TechnoFusión
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The TechnoFusión project, currently in a preparatory study phase, involves the construction of a Singular Scientific-Technical Facility (National Centre for Fusion Technologies - TechnoFusión) in the Region of Madrid, Spain, creating the required infrastructure for the development of the technologies required for future commercial fusion reactors, and assuring participation by Spanish research groups and companies.
The Spanish scientific community already possesses a critical amount of expertise on the science and technology that is needed for the success of this ambitious project, as is evident from the results obtained by Spanish researchers in the fusion field over the past few decades. TechnoFusión intends to take advantage of the existing expertise of university research groups, public research organisations (Organismo Público de Investigación, OPI) and private companies, by focussing on priority areas for the development, testing and analysis of materials that are needed for the construction of a commercial thermonuclear fusion reactor or complex remote handing systems.
The behaviour of components under the extreme conditions of a reactor is largely unknown, and this is precisely what TechoFusión pretends to explore. For this purpose, facilities are required for the manufacture, testing and analysis of critical materials, as well as facilities for the development and exploitation of numerical codes for the simulation of the behaviour of materials under extreme conditions.
In summary, TechnoFusión will focus on the creation of infrastructures for the following research areas: 1) material production and processing, 2) material irradiation, 3) plasma-wall interaction (thermal loads and the mechanism of atomic damage), 4) liquid metal technology, 5) material characterization techniques, 6) remote handling and 7) computer simulation.
The Singular Scientific-Technical Facility TechnoFusión will thus consist of a complex of seven large experimentation areas, many of which are unique in the world, with the following main technical objectives:
Material Production and Processing
There are still some uncertainties about the materials that will be used to construct future fusion reactors, partly because it has not yet been possible to reproduce the extreme conditions to which such materials will be subjected. Therefore, it is of utmost importance to dispose of installations capable of manufacturing new materials on a semi-industrial scale and fabricating prototypes. Top priority materials include metals such as reinforced low activation ODS type steels (Oxide Dispersion Strengthened steels) and tungsten alloys. To manufacture such materials, equipment is required that currently is scarce or inexistent in Spain, such as a Vacuum Induction Furnace (VIM), a Hot Isostatic Pressing Furnace (HIP), a Furnace for Sintering assisted by a Pulsed Plasma Current (SPS), or a Vacuum Plasma Projection System (VPS).
Material Irradiation
Even though the exact reactor conditions are only reproduced inside a reactor, it is possible to simulate the effects of neutrons and gamma radiation on materials by irradiating by ion and electron accelerators. The effect of neutronic radiation will be characterized by combining three ion accelerators: one light ion accelerator of the tandem type for irradiating with He, with an energy of 6 MV, one light ion accelerator of the tandem type for irradiating with H (or D), with an energy of 5-6 MV, and a heavy ion accelerator of the cyclotron type, with k = 110, to implant heavy ions (Fe, W, Si, C) or high energy protons. Additionally, a high magnetic field, between 5 and 10 T, must be incorporated into this facility in order to study the simultaneous effect of radiation and magnetic fields on materials. The effects of ionizing gamma radiation will be studied using a Rhodotron® electron accelerator with a fixed energy of 10 MeV that will be shared with other TechnoFusión areas.
Plasma Wall Interaction
Inside a fusion reactor, some materials will not be subjected only to radiation, but also to enormous heat loads in the case of plasma disruptions. In view of this, both: i) stationary conditions due to the intrinsic reactor properties: high density, low temperature and high power and ii) violent transient events (known as ELMs in plasma physics literature) must be reproduced. Therefore, it is essential to dispose of a device (a so-called “plasma gun”) to study plasma-material interactions simultaneously in steady state and transient regimes, thereby allowing an analysis of the modification of the materials and their properties in fusion reactors. The mentioned plasma gun would consist of two main elements: i) a linear plasma device capable of generating hydrogen plasmas with steady state particle fluxes of up to 10<sup>24</sup> m<sup>-2</sup>s<sup>-1</sup> (i.e., of the order of the expected ITER fluxes) and impact energies in the range of 1-10 eV, and ii) a device of the quasi-stationary plasma accelerators (QSPA) type, providing pulses lasting 0.1-1.0 ms and energy fluxes in the 0.1-20 MJm<sup>-2</sup> range, in a longitudinal magnetic field of the order of 1 T or greater. These devices are connected by a common vacuum chamber, allowing the exchange of samples, and their simultaneous or consecutive exposure to the steady state and transient plasma flows under controlled conditions. Both devices will operate with hydrogen, deuterium, helium, and argon.
Liquid Metal Technology
A number of ITER, DEMO and IFMIF components will use liquid metals as refrigerants, tritium generators, neutron reproducers, moderators, etc., all of them under extreme conditions. Therefore, these applications need further research to be finally implemented in such installations. The basic working scheme for this area in TechnoFusión facility is an arrangement of two liquid lithium loops, one of them coupled to the Rhodotron® electron accelerator to investigate the effects of gamma radiation on different conditions of the liquid lithium. The main goals of this area are the studies of i) the free surface of liquid metals under conditions of internal energy deposition, and ii) the compatibility of structural materials and liquid metals in the presence of radiation. In addition, it will be possible to study the influence of magnetic fields on the cited phenomena as well as the development of methods for i) purification of liquid metals, ii) enrichment of lithium, iii) extraction of tritium, and iv) development of safety protocols for liquid metal handling.
Characterization Techniques
The implementation of a wide range of techniques for the detailed characterisation of commercial or locally developed materials is proposed, applied before, during, and after their exposure to radiation or heat loads. The characterisation techniques include mechanical techniques (electromechanical devices, miniature mechanical testing devices, thermal fluency testing devices, nano-indenting techniques, etc.), compositional techniques (Secondary Ions Mass Spectrometry (SIMS) and Atomic Probe Tomography (APT)), structural and microstructural techniques (High Resolution Transmission Electron Microscopy (HRTEM) and X-Ray Diffraction (XRD)), and material processing techniques (Focused Ion Beam Systems coupled to a Scanning Electron Microscope (FIB/SEM)). Various systems will be used to characterise physical properties (electrical, dielectric, optical, etc.). TechnoFusión aspires to become the national materials characterisation laboratory of reference, in view of the fact that some of the cited techniques, such as SIMS or APT, are not readily available in Spain.
Remote Handling Techniques
The conditions inside a fusion reactor are incompatible with the manual repair or replacement of parts, so that remote handling is indispensable. New robotic techniques need to be developed that are compatible with the hostile conditions, and existing techniques need to be certified for application at installations such as ITER or IFMIF. The size of the components that will be manipulated and the complications associated with their spatial location will require developing new remote handling techniques. Prototypes will be tested in an installation that is connected to the electron accelerator in order to simulate working conditions with gamma radiation, similar to those experienced during maintenance operations inside a reactor. Some prototypes considered for demonstrating remote handling capabilities are: the diagnostic Port Plugs (PP) and the Test Blanket Modules (TBM) for ITER, or the irradiation modules of IFMIF.
Computer Simulation
In order to study conditions that cannot be reached in experiment and to accelerate the development of novel systems for a future commercial fusion power plant, TechnoFusión will stimulate an ambitious programme of computer simulations, combining the existing experience in the fusion field with resources from the National Supercomputation Network. Its goals include the implementation of the global simulation of a commercial fusion reactor, the interpretation of results, the validation of numerical tools, and the development of new tools. Another indispensable goal is the creation of a data acquisition system and the visualisation of results.