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171.
172.
A 100 MWt reactor design has been conceived to support flux level of the order of 1015 n/cm2/s in selected flux trap zones. The physics design considers high enriched metallic alloy fuel in the form of annular plates
placed in a D2O moderator tank in a hexagonal lattice arrangement. By choosing a tight lattice pitch in the central region and double the
lattice pitch in the outer region, it is possible to have both high fast flux and thermal flux trap zones. By design the flux
level in the seed fuel has been kept lower than in the high flux trap zones so that the burning rate of the seed is reduced.
Another important objective of the design is to maximize the time interval of refueling. As against a typical refueling interval
of a few weeks in such high flux reactor cores, it is desired to maximize this period to as much as six months or even one
year. This is possible to achieve by eliminating the conventional control absorbers and replacing them with a suitable amount
of fertile material loading in the reactor. Requisite number of seedless thorium-aluminum alloy plates are placed at regular
lattice locations vacated by seed fuel in alternate fuel layers. It is seen that these thorium plates are capable of acquiring
asymptotic fissile content of 14 g/kg in about 100 days of irradiation at a flux level of 8 × 1014 n/cm2/s. In summary, the core has a relatively higher fast flux in the central region and high thermal flux in the outer region.
The present physics design envisages a flat core excess reactivity for the longest possible cycle length of 6 months to one
year. It is also possible to modify the design for constant subcriticality for about the same period or longer duration by
considering neutron spallation source at the centre and curtailing the power density in the inner core region by shielding
it with a layer of thoria fuel loading.
相似文献
173.
随着互联网的进一步发展,调动互联网用户之间的互动类业务已经成为互联网业务新的发展趋势,以网民之间的协作和互动为显著特征的Web 2.0类业务正在蓬勃发展。在众多Web 2.0类业务中,Second Life所引领的虚拟世界类应用不论是其注册用户数以及商业模式创新方面都取得了巨大的成功。通过介绍Second Life的产生和发展,分析Second Life的业务特点以及商业模式,并结合国内虚拟世界的发展情况分析了虚拟世界类应用在中国的发展前景。 相似文献
174.
就残余气体对微波电子管性能和寿命的影响进行了深入地研究。通过研究残余气体的成分,找到了减少各种气源漏气、渗气、放气的主要途径。在生产中,合理选材、优化工艺和加强质量控制,可以有效地减少残余气体,提高电子管寿命。 相似文献
175.
This paper presents the results of calculations for CANDU reactor operation in thorium fuel cycle. Calculations are performed
to estimate the feasibility of operation of heavy-water thermal neutron power reactor in self-sufficient thorium cycle. Parameters
of active core and scheme of fuel reloading were considered to be the same as for standard operation in uranium cycle. Two
modes of operations are discussed in the paper: mode of preliminary accumulation of 233U and mode of operation in self-sufficient cycle. For the mode of accumulation of 233U it was assumed for calculations that plutonium can be used as additional fissile material to provide neutrons for 233U production. Plutonium was placed in fuel channels, while 232Th was located in target channels. Maximum content of 233U in target channels was estimated to be ∼13 kg/t of ThO2. This was achieved by irradiation for six years. The start of the reactor operation in the self-sufficient mode requires
233U content to be not less than 12 kg/t. For the mode of operation in self-sufficient cycle, it was assumed that all channels
were loaded with identical fuel assemblies containing ThO2 and certain amount of 233U. It is shown that nonuniform distribution of 233U in fuel assembly is preferable.
相似文献
176.
The ridge waveguide fabrication with periodically poled MgO-doped lithium niobate for green laser 总被引:1,自引:0,他引:1
Ridge waveguides were fabricated using an external field, a precision lapping machine and neutron loop discharge (NLD) in magnesium-oxide-doped lithium niobate. The measured quasi-phase-matching (QPM) wavelength of the second-harmonic generation (SHG) in a 30 mm long periodically poled magnesium-doped lithium niobate (PPMgLN) ridge waveguide which has a domain period of 6.8 μm is about 532 nm. A fabricated periodically poled magnesium-doped lithium niobate ridge waveguide was duty cycle of 51.9 ± 2.83% and demonstrated second-harmonic generation. By using this periodically poled magnesium-doped lithium niobate ridge waveguide, highly effective, low-cost optical devices with high power or short wavelength can be achieved. 相似文献
177.
本文对采用二氧化碳作为基本工作流体的半闭环燃气轮机循环的空气动力学特性进行了详尽的分析.结果表明,不同工作流体的比热比值对压气机的压比、等熵效率及临界堵塞质量流量影响很大,并详细阐述了一种比热比对透平机械性能影响的修正方法,进而提出了一种零排放发动机的设计新思路,揭示了最初为空气工质而设计的压气机可以直接用于CO2零排放发动机中. 相似文献
178.
二层信用策略下部分延期付款的库存模型 总被引:1,自引:0,他引:1
当前二层信用期相关文献考虑的都是零售商提供给其顾客相同的信用期,但现实中零售商往往会根据物品的种类不同提供给顾客不同的信用期.为研究此问题,建立了优化供货周期使零售商平均相关成本最小的库存模型,证明了最优供货周期的存在性,并给出实例加以说明. 相似文献
179.
We developed a novel microfluidic cell culture device in which magnetic beads repetitively collide with osteoblast cells, MC3T3‐E1, owing to attractive forces generated by pulsed electromagnetic fields and consequently the cells were physically stimulated by bead impacts. Our device consists of an on‐chip microelectromagnet and a microfluidic channel which were fabricated by a microelectromechanical system technique. The impact forces and stresses acting on a cell were numerically analyzed and experimentally generated with different sizes of bead (4.5, 7.6 and 8.4 μm) and at various pulse frequencies (60 Hz, 1 kHz and 1 MHz). Cells were synchronized at each specific phase of the cell cycle before stimulation in order to determine the most susceptible phase against bead impacts. The cells were stimulated with different sizes of bead at various pulse frequencies for 1 min at G1, S and G2 phases, respectively, and then counted immediately after one doubling time. The growth rate of cells was highly accelerated when they were stimulated with 4.5 μm beads at G1 phase and a pulse frequency of 1 MHz. Almost all of the cells were viable after stimulation, indicating that our cell stimulator did not cause any cellular damage and is suitable for use in new physical stimulus modalities. 相似文献
180.
We present a new algorithm for continuation of limit cycles of autonomous systems as a system parameter is varied. The algorithm
works in phase space with an ordered set of points on the limit cycle, along with spline interpolation. Currently popular
algorithms in bifurcation analysis packages compute time-domain approximations of limit cycles using either shooting or collocation.
The present approach seems useful for continuation near saddle homoclinic points, where it encounters a corner while time-domain
methods essentially encounter a discontinuity (a relatively short period of rapid variation). Other phase space-based algorithms
use rescaled arclength in place of time, but subsequently resemble the time-domain methods. Compared to these, we introduce
additional freedom through a variable stretching of arclength based on local curvature, through the use of an auxiliary index-based
variable. Several numerical examples are presented. Comparisons with results from the popular package, MATCONT, are favorable
close to saddle homoclinic points. 相似文献