Redesign of gravity support system for ITER construction

In this article, we describe an alternative design for ITER gravity support, which use various connection bolts and shear keys to assemble all the parts, rather than welding them together. The finite element model (FEM) analysis of this structure shows that the maximum static stress intensity of all the components is within the stress limitation under ITER operation condition. No terrible stress concentration and large deformation would occur during normal operation and abnormal operation. The buckling analysis shows that the new designed structure is stable, and no destructive damage would occur. The fatigue simulation calculation shows that the fatigue life is up to 1,361,445 repetitions for normal operation, which is far larger than that of the ITER 30,000 times discharge requirement. Therefore, it can be concluded that the new designed structure is safe and can be utilized in the ITER construction.     

Mechanical testing of a FW panel attachment system for ITER

An objective of experiments and finite element simulations was to check the stiffness, the strength and the fatigue resistance of the attachment of the First Wall panels onto a shield block of blanket modules according to the ITER 2001 design. The panel has a poloidal key at the rear side (in so-called option A with the rear access bolting) and it is attached by means of special studs located on a key-way in the shield block. Special device for a test of stud tensile pre-load relaxation during a thermal cycling was developed. True-to-scale panels, the shield block mock-up and simplified studs were fabricated and the assembly was loaded alternatively by radial moment, poloidal force or poloidal moment simulating the loading during off-normal plasma operations. Thermal cycling led to an acceptable stud pre-load relaxation. Mechanical cycling caused neither the pre-load relaxation nor the loss of the contact in the key-way nor a damage of the attachment system. The combination of poloidal moment and radial force during vertical displacement events (VDEs) seems to be a most dangerous case because it could lead to the loss of the key–key-way contact.     

Research on 3D loading system for ITER gravity support prototype

The objective and importance of structural performance tests for the ITER gravity support prototype were described. The model of the gravity support system was established. Based on the analysis of loads, the torque transformation method and the 3D loading method for prototypes under complex load conditions were proposed. The proposed methods overcome 3D loading problems in the case of the complex load cases. The structural design schemes of the mixed 3D loading system with hydraulic bolt tensioners and the 3D loading system with bidirectional hydraulic cylinders were discussed. Two design schemes were compared and analyzed. Based on the finite element method, the numerical analysis of the 3D loading framework for bidirectional hydraulic cylinders was done. Results show the proposed 3D loading system meets the performance test requirements of the ITER gravity support prototype and should be preferred for the prototype loading experiment.     

Design of a high power millimeter wave launcher for EC H&CD system on ITER

An optimization procedure of the quasi-optical system for a millimeter wave launcher is developed for the ITER electron cyclotron heating and current drive (EC H&CD) launcher. In the launcher, the radiated RF beams from eight corrugated waveguides are reflected sequentially by two mirrors and injected into a plasma through a small aperture in the blanket shield module on the top of the launcher. Using a steepest decent method, the heat load on the mirrors is successfully reduced to the acceptable level by flattening the RF power profile on the mirrors keeping the scattering of the RF power to a minimum from the mirrors. It is found that 20 MW injection will be acceptable even when the resistivity of 2.64 × 10⁻⁸ Ωm for the surface of the mirror (dispersion strengthened copper, 151 °C assumed) is increased by a factor of ∼10 with a contamination.     

Design of a cooling system for the ITER Ion Source and Neutral Beam test facilities

This paper deals with the requirements, operational modes and design of the cooling system for the ITER Neutral Beam test experiments. Different operating conditions of the experiments have been considered in order to identify the maximum heat loads that constitute, with the inlet temperature and pressure at each component, the design requirements for the cooling system.The test facility components will be actively cooled by ultrapure water realizing a closed cooling loop for each group of components. Electrochemical corrosion issues have been taken into account for the design of the primary cooling loops and of the chemical and volume control system that will produce water with controlled resistivity and pH. Draining and drying systems have been designed to evacuate water from the components and primary loops in case of leakage, and to carry out leak detection.Tritium concentration, water resistivity and pH will be measured and monitored at each primary loop for safety reasons and high voltage holding reliability. The measured water flow rates and temperatures will be used to calculate the exchanged heat fluxes and powers. Flow regulating valves and speed of variable driven pumps will be adjusted to control the component temperatures in order to fulfil the functional and thermohydraulic requirements.     

Concept design of CFETR superconducting magnet system based on different maintenance ports

CFETR which stands for “China Fusion Engineering Test Reactor” is a new tokamak device. Its magnet system includes the Toroidal Field (TF) winding, Center solenoid winding (CS) and Poloidal Field (PF) winding. The main goal of the project is to build a fusion engineering Tokamak reactor with its fusion power is 50–200 MW and should be self-sufficiency by blanket.In order to ensure the maintenance ports design and maintenance method, this article discussed the concept design of the magnet system based on different maintenance port cases. The paper detailed studied the magnet system of CFETR including the electromagnetic analysis and parameters for TF (CS)PF. Besides, the volt-seconds of ohmic field are presented as detailed as possible in this paper. In addition, the calculations and optimizations of equilibrium field which should guarantee the plasma discharge of single null shape is carried out. The design work reported here illustrates that the present maintenance ports will not have a great impact on the design of the magnet system. The concept design of the magnet system can meet the requirement of the physical target.     

Preliminary concept design of the divertor remote handling system for DEMO power plant

This paper is based on the remote maintenance system project (WPRM) for the demonstration fusion power reactor (DEMO). Following ITER, DEMO aims to confirm the capability of generating several hundred of MW of net electricity by 2050. The main objective of these activities is to develop an efficient and reliable remote handling (RH) system for replacing the divertor cassettes.This paper presents the preliminary results of the concept design of the divertor RH system. The proposed divertor mover is a hydraulic telescopic boom driven from the transportation cask through the maintenance tunnel of the reactor. The boom is divided in three sections of 4 m each, and it is driving an end-effector in order to perform the scheduled operations of maintenance inside the vacuum vessel.Two alternative design of the end effector to grip and manipulate the divertor cassette are also presented in this work. Both the concepts are hydraulically actuated, basing on the ITER previous studies. The divertor cassette end-effector consists of a lifting arm linked to the divertor mover, a tilting plate, a cantilever arm and a hook-plate.The main objective of this paper is to illustrate the feasibility of DEMO divertor remote maintenance operations.     

Improving concept design of divertor support system for FAST tokamak using TRIZ theory and AHP approach

The paper focuses on the application of the Theory of Inventive Problem Solving (TRIZ) to divertor Remote Handling (RH) issues in Fusion Advanced Studies Torus (FAST), a satellite tokamak acting as a test bed for the study and the development of innovative technologies oriented to ITER and DEMO programs. The objective of this study consists in generating concepts or solutions able to overcome design and technical weak points in the current maintenance procedure. Two different concepts are designed with the help of a parametric CAD software, CATIA V5, using a top-down modeling approach; kinematic simulations of the remote handling system are performed using Digital Mock-Up (DMU) capabilities of the software. The evaluation of the concepts is carried out involving a group of experts in a participative design approach using virtual reality, classifying the concepts with the help of the Analytical Hierarchy Process (AHP).     

Effect of the ITER FW Manufacturing Process on the Microstructure and Properties of a CuCrZr Alloy

The first wall(FW) is one of the core components in ITER. As the heat sink material,the CuCrZr alloy shall be properly jointed with beryllium and stainless steel. At present, the grains of CuCrZr are prone to coarsen seriously in the thermal cycle process of FW manufacturing, which has become a critical issue for ITER parties. To investigate the mirostructure and mechanical properties of the optimized CuCrZr alloy in the first wall fabricating thermal cycle, simulative experiments have been done in this study. The alloy ingot was forged and hot rolled into plates,and then solid solution annealed, cold rolled and aged for strengthening. Several heat treatments were done to the CuCrZr samples, and the changes of microstructure, micro-hardness and tensile strength were investigated. The results indicated that the original elongated grains had changed into equiaxed ones, and the vickers hardness had declined to about 60 after experiencing the process of CuCrZr/316L(N) bi-metallic plate manufacturing, either by hot isostatic pressing at a higher temperature or by explosion welding followed by solution annealing. Joining Be/CuCrZr by hot isostatic pressing acts as an aging process for CuCrZr, so after the simulated heat treatment,the hardness of the alloy increased to about 110 HV and the tensile yield strength at 250?C rose to about 170 MPa. Meanwhile, the average grain size was controlled below 200 μm.     

Discharge electrode configuration effects on the performance of a plasma sparker

A multi-electrode array is commonly applied in a plasma sparker to generate stable acoustic pulses.In this paper,the effects of the electrode configuration on the performance of a plasma sparker have been investigated.In terms of the load electrical characteristics,the electrode radius and distance have negligible influence on the electric characteristics,whereas a larger electrode number results in a smaller voltage and a larger current but has little effect on the load energy.Regarding the acoustic characteristics,both the expansion and collapse pulses can be increased by decreasing the electrode tip radius.the influence of the electrode number and electrode gap distance on the amplitude of the expansion pulse was found to be negligible.And the amplitude of the collapse pulse decreases significantly with increasing electrode number.Increasing the electrode number decreases the energy efficiency for intense bubble interactions,thus,a small electrode tip radius and a small electrode number are preferred for the design of a plasma sparker if the total discharge energy is given.     

A revised design approach of the attachment system for the ITER EU-HCPB-TBM based on a central cylindrical connection element

The EU-Helium Cooled Pebble Bed Test Blanket Module (HCPB-TBM), which is located inside an equatorial port plug, is attached to the shield by an attachment system. The design of the attachment system has to fulfill two conflicting requirements. On the one hand, it has to transfer the high electromagnetic forces acting on the TBM to the shield and on the other hand, it has to compensate the different thermal expansions between the shield and the back plate of the TBM. The recent design approach of the attachment system consists of a hollow cylinder located at the center of the back plate. This design combines two advantages: a simple geometry and correspondingly low fabrication effort and the central location where the differential strain between back plate and shield is minimal. Static and transient thermal-structural analyses of the most demanding load cases, a fast vertical displacement event type II and the operation state tritium outgassing, have been performed to evaluate the design and confirm the compliance with the relevant design codes. A welded connection of the attachment system to the TBM back plate and a bolted connection in combination with a splined shaft is proposed for the shield side because of the dissimilar materials.     

基于微通道板的二维位置灵敏探测器的研制

介绍了基于微通道板的二维位置灵敏探测器的基本原理及其关键部分电阻阳极面板和数据读出系统的设计。通过测试,获得令人满意的线性和位置分辨。     

Harmonics analysis of the ITER poloidal field converter based on a piecewise method

Poloidal field (PF) converters provide controlled DC voltage and current to PF coils.The many harmonics generated by the PF converter flow into the power grid and seriously affect power systems and electric equipment.Due to the complexity of the system,the traditional integral operation in Fourier analysis is complicated and inaccurate.This paper presents a piecewise method to calculate the harmonics of the ITER PF converter.The relationship between the grid input current and the DC output current of the ITER PF converter is deduced.The grid current is decomposed into the sum of some simple functions.By calculating simple function harmonics based on the piecewise method,the harmonics of the PF converter under different operation modes are obtained.In order to examine the validity of the method,a simulation model is established based on Matlab/ Simulink and a relevant experiment is implemented in the ITER PF integration test platform.Comparative results are given.The calculated results are found to be consistent with simulation and experiment.The piecewise method is proved correct and valid for calculating the system harmonics.     

FIRE,a novel concept of massive gas injection for disruption mitigation in ITER: Validation on Tore Supra

Disruptions in large size tokamak like ITER must be mitigated to reduce detrimental effects on the device. Massive impurity injection prior to disruption is a promising mitigation technique. Many injector designs have already been tested on nowadays tokamaks. A novel concept of injector has been designed and tested on Tore Supra. It is based on the use of high pressure cartridges sealed with a bursting disc. For firing, an electric arc is generated inside the cartridge close to the rupture disc. This initiates a shock wave which breaks the disc. Tests show that the opening is achieved in less than 400 μs. A detailed modeling of the fast injector operation is presented. One result is that the gas is expelled in about 2 ms and an outflow rate as large as 4.2 × 10²⁵ atoms/s can be achieved at the nozzle exit (1 cm diameter). Massive neon gas injections have be performed on stable plasma to validate the concept. The gas penetration into the plasma prior to disruption is followed by a fast camera. Comparison with a ferromagnetic-valve based injector was also carried out. It is found that the velocity of the cold front penetration into the hot plasma is larger using this new injector.     

ARM在核数据采集系统中的应用与软件设计

介绍了一种新型核信号数据采集系统,其系统采用高速AD芯片,基于ARM对微弱快信号进行采集分析,并讨论了在Visual C 环境下,运用多线程和面向对象方法,开发数据采集领域的串口通讯模块的相关技术.     

基于放射免疫测试系统的数据管理实现

阐述了放射免疫分析及数据管理的概念,结合实际对放射免疫测试系统进行了需求分析,采用了模块化设计方案及相关技巧。通过实例实现了放射免疫测试系统的数据管理功能。     

基于ARM的通信接口测试系统的开发

分布式数据采集系统各子系统间的连接测试,需要专门的接口测试工具。随着私有协议的广泛使用,设备生产、维修中的调试测试问题也大大增加。这些问题往往无法使用传统的通用协议测试仪器进行测试,本文提出一种由测试模块加PC机方式构成专用接口测试系统的开发策略,并且重点介绍基于ARM的测试模块设计实现方法。文章分析了测试模块的接口特性、基本结构和软件流程,随后探讨了其与PC组成测试系统的应用方法。实验结果表明,该测试系统较好地满足了专用接口测试需求。这种测试模块加PC机构成简便系统的开发思路,为此类专用接口测试系统的快速开发提供了一种途径。     

基于加速器质谱的新型双用注入系统设计

提高14C的测试精度和10Be、26Al等长寿命放射性核素的丰度灵敏度是加速器质谱(AMS)领域的热点问题之一.西安加速器质谱中心设计了一套基于HVEE公司4130型加速器质谱计的双用注入系统.通过速度分析器的作用,在一套系统上实现交替注入和同时注入两种工作模式,较大程度上简化了以往两套系统共存的布局.计算结果表明,此系统既可以进行10Be、26Al的超高灵敏度测量,又继承了4130型AMS高精度的14C测试能力,拓展了其测量核素的范围.