Wall Forum 2021

Net erosion, deposition and material transport in the stellarator W7-X were investigated on the Test Divertor Unit (TDU) using special carbon marker coatings during the operational phases OP1.2a in the year 2017 and OP1.2b in 2018, and on the divertor baffles by analysis of regular wall elements after OP1.2b. While OP1.2a was characterised by high concentrations of oxygen and carbon impurities in the plasmas, OP1.2b had much smaller impurity concentrations due to regular boronizations and ... [mehr]

Most of the challenges in joining and additive manufacturing of metallic structures are related to metallurgical phenomena or inadequate processing routes. Within this talk, the core areas of research at the chair of materials engineering of additive manufacturing will be presented. Targeting a solid understanding of metallurgical phenomena, influenced by various processing variants allows the derivation of structure-process-property relationships, which can then in turn result in tailored ... [mehr]

During the last years, the use of high-Z plasma facing-materials (PFCs) in fusion devices renewed the interest in arcing. Arcs are considered as source of dust particles and additional, localized erosion mechanism of the PFCs. In this talk arc investigations at IPP of during the last years will be resumed. Present investigations yields that the erosion by arcs depends strongly on the melting temperature of the substrate and higher permeability enhances the erosion by an order of magnitude ... [mehr]

Thermomechanical simulation of the new upper divertor tiles in AUG using ANSYS Workbench . Non-linear modelling was used, including contacts and material properties as a function of the temperature. After the completion of the analyses, benchmarking at GLADIS was performed to verify the behaviour. Finally, normal operation at AUG was modelled to assess the performance and resistance of the tile. [mehr]

Experimental studies of tungsten (W) melt dynamics during repeated ELM transients on both ASDEX Upgrade and JET, together with MEMOS-U melt code analysis, have shown conclusively that melt motion is mainly driven by the Lorentz force due to the magnetic field acting on an electric current passing through the melt layer arising to compensate the thermionic electron emission from the hot plasma-facing surface. To further verify the melt transport model a new experiment has been carried out at ... [mehr]

Prof. Große will at first present his chair of Non-destructive Testing (NDT) at the TU Munich. He will introduce his team, speak about teaching and available measuring techniques. After giving an overview of the field of research he is working in he will show modules for efficient NDE (nondestructive evaluation) applications. Finally he will talk about selected projects as for example the rehabilitation of a bridge in Munich, NDE of a ME163b of Flugwerft and very detailed about the archeological ... [mehr]

Structural components in commercial fusion reactor designs will be subjected to unprecedented heat and neutron fluxes, potentially leading to severe degradation of their performance. The key challenge of materials modelling is therefore the prediction of thermomechanical properties of structural components over their operational lifetime. I will present recent progress on simulating irradiated microstructure in the Materials Modelling Group at the Culham Centre for Fusion Energy (CCFE), and how ... [mehr]

Das Ziel dieser Arbeit war es, Wolfram-Kupfer-Verbundwerkstoffe auf Basis additiv gefertigter Vorformen herzustellen und zu charakterisieren. Dazu wurden 3D-Modelle sowohl für gitter-basierte als auch wabenbasierte Vorformen erstellt, die anschließend am Fraunhofer-Institut für Gießerei-, Composite- und Verarbeitungstechnik hergestellt wurden. In Vorexperimenten wurden optimale Fertigungsparameter ermittelt und damit Material basierend auf einer Gitter- oder einer Wabenstruktur mit einen ... [mehr]

Within European material’s programme, the portfolio of baseline materials for DEMO contains the following items: (i) EUROFER(97), a 9Cr Reduced Activation Ferritic Martensitic (RAFM) steel, as structural material for the breeding blanket, (ii) commercially pure tungsten as plasma facing component armor material, and (iii) copper chromium zirconium (CuCrZr) alloy as heat sink material for the divertor coolant interface. This contribution reviews the efforts done towards the assessment of the ... [mehr]

In this talk, the development status of self-passivating W-Cr-Y alloys manufactured by powder metallurgy is reviewed. This development has been started to prevent the potential release of volatile, neutron activated tungsten oxides from a pure W first wall (FW) in case of a loss-of-coolant accident (LOCA) with simultaneous air ingress, where temperatures of the in-vessel components exceeding 1000°C are expected. Properties relevant for the case of a LOCA, as the oxidation resistance, are ... [mehr]

The ITER Test Blanket Module (TBM) is tasked with demonstrating efficient breeding and extraction of tritium inside the environment of a nuclear fusion reactor. In order to meet the strict requirements for tritium self-sufficiency necessary for future fusion power plants, and to address safety concerns and minimize radioactive waste, retained T inventory in and T losses out of the TBM must be accurately assessed. In this work, at the request of F4E, T losses due to retention and permeation in ... [mehr]

The Creation-Relaxation Algorithm (CRA) [1] has attracted a lot of interest recently as it offers a parameter-free method for generating high-dose (>1 dpa) microstructures using atomistic lattice statics with a clear interpretation of the damage dose. We have shown that this method provides quantitative estimations of experimentally measurable properties [2], and having atomistic detail allows us to watch key processes like loop habit plane rotation and coalescence occur. But the method operates ... [mehr]

Ions are used to simulate, accelerated-irradiation damage in materials. Most studies focus on displacement damage using self-ions or low-energy protons. Energetic protons between 16 – 30 MeV have the ability to induce combined-displacement and transmutation damage, over macroscopic ranges of 300 – 500 µm in tungsten. However the samples are radioactive post irradiation and radiation protection measures must be followed.Additionally, electronic losses from ions are converted into heat, which ... [mehr]

In fusion reactors tungsten is exposed to high doses of neutron radiation, which causes an embrittlement of the material. The irradiation leads to microstructural damage and causes transmutation. The microstructural damage can be simulated by heavy ion irradiation. In this work, tungsten ion-radiation was used as an easy to control damage source. Fine grained drawn tungsten fibers with a diameter of 16 µm were used as sample material. Due to limited penetration depth of the ions, the fibers ... [mehr]

Fuel retention in tungsten (W) as a plasma-facing material, especially of the radioactive hydrogen isotope (HI) tritium, presents severe concerns for operation cost and safety of future fusion devices. In tungsten with very low intrinsic H solubility, HI retention is dominated by trapping at irradiation-induced defects. In our previous work, strong lattice distortion was observed in W surfaces after deuterium (D) plasma exposure with kinetic ion energies significantly below the thresholds for ... [mehr]

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