| As one of important fuels for the fusion reactor,tritium is extremely scarce in nature,so the tritium must be generated by the fusion reactor blanket to realize the circulation and self-sufficiency of tritium in the fuel cycle system and maintain the stable operation of the fusion reactor.Tritium has the property of diffusion and permeability in the material.During the operation of the fusion reactor,tritium is produced in the blanket and will be retained in the blanket and the system,while it will easily permeate into the coolant and release outside the reactor,causing the tritium losses,which is not conducive to the safe operation of the blanket and also poses a potential radioactive hazard to the public,and is detrimental to the realization of tritium self-sufficiency.The transport behavior of tritium in a fusion reactor will be directly related to the retention and permeation of tritium in the blanket and its system,and also affects tritium self-sufficiency and tritium radioactivity safety.The purpose of this paper is to simulate the tritium transport behavior in the fusion reactor blanket system to provide reference to the system design and the fusion reactor radiation safety study.Firstly,based on the tritium analysis model,two-dimensional and threedimensional tritium transport simulations are carried out for the simplified unit of Helium Cooled Pebble bed(HCPB)blanket and the European HCPB blanket,and the tritium distribution,tritium inventory,tritium permeation,etc.of the blanket are calculated and compared with the results in the literature,and the simulation results are in good agreement with the results in the literature.As for the results of the simplified unit of Helium Cooled Pebble bed blanket,the calculation deviation is about 5%,the calculation deviation is less than 20%for the European HCPB blanket.Subsequently,two-dimensional and three-dimensional tritium transport analyses are performed for the Water-Cooled Ceramic Breeder(WCCB)blanket,one of the candidate blankets for the Chinese Fusion Engineering Test Reactor(CFETR).A twodimensional multi-physical field coupled tritium analysis model is developed for the WCCB blanket module of version 2015,and quantitative assessment of tritium inventory in the breeder zone,purge gas,structural materials as well as the tritium permeation are performed for all blanket modules of the reactor,and the near wall effect of purge gas flow rate is identified and sensitivity analysis of key parameters is performed.The amount of tritium inventory,permeation,and tritium taken by purge gas of all blankets in CFETR are 11.13 g,79.79 g/y and 13957.76 g/y,respectively.The two-dimensional and three-dimensional multi-physical field coupled tritium analysis models are established for typical blanket module of version 2018,and the tritium inventory and permeation quantities are calculated for the two-dimensional and threedimensional models,and sensitivity analyses of key parameters are performed,and results of two-dimensional and three-dimensional models are compared.The results show that the amount of tritium inventory in the breeder of three-dimensional simulation is 27%larger than that of two-dimensional simulation.The amount of tritium inventory in the structure of three-dimensional simulation is 13%larger than that of two-dimensional simulation.The amount of tritium permeation of threedimensional simulation is 35%larger than that of two-dimensional simulation.Meanwhile,the tritium permeation will be reduced by H2 significantly.The tritium inventory under H2 content of 0.1%accounts for 2%of the condition without H2.The tritium permeation under H2 content of 0.1%accounts for 3%of the condition without H2.Then the three-dimensional tritium analysis for the Water Cooled Lithium Lead(WCLL)blanket module is conducted,the tritium distribution,tritium inventory,tritium permeation,and tritium transported out of the blanket are calculated,and compared with the results in the literature,and the simulation results were in good agreement with the results in the literature,the calculation deviation is less than 30%.In addition,a two-dimensional tritium transport analysis study was conducted for the supercritical CO2 cooled Lithium-lead(COOL)blanket,which is one of the candidate blankets for CFETR.A two-dimensional multi-physical field coupled tritium analysis model is developed for the inner and outer blanket sectors of the COOL blanket,and the tritium inventory,permeation,and tritium transported quantities are obtained for the inner and outer blanket sectors as well as in the whole reactor.The amount of tritium permeation and tritium taken by purge gas are 8.46 kg/y and 90.76 kg/y,respectively.In order to investigate the effect of MHD effect on tritium analysis,the tritium distribution under the MHD effect and the effect of MHD effect on tritium retention and permeation are investigated in a simple straight pipe section.The increase of the flow velocity in the sidewall boundary layer and Hartmann layer of the MHD effect increases the convective effect and decreases the tritium concentration,which can play a suppressive role in the tritium retention and permeation.Finally,different tritium analysis code are developed for the blanket system.Firstly,a tritium analysis model combinend one dimension with zero dimension is established for the solid blanket system,a defect model of the structural material is added,and the corresponding program is developed based on MATLAB.The data of tritium inventory,tritium extraction,and tritium permeation of the WCCB blanket system are obtained,the influence of different permeation models on the tritium related quantities is studied,and sensitivity analysis of key parameters is performed.The amount of tritium generation rate is 97.9 kg/y.The amount of tritium inventory in the breeder,structure,purge gas loop and coolant loop are 5.46 g,25.10 g,1.49×10-1 g,2.91 g,respectively.The tritium extracted by the tritium extraction system and coolant purification system are 95.90 kg/y and 2.08 kg/y,respectively.The tritium permeation from the steam generator to the secondary loop is 16.07 Ci/y.The results show that the permeation model of the steam generator basically has a significant effect only on the amount of tritium permeation to the secondary loop,the permeation model of the structural material in the blanket has a more significant effect on the system,especially for the amount of tritium inventory in the structural material and the tritium permeation through the steam generator.Tritium calculation analysis for the solid blanket system based on the model combined two-dimension and zero-dimension is performed.An integrated kinetic tritium analysis program based on COMSOL and MATLAB is developed to simulate the tritium concentration distribution in each region of the blanket module,and to calculate the tritium inventory,tritium extraction,and tritium permeation of the WCCB blanket system.Sensitivity analysis of the key parameters is performed.The amount of tritium inventory in the breeder,structure,purge gas loop and coolant loop are 7.50 g,18.44 g,9.85×10-2 g,2.15×10-1 g,respectively.The tritium extracted by the tritium extraction system and coolant purification system are 97.83 kg/y and 152.09 g/y,respectively.The tritium permeation from the steam generator to the secondary loop is 1.19 Ci/y.The sensitivity analysis results show that the tritium inventory of the purge gas and coolant loop and the tritium permeation through the steam generator decrease with the increase of the tritium extraction system efficiency,while the tritium inventory of the purge gas loop is particularly affected by the tritium extraction system efficiency,the tritium inventory in the coolant loop and the tritium permeation through the steam generator decrease with the increase of the the percentage of coolant flowing into coolant purification system,and the tritium concentration in the purge gas loop basically does not change with the increase of the percentage of coolant flowing into coolant purification system. |
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