to control dynamically the ultrasonic beam. This paper presents the general architecture of the system and some applications of it for defect characterization and improvement of the ultrasonic inspections.

Rehabilitation of a uranium-ore processing residues storage site at Le Bouchet, Paris Region, France

From 1949 to 1971, the French Atomic Energy Commission operated a uranium-ore processing plant in the Paris region. After the plant was dismantled in the 70s, the plot of land that had been used to store the processing residues, and the area covered by the settling basin, were locked up. A study of the site in 1990 showed that the level of radon emissions and radon daughters from these premises was 10 to 100 times greater than the mean level above the ground. In 1992, the local authorities decided to rehabilitate the site. To limit the radon emissions, the land was buried under various materials, including a bed of clay several tens of centimetres thick. The measurements made on the site and in the surroundings of it, after the land was covered, showed clearly that the radon and the radon decay product concentrations were lowered to the same order of magnitude as the representative regional background noise in the Paris basin, typical of a sedimentary rock environment.

Inter-laboratory comparisons: Determination of actinides in excreta

Inter-laboratory tests are a means of assessing the analytical coherence of medical laboratories. In radiotoxicology, this kind of exercise makes it possible to keep up with laboratory know-how and with the evolution and relative performances of analytical techniques (precision and reproducibility). However, the goal of the laboratories taking part in these annual exercises is not only to check the accuracy of their results. The analytical discussions and the chance to compare experiences enrich the group's general competence. French biologists have been organizing annual radiotoxicology intercomparison exercises since 1978. The exercises are carried out within the framework of a working group (GT1) operating under the aegis of the French Atomic Energy Commission's (CEA) Medical Coordinator. Using reports and diagrams which present the results obtained by the participants in the form of syntheses, the authors describe how the exercises for determining actinides in excreta (urine and faeces) are organized, how the results are evaluated in terms of the analytical methods used, and the improvements made in analytical and metrological performance. Up until 1985, these exercises were limited to French laboratories. Since then, the exercises have acquired an international dimension, opening up to include interested foreign radiochemists, initially from European laboratories, and now from laboratories worldwide. At the present time, 35 laboratories representing 9 countries take part regularly in these intercomparison exercises.

Latest developments on valve seat-seal assembly

The Helicoflex® metallic seal initially designed for static assemblies is presently used as a valve primary seal for specific applications where the elastomeric seal commonly used in such a configuration is totally unsuitable owing to low resistance to radiation and high temperature, and incompatibility with ultrahigh vacuum conditions. The hydrogen injection quick valves of the JET fusion reactor, as well as the aluminium ultrahigh vacuum valves of the TRISTAN accelerator already operate using this technology over a rather narrow range of working conditions. In order to widen the field of applications and establish the basic principles of the sealing function applied to a valve seat-seal assembly, tests were carried out in the Sealing Techniques Laboratory of the French Atomic Energy Commission (CEA). The seat configuration and seal holding device have been reconsidered. Seals have been tested using different grades of sealing lining material, i.e. successively aluminium, silver and copper. In this respect, such an assembly configuration was found to be in full compliance with the requirements of the new types of valve, those which are being considered for applications where ultrahigh vacuum is combined with a leak rate requirement of 10 −10 Pa m 3 s −1 and a high bake-out temperature.

Solution to level 3 dismantling of gas-cooled reactors: the graphite incineration

This paper presents an approach developed to solve the specific decommissioning problems of the G2 and G3 gas-cooled reactors at Marcoule, and the strategy applied with emphasis on incinerating the graphite core components, using a fluidized-bed incinerator developed jointly between the French Atomic Energy Commission (CEA), Electricité de France and FRAMATOME. The incineration option was selected over subsurface storage for technical and economic reasons. Environmental studies have shown that gaseous incineration releases are environmentally acceptable. By using a pilot plant of a fluidized-bed incinerator (30–50 kg h −1), it has been demonstrated that it is possible to incinerate moderator blocks or other graphite components of gas-cooled power reactors, and to reduce significantly the residual amount of waste to be stored after incineration. More than 20 tons of nuclear-grade graphite was incinerated in a fluidized-bed incinerator pilot plant located at the FRAMATOME research centre. The volume of secondary waste after incineration is about 1%–2% of the original mass, and the combustion efficiency is very high at more than 99.8%.

Qu'attenf l'industrie automobile l'avenir de la metallurgie des poudres: C. Delarch (Peugeot Citröen, Velizy, France). (In French)

In PSA Peugeot Citroen factories, high precision requirements of workstations make them being manual. One of the main goal of the car manufacturer is to minimize the pain of workers while maintaining high efficiency of production lines. Consequently, assisting operators with an exoskeleton is a potential solution for improving ergonomics of painful workstations while respecting industrial constraints. To determine ergonomic performances of an exoskeleton, human joint angles and torques, ground reaction forces, and duration of operations are analysed for eight subjects performing a representative screwing task. Experiments were performed using ABLE upper-limb exoskeleton, developed by the French Atomic Energy Commission (CEA), which has the functionality to compensate arm and tools loads. Results show a clear reduction of the sum of the joints torques, up to 38.9%, given by ABLE supply and invite to make concrete the use of exoskeletons in car assembly lines.In industries, workers performing manual operations are subjected to musculoskeletal disorders (MSD). The usage of robotic devices such as exoskeletons might then be a relevant solution to reduce workers pain and prevent MSD. The paper describes how to assess ergonomic performances of such robotic devices for a future usage in industry.

Heating Panels for Accomodation Obtained from Textiles Made Electrically Conductive by Polypyrrole Deposit

The Centre d'Etudes et de Recherches sur les Matériaux (CEREM: Materials Research Centre) of the French Atomic Energy Commission (CEA) devel ops, as part of its research result valorization assignment, specific products making use of electronic conductive polymers. The low temperature radiant heating panels for accommodation have been studied together with the Centre Scientifique et Tech nique du Bâtiment (CSTB: Building Scientific and Technical Centre). The heating el ements are produced from textiles made electrically conductive from polypyrrole deposit. The synthesis conditions have been optimized, a process for making the electrical connections has been proposed, and the evolution in time of the perfor mances of these heating elements has been studied for a period of time greater than 500 days and compared to the previously established predictive models. Finally, tech nical solutions aiming at increasing stability in time of these elements have been pro vided and evaluated.

Purification of D 2 and DT gas by cryosorption on a 5 A molecular sieve

A DT gas purification process has been developed at the Bruyères-le-Châtel Research Center of the French Atomic Energy Commission. This process is based upon the impurities cryosorption on a 5A molecular sieve cooled at 77 K. In order to understand and foresee the cold trap behaviour, adsorption isotherms of several impurities and of hydrogen isotopes have been determined and modeled. At the same time, several purifications of D 2 and DT gas streams have been performed at low gas flowrate (5 1 NTP/min). Indeed larger flowrates involve important thermal gradients and reduce the retention time of the impurities. With this condition, we have shown that the retention time of an impurity is inversely proportional to its content in the DT gas stream. For a fixed content of a mixture of impurities, the overall retention time is only due to differences between the adsorption capacities of the sieve towards each of these impurities. On the other hand, the tritium inventory inside the cold trap is minimized when saturating the sieve with the impurities. The major part of tritium is then easily recovered by a single expansion of the trap. The experiments prove not only the feasibility of the purification of DT gas streams but also the good efficiency of the process elaborated in our laboratory.

Evaluation of amorphous silicon module outdoor performances

Abstract A two-year program, called ASILEC, between the French Atomic Energy Commission and the Commission of European Communities was initiated in 1990 to investigate the effects related to stability performance of amorphous silicon modules as a function of time. The on-site tests of modules operating under normal in-situ conditions are carried out on the CEA-Cadarache test facility in the south of France. The Photovoltaic Group at the Technical Valorisation Laboratory CEA-Cadarache has been assigned the lead responsibility for measuring, identifying, and analysing the quantitative weight of phenomena likely to cause a decrease in performance of a-Si:H modules under natural sunlight exposure. In this work we present the results of measurements in outdoor conditions of 216 amorphous modules commercially available, made by three American and two French manufacturers. Test results of short-term degradation and long-term degradation are analysed.

Magnetic Logging: Detection of the Earth's Magnetic Field Reversals and Application to Borehole Magnetostratigraphy

TOTAL CFP and CEA (the French Atomic Energy Commission) designed and developed two magnetic logging tools for precise and reliable in-situ magnetic measurements in the low magnetized sedimentary formations encountered when drilling for oil. The tools, measuring respectively the magnetic field and the magnetic susceptibility of the rocks, are operated as standard logging tools, and logs are recorded during standard logging operations. A proper combination of these magnetic respectively the magnetic field and the magnetic susceptibility of the rocks, are operated as standard logging tools, and logs are recorded during standard logging operations. A proper combination of these magnetic measurements leads to the determination, every meter, of natural remanent magnetization polarity, from which the direction of the Earth's magnetic field at the time of sedimentation is derived. A magnetostratigraphic sequence is obtained for each well and appears to be similar to the magnetostratigraphic reference scale. Application of this method to wells in the North Sea gives good results for correlations and absolute age determination, as well as facies diachronism. Further comparison of results obtained from magnetic measurements and from sequence stratigraphy applied to conventional logs shows that third-order sequence boundaries can be diachronous in wells 80 km apart. Although themore » potential of magnetic measurements is still under investigation, the first encouraging results clearly show that the new dating method presented in this paper can be very helpful in petroleum geology.« less

PWR steam generator R&D in France: thermal-hydraulic and vibratory aspects

Concomitant with the launching of the French pressurized water reactor (PWR) nuclear power program, a large research and development (R&D) effort was initiated, devoted to the steam generators (SGs). This program, managed cooperatively by Framatome, the SG designer and manufacturer; Electricité de France (EDF), the French electrical utility; and the Commissariat à l'Energie Atomique (CEA), the French Atomic Energy Commission, primarily responsible for nuclear research; was focused on four main objectives: 1. (1) To obtain a better understanding of the physical phenomena existing in these steam generators and leading to SG performance alterations or operating life reductions. 2. (2) To test and validate improved design solutions for the model 51 Framatome steam generator, which was the first one designed under Westinghouse license. 3. (3) To test and validate new Framatome SG designs. 4. (4) To test and validate new, high-performance design tools. This vast R&D program covers the following theses: • - SG thermal-hydraulics, • - SG tube vibration and wear, • - SG materials (production, corrosion, etc.), • - Primary and secondary fluid chemistry, • - SG technology (manufacturing processes, NDT, etc.), • - SG in-service inspection, and • - SG maintenance. These themes are too numerous to be dealt with in a single article. Consequently, the present article will focus on only the first two themes.

The economics of fast breeder reactors

The overall status of the fast breeder reactor (FBR) system is periodically reviewed in France. In 1983, a report was prepared on the status and prospects of the FBR system at the request of the then Minister of Industry. Five years later, Electricite de France (EdF) and the French Atomic Energy Commission (CEA) jointly updated this report. The FBR reactor system economic considerations mentioned here are taken from the work performed in 1987—88 for this updating. The position in 1983 is reviewed to highlight concrete developments. Developments that have occurred since then are presented, along with the prospects that today enable us to define better the technical and economic potential of the FBR system. In conclusion, the effects of these findings on desirable directions are discussed, in particular with regard to European FBR cooperation.

Tritium research and technology facilities for fusion inside the bruyeres-le-chatel research center of the French atomic energy commission

Because of a large tritium experience in the Bruyeres-le-Chatel Research Center (Atomic Energy Commission-FRANCE), new activities could be undertaken in 1986 inside the European Fusion Technology Program, especially tritium studies within the frame work of the Next European Torus. After presenting the general tritium research program which concerns the Torus Exhaust Gas Processing (deuterium-tritium purification and storage) and involved materials (weldability of tritium-helium containing steels and corrosion of steels by tritiated water), major obtained results are given before describing the associated equipments.

Up Close: Materials Research at the Grenoble Nuclear Research Center of the French Atomic Energy Commission (CEA)

Most great technological advances initially required finding a solution to materials problems, a fact that is not very often recognized. The development of nuclear energy is no exception to this rule. The fuel in the reactor core, cladding of the fuel, and structures which support the core or which carry the coolant are, indeed, subjected to extreme conditions of radiation flux, temperature, pressure, and corrosion. In order to achieve safe, industrial reactors, the French Atomic Energy Commission (CEA) had to build an enormous program in materials research and development from the ground floor. At present, CEA has reached a very high level of knowledge and expertise through excellent scientific teams and exceptional equipment.In its present industrial phase, the French Nuclear Program still requires considerable effort in research, but it does enable the nation's industry to take advantage of the CEA's materials capabilities. In accordance with its mission to facilitate the utilization of research results, the CEA launched research and development programs in different non-nuclear industries where its research could find new applications.Since its creation in 1955, the Grenoble Nuclear Research Center (CEN-G), one of the five civilian centers of the CEA, has concentrated a great part of its research on basic (solid-state physics) and applied aspects (nuclear metallurgy). This double orientation, in which basic research is used as a basis for applied research, is an original feature of the CEN-G.

Book reviews

This book is the proceedings of a workshop held under the joint sponsorship of the CEC Radiation Protection Programme and the French Atomic Energy Commission Institute of Nuclear Protection, Fontenay aux Roses. One of the major problems in estimating radiation doses from the uptake of radionuclides in the environment, or in developing models with which to predict such doses and to set emergency reference levels for public safety, is the fact that the metabolism of and response to such nuclides vary considerably with age or stage of development of the organism.

Islamic Republic of Iran and Others v. Société Eurodif and Others

State immunity — Attachment and execution — Debt owed to foreign State — France-Iran agreements for construction and financing of enriched uranium plant and nuclear reactors — Loans made to French Atomic Energy Commission and other undertakings by Iran — Repudiation of agreements by Iran — Claim for compensation by companies involved — Whether companies entitled to attach funds representing loan repayments due to Iran — Whether such funds to be regarded as allocated for a specific purposeState immunity — Jurisdictional immunity — Commercial activities — Whether construction and financing of uranium plant and nuclear reactors a commercial activityState immunity — Waiver — Agreement containing provision for International Chamber of Commerce arbitration — Whether amounting to waiver of immunity — The law of France

Nuclear data qualification through French LWR integral experiments

Abstract For ten years the Light Water Reactor Department of the French Atomic Energy Commission (CEA) has performed an exhaustive experimental program, based on several facilities, in order to qualify neutronic computer codes. Specific critical experiments have been performed in the EOLE and MINERVE zero power reactors. LWR assemblies were burned at the center of an experimental irradiaion reactor called MELUSINE. Sensitivity studies on interpretation results, as well as spent fuel analysis of Framatome PWR's, allowed us to improve the multigroup library of heavy isotopes. Nuclear data such as v 25, thermal [sgrave]25, [sgrave]28(n, 2n) and γy28 was deduced.

Signal processing and spectral analysis of the aftershocks of the 1980 El Asnam, Algeria earthquake—engineering application

Seismic recording stations were set up in the El Asnam region of Algeria by the Department of Nuclear Safety of the French Atomic Energy Commission (CEA/IPSN) after the severe October 10, 1980 earthquake, to study the aftershocks of this important event. Three of these stations, equipped with SMA-1 instruments, were intended to record strong ground motion and were accordingly installed near the trace of the fault responsible for the main shock. Three other more sensitive stations were placed in such a way as to make up a small network enclosing the central portion of this fault. Over 400 events were thus recorded during October and November 1980, of which certain events presented accelerations of nearly 0.2 g. The SMA-1 recordings were used as a basis for comparing different methods of correcting time histories, demonstrating the influence of the digitization rate, especially upon the high-frequency elements of the ground acceleration and that of the type of low-frequency filtering upon the integrated velocity and displacement time histories. The most significant recordings from both types of station were processed and their response spectra computed. From recordings of the same earthquake obtained on a massive concrete slab and in the free field, a marked filtering effect in the high-frequency range is to be observed.