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Nuclear fusion for energy production

Published on 28 June 2016

​The CEA is one of the leading European research organisations in magnetic confinement fusion. It is actively involved in the international roadmap for research in this field via its institute for magnetic fusion research (CEA-IRFM) at Cadarache. The international project called ITER is at the centre of this research, which brings together the European Union, Russia, the US, Japan, China, South Korea and India. The purpose of this tokamak, which is under construction near the Cadarache Centre, is to demonstrate the feasibility of a technology harnessing thermonuclear fusion.

​The CEA has supported the ITER project from the outset, and in recent years has adapted and equipped itself with special tools and test benches to meet the major technological and scientific challenges of the future reactor. It has its own platforms and test equipment for R&D on fusion, both at the IRFM and also at the Institute of Research into the Fundamental Laws of the Universe at the Saclay centre and the Institute for Nanoscience and Cryogenics in Grenoble.

Reproducing the reactions that occur in stars

As early as the 1950s, the Soviets obtained and confined particles at temperatures of several million degrees when they developed the first tokamak. From 1959 onwards, the CEA has been involved in building several experimental tokamaks, including TFR at Fontenay-aux-Roses and Petula in Grenoble, for developing technologies for the production, management and analysis of plasma at very high temperature, needed for generating fusion reactions. Jet (Joint European Torus) was built between 1978 in 1982 in Great Britain. Tore Supra, which has been in operation at Cadarache since 1988, is currently in the process of being modified to become the West platform. These machines have made pioneering steps in understanding the physical phenomena associated with fusion reactions, and in identifying the technological issues to be resolved, e.g. erosion of materials used in the vacuum vessel or continuously operating the reactor. In 2003, the Tore Supra engineers and researchers obtained a record plasma pulse of more than six minutes, and in 1997 those at Jet set a world record, producing 16 MW of fusion power.

From Tore Supra to West

The West project is a development of the Tore Supra tokamak, at the CEA Cadarache centre. This facility is the only one in the world which combines all the technical resources for creating long plasma pulses. The West project (West stands for Tungsten (W) Environment in Steady-state Tokamak) consists in installing and testing a divertor in Tore Supra which uses the same technology as the ITER divertor. Tore Supra has thus become a test bench for ITER. With its special equipment for creating long plasma pulses, and in particular the “active” cooling of the components, this machine constitutes is a unique experimental facility for plasma-facing materials, before they are assembled at ITER.

demonstrating the physical feasibility

The purpose of this experimental tokamak will be to demonstrate that it is possible to generate fusion reactions producing 500 MW for more than 6 minutes, and then that these reactions can be maintained for more than 16 minutes. It should be operational within the next decade and is scheduled to operate for 20 years. International partners from 34 countries are involved in its design, construction and operation. The CEA teams are helping ITER build up the skills of its own teams, as well as contributing to the construction of the machine located in the immediate vicinity of the CEA Cadarache centre.

demonstrating the industrial feasibility

The experiments on ITER will be followed by the construction of a demonstration power reactor - Demo - prior to a fleet of industrial fusion reactors. Demo must enable scientists and engineers to demonstrate the production of electricity and to qualify the technologies specific to an industrial reactor. The CEA is involved in the design of Demo in the context of international collaborations, such as the development of a system code for incorporating all the physical, technological and nuclear requirements. The CEA is also carrying out R&D on tritium-breeding blankets and materials capable of resisting the neutrons produced by fusion reactions - two essential technologies for industrial reactors.

The broader approach

To support the international roadmap for R&D on fusion, which includes the ITER project, the European Atomic Energy Community (Euratom) and the Japanese government signed the “Broader Approach” cooperation agreement, defining a joint research and development programme. The objectives of the Broader Approach are to prepare for the operation of ITER, to broaden its research programme and to develop R&D in order to design an economically attractive prototype power reactor, Demo. The Broader Approach includes three large research infrastructures in Japan:

  • The JT60SA tokamak
  • The IFERC research centre
  • The EVEDA (Engineering Validation and Engineering Design Activities) centre where engineering work is carried out for the design and validation of the future IFMIF irradiation source

The CEA is responsible for France’s contribution within the “Broader Approach” agreement. The organisation is leading several key projects in the collaboration, with the support of numerous industrial partners in Europe.

CEA expertise

The IRFM is recognised by the international scientific community for its expertise on long plasma pulses and the associated technologies. It has highly specialised platforms for experimentation (West/Tore Supra), testing components (infrared imaging, robotics, etc.) and for simulation (high-performance computing, modelling and 3D virtual reality representation).
Two of the CEA’s other institutes are also making key contributions to the design of technologies needed for fusion.

The Institute of Research into the Fundamental Laws of the Universe, at the CEA’s Saclay centre, is conducting research programmes in the fields of astrophysics, nuclear physics and particle physics. The expertise it has developed in particle accelerators and particle detectors for these three fields is now being extended to other fields, including cryo-magnetic components for fusion reactors and for ultra-high resolution medical imaging machines.
Following successful testing of the 70 coils from the German W7-X fusion machine (Institute of Plasma Physics in Garching), the Institute is responsible for testing 18 superconducting toroidal field coils from the Japanese JT-60SA tokamak, within the framework of the “Broader Approach”.

The Institute for Nanoscience and Cryogenics (INAC) at the CEA’s Grenoble centre is a joint CEA-Joseph Fourier University laboratory carrying out fundamental research on condensed matter, soft matter and cryogenics. The institute has considerable expertise in space cryogenics and large instruments for physics (Tore Supra, CERN). Its engineers and researchers have been involved in the development of the Tore Supra cryogenic system, and in the design and monitoring of the JT-60SA cryogenic plant. The INAC also has long-standing expertise in the field of solid frozen deuterium pellet injectors, one of the ways of injecting the fusion “fuel” directly into the tokamak plasma core.

The CEA’s Nuclear Energy Division is carrying out R&D on the design and manufacture of tritium-breeding blankets, and on structural materials for the first wall, tritium-breeding blankets and the divertor, and materials capable of resisting the neutrons produced by fusion reactions at high temperatures. These two technologies are essential for future industrial reactors.

Tokamak Tore Supra
Tore Supra tokamak - Inspection of the guard rings, module 4 © P.Stroppa / CEA

what is a divertor ?

The divertor is one of the fundamental components of ITER. Running across the “floor” of the tokamak chamber, it extracts heat and helium ash, two products of the fusion reaction, as well as other impurities from the plasma. The divertor operates like a huge extraction system. It will comprise two main parts: a support structure, mainly made of stainless steel, and plasma-facing components, made of tungsten, a highly refractory material.

inertial confinement fusion

The CEA is also interested in another way of creating thermonuclear fusion conditions. This involves converting laser-amplified light into X-rays, by laser-matter interaction within a cavity, then using these X-rays to compress a target containing a few micrograms of fusionable material. This is one of the objectives of the Megajoule Laser (LMJ website) the aim of which is not to carry out research for energy production but to re-create thermodynamic conditions similar to those encountered during the operation of nuclear weapons, in the laboratory.

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