Structural Design And Engineering Research Of Water-cooled CFETR Divertor

The Chinese Fusion Engineering Test Reactor(CFETR)is an experimental fusion reactor project between ITER and DEMO,which is proposed by China after its participation in the International Thermonuclear Fusion Reactor(ITER)and its decision to carry out research on high tritium breeding ratio and high fusion power.The project is based on a tokamak-type magnetic confinement fusion reactor,and the engineering design and related research are carried out,among which the breakthrough of the divertor,an important component of the device,is an internationally recognized challenge and has always been one of the research focuses of the project.The main functions of the divertor include:removing heat;discharging impurities and fusion reaction products helium ash.For CFETR,which conducts high fusion power research,the divertor is equipped with several challenges:the power density of the peak heat load reaching the target plate of the divertor will reach 20 MW/m2,while the neutron nuclear heat cannot be avoided in the design of the divertor,which means that the divertor has to be able to withstand extremely high heat loads and be equipped with a cooling system with high heat transfer efficiency.Plasma currents of up to 14 MA are generated during plasma disruption and vertical displacement events,which generate extremely strong electromagnetic forces on the divertor components,requiring reliable strength and stiffness of the divertor.The nuclear fusion reaction generates a large number of highenergy neutrons,which will irradiate the surrounding components,thus causing the activation of the materials in the vacuum chamber,including the divertor components,and the activated materials will release gamma rays to the outside world for a certain period of time,forming a radiation source,and the operator cannot enter the environment with strong nuclear radiation for maintenance,which can only be done by remote handling system,while the divertor components in the vacuum chamber are in direct contact with the plasma.Facing the plasma,the working conditions are very complex environment,for the divertor is a wear parts,need regular and irregular maintenance or replacement,so the research and design of CFETR divertor need to consider the compatibility of divertor components and remote handling system,in order to meet the divertor maintenance needs.In view of the above problems,the study of divertors and related technologies is of non-negligible significance for the stable and sustainable operation of fusion devices.This thesis combines the above challenges,and the main research elements include.1.A divertor design that can be adapted to the needs of CFETR is proposed,and a more advanced long-legged divertor configuration shape is innovatively proposed,which is able to effectively reduce the thermal load of the component in terms of physical input.2.Based on the traditional overall maintenance strategy of the divertor and the shortcomings of the overall maintenance strategy,a removable target plate structure is innovatively proposed,which makes the divertor possible to maintain the target plate individually,and greatly improves the divertor maintenance efficiency and saves a large amount of maintenance cost and time cost compared with the previous single maintenance strategy of the divertor.3.By adopting advanced materials suitable for the operating situation of fusion reactor,we have studied the structure and heat transfer performance of the target plate of the flat-plate divertor,optimized the cooling flow path,and achieved a thermal load capacity of steady state heat load 20 MW/m2.The feasibility of the design was also confirmed laterally by EAST 1/8 fluid modeling experiments.4.Systematic structural analysis,electromagnetic analysis,and thermal hydraulic analysis are carried out for this divertor,and the feasibility of the design is evaluated in a more complete and systematic way.Based on the physical configuration,the structural design is completed,and then after thermal-hydraulic analysis,electromagnetic analysis,and structural analysis,the design of the CFETR divertor in this project basically meets the requirements of the system.