![IFMIF_Target_Area](https://upload.wikimedia.org/wikipedia/commons/9/96/IFMIF_Target_Area.svg)
The International Fusion Materials Irradiation Facility, also known as IFMIF, is a projected material testing facility in which candidate materials for the use in an energy producing fusion reactor can be fully qualified. IFMIF will be an accelerator-driven neutron source producing a high intensity fast neutron flux with a spectrum similar to that expected at the
first wall
In nuclear fusion power research, the plasma-facing material (or materials) (PFM) is any material used to construct the plasma-facing components (PFC), those components exposed to the plasma within which nuclear fusion occurs, and particularly t ...
of a
fusion reactor
Fusion power is a proposed form of power generation that would generate electricity by using heat from nuclear fusion reactions. In a fusion process, two lighter atomic nuclei combine to form a heavier nucleus, while releasing energy. Devices des ...
using a deuterium-lithium nuclear reaction. The IFMIF project was started in 1994 as an international scientific research program, carried out by Japan, the European Union, the United States, and Russia, and managed by the
International Energy Agency
The International Energy Agency (IEA) is a Paris-based autonomous intergovernmental organisation, established in 1974, that provides policy recommendations, analysis and data on the entire global energy sector, with a recent focus on curbing carb ...
. Since 2007, it has been pursued by Japan and the European Union under the Broader Approach Agreement in the field of fusion energy research, through the IFMIF/EVEDA project, which conducts engineering validation and engineering design activities for IFMIF. The construction of IFMIF is recommended in the European Roadmap for Research Infrastructures Report, which was published by the European Strategy Forum on Research Infrastructures (ESFRI).
Background
The
deuterium
Deuterium (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two Stable isotope ratio, stable isotopes of hydrogen (the other being Hydrogen atom, protium, or hydrogen-1). The atomic nucleus, nucleus of a deuterium ato ...
-
tritium
Tritium ( or , ) or hydrogen-3 (symbol T or H) is a rare and radioactive isotope of hydrogen with half-life about 12 years. The nucleus of tritium (t, sometimes called a ''triton'') contains one proton and two neutrons, whereas the nucleus o ...
fusion reaction generates mono-energetic neutrons with an energy of 14.1 MeV. In fusion power plants, neutrons will be present at
fluxes in the order of 10
18 m
−2s
−1 and will interact with the material structures of the reactor by which their spectrum will be broadened and softened. A fusion relevant neutron source is an indispensable step towards the successful development of
fusion energy
Fusion power is a proposed form of power generation that would generate electricity by using heat from nuclear fusion reactions. In a fusion process, two lighter atomic nuclei combine to form a heavier nucleus, while releasing energy. Devices de ...
. Safe design, construction and licensing of a fusion power facility by the corresponding Nuclear Regulatory agency will require data on the
plasma-facing material
In nuclear fusion power research, the plasma-facing material (or materials) (PFM) is any material used to construct the plasma-facing components (PFC), those components exposed to the plasma within which nuclear fusion occurs, and particularly ...
s degradation under neutron irradiation during the life-time of a fusion reactor. The main source of materials degradation is structural damage which is typically quantified in terms of
displacements per atom
Radiation materials science is a subfield of materials science which studies the interaction of radiation with matter: a broad subject covering many forms of irradiation and of matter.
Main aim of radiation material science
Some of the most p ...
(dpa). Whereas in the currently constructed large fusion experiment,
ITER
ITER (initially the International Thermonuclear Experimental Reactor, ''iter'' meaning "the way" or "the path" in Latin) is an international nuclear fusion research and engineering megaproject aimed at creating energy by replicating, on Earth ...
, structural damage in the reactor steels will not exceed 2 dpa at the end of its operational life, damage creation in a fusion power plant is expected to amount to 15 dpa per year of operation.
None of the commonly available
neutron source
A neutron source is any device that emits neutrons, irrespective of the mechanism used to produce the neutrons. Neutron sources are used in physics, engineering, medicine, nuclear weapons, petroleum exploration, biology, chemistry, and nuclear p ...
s are adequate for fusion materials testing for various reasons. The accumulation of gas in the material microstructure is intimately related to the energy of the colliding neutrons. Due to the sensitivity of materials to the specificities in the irradiation conditions, such as the α-particle generation/dpa ratio at damage levels above 15 dpa per year of operation under temperature controlled conditions, material tests require the neutron source to be comparable to a fusion reactor environment.
In steels, the
54Fe(n,α)
51Cr and
54Fe(n,p)
54Mn reactions are responsible for most of the protons and α-particles produced, and these have an incident neutron energy threshold at 0.9 MeV and 2.9 MeV respectively. Therefore, conventional fast
fission reactors, which produce neutrons with an average energy around 1-2 MeV, cannot adequately match the testing requirements for fusion materials. In fact the leading factor for embrittlement, the generation of α-particles by transmutation, is far from realistic conditions (actually around 0.3
appm He/dpa).
Spallation neutron sources provide a wide spectrum of energies up to the order of hundreds of MeV leading to potentially different defect structures, and generating light transmuted nuclei that intrinsically affect the targeted properties of the alloy.
Ion implantation
Ion implantation is a low-temperature process by which ions of one element are accelerated into a solid target, thereby changing the physical, chemical, or electrical properties of the target. Ion implantation is used in semiconductor device fab ...
facilities offer insufficient irradiation volume (maximum values of a few hundreds µm layer thickness) for standardized mechanical property tests. Also the low elastic scattering cross section for light ions makes damage levels above 10 dpa impractical.
In 1947,
Robert Serber
Robert Serber (March 14, 1909 – June 1, 1997) was an American physicist who participated in the Manhattan Project. Serber's lectures explaining the basic principles and goals of the project were printed and supplied to all incoming scientific st ...
demonstrated theoretically the possibility of producing high energy neutrons by a process in which high energy
deuterons
Deuterium (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two stable isotopes of hydrogen (the other being protium, or hydrogen-1). The nucleus of a deuterium atom, called a deuteron, contains one proton and one n ...
are stripped of their proton when hitting a target, while the neutron continues on its way. In the 1970s, the first designs for high energy neutron sources using this stripping reaction were developed in the USA. In the 1980s, the rapid advances in high-current
linear accelerator
A linear particle accelerator (often shortened to linac) is a type of particle accelerator that accelerates charged subatomic particles or ions to a high speed by subjecting them to a series of oscillating electric potentials along a linear beam ...
technology led to the design of several accelerator-driven neutron sources for satisfying the requirements of a high-flux high-volume international fusion materials testing facility. The Fusion Materials Irradiation Test (FMIT) facility based on a deuterium-lithium neutron source was proposed for fusion materials and technology testing.
The deuterium-lithium reaction exploited for IFMIF is able to provide an adequate fusion neutron spectrum as shown by the comparison of IFMIF with other available neutron sources.
In an experiment with 40 MeV deuterons from a
cyclotron
A cyclotron is a type of particle accelerator invented by Ernest O. Lawrence in 1929–1930 at the University of California, Berkeley, and patented in 1932. Lawrence, Ernest O. ''Method and apparatus for the acceleration of ions'', filed: Janu ...
impinging on lithium, the neutron spectrum and the radioactivity production in the lithium were measured, and sufficient agreement with calculated estimates was found.
Description
IFMIF will consist of five major systems: an accelerator facility, a Li target facility, a test facility, a
post-irradiation examination (PIE) facility and a conventional facility.
[IFMIF International Team, IFMIF Comprehensive Design Report, IEA on-line publication][IFMIF Intermediate Engineering Design Report: IFMIF Plant Design Description document (not available on-line; delivered upon request at ifmif-eveda@ifmif.org)] The whole plant must comply with international nuclear facility regulations. The energy of the beam (40 MeV) and the current of the parallel accelerators (2 x 125 mA) have been tuned to maximize the neutron flux (10
18 m
−2 s
−1) while creating irradiation conditions comparable to those in the first wall of a fusion reactor. Damage rates higher than 20 dpa per year of operation could be reached in a volume of 0.5 L of its High Flux Test Module that can accommodate around 1000 small
test specimens. The small specimen testing techniques developed aim at full mechanical characterization (fatigue, fracture toughness, crack growth rate, creep and tensile stress) of candidate materials, and allow, besides a scientific understanding of fusion neutron induced degradation phenomena, the creation of the major elements of a fusion materials database suited for designing, licensing and reliably operating future fusion reactors. The main expected contributions of IFMIF to the nuclear fusion community are to:
[A. Moeslang, Development of a Reference Test Matrix for IFMIF Test Modules, Final report on the EFDA Task TW4-TTMI-003D4, (2006)]
# provide data for the engineering design for
DEMO
Demo, usually short for demonstration, may refer to:
Music and film
*Demo (music), a song typically recorded for reference rather than release
* ''Demo'' (Behind Crimson Eyes), a 2004 recording by the band Behind Crimson Eyes
* ''Demo'' (Deafhea ...
,
# provide information to define performance limits of materials,
# contribute to the completion and validation of existing databases,
# contribute to the selection or optimization of different alternative fusion materials,
# validate the fundamental understanding of the radiation response of materials including benchmarking of irradiation effects modelling at length-scales and time-scales relevant for engineering application,
# tests blanket concept and functional materials prior to or complementary to ITER test blanket module testing.
IFMIF Intermediate Engineering Design
The engineering design of the IFMIF plant is intimately linked with the validation activities and was conducted during the first phase of the so-called IFMIF Engineering Validation and Engineering Design Activities project (IFMIF/EVEDA). The IFMIF Intermediate Engineering Design Report was established in June 2013
and adopted by the stakeholders in December 2013. The IFMIF Intermediate Engineering Design defines the major systems in outline.
Accelerator facility (LiPac)
The two accelerator CW deuteron beams of 5 MW each impinge in an overlapping manner at an angle of ±9° with a footprint of 200 mm x 50 mm and a steady time profile on the liquid Li jet, with the
Bragg peak
The Bragg peak is a pronounced peak on the Bragg curve which plots the energy loss of ionizing radiation during its travel through matter. For protons, α-rays, and other ion rays, the peak occurs immediately before the particles come to res ...
absorption region at about 20 mm depth.
Target facility
The target facility, which holds the inventory of about 10 m
3 of Li, forms and conditions the beam target. The Li screen fulfills two main functions: to react with the deuterons to generate a stable neutron flux in the forward direction and to dissipate the beam power in a continuous manner. The flowing Li (15 m/s; 250 °C) is shaped and accelerated in the proximity of the beam interaction region by a two-stage reducer nozzle forming a concave jet of 25 mm thickness with a minimum radius of curvature of 250 mm in the beam footprint area. The resulting centrifugal pressure raises the boiling point of the flowing Li and thus ensures a stable liquid phase. The beam power absorbed by the Li is evacuated by the heat removal system and the lithium is cooled to 250 °C by a serial of heat exchangers. The control of impurities, essential for the quality of the liquid screen, will be done through a tailored design of cold and hot trap systems, and purities of Li during operation better than 99.9% are expected. On-line monitoring of impurities will detect impurity levels over 50 ppm. Based on numerical analyses carried out in the last three decades, the beam-target interaction is not expected to have a critical impact on jet stability.
Test facility
The Test Facility will provide high, medium and low flux regions ranging from ›20 dpa/full power year (fpy) to ‹1 dpa /fpy with increasingly available irradiating volumes of 0.5 L, 6 L and 8 L that will house different metallic and non-metallic materials potentially subjected to the different irradiation levels in a power plant. More specifically, in the high flux region, fluences of 50 dpa in ‹3.5 years in a region of 0.5 L, together with power plant relevant fluences of ›120 dpa in ‹5 years in a region of 0.2 L, are planned. The high flux region will accommodate about 1000 small specimens assembled in 12 individual capsules independently temperature controlled that will allow not only mechanical characterization of the candidate structural materials tested, but also an understanding of the influence in their degradation with material temperature during irradiation.
Post-irradiation facility
The Post-Irradiation Examination facility, an essential part of IFMIF, is hosted in a wing of the main building in order to minimize the handling operations of irradiated specimens. It will not only allow testing irradiated specimens out of the different testing modules, but also characterizing metallographically the specimens after destructive testing.
IFMIF Engineering Validation Activities
![LIPAc LEBT Rokkasho](https://upload.wikimedia.org/wikipedia/commons/3/32/LIPAc_LEBT_Rokkasho.png)
To minimise the risks in constructing IFMIF, the IFMIF/EVEDA project has constructed or is constructing prototypes of those systems which face the main technological challenges that have been identified throughout the years of international cooperation in establishing a fusion relevant neutron source,
namely 1) the Accelerator Facility, 2) the Target Facility, and 3) the Test Facility. An Accelerator Prototype (LIPAc), designed and constructed mainly in European laboratories
CEACIEMAT INFN
The Istituto Nazionale di Fisica Nucleare (INFN; "National Institute for Nuclear Physics") is the coordinating institution for nuclear, particle, theoretical and astroparticle physics in Italy.
History
INFN was founded on 8 August 1951, to furth ...
and
SCK•CEN
SCK CEN (the Belgian Nuclear Research Centre), until 2020 shortened as SCK•CEN, is the Belgian nuclear research centre located in Mol, Belgium, more specifically near the township of Donk. SCK CEN is a global leader in the field of nuclear re ...
under the coordination of
F4E and under installation at
Rokkasho
is a village in Aomori Prefecture, Japan. , the village had an estimated population of 10,200, and a population density of 40 persons per km², in 4,855 households. The total area of the village is .
Geography
Rokkasho occupies the eastern coa ...
at
JAEA
The is an Independent Administrative Institution formed on October 1, 2005 by a merger of two previous semi-governmental organizations. While it inherited the activities of both JNC and JAERI, it also inherited the nickname of JAERI, "Genken" ...
premises, is identical to the IFMIF accelerator design up to its first superconductive accelerating stage (9 MeV energy, 125 mA of D+ in Continuous Wave (CW) current), and will become operational in June 2017. A Li Test Loop (ELTL) at the
Oarai premises of JAEA, integrating all elements of the IFMIF Li target facility, was commissioned in February 2011, and is complemented by corrosion experiments performed at a Li loop (Lifus6) in
ENEA, Brasimone. A High Flux Test Module (two different designs accommodating either Reduced Activation Ferritic-Martensitic steels (RAFM) or
SiC
The Latin adverb ''sic'' (; "thus", "just as"; in full: , "thus was it written") inserted after a quoted word or passage indicates that the quoted matter has been transcribed or translated exactly as found in the source text, complete with any e ...
), with a prototype of the capsules housing the small specimens were irradiated in th
BR2 research reactorof SCK•CEN and tested in the cooling helium loop HELOKA of the
Karlsruhe Institute of Technology
The Karlsruhe Institute of Technology (KIT; german: Karlsruher Institut für Technologie) is a public research university in Karlsruhe, Germany. The institute is a national research center of the Helmholtz Association.
KIT was created in 2009 w ...
, Karlsruhe, together with a Creep Fatigue Test Module manufactured and tested at full scale at the
Paul Scherrer Institute
The Paul Scherrer Institute (PSI) is a multi-disciplinary research institute for natural and engineering sciences in Switzerland. It is located in the Canton of Aargau in the municipalities Villigen and Würenlingen on either side of the River A ...
. Detailed specific information on the ongoing validation activities is being made available in related publications.
See also
*
ITER
ITER (initially the International Thermonuclear Experimental Reactor, ''iter'' meaning "the way" or "the path" in Latin) is an international nuclear fusion research and engineering megaproject aimed at creating energy by replicating, on Earth ...
(International Thermonuclear Experimental Reactor, and Latin for "the way")
References
External links
*
{{fusion experiments, state=collapsed
ITER
Neutron facilities