Minyou Ye

Concept design of CFETR Tokamak machine

CFETR (China Fusion Engineering Test Reactor) is a tokamak reactor, one option of which is superconducting machine and under designing by China national integration design group. The fusion power was designed as 50-200 MW and its duty cycle (or burning time) was envisioned as 30-50%. The plasma current will be 10MA and its major radius and minor radius is 5.7m and 1.6 m, respectively. The concept engineering design including the magnet system, vacuum vessel system and maintenance method has been done in the past year. The center magnetic field strength on the TF magnet is 5.0 T, the maximum capacity of the volt seconds provided by center solenoid winding will be 160 VS. The main design work was carried out including the electromagnetic analysis and parameters for magnet system. In addition, the vacuum vessel systems design and optimization based on three types of maintenance ports was discussed in this paper. Whats more, the maintenance method which is one of the most important design works was presented as detailed as possible in this paper. It includes the design of the maintenance ports and the the remote handling system design and so on. The next optimized design mainly includes the mechanical design, conductor stability and different types of divertor system design and so on.

Upgrades of imaging x-ray crystal spectrometers for high-resolution and high-temperature plasma diagnostics on EAST

Upgrade of the imaging X-ray crystal spectrometers continues in order to fulfill the high-performance diagnostics requirements on EAST. For the tangential spectrometer, a new large pixelated two-dimensional detector was deployed on tokamaks for time-resolved X-ray imaging. This vacuum-compatible detector has an area of 83.8 × 325.3 mm(2), a framing rate over 150 Hz, and water-cooling capability for long-pulse discharges. To effectively extend the temperature limit, a double-crystal assembly was designed to replace the previous single crystals for He-like argon line measurement. The tangential spectrometer employed two crystal slices attached to a common substrate and part of He- and H-like Ar spectra could be recorded on the same detector when crystals were chosen to have similar Bragg angles. This setup cannot only extend the measurable Te up to 10 keV in the core region, but also extend the spatial coverage since He-like argon ions will be present in the outer plasma region. Similarly, crystal slices for He-like iron and argon spectra were adopted on the poloidal spectrometer. Wavelength calibration for absolute rotation velocity measurement will be studied using cadmium characteristic L-shell X-ray lines excited by plasma radiation. A Cd foil is placed before the crystal and can be inserted and retracted for in situ wavelength calibration. The Geant4 code was used to estimate X-ray fluorescence yield and optimize the thickness of the foil.

Computational study on the behaviors of granular materials under mechanical cycling

Considering that fusion pebble beds are probably subjected to the cyclic compression excitation in their future applications, we presented a computational study to report the effect of mechanical cycling on the behaviors of granular matter. The correctness of our numerical experiments was confirmed by a comparison with the effective medium theory. Under the cyclic loads, the fast granular compaction was observed to evolve in a stretched exponential law. Besides, the increasing stiffening in packing structure, especially the decreasing moduli pressure dependence due to granular consolidation, was also observed. For the force chains inside the pebble beds, both the internal force distribution and the spatial distribution of force chains would become increasingly uniform as the external force perturbation proceeded and therefore produced the stress relief on grains. In this case, the originally proposed 3-parameter Mueth function was found to fail to describe the internal force distribution. Thereby, its improved functional form with 4 parameters was proposed here and proved to better fit the data. These findings will provide more detailed information on the pebble beds for the relevant fusion design and analysis.

Concept design of hybrid superconducting magnet for CFETR Tokamak reactor

CFETR which stands for “China Fusion Engineering Test Reactor” is a new tokamak device. The mission and goal of CFETR are as follows: (1) ITER-like; complementary with ITER; (2) Fusion power 50-200 MW; (3) Duty cycle time (or burning time)~(30-50%); (4) Tritium must be self-sufficiency by blanket. The main parameters of low temperature superconducting magnet system are as follows: (1) The central magnetic field in plasma area is designed as 5.0 T. (2) The major and minor radius of plasma is 5.7 m and 1.6m. The main parameters of CFETRs were optimized several times within past year according to the further physical target and engineering. Due to the restrictions of the critical magnetic field strength, low temperature superconducting conductor may difficulty applied in low aspect ratio tokamak device in a limited space. In order to achieve a much higher central magnetic field in plasma area and much higher maximum capacity of the volt seconds provided by center solenoid winding, it is possible to apply hybrid superconducting magnet to the TF coil and CS coil in a low aspect ratio design condition. In this paper, the hybrid magnet winding by using of Nb3Sn and Bi2212 are designed and detailed analyzed which can be selected as a reference for CFETRs magnet system design. The high temperature magnet part is Bi2212 conductor, its dimension is 30 mm×35 mm/turn and current density is 117.46 A/mm2. The low temperature magnet part is Nb3Sn conductor which can good work under 11T, its current density is about 80A/mm2. In addition, the hybrid superconducting magnet system will be expected to save space for sufficient tritium blanket due to reduced conductor size.

Conceptual design and analysis of CFETR magnets

CFETR (China Fusion Engineering Test Reactor) is a test reactor which shall be constructed by National Integration Design Group for Magnetic Confinement Fusion Reactor of China. The Reactor has the equivalent scale compared with ITER, but has the complementary function to ITER. CFETR is a demonstration of long pulse or steady-state operation with duty cycle time not less than 0.3~0.5 and the full cycle of tritium self-sustained with TBR not less than 1.2. The magnets design of CFETR is based on the ITER magnet technology. This paper describes a conceptual design and analysis of the CFETR magnets. The constant tension toroidal field coil and three different magnetic equilibrium shapes are present in this paper.

Development of Vacuum Vessel Design and Analysis Module for CFETR Integration Design Platform

An integration design platform is under development for the design of the China Fusion Engineering Test Reactor (CFETR). It mainly includes the integration physical design platform and the integration engineering design platform. The integration engineering design platform aims at performing detailed engineering design for each tokamak component (e.g., breeding blanket, divertor, and vacuum vessel). The vacuum vessel design and analysis module is a part of the integration engineering design platform. The main idea of this module is to integrate the popular CAD/CAE software to form a consistent development environment. Specifically, the software OPTIMUS provides the approach to integrate the CAD/CAE software such as CATIA and ANSYS and form a design/analysis workflow for the vacuum vessel module. This design/analysis workflow could automate the process of modeling and finite element (FE) analysis for vacuum vessel. Functions such as sensitivity analysis and optimization of geometric parameters have been provided based on the design/analysis workflow. In addition, data from the model and FE analysis could be easily exchanged among different modules by providing a unifying data structure to maintain the consistency of the global design. This paper describes the strategy and methodology of the workflow in the vacuum vessel module. An example is given as a test of the workflow and functions of the vacuum vessel module. The results indicate that the module is a feasible framework for future application.

Measurement of helium-like and hydrogen-like argon spectra using double-crystal X-ray spectrometers on EAST

A two-crystal assembly was deployed on the tangential X-ray crystal spectrometer to measure both helium-like and hydrogen-like spectra on EAST. High-quality helium-like and hydrogen-like spectra were observed simultaneously for the first time on one detector for a wide range of plasma parameters. Profiles of line-integrated core ion temperatures inferred from two spectra were consistent. Since tungsten was adopted as the upper divertor material, one tungsten line (W XLIV at 4.017 Å) on the short-wavelength side of the Lyman-α line (Lα1) was identified for typical USN discharges, which was diffracted by a He-like crystal (2d = 4.913 Å). Another possible Fe XXV line (1.85 Å) was observed to be located on the long-wavelength side of resonance line (w), which was diffracted from a H-like crystal (2d = 4.5622 Å) on the second order. Be-like argon lines were also observable that fill the detector space between the He-like and H-like spectra.

Measurement of leakage neutron spectra from graphite cylinders irradiated with D-T neutrons for validation of evaluated nuclear data

A benchmark experiment for validation of graphite data evaluated from nuclear data libraries was conducted for 14MeV neutrons irradiated on graphite cylinder samples. The experiments were performed using the benchmark experimental facility at the China Institute of Atomic Energy (CIAE). The leakage neutron spectra from the surface of graphite (Φ13cm×20cm) at 60° and 120° and graphite (Φ13cm×2cm) at 60° were measured by the time-of-flight (TOF) method. The obtained results were compared with the measurements made by the Monte Carlo neutron transport code MCNP-4C with the ENDF/B-VII.1, CENDL-3.1 and JENDL-4.0 libraries. The results obtained from a 20cm-thick sample revealed that the calculation results with CENDL-3.1 and JENDL-4.0 libraries showed good agreements with the experiments conducted in the whole energy region. However, a large discrepancy of approximately 40% was observed below the 3MeV energy region with the ENDF/B-VII.1 library. For the 2cm-thick sample, the calculated results obtained from the abovementioned three libraries could not reproduce the experimental data in the energy range of 5-7MeV. The graphite data in CENDL-3.1 were verified for the first time and were proved to be reliable.

Conceptual Design of a Helium-Cooled Ceramic Breeder Blanket for CFETR

Abstract The China Fusion Engineering Test Reactor (CFETR) is a superconducting tokamak reactor proposed by the China National Integration Design Group. The aim is to develop China’s next-step fusion device. A helium-cooled ceramic breeder (HCCB) blanket concept has been put forward by the blanket integration design team of the Institute of Plasma Physics of the Chinese Academy of Sciences. The present blanket configuration is based on the upper port dimension and maintenance scheme. The HCCB blanket comprises a U-shaped first wall, cap, breeder unit, middle plate, and back plate. The breeder unit includes a cooling plate, beryllium pebble bed, and lithium silicate pebble bed. The structure of the HCCB blanket concept is obviously different from the ITER HCCB test blanket module of China. The CFETR HCCB blanket will meet the requirements of CFETR long-pulse or steady-state operation with a duty cycle time greater than 0.3. The maintenance scheme of the blanket is introduced in this paper. Three-dimensional neutronic analysis results show that the tritium breeding ratio can satisfy the design requirement. Besides, the thermal-hydraulic behavior of the first wall has been studied using ANSYS CFX code.

The Integration Platform Development of System Code for CFETR

The System Code is under developing aiming to integrate the design of engineering and physics for China Fusion Engineering Testing Reactor (CFETR). The System Code comprises the engineering design platform and the physics design platform. We developed the integration platform to handle the data and work-flow interaction of the sub-modules and to integrate the engineering platform and the physics platform together. In this presentation, a methodology of developing an integration platform of the System Code with Java, MySQL and OPTIMUS is presented. We developed the GUI of the integration platform with the help of Java JRE System library such as AWT and Swing. Secondly we chose EXCEL documents as the carrier of our system data and we used the software called OPTIMUS to establish the core workflow of the system code. Finally, the relational database software, MySQL, was chose to create user database, material database, manipulate record database and judgment database.