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Water Cooled Solid Breeder (WCSB) blanket was put forward as one of the breeding blanket candidate schemes for Chinese Fusion Engineering Test Reactor (CFETR). In this study, a simplified tritium transport model was developed. Based on the conceptual engineering design, neutronics and thermal-hydraulic analyses of CFETR WCSB blanket, tritium transport process was analyzed. The results show that high tritium concentration and inventory exist in primary water loop and total tritium losses exceed CFETR limits under current conditions. Conducted were sensitivity analyses of influential parameters, including tritium source, temperature, flow-rate capacity and surface condition. Tritium performance of WCSB blanket can be significantly improved under a smaller tritium impinging rate, a larger flow-rate capacity or a better surface condition. This work provides valuable reference for the enhancement of tritium transport behavior in CFETR WCSB blanket. [ABSTRACT FROM AUTHOR]

China Fusion Engineering Test Reactor (CFETR), the first fusion reactor experiment project planned in China, is now being investigated in detail. Recently, a conceptual structural design of the Water-Cooled-Solid-Breeder (WCSB) blanket was proposed as one of the breeding blanket candidates for CFETR. In this research, based on the present design of the CFETR WCSB blanket, the heat transfer performance in the first wall (FW) under the pressurized water cooling condition was analyzed. The 3D computational fluid dynamics (CFD) results show that the maximal temperature of the FW will not exceed the limited temperature under normal or even higher heat flux condition. In addition, the effect of buoyancy on heat transfer is negligible under both conditions. The influence of roughness becomes increasingly important when the roughness height lies in the fully turbulent regime. The maximal temperature increases approximately linearly as the thickness of the front wall increases. It is also found that the heat flux and the local heat transfer coefficient are extremely non-uniform in the circumferential direction. Two 1D CFD methods are also evaluated by 3D CFD data, with the conclusion that both 1D results have some differences with the 3D data. The improved 1D method is more accurate than the former one. However, we ascertain that 1D methods should be used with caution for the water-cooling FW design. [ABSTRACT FROM AUTHOR]

• The mathematical and physical model of the particle pebble bed under the magnetic field is constructed. • The fundamental rule of the neutron multiplier pebble bed under the disturbance of the magnetic field is established. • The dynamic behavior of the particle system under the magnetic field are investigated based on the neutron multiplier pebble bed in the solid blanket. The functionality of solid blanket pebble bed in a fusion reactor is inevitably subjected to heat flux and electromagnetic forces during the operation. Since the dynamic behavior under the heat flux and forces has strong influence on the packing factor of the pebble bed, and the packing factor is essential to the higher TBR (tritium breeder rate) of the neutron multiplier pebble bed, it's necessary to study the impact of the dynamic forces on the neutron multiplier pebble bed. Some researchers have investigated the influences of the heat flux and electromagnetic forces on pebble bed. But, till date the influences of the heat flux and electromagnetic forces on the pebble bed of solid breeder materials in presence of neutron multiplier have not been studied yet. Thus, in this paper, the dynamic behavior of the particle system under the magnetic field are investigated based on the neutron multiplier pebble bed in the solid blanket. The mathematical and physical model of the particle pebble bed under the magnetic field was constructed, and the fundamental rule of the neutron multiplier pebble bed under the disturbance of the magnetic field is established. The presented work will provide basic parameters and data for the CFETR (China fusion testing reactor) pebble bed design. [ABSTRACT FROM AUTHOR]

Abstract The solid blanket is the main choice of the fusion reactor using the structure of pebble beds with beryllium as neutron multiplier and lithium silicate or lithium titanate as tritium breeder. The packing factor of the pebble bed is essential to the TBR(tritium breeder ratio), so it is important to study the mechanical behavior of particle system under the different kinds of the perturbations. In this paper, based on the mechanical behavior of solid pebble bed, the dynamic behavior of single particle system and mixed particle system under the different perturbation are simulated and analyzed by the EDEM software. The results show that, the perturbation can cause the packing factor of the particle system to increase continuously. In order to study the different way of the perturbation, three different typical models have been constructed. For the sinusoidal perturbation under the same strain, the stress of particle system decreases gradually, but the stress variation in the contraction and expansion process are different. The relationship between stress and vibration frequency roughly obeys the exponential decay law, and the stress drops faster with more violent disturbance. Then we use the mathematical model for fitting the relevant formula, which is valuable reference for engineering design in the future. [ABSTRACT FROM AUTHOR]

The Water Cooled Solid Blanket (WCSB) is selected as a basic choice of the CFETR blanket design, where the tritium would be bred by lithium and extracted subsequently in the tritium cycling loop. However, there always some inevitable losses exist during the tritium cycle due to the complexity of the system, which is considered as a big concern of the tritium self-consistency. In order to realize the tritium self-consistency of CFETR, a mathematical-physical model is developed to analyze the tritium transport in the WCSB. In the present work, the sensitivity study of some key parameters on tritium losses and inventories were conducted. It was found that the tritium transport in the WCSB is influenced by the (a) thickness of the tungsten which covers the first wall, (b) the concentration of the hydrogen in the coolant water and (c) the content of the water in the purge gas, etc. [ABSTRACT FROM AUTHOR]

China is carrying out the conceptual design of Chinese Fusion Engineering Testing Reactor (CFETR), and the Helium Cooled Pebble Bed (HCPB) blanket concept is one of the main choices for tritium production. Li 4 SiO 4 and Li 2 TiO 3 are the candidate breeder materials for the HCPB blanket concept. In the HCPB blanket, breeding pebbles with the diameter range of 0.6–1.2 mm are placed between two plates and the bed shall be cooled. Accordingly, effective thermal conductivity of pebble beds needs to be determined for the heat transfer calculation. Measurements of the heat transfer parameters of Li 4 SiO 4 and Li 2 TiO 3 pebble beds are being performed at the University of Science and Technology of China (USTC). Two measurement methods are being used. One is the steady state method with the use of thermocouples to measure the temperature distribution of the pebble bed. Another is transient thermal probe method using the temperature variation of the thermal probe and Monte Carlo inversion method to calculate the heat transfer parameters of the pebble bed. This paper will report on the progress of these measurement platforms. [ABSTRACT FROM AUTHOR]