The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
N Baluc - One of the best experts on this subject based on the ideXlab platform.
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radiation damage in ferritic martensitic steels for Fusion Reactors a simulation point of view
Nuclear Fusion, 2007Co-Authors: R Schaublin, N BalucAbstract:Low activation ferritic/martensitic steels are good candidates for the future Fusion Reactors, for, relative to austenitic steels, their lower damage accumulation and moderate swelling under irradiation by the 14 MeV neutrons produced by the Fusion reaction. Irradiation of these steels, e.g. EUROFER97, is known to produce hardening, loss of ductility, shift in ductile to brittle transition temperature and a reduction of fracture toughness and creep resistance starting at the lowest doses. Helium, produced by transmutation by the 14 MeV neutrons, is known to impact mechanical properties, but its effect at the microstructure level is still unclear. The mechanisms underlying the degradation of mechanical properties are not well understood, despite numerous studies on the evolution of the microstructure under irradiation. This impedes our ability to predict materials' behaviour at higher doses for use in the future Fusion Reactors. Simulations of these effects are now essential. An overview is presented on molecular dynamics simulations of the primary state of damage in iron and of the mobility of a dislocation, vector of plasticity, in the presence of a defect.
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on the potentiality of using ferritic martensitic steels as structural materials for Fusion Reactors
Nuclear Fusion, 2004Co-Authors: N Baluc, P Spatig, R Schaublin, M VictoriaAbstract:Reduced activation ferritic/martensitic (RAFM) steels are the reference structural materials for future Fusion Reactors. They have proven to be a good alternative to austenitic steels for their higher swelling resistance, lower damage accumulation and improved thermal properties. However, irradiated RAFM steels exhibit a low temperature hardening and an increase in the ductile-to-brittle transition temperature, which imposes a severe restriction on reactor applications at temperatures below about 350°C. Furthermore, a high density of small cavities (voids or helium bubbles) has been recently evidenced in specimens irradiated with a mixed spectrum of neutrons and protons at about 300°C at a dose of 10 dpa, which could affect their fracture properties at intermediate temperatures. The upper temperature for the use of RAFM steels is presently limited by a drop in mechanical strength at about 500°C. New variants that can withstand higher temperatures are currently being developed, mainly using a stable oxide dispersion. This paper reviews European activity in the development of RAFM steels.
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structural materials for Fusion Reactors
Nuclear Fusion, 2001Co-Authors: M Victoria, N Baluc, P SpatigAbstract:In order to preserve the conditions for an environmentally safe machine, at present the selection of materials for the structural components of Fusion Reactors is made not only on the basis of adequate mechanical properties, behaviour under irradiation, and compatibility with other materials and cooling media, but also on their radiological properties, i.e. radioactivity, decay heat and radiotoxicity. These conditions strongly limit the number of suitable materials to a few families of alloys, generically known as low activation materials. The criteria for making decisions about such materials, the alloys resulting from the application of these ideas and the main issues and problems with their use in a Fusion environment are discussed.
M Victoria - One of the best experts on this subject based on the ideXlab platform.
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on the potentiality of using ferritic martensitic steels as structural materials for Fusion Reactors
Nuclear Fusion, 2004Co-Authors: N Baluc, P Spatig, R Schaublin, M VictoriaAbstract:Reduced activation ferritic/martensitic (RAFM) steels are the reference structural materials for future Fusion Reactors. They have proven to be a good alternative to austenitic steels for their higher swelling resistance, lower damage accumulation and improved thermal properties. However, irradiated RAFM steels exhibit a low temperature hardening and an increase in the ductile-to-brittle transition temperature, which imposes a severe restriction on reactor applications at temperatures below about 350°C. Furthermore, a high density of small cavities (voids or helium bubbles) has been recently evidenced in specimens irradiated with a mixed spectrum of neutrons and protons at about 300°C at a dose of 10 dpa, which could affect their fracture properties at intermediate temperatures. The upper temperature for the use of RAFM steels is presently limited by a drop in mechanical strength at about 500°C. New variants that can withstand higher temperatures are currently being developed, mainly using a stable oxide dispersion. This paper reviews European activity in the development of RAFM steels.
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structural materials for Fusion Reactors
Nuclear Fusion, 2001Co-Authors: M Victoria, N Baluc, P SpatigAbstract:In order to preserve the conditions for an environmentally safe machine, at present the selection of materials for the structural components of Fusion Reactors is made not only on the basis of adequate mechanical properties, behaviour under irradiation, and compatibility with other materials and cooling media, but also on their radiological properties, i.e. radioactivity, decay heat and radiotoxicity. These conditions strongly limit the number of suitable materials to a few families of alloys, generically known as low activation materials. The criteria for making decisions about such materials, the alloys resulting from the application of these ideas and the main issues and problems with their use in a Fusion environment are discussed.
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tensile and fatigue properties of two titanium alloys as candidate materials for Fusion Reactors
Journal of Nuclear Materials, 2000Co-Authors: Pierre Marmy, T Leguey, I Belianov, M VictoriaAbstract:Titanium alloys have been identified as candidate structural materials for the first wall, the blanket and the magnetic coil structures of Fusion Reactors. Titanium alloys are interesting materials because of their high specific strength and low elastic modulus, their low swelling tendency and their fast induced radioactivity decay. Other attractive properties are an excellent resistance to corrosion and good weldability, even in thick sections. Furthermore titanium alloys are suitable for components exposed to heat loads since they have a low thermal stress parameter. Titanium alloys with an a structure are believed to have a good resistance against radiation embrittlement and alpha + beta alloys should possess the best tolerance to hydrogen embrittlement. Two classical industrially available alloys in the two families, the Ti5Al2.4Sn and the Ti6Al4V alloys have been used in this study. The tensile properties between room temperature and 450 degreesC are reported. A low cycle fatigue analysis has been performed under strain control at total strain ranges between 0.8% and 2% and at a temperature of 350 degreesC. The microstructure of both alloys was investigated before and after both types of deformation. Both alloys exhibit excellent mechanical properties comparable to or better than those of ferritic martensitic steels. (C) 2000 Elsevier Science B.V. All rights reserved.
P Spatig - One of the best experts on this subject based on the ideXlab platform.
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on the potentiality of using ferritic martensitic steels as structural materials for Fusion Reactors
Nuclear Fusion, 2004Co-Authors: N Baluc, P Spatig, R Schaublin, M VictoriaAbstract:Reduced activation ferritic/martensitic (RAFM) steels are the reference structural materials for future Fusion Reactors. They have proven to be a good alternative to austenitic steels for their higher swelling resistance, lower damage accumulation and improved thermal properties. However, irradiated RAFM steels exhibit a low temperature hardening and an increase in the ductile-to-brittle transition temperature, which imposes a severe restriction on reactor applications at temperatures below about 350°C. Furthermore, a high density of small cavities (voids or helium bubbles) has been recently evidenced in specimens irradiated with a mixed spectrum of neutrons and protons at about 300°C at a dose of 10 dpa, which could affect their fracture properties at intermediate temperatures. The upper temperature for the use of RAFM steels is presently limited by a drop in mechanical strength at about 500°C. New variants that can withstand higher temperatures are currently being developed, mainly using a stable oxide dispersion. This paper reviews European activity in the development of RAFM steels.
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structural materials for Fusion Reactors
Nuclear Fusion, 2001Co-Authors: M Victoria, N Baluc, P SpatigAbstract:In order to preserve the conditions for an environmentally safe machine, at present the selection of materials for the structural components of Fusion Reactors is made not only on the basis of adequate mechanical properties, behaviour under irradiation, and compatibility with other materials and cooling media, but also on their radiological properties, i.e. radioactivity, decay heat and radiotoxicity. These conditions strongly limit the number of suitable materials to a few families of alloys, generically known as low activation materials. The criteria for making decisions about such materials, the alloys resulting from the application of these ideas and the main issues and problems with their use in a Fusion environment are discussed.
Ch. Linsmeier - One of the best experts on this subject based on the ideXlab platform.
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atmospheric plasma spraying of functionally graded steel tungsten layers for the first wall of future Fusion Reactors
Surface & Coatings Technology, 2019Co-Authors: S Heuer, Jiři Matějicek, Monika Vilemova, Martin Koller, Ksenia Illkova, Jakub Veverka, Th Weber, G Pintsuk, J W Coenen, Ch. LinsmeierAbstract:Abstract Functionally graded steel/tungsten layers may be used as interlayers in the first wall of future Fusion Reactors to balance thermally-induced stress peaks in the steel‑tungsten joint. In this work, a modified water-stabilized atmospheric plasma spraying set-up is used to deposit uniform and functionally graded steel/tungsten coatings at elevated substrate temperatures. Uniform coatings were used to characterise individual sublayers of graded coatings in detail. The thermal expansion, thermal conductivity, Young's modulus and yield strength of the layers are promising for the application in steel‑tungsten joints and can be explained by microstructural observations. Only at a substrate preheating temperature of 900 °C the formation of intermetallic precipitates during deposition was observed.
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ultra fast sintered functionally graded fe w composites for the first wall of future Fusion Reactors
Composites Part B-engineering, 2019Co-Authors: S Heuer, Th Weber, G Pintsuk, J W Coenen, T Lienig, A Mohr, F Gormann, W Theisen, Ch. LinsmeierAbstract:Abstract Aiming at the realisation of nuclear Fusion Reactors, the joining of W and steel parts is currently examined. Based on proposals to implement functionally graded steel/W materials (FGMs) in the joint to cope with thermal stresses, the present contribution introduces a novel fabrication method for steel/W FGMs. Electro Discharge Sintering (EDS) was used to consolidate Fe/W powders within milliseconds at atmosphere. Due to the short process time, the formation of detrimental intermetallic Fe-W precipitates is limited compared to established fabrication methods. The current work first presents results of the Fe/W powder processing, then a feasibility study regarding the fabrication of homogeneous and graded Fe/W composites with W volume fractions of 0, 25, 50 and 75 % via EDS is presented. Lastly, the composites are characterised microstructurally, thermo-physically, and mechanically in detail.
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Beryllides for Fusion Reactors
2009 23rd IEEE NPSS Symposium on Fusion Engineering, 2009Co-Authors: J. Reimann, P. Kurinskiy, Rainer Lindau, A. Moeslang, M. Rohde, C. Dorn, W. Haws, A.a. Goraieb, H. Harsch, Ch. LinsmeierAbstract:In Fusion Reactors, Be is a candidate material for both ceramic breeder blankets in the form of pebbles and as plasma facing components (PFC) at the First Wall in the form of tiles.
Takashi Okazaki - One of the best experts on this subject based on the ideXlab platform.
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Development of time dependent safety analysis code for plasma anomaly events in Fusion Reactors
Journal of Nuclear Science and Technology, 1997Co-Authors: Takuro Honda, H-w Bartels, Nermin A. Uckan, Yasushi Seki, Takashi OkazakiAbstract:A safety analysis code SAFALY has been developed to analyze plasma anomaly events in Fusion Reactors, e.g., a loss of plasma control. The code is a hybrid code comprising a zero-dimensional plasma dynamics and a one-dimensional thermal analysis of in-vessel components. The code evaluates the time evolution of plasma parameters and temperature distributions of in-vessel components. As the plasma-safety interface model, we proposed a robust plasma physics model taking into account updated data for safety assessment. For example, physics safety guidelines for beta limit, density limit and H-L mode confinement transition threshold power, etc. are provided in the model. The model of the in-vessel components are divided into twenty temperature regions in the poloidal direction taking account of radiative heat transfer between each surface of each region. This code can also describe the coolant behavior under hydraulic accidents with the results by hydraulics code and treat vaporization (sublimation) from plasma facing components (PFCs). Furthermore, the code includes the model of impurity transport form PFCs by using a transport probability and a time delay. Quantitative analysis based on the model is possible for a scenario of plasma passive shutdown. We examined the possibility of the code as a safety analysis code for plasma anomaly events in Fusion Reactors and had a prospect that it would contribute to the safety analysis of the International Thermonuclear Experimental Reactor (ITER).
