Papers by Keyword: ITER

Abstract: The purpose of this study was the research for a non-standardized method of measuring the shear bond strength at constant compression force and compare with the shear testing methods on cylindrical and prismatic samples, like DIN 50161:1977-10, DIN EN15340-2007. The conducted comparative analysis showed a significant shortcoming of the well-known methods for assessing the shear bond strength on samples for industrial application. The main one is an inability to measure the “actual/real” adhesion shear strength of thermal spray coatings for industrial parts. The shear bond strength of plasma-sprayed coating MgAl₂O₄ with thickness 0.30-has been investigated by applying the prismatic samples (linear dimensions of shear area 1.5-), using Nanovea scratch tester at compression forces ranging from 1 to 70 N. Shear force-displacement curves get essential information about adhesion/cohesion, delamination and cracking properties of thermal spray coating. An increase of shear forces is primarily associated with a rise in friction forces at the coating delamination boundary. Applying for parts of the ITER blanket modules, this research has demonstrated the importance of practical application of the shear testing results at compressive loads for ensuring product life.

Abstract: International Thermonuclear Experimental Reactor (ITER) is build based on the ‘tokamak’ concept of magnetic confinement, in which the plasma is contained in a doughnut-shaped vacuum vessel which powered up by the fuel of a mixture of deuterium and tritium. The two isotopes of hydrogen are then heated to a certain temperatures in excess of 150 million °C, forming hot plasma. The Blanket Module (BM) is arranged around the plasma to provide thermal and nuclear shielding for the vacuum vessel (VV), magnets, and other external component. Therefore, it is important to determine parameter that would affect the development process of BM. Analysis is very important in the design process for the ITER BM as well as nearby components. So a finite element model was developed on the BM and the detail part of the BM was developed using computer aided design (CAD) software. The detail part was inserted into the VV and several simulations were performed to find out the stress distribution within the wall of the BM. The constraint condition was find out and evaluated. The result shows that the maximum shear stress is 539.97MPa which exceed the allowable value of 515MPa. The result shows some acceptable stress levels in most of the analysed geometry. The result obtained was used to further modify the BM design in the cases where limits are exceeded.

Abstract: A Monte Carlo N-particle transport code was used to study physics of the helium-cooled solid-breeder tritium breeding blanket in the Chinese Fusion Engineering Thermal Reactor （CFETR）for various volume ratio of the neutron multiplier and tritium breeder and various thickness of the first wall. A sandwich-type of Be and loading model is used to analyze the compact of volume ratio and the thickness of the first wall for the tritium breeding rate. The results of different volume ratio models show that the tritium breeding ratio would reach 1.51 for volume ratio from 2 to 5.And the results of the different first wall thickness show that the upper limit of the thickness should be 33mm to keep the tritium self-sustain.

Abstract: Measurements of internal strains in the superconducting constituent (Nb₃Sn phase in Nb₃Sn strand) in two cable-in-conduit conductors (CICC) for International Thermonuclear Experimental Reactor were performed using an engineering materials diffractometer TAKUMI of J-PARC. From strain measurements in a CICC for the toroidal field magnet after a performance test of cyclic current, in 100 mm long cut bars, a peak broadening and a large relaxation on residual strain were observed in Nb₃Sn phase at a portion received a high magnetic field (high field zone). Internal strain measurements were also conducted in a CICC for the central solenoidal magnets after the similar performance test, in the full-size shape as used in the performance test (3.6 m long) and in 100 mm long cut bars. Three main results were obtained. (1) Residual strain difference before and after the cutting to 100 mm long bar was about 0.1%, (2) a large relaxation on residual thermal strain was observed at the high field zone, and (3) the large relaxation on residual thermal strain at the high field zone was found mainly in a cross sectional side where the Lorentz force coming in.

Abstract: A conceptual design of tritium-breeder blanket for prototype DEMO is introduced. In this concept, Li4SiO4 pebbles are chosen as tritium-breeder material and Be for neutron multiplication. To confirm the thermal effectiveness,a CFD code FLUENT is used for the calculation. The result indicated that, the thermal effectiveness of the concept is acceptable.

Abstract: This paper deals with the new numerical methodology for prediction and optimization distortion of large welded structures. The methodology is presented on the example of fusion vacuum vessel of ITER which will be manufactured by welding. All necessary steps of methodology have been verified and now the methodology is ready for practical application. Application of our methodology leads to improve of knowledge about complex behavior and save time and budget.

Abstract: Lithium titanate (Li₂TiO₃) ceramic pebbles are considered to be a candidate material of the tritium breeders for fusion reactor from the viewpoints of good tritium recovery, chemical stability and other excellent properties. In this study, fine grain and pure Li₂TiO₃ powders were prepared by solid-state method at 700°C using TiO₂ and Li₂CO₃ as raw materials. Li₂TiO₃ pebbles were prepared by gel-casting method using acrylamide (AM) as organic monomer, N,N’-methylenebisacrylamide (MBAM) as cross-linker, ammonium citrate as dispersant, and isooctyl alcohol as defoamer. The effect of solid content, dispersant, pH and the ball milling time on the fluidity and dispersion of ceramics slurry were investigated, and the effects of sintering temperature and holding time were also discussed in present study. The sintered ceramic pebbles with diameter of 1.0 mm show a smooth surface, uniform grain size and perfect sphericity. The Li₂TiO₃ ceramic pebbles sintered at 1250°C for 8 hours had the highest density (> 90% of theoretical density) and crush strength.

Abstract: International thermonuclear experimental reactor (ITER) soft x-ray (SXR) diagnostic camera is an indispensible component used to measure signal intensity of SXR, which can reflect the internal properties of plasma. In this paper, the preliminary structural design and working principle of SXR camera is demonstrated, to investigate its seismic performance, modal analysis has been performed to obtain natural frequencies, effective mass and mode of vibration in first ten modes by means of ANSYS software. Then according to two parallel seismic analysis methods used in ITER, the calculations have been performed and the corresponding results have been illustrated respectively, the stress intensity and displacement are all within the allowable margin, which indicates that the design is reasonable and feasible. It will also provide beneficial reference for subsequent work.

Abstract: The temperature and strain distributions of the mockup composed of Cu-alloy with distinct structural material (SS316L and China Low Activation martensitic steel (CLAM)) were calculated and analyzed, based on a high heat flux (HHF) test recently reported with heat flux of 3.2MW/m². The calculated temperature and strain results in the first wall (FW), in which SS316L is as the structural material, showed good agreement with HHF test. By substituting CLAM steel for SS316L the contrast analysis indicates that the thermo-mechanical property for CLAM steel is better than that of SS316 at the same condition. Furthermore, the temperature and strain distributions of the FW were calculated under the condition of normal ITER operation: the surface heat flux is about 0.5MW/m² and volumetric heating due to neutron radiation is on the order of 15~20 MW/m².

Abstract: Thermal anchor is one of the key components in ITER magnet supports to maintain the low temperature for superconductor coils. The sufficient attachment of the cooling pipe to the support plates is needed to minimize the risk of helium leakage. Brazing is one of the best choices. Three kinds of special brazing filler, including SnPb brazing filler, Ag-based and Cu-based brazing filler, were developed, which have good thermal conductivity, and toughness for brazing connection of SS 316LN at both room temperature and 77K environment. Some brazing technologies, including induction brazing, vaccum brazing, fire brazing, and arc brazing, have being investigated.