分类： 核科学技术 >> 辐射物理与技术 提交时间： 2024-04-26
摘要： Small-scale measurements of the radon exhalation rate using the flow-through and closed-loop methods were conducted on the surface of a uranium tailing pond to better understand the differences between the two methods.An abnormal radon exhalation behavior was observed, leading to computational fluid dynamics (CFD)-based simulations in which dynamic radon migration in a porous medium and accumulation chamber was considered.Based on the in-situ experimental and numerical simulation results, variations in the radon exhalation rate subject to permeability, flow rate, and insertion depth were quantified and analyzed. The in-situ radon exhalation rates measured using the flow-through method were higher than those measured using the closed-loop method, which could be explained by the negative pressure difference between the inside and outside of the chamber during the measurements. The consistency of the variations in the radon exhalation rate between the experiments and simulations suggests the reliability of CFD-based techniques in obtaining the dynamic evolution of transient radon exhalation rates for diffusion and convection at the porous medium–air interface. The synergistic effects of the three factors (insertion depth, flow rate, and permeability) on the negative pressure difference and measured exhalation rate were quantified, and multivariate regression models were established, with positive correlations in most cases; the exhalation rate decreased with increasing insertion depth at a permeability of 1×10−11 m2. CFD-based simulations can provide theoretical guidance for improving the flow-through method and thus achieve accurate measurements
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2024-04-26
摘要： 本文介绍了一种超疏水性三聚氰胺（ME）海绵（ME-g-PLMA），该海绵通过高能辐射诱导的原位共价接枝长烷基十二烷基甲基丙烯酸酯（LMA）到ME海绵上，以实现高效的油水分离。所得的ME-g-PLMA海绵具有优良的孔隙结构，具有超疏水性（水接触角为154°）和超亲油性，可吸收高达自身重量66-168倍的各类油脂。所得到的ME-g-PLMA海绵可以通过连接泵连续分离水面上的浮油，或者通过重力驱动装置分离水下的浮油。ME-g-PLMA海绵在长期浸泡在不同的腐蚀性溶液中，多次反复吸油后，也能保持其高疏水性。所得改性ME-g-PLMA海绵具有优异的分离性能，在溢油清理方面具有巨大的潜力。
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2024-04-26
摘要： BL02U2 of the Shanghai Synchrotron Radiation Facility (SSRF) is a surface diffraction beamline with a photon flux of 5.5 × 1012 photons/s at 10 keV and a beam size of 160×80 µm2 at the sample site. It is dedicated to studying surfaces (solid–vacuum, solid–gas) and interfaces (solid–solid, solid–liquid, and liquid–liquid) in nanoscience, condensed matter, and soft matter systems using various surface scattering techniques over an energy range of 4.8–28 keV with transmission and reflection modes. Moreover, BL02U2 has a high energy resolution, high angular resolution, and low beam divergence, which can provide excellent properties for X-ray diffraction experiments, such as grazing incident X-ray diffraction, X-ray reflectivity, crystal truncation rods, and liquid X-ray scattering. Diversity of in-situ environments can also be provided for the samples studied. This paper describes the setup of the new beamline and its applications in various fields.
分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2024-04-26
摘要： 高能宇宙辐射探测设施（HERD）是计划部署在中国空间站上的旗舰级科学装置，旨在间接探测暗物质、精确测量宇宙线成分以及进行高能伽马射线的巡天观测。其中，硅电荷探测器是HERD的关键组成部分之一，用于测量从氢到镍的宇宙射线的电荷。为了对硅电荷探测器的电荷测量能力进行验证和分析，设计了硅电荷探测器束流样机的地检系统。该系统采用了Xilinx公司的ZYNQ UltraScale+ MPSoC芯片作为控制芯片，并实现了LVDS数据接收、编解码、RS-422控制和千兆以太网数据接收存储功能。硅电荷探测器束流样机参加了欧洲核子中心的重核束流实验，地检系统在束流实验采集了100G实验数据,功能稳定可靠为HERD项目硅电荷探测器的后续实验提供了重要的技术支持和数据基础。
分类： 核科学技术 >> 同位素技术 提交时间： 2024-04-26
摘要： We proposed and compared three methods (filter burnup, single-energy burnup, and burnup extremum analysis) to build a high-resolution neutronics model for 238Pu production in high-flux reactors. The filter burnup and single-energy burnup methods have no theoretical approximation and can achieve a spectrum resolution of up to ~1 eV, thereby constructing the importance curve and yield curve of the full energy range. The burnup extreme analysis method combines the importance and yield curves to consider the influence of irradiation time on production efficiency, thereby constructing extreme curves. The three curves, which quantify the transmutation rate of the nuclei in each energy region, are of physical significance because they have similar distributions. A high-resolution neutronics model for 238Pu production was established based on these three curves, and its universality and feasibility were proven. The neutronics model can guide the neutron spectrum optimization and improve the yield of 238Pu by up to 18.81%. The neutronics model revealed the law of nuclei transmutation in all energy regions with high spectrum resolution, thus providing theoretical support for high-flux reactor design and irradiation production of 238Pu
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2024-04-25
摘要： A Laue microdiffraction beamline (BL03HB) was constructed at the Shanghai Synchrotron Radiation Facility (SSRF). This beamline features two consecutive focusing points in two different sectors within its end station, the first dedicated to protein crystallography and the other tailored to materials science applications. Based on a superbend dipole magnet with a magnetic field of 2.29 T, a two-stage focusing design was implemented with two sets of Kirkpatrick–Baez mirrors to achieve a micro white beam as small as 4.2×4.3 µm 2 at the first sector and 0.9×1.3 µm 2 at the second sector in the standard beamline operation mode at SSRF. The X-ray microbeam in the two sectors can be easily switched between monochromatic and white beams by moving a four-bounce monochromator in or out of the light path, respectively. In the protein crystallography sector, white-beam Laue microdiffraction was demonstrated to successfully determine the structure of protein crystals from only a few images of diffraction data collected by a Pilatus 2M area detector. In the materials science sector, the white-beam Laue diffraction was collected in a reflection geometry using another Pilatus 2M area detector, which could map the microstructural distribution on the sample surface by scanning the samples. In general,the BL03HB beamline promotes the application of Laue microdiffraction in both protein crystallography and materials science. This paper presents a comprehensive overview of the BL03HB beamline, end station, and the first commission results.
点击量
通过
点击量
下载量
评论
