Thermo-hydraulic Analysis Of The Cool-down Of ITER Toroidal Field Coils

Thermo-hydraulic analysis of the cool-down of ITER Toroidal Field CoilsPENG Nan(Refrigerator and Cryogenic Engineering) Directed by Prof.ZHANG Liang and Associate Prof.XIONG LianyouFusion energy is a strategy energy source which is the main power source of century 21.But the using of fusion energy is still under developing.China is the one of 7 partners of the International Thermonuclear Experimental Reactor (ITER)plan which is a joint international research and development project whose aims are to demonstrate the scientific and technical feasibility of fusion power.As an independent state,China will obtain the full technical knowledge and research results.And this will be helpful for the development of the fusion power plants in China.This subject is supported by the cryogenic department of ITER organization, which is the thermo-hydraulic analysis of cool-down of of ITER Toroidal Field (TF)coils.The main reseach work of the paper is shown as follows:(1)According to the requirement of cool-down TF coils from 300 K to 80 K, a model of preliminary calculation is built up to assess the entired cryogenic system.The simulation results obtain the supply mass flow rate from refrigerators during the gradual cool-down step and the relationship between TF coils and the whole cryogenic system.(2)Based on the results of the preliminary calculation,a quasi-3D model is developed for the cool-down to 80 K of TF coils.The simulation results obtained from this model explain that the cool-down profiles of winding packs will be wiggly and the temperature profiles decrease with time homogeneously.And the temperature decreased speed of the winding packs is fast than that of cases.(3)The results also claim that the design inlet temperature decreasing speed can not suffice the requirement of keeping the maximum temperature differences below 50K.To meet this challenge and shorten the cool-down time as possible,an improved inlet temperature decreasing speed is found,which can keep the maximum temperature differences below 50 K with a margin of 15%and make the cool-down period in 500 hours.(4)Another mathematical model and cool-down analysis of the helium refrigerator for ITER is developed to simulate off-design mode of the cryoplants.The creditability of this model is validated by the comparision of the T-S diagram from the refrigerator company.Based on the model of the refrigerators and that of TF coils,the cool-down results of TF coil from 80 K to 6 K are obtained.The results show that the temperature profiles also decrease with time homogeneously and this cool-down step can be achieved in 1 week.(5)At last,the paper presents a design of superconductivity solenoid magnet for the standardization of Hall-element.A 3D FEM model is developed to study the quench behaviors of this magnet.The intending results of quench behaviors are obtained and analyzed.The cool-down test and the excitation experiment have been performed and the experimental results greatly support the design.