A modular helium-cooled divertor design HEMJ (helium-cooled modular divertor concept with multiple-jet cooling) for the 'post-ITER' demonstration (DEMO) fusion reactor has been developed at the ...Forschungszentrum Karlsruhe. The design goal is to withstand a surface heat flux of at least 10 MW/m2 at an acceptable pumping power. A conical design of a brazed joint between two structural components of the HEMJ finger module which are made of different materials has been investigated. This new transition piece design should withstand at least 1000 temperature load cycles between operating and room temperatures. Due to the large mismatch of the thermal expansion coefficients (TECs) of the different materials used, high thermal stresses caused by the thermocyclic loads could lead to the plasticization of both materials in the joint region. To demonstrate the feasibility of this transition piece design, a systematic investigation is required, which includes a numerical simulation, the choice of the brazing material, a study of the brazing technology, and thermocyclic tests of the finger mock-up. This paper shall present a method of numerical investigation as the first step of investigation. Plastic stress calculations are performed using the commercial software ANSYS(R) taking into account thermocyclic as well as internal pressure loads. The calculation results, in particular the plastic behavior of the brazed joint, will be discussed.
A divertor concept for DEMO has been investigated at Karlsruhe Institute of Technology (KIT) which has to withstand a heat flux of 10MW/m2. The design utilizes small finger module composed of a small ...tungsten tile brazed on a thimble made from tungsten alloy. The divertor finger is cooled by helium jet impingement at 10MPa and 600°C. The subject of this paper is technological studies on machining and braze joining the divertor components. Goal of this task, which is considered an important R&D issue, is to find out appropriate manufacturing methods to ensure high functionality and high reliability of the divertor as well as to meet the economic aspect. One of the major requirements for manufacturing is micro-crack-free surface of tungsten parts, since crack propagations in tungsten were observed in the previous high-heat-flux tests at Efremov. Different manufacturing methods and the corresponding results are discussed in the following report.
He-cooled divertor development for DEMO Norajitra, P.; Giniyatulin, R.; Ihli, T. ...
Fusion engineering and design,
10/2007, Letnik:
82, Številka:
15
Journal Article
Recenzirano
Goal of the He-cooled divertor development for future fusion power plants is to resist a high heat flux of at least 10
MW/m
2. The development includes the fields of design, analyses, and ...experiments. A helium-cooled modular jet concept (HEMJ) has been defined as reference solution, which is based on jet impingement cooling. In cooperation with the Efremov Institute, work was aimed at construction and high heat flux tests of prototypical tungsten mockups to demonstrate their manufacturability and their performances. A helium loop was built for this purpose to simulate the realistic thermo-hydraulics conditions close to those of DEMO (10
MPa He, 600
°C). The first high heat flux test results confirm the feasibility and the performance of the divertor design.
A He-cooled divertor for future fusion power plants has been developed at KIT. Tungsten and tungsten alloys are presently considered the most promising materials for functional and structural ...divertor components. The advantages of tungsten materials lie, e.g. in the high melting point, and low activation, the disadvantages are high hardness and brittleness. The machinig of tungsten, e.g. milling, is very complex and cost-intensive. Powder Injection Molding (PIM) is a method for cost effective mass production of near-net-shape parts with high precision.
The complete W-PIM process route is outlined and, results of product examination discussed. A binary tungsten powder feedstock with a grain size distribution in the range 0.7–1.7μm FSSS, and a solid load of 50vol.% was developed. After heat treatment, the successfully finished samples showed promising results, i.e. 97.6% theoretical density, a grain size of approximately 5μm, and a hardness of 457HV0.1.
A helium-cooled divertor concept for DEMO has been investigated extensively at the Forschungszentrum Karlsruhe under the EU power plant conceptual study, the goal being to demonstrate performance ...under heat flux of 10
MW/m
2 at least. Work covers different areas ranging from conceptual design to analysis, materials and fabrication issues to experiments. Meanwhile, the He-cooled modular divertor concept with jet cooling (HEMJ) has been proposed as reference design. In cooperation with the Efremov Institute, manufacture and high heat flux testing of divertor elements was performed for design verification and proof-of-principle. This paper focuses on the technological study of the fabrication of mock-ups from W/W alloy and Eurofer steel supporting structure material. The high heat flux test results of 2006 and 2007 are summarised and discussed.
A concept of helium-cooled tungsten finger module was developed for the European DEMO divertor. The concept was realized and tested under DEMO specific cyclic thermal loads up to 10
MW/m
2. The ...modules were examined carefully before and after loading by metallography and microstructural analyses. While before loading mainly discrete and shallow cracks were found on the tungsten surface due to the manufacturing process, dense crack networks were observed at the loaded surfaces due to the thermal stress. In addition, cracks occurred in the structural, heat sink part and propagated along the grains orientation of the deformed tungsten material. Facilitated by cracking, the molten brazing metal between the tungsten plasma facing material and the W–La
2O
3 heat sink, that could not withstand the operational temperatures, infiltrated the tungsten components and, due to capillary forces, even reached the plasma facing surface through the cracks. The formed cavity in the brazed layer reduced the heat conduction and the modules were further damaged due to overheating during the applied heat loads. Based on this detailed characterization and possible improvements of the design and of the manufacturing routes are discussed.
A He-cooled divertor concept for DEMO is being investigated at the Forschungszentrum Karlsruhe within the framework of the EU power plant conceptual study. The design goal is to resist a heat flux of ...10
MW/m
2 at least. The major R&D areas are design, analyses, fabrication technology, and experimental design verification. A modular design is preferred for thermal stress reduction. The HEMJ (He-cooled modular divertor with multiple-jet cooling) was chosen as reference concept. It employs small tiles made of tungsten, which are brazed to a thimble made of tungsten alloy W-1%La
2O
3. The W finger units are connected to the main structure of ODS Eurofer steel by means of a copper casting with mechanical interlock. The divertor modules are cooled by helium jets (10
MPa, 600
°C) impinging onto the heated inner surface of the thimble.
In cooperation with the Efremov Institute a combined helium loop & electron beam facility (60
kW, 27
keV) was built in St. Petersburg, Russia, for experimental verification of the design. It enables mock-up testing at a nominal helium inlet temperature of 600
°C, an internal pressure of 10
MPa, and a pressure difference in the mock-up of up to 0.5
MPa. Technological studies were performed on manufacturing of the W finger mock-ups. Several high heat flux tests were successfully performed till now. Post-examination and characterisation of the mock-ups subjected to the high heat flux tests were performed in collaboration with Forschungszentrum Jülich. Altogether, the test results confirm the divertor performance required. The helium-cooled divertor concept was demonstrated to be feasible. The knowledge gained from these experiments and some aspects on the design improvement are discussed in this contribution.
•Short description of the new Breeding Blanket Project in the EUROfusion consortium for the design of the EU PPPT DEMO: objectives.•Presentation of the design approach used in the development of the ...Breeding Blanket design: requirements.•Breeding Blanket design; in particular the four blanket concepts included in the study are presented, recent results highlighted and the status discussed.•Auxiliary systems and related R&D programme: in particular the work areas addressed in the Project (Tritium Technology, Pb-Li and Solid Breeders Technology, First Wall Design and R&D, Manufacturing) are presented, recent results highlighted and the status discussed.
The design of a DEMO reactor requires the design of a blanket system suitable of reliable T production and heat extraction for electricity production. In the frame of the EUROfusion Consortium activities, the Breeding Blanket Project has been constituted in 2014 with the goal to develop concepts of Breeding Blankets for the EU PPPT DEMO; this includes an integrated design and R&D programme with the goal to select after 2020 concepts on fusion plants for the engineering phase. The design activities are presently focalized around a pool of solid and liquid breeder blanket with helium, water and PbLi cooling. Development of tritium extraction and control technology, as well manufacturing and development of solid and PbLi breeders are part of the programme.
For future fusion power plants, a He-cooled divertor design has been developed by the Forschungszentrum Karlsruhe. The divertor, as one of the plasma facing components has to withstand high heat ...loads of 10
MW/m
2 as well as sputtering due to ion impact on the surface of the divertor. Tungsten is considered to be the most promising material to be used for this application. Because of the high hardness of tungsten, fabrication of these parts by standard shaping technologies for steels such as milling is depending on the design, either difficult or even impossible. Thus, powder injection moulding (PIM) as a way for time and cost effective net shape fabrication of ceramics and metals, has been developed for tungsten.
The key steps in injection moulding such as feedstock formulation, the injection moulding process itself as well as debinding and sintering were studied. A tungsten feedstock with an optimised solid load of 55
vol.% was developed and successfully tested in injection moulding experiments applying complex shaped cavities. Thermal consolidation of injection moulded components lead to a sintered density of approximately 96% and a grain size of approximately 18
μm. For final densification and grain size reduction, hot isostatic pressing (HIP) was investigated.
A modular He-cooled divertor concept is being developed at the Forschungszentrum Karlsruhe. The design goal is to withstand a high heat flux of 10
MW/m
2 at least. The work programme of 2004 focused ...on experiments to verify the design and thermohydraulics layout. In cooperation with the Efremov Institute, experimental investigations were performed for the joining of tungsten parts and/or tungsten parts with steel and the fabrication of divertor components from tungsten. Moreover, gas puffing experiments were carried out with a stationary approach to measuring pressure loss and heat transfer for the purpose of screening the design options and verifying the computational fluid dynamics (CFD) calculations. The status and results of the technological and helium experiments shall be outlined in this report.
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