Results 1 - 10 of 2434
Results 1 - 10 of 2434. Search took: 0.037 seconds
|Sort by: date | relevance|
[en] The development of a reliable solution for the power and particle exhaust in a reactor is recognized as a major challenge towards the realization of DEMO. Alternative magnetic configurations such as Double Null, Snowflake, X and Super-X divertors are considered as a promising solution to reduce the heat load on the divertor targets even if their scalability on a DEMO size device is a challenging engineering problem.
[en] By using the strain-range partitioning method, the fatigue life of high-heat-load components made of oxygen-free copper have been successfully predicted within a factor of two. Following a successful study on the prediction of fatigue life of high-heat-load components made of Glidcop, the thermal limitation of oxygen-free copper (OFC), which is used more commonly than Glidcop, has been studied. In addition to its general mechanical properties, the low-cycle-fatigue (LCF) and creep properties of OFC were investigated in detail and compared with those of Glidcop. The breaking mode of OFC, which was observed to be completely different from that of Glidcop in a fatigue fracture experiment, clarified the importance of considering the creep–fatigue interaction. An additional LCF test with compressive strain holding was conducted so that the creep–fatigue life diagram for out-of-phase thermal fatigue could be obtained on the basis of the strain-range partitioning method. The life predicted from elasto-plastic creep analysis agreed well with that determined from the void ratio estimated in the fatigue fracture experiment
[en] The power grid peaking capacity is insufficient due to the increasing installed capacity of renewable power. Moreover, it is also restricted by the operation mode of combined heat and power units (CHPs), the minimum electricity loads of which are determined by the heat load. It is significant to study the heat-electricity decoupling technologies for CHPs. Therefore, the low-pressure steam turbine renovation technology is studied in this paper with a 300MW unit as reference case. Results show that the minimum electric load rate and the coal consumption are decreased, and the heat-electricity ratio is increased significantly for CHP with low-pressure steam turbine renovation. When the heat load is 1200 GJ/h, the minimum electric load rate and coal consumption with low-pressure steam turbine renovation can be reduced by 32.4 and 30.9 % respectively. The heat-electricity ratio can be increased by 68.8 % after renovation of low-pressure steam turbine. (paper)
[en] It is known that NBI ion losses may pose a problem to the Wendelstein 7-X first wall, but the so-far utilized wall models had insufficient details for reproducing the locations and magnitude of the hot-spots. This study aims to exhaustively analyse the detailed wall loads in the reference magnetic configurations and in various plasma scenarios. The goal is to pinpoint the endangered plasma facing components and to calculate heat loads to them in preparation for the first NBI operations. This study can be used to prepare monitoring of the heat loads and paves the way to future searches of improved configurations. (paper)
[en] Life extension package LE3 (9975-03203) has been instrumented and subjected to an elevated temperature environment for approximately 8 years. During this time, the cane fiberboard has been maintained at a maximum temperature of ~160 - 165 °F, which was established by a combination of internal (19 watts) and external heat sources. Several tests and parameters were used to characterize the package components. Results from these tests generally indicate agreement between this full-scale shipping package and small-scale laboratory tests on fiberboard samples, including the degradation models based on the laboratory tests. These areas of agreement include the rate of change of fiberboard weight, dimensions and density, and change in fiberboard thermal conductivity. Corrosion of the lead shield occurred at a high rate during the first several weeks of aging, but dropped significantly after most of the moisture in the fiberboard migrated away from the lead shield. Dimensional measurements of the lead shield indicate that no significant creep deformation has occurred. This is consistent with literature data that predict a very small creep deformation for the time at temperature experienced by this package. The SCV O-rings were verified to remain leak-tight after ~5 years aging at an average temperature of ~170 °F. This package provides an example of the extent to which moisture within a typical fiberboard assembly can redistribute in the presence of a temperature gradient such as might be created by a 19 watt internal heat load. The majority of water within the fiberboard migrated to the bottom layers of fiberboard, with approximately 2 kg of water (2 liters) eventually escaping from the package. Two conditions have developed that are not consistent with package certification requirements. The axial gap at the top of the package increased to a maximum value of 1.549 inches, exceeding the 1 inch criterion. In addition, staining and/or corrosion have formed in a few spots on the drum. However, the package remains capable of performing its function. Aging of this package continues.
[en] Spreading the heat load at stick point one of the most important works for increase the plasma performance. The Snowflake divertor(SFD) configuration could increase the flux expansion near the stick points, which fact for spreading the divertor heat load .Snowflake divertor configuration requires not only the first-order null at X-point as usual divertor configuration, but also the second-order derivative of the poloidal flux at X-point to be zero. Due to the Poloidal Field (PF) coils current limit, standard SFD configuration is difficult for EAST. One Quasi-SFD configuration can keeps the current within the allowable range of the coils.
[en] The first review is presented for the recent stellarator designs of FFHR, HSR, ARIES-CS, which are based on the experimental device projects of LHD, W-7X, NCSX, respectively. The main advantageous features of those designs are common on (1) current-free plasmas, which leads to steady, high Q and disruption-free reactors and (2) high density operations, which largely reduces the diverter heat load. Design optimization and engineering feasibility are highlighted including maintainability, fabricability and showing future R and D key issues with prospect towards DEMO.