Structural Design And Thermal-hydraulic Analysis Research Of Helium Cooled Solid Blanket For CFETR

Chinese Fusion Engineering Test Reactor (CFETR) is a fusion experiment device between International Thermonuclear Experimental Reactor (ITER) and future fusion demonstration (DEMO) reactor. At present the design of CFETR is in progress. The main objectives of CFETR is to achieve long pulse or steady-state operation with50-200MW fusion power, to demonstrate tritium self-sufficiency of fusion reactor, and to explore remote handling technology as well as the technological approaches for obtaining license of DEMO-level fusion power plant. Blanket is a kind of key component in CFETR. It is required to achieve relative high capacity of tritium breeding in the limit space in CFETR for satisfying the requirement of tritium self-sufficiency of reactor, which make the design of CFETR blanket challenging.In this thesis, a kind of helium cooled solid blanket structure with good performance of tritium breeding as well as relatively simple structure and low pressure drop of coolant is proposed based on CFETR. Thermal-hydraulic performance of the typical blanket module was analyzed and researched. The reasonability of the design scheme of the blanket is preliminary assessed. Meanwhile, the blanket structure as well as thermal-hydraulic performance are optimized, which will provide important basis and reference for further design and research of the blanket.Detailed structural design and thermal-hydraulics analysis were carried out for the typical blanket module. Multilayer U-shaped pebble beds was adopted to make blanket structure more simple. Compact gas manifolds was proposed to gain more space for tritium breeding zone, which is conducive to improving the performance of tritium breeding. The arrangement of the coolant channels in the components are simple and flexible, and the pressure loss of coolant in the channels is relatively small. Based on the blanket structural design, the preliminary result from three-dimensional neutronics analysis showed that the blanket scheme can meet the tritium self-sufficiency requirement of CFETR. On the basis of the heat source data provided by neutronics calculation, helium flow scheme in the blanket module was determined from the perspective of cooling needs of components, cooling effect of coolant and structural complexity of the blanket. Besides, mass flow rate, temperature and pressure drop of helium inside the coolant channels of the blanket components were analyzed.Thermal performance of the typical blanket module was evaluated using the methods of theoretical calculation and finite element numerical simulation. Temperature distribution of the blanket module under average and maximum first wall surface heat flux was respectively investigated. The results showed that the temperature on the blanket module can be well controlled within the allowance temperature limits of the materials even if the first wall is suffering the maximum surface heat flux, which verified the reasonability of the design of blanket cooling scheme. Finally, the effect of loss of helium flow and fusion power excursion on the temperature distribution of blanket is respectively analyzed from the thermal safety point of view.Analyses of flow distribution of helium from the helium manifolds inside the typical blanket module were carried out using computational fluid dynamics software. The flow details of helium in each manifold and the flow distribution of helium in the outlets of the manifolds were obtained. The uniformity of helium distribution was greatly improved by using the method of changing the size of helium inlet and adding fluid guide plate. Based on the flow distribution analyses, pressure drop of helium in the manifolds were investigated. The pressure drop of helium was greatly reduced by improving the configuration and dimension of the inner structure of manifold. Temperature performance of the walls of the manifolds walls was evaluated according to the allowance temperature limit of structural material. In addition, the convective heat transfer coefficients of the manifold walls were extracted, which will provide important reference for thermal stress analysis of manifold in the future.According to ITER Structural Design Criteria for In-vessel Components (SDC-IC), thermo-mechanical analyses of the typical blanket module were performed by using finite element method software. The bearing capacity of the blanket module under normal operation condition and over-pressurization of blanket box were respectively assessed without regard to electromagnetic loads. The method of using cooling plate to reinforce cap was proposed so as to improve the structural strength of blanket and to resist the accident of over-pressurization of blanket box. The validity of the method was verified through analysis. It will provide an important reference for the further design and optimization of the blanket structure in the future.