Rapid Thermal-Hydraulic Analysis and Design Optimization of ITER Upper ELM Coils

ITER edge localized mode （ELM） coils are important components of the in-vessel coils （IVCs） and they are designed for mitigating or suppressing ELMs. The coils located on the vacuum vessel （VV） and behind the blanket are subjected to high temperature due to the nuclear heat from the plasma, the Ohmic heat induced by the working current and the thermal radiation from the environment. The water serves as coolant to remove the heat deposited into the coils. Based on the results of nuclear analysis, the thermal-hydraulic analysis is performed for the preliminary design of upper ELM coils using a rapid evaluation method based on 1D treatment. The thermal-hydraulic design and operating parameters including the water flow velocity are optimized. It is found that the rapid evaluation method based on 1D treatment is feasible and reliable. According to the rapid analysis method, the thermal hydraulic parameters of two water flow schemes are computed and proved similar to each other, providing an effective basis for the coil design. Finally, considering jointly the pressure drop requirement and the cooling capacity, the flow velocity is optimized to 5 m/s.     

Static Structural Analysis for a Neutron Shielding Block in ITER

The ITER neutron shielding blocks are located between the outer shell and the inner shell of the vacuum vessel to provide neutron shielding. Considering the combined loads acting on the shielding blocks during ITER plasma operation, the structure of the shielding blocks must be evaluated. Using the finite element method with ANSYS analysis software, static structural analysis is performed, including elastic analysis and limit analysis for one typical shielding block. The evaluated results based on RCC-MR code show that the structure of this shielding block can meet the design requirement.     

ITER边校正场线圈测试冷屏结构设计与数值模拟北大核心CSCD

针对国际热核聚变实验堆(ITER)边校正场线圈测试过程的重要装置-冷屏进行结构设计、理论计算与数值模拟。选择的冷屏面板材料为6061铝合金;确定的冷却管截面为外方内圆的结构型式,其布置间距为450 mm;采用的为G10复合材料加工而成的多层叠片式柔性结构支撑件。为验证设计合理性,对冷屏各部件进行仿真分析,并通过理论计算得出冷屏表面热负荷大小,最后利用有限元方法对冷屏整体结构传热性能进行数值模拟。结果表明:冷屏部件结构强度满足材料屈服极限;热负荷理论计算结果符合技术要求;冷屏表面温度分布均匀。此设计为后续边校正场线圈测试过程提供了理论参考和技术支撑。     

Verification and Optimization of Vacuum Vessel Supports Design in KTX

The Vacuum Vessel(VV) system is an essential component of Keda Torus for experiment(KTX),and various scenarios might take place on it.The VV’s supports should be adequately strong to stand against various loads on VV,which might happen in extreme scenarios.Therefore,the design of VV supports is verified in a single extreme scenario and is subsequently optimized in this report.The numerical simulation based on Finite Element theory is performed as the major method for analysis and optimization.The electromagnetic force in previous analyses serves as the load for the mechanical analyses of supports.During the optimization,the stresses of the W supports decrease remarkably after introducing cotters.Finally,the optimum design has been worked out.It satisfies the requirements regarding the strength and convenience in assembly.     

Mechanical Analysis and Optimization of ITER Upper ELM Coil & Feeder

International thermonuclear experimental reactor （ITER） edge localized mode （ELM） coils are used to mitigate or suppress ELMs. The location of the coils in the vacuum vessel and behind the blankets exposes them to high radiation levels and high temperatures. The feeders provide the power and cooling water for ELM coils. They are located in the chinmey ports and experience lower radiation and temperature levels. These coils and feeders work in a high magnetic field environment and are subjected to alternating electromagnetic force due to the interaction between high magnetic field and alternating current （AC） current in the coils. They are also subjected to thermal stresses due to thermal expansion. Using the ITER upper ELM coil and feeder as an example, mechanical analyses are performed to verify and optimize the updated design to enhance their structural performance. The results show that the conductor, jacket and bracket can meet the static, fatigue and crack threshold criteria. The optimization indicates that adding chamfers to the bracket can reduce the high stress of the bracket, and removing two rails can reduce the peak reaction force on the two rails arising from thermal expansion.     

Design of Tokamak ELM Coil Support in High Nuclear Heat Environment

In Tokomak, the support of the ELM coil, which is close to the plasma and subject to high radiation level, high temperature and high magnetic field, is used to transport and bear the thermal load due to thermal expansion and the alternating electromagnetic force generated by high magnetic field and AC current in the coil. According to the feature of ITER ELM coil, the mechanical performance of rigid and flexible supports under different high nuclear heat levels is studied. Results show that flexible supports have more excellent performance in high nuclear heat condition than rigid supports. Concerning thermal and electromagnetic （EM） loads, optimized results further prove that flexible supports have better mechanical performance than rigid ones. Through these studies, reasonable support design can be provided for the ELM coils or similar coils in Tokamak based on the nuclear heat level.     

Limit Analysis for the Mechanical Structure of the ITER Neutron Shielding Block

The ITER neutron shielding blocks are located between the inner shell and the outer shell of the vacuum vessel (VV) with the main function of providing neutron shielding. Considering the combined loads of the shielding blocks during the plasma operation of the ITER, limit analysis for one typical ferromagnetic (FM) shielding block has been performed and the structural design has been evaluated based on the American Society of Mechanical Engineers (ASME) criterion and European standards. Results show that the collapse load of this shielding block is three times the specified load, which is much higher than the design requirement of 1.25. The structure of this neutron shielding block has a sufficient safety margin.     

ITER校正场线圈等效材料属性有限元分析

校正场线圈是ITER大型超导磁体系统的重要组成部分,其线圈体由多种材料组成且周期性排列,对其等效材料属性预测很重要。目前主要采用基于均匀化理论的有限元方法,但其处理过程复杂。本文提出了基于广义虎克定律的有限元方法,使求解过程更简便。分析对比两种方法,后一种方法处理过程更简单,结果更精确,所得结果为校正场线圈的结构分析和热分析提供了必要的参数。     

聚变反应堆校正场结构优化及性能分析

针对核聚变反应堆校正场线圈的结构进行了优化,确定了满足物理和工程装配的线圈结构。针对校正场线圈进行电磁分析,并得到线圈磁场和电磁力分布。根据广义胡克定律,利用有限元方法将线圈绕组材料属性等效,以简化结构计算模型。通过建立结构分析模型,计算电磁力载荷下的校正场线圈强度,确定了线圈盒厚度,支撑位置及支撑数目。最后为保证校正场线圈始终处于低温工作环境,根据校正场线圈结构和热负载,提出并确定线圈液氦冷却管方案。