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[en] Several designs of main feedwater system isolation in the present nuclear power plants are introduced. The characteristics of each design are demonstrated by their behaviors during accident conditions and operational events. The design that meets nuclear safety principles is presented. This analysis can be used in design and technical improvements for nuclear power plants. (author)

[en] We propose that quantum anomalous Hall effect may occur in the Lieb lattice, when Rashba spin–orbit coupling, spin-independent and spin-dependent staggered potentials are introduced into the lattice. It is found that spin Chern numbers of two degenerate flat bands change from 0 to ±2 due to Rashba spin–orbit coupling effect. The inclusion of Rashba spin–orbit coupling and two kinds of staggered potentials opens a gap between the two flat bands. The topological property of the gap is determined by the amplitudes of Rashba spin–orbit coupling and staggered potentials, and thus the topological phase transition from quantum anomalous Hall effect to normal insulator can occur. Finally, the topological phase transition from quantum spin Hall state to normal insulator is discussed when Rashba spin–orbit coupling and intrinsic spin–orbit coupling coexist in the Lieb lattice. - Highlights: • Spin Chern numbers of the bulk states on the Lieb lattice are calculated. • RSOC plays an important role on the topological phase transition on the Lieb lattice. • Quantum anomalous Hall effect can occur due to RSOC and staggered potentials. • Topological phase transition can occur when ISOC and RSOC coexist.

[en] Using the variation method, authors obtain a transcendental inequality about the constant of nuclear forces that is determined by Yukawa potential, and educe that constant of nuclear forces is more than 1 in meson theory

[en] The count of radon concentration can cause error in the process of transmission because the FH-463 is interfered in the process of measurement by external factors such as electromagnetic waves etc. It makes measurements vary greater than the expectations. And it can only process 10% or less Outlier when using Grubbs' criterion directly. In order to meet the Radon Concentration for inspection, the paper makes some necessary improvement on the criterion to adapt itself and estimates the samples data with linear regression. The experimental results show that the method is very convenient to reject the mistaken error more effective. The method in this paper can also be used in other fields. (authors)

[en] Radionuclides released from waste can migrate from the repository to the rock and soil outside. On the other hand, nuclides also are retarded by the backfill material. Radionuclide migration is the main geochemical process of the waste disposal. This paper introduces various methods for radionuclide migration research, and give a brief analysis of the geochemical process of radionuclide migration. Finally, two of the most important processes of the radionuclide migration have been instanced. (authors)

[en] We assessed freshwater consumption, greenhouse gas (GHG) emissions, and air emissions of using compressed and liquefied natural gas (NG) as transportation fuels by three heavy-duty NG vehicles (NGV) types from a wells-to-wheels (WTW) perspective. We analyzed freshwater consumption for NG production in major U.S. shale gas plays from recent reports and studies. We reviewed recent literature quantifying methane leakage from the NG supply chain and vehicle use to improve the estimates of NGV GHG emissions. Results show that NGVs could reduce freshwater consumption significantly and offer air emissions reduction benefits compared to their diesel counterparts. NGV WTW GHG emissions are largely driven by the vehicle fuel efficiency, as well as methane leakage rates of both the NG supply chain and vehicle end use: we estimate WTW GHG emissions of NGVs to be slightly higher than those of the diesel counterparts given the estimated WTW methane leakage. NGVs utilizing the newest aftertreatment systems have lower WTW and vehicle operation NO_x emissions across different duty-cycles and slightly lower WTW PM emissions than their diesel counterparts. We found that the cost-effectiveness of NGVs is impacted by incremental cost of NG storage tanks and the price difference between NG and diesel fuels. These findings for NGVs shed light on their environmental and economic impacts from a WTW holistic point of view. - Highlights: • Natural gas vehicles (NGVs) consume less WTW water relative to diesel counterparts. • NGVs offers tailpipe and WTW NO_x emission benefits. • NGVs offers WTW PM emission benefits. • Cost-effectiveness of NGVs is impacted by cost of NG storage tanks and fuel prices.

[en] Decontamination of refuel pool is a job in the heavy repair of nuclear power plant in order to protect repair men from radiation hurt. The character of pool decontaminating is analyzed and the deficiency for radiation protection is found. The optimization design of decontaminating refuel pool for radiation protection is showed in this paper, which make use of γ-ray image devices, wireless electronic personal dosimeters and other new type devices. The designed system can monitor the radioactivity distribution in the refuel pool and the situation of worker in real time. The radiation dose of worker will be controlled, and the risk of radioactivity contamination will be reduced, and decontaminating efficiency will be increased. (authors)

[en] The percolation flux through the unsaturated zone at the proposed Yucca Mountain repository for high-level nuclear waste can potentially affect (a) the occurrence and magnitude of water influx into the emplacement drifts, (b) the onset and rates of waste-package corrosion, (c) the mobilization of waste into aqueous states, and (d) the transport of radionuclides to the saturated zone. The magnitude and spatial and temporal variations of percolation flux depend on the infiltration rate but may be significantly influenced by (a) lateral diversion of flow at stratigraphic interfaces between nonwelded and welded tuffs above the repository horizon, (b) focusing of flow within or near steeply dipping fault zones, and (c) lateral diversion of flow within thermal-mechanical altered zones. Results from numerical modeling are presented to argue that (a) areas of the repository located close to and on the up-dip side of faults that intersect the Paintbrush nonwelded Tuff (PTn) would experience elevated percolation flux, irrespective of whether the faults act as flow barriers or conduits; (b) mechanical response of the rock mass to waste-generated heat will likely cause the development of laterally discontinuous zones characterized by dilation of horizontal fractures and net dilation or closure of vertical fractures; (c) areas of the repository located on the downstream side of the thermal-mechanical altered zones would experience elevated percolation flux; and (d) repository areas subjected to elevated percolation flux would experience faster rewetting of dryout zones and, thus, longer periods of wetness and elevated humidity. These results indicate that models used to predict the occurrence and magnitudes of water influx into emplacement drifts and the variations of relative humidity within the drifts need to consider the location of the drifts relative to faults that intersect the PTn and the development, geometry, and hydrological characteristics of thermal-mechanical altered zones

[en] The finite size effect in a two-dimensional topological insulator can induce an energy gap E_g in the spectrum of helical edge states for a strip of finite width. In a recent work, it has been found that when the spin–orbit coupling due to bulk-inversion asymmetry is taken into account, the energy gap E_g of the edge states features an oscillating exponential decay as a function of the strip width of the inverted HgTe quantum well. In this paper, we investigate the effects of the interface between a topological insulator and a normal insulator on the finite size effect in the HgTe quantum well by means of the numerical diagonalization method. Two different types of boundary conditions, i.e., the symmetric and asymmetric geometries, are considered. It is found that due to the existence of the interface between topological insulator and normal insulator this oscillatory pattern on the exponential decay induced by bulk-inversion asymmetry is modulated by the width of normal insulator regions. With the variation of the width of normal insulator regions, the shift of the Dirac point of the edge states in the spectrum and the energy gap E_g closing point in the oscillatory pattern can occur. Additionally, the effect of the spin–orbit coupling due to structure-inversion asymmetry on the finite size effects is also investigated. (paper)