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  • Superhydrophobic melamine sponge prepared by radiation induced grafting technology for efficient oil-water separation

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-06-07

    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。

  • 反应堆堆芯热工水力精细计算辅助支撑技术研究

    分类: 核科学技术 >> 核科学与技术 提交时间: 2024-06-07

    摘要: 反应堆堆芯全流域或大流域CFD计算分析有利于认知并预测堆芯热工水力精细运行状态,优化设计与运行,保障安全。但堆芯CFD计算分析面临巨量网格建模难、计算量大、耗时长、资源需求多等挑战问题,且CFD计算的堆型普适性差,变换堆型需重新开展全流程工作。为此,基于反应堆结构特点与冷却剂流动规律,研发了反应堆堆芯“专用”且不同堆型“通用”的CFD计算辅助支撑技术,能够分解CFD计算量,有效降低精细网格建模与计算分析难度,成功用于绕丝棒束组件、定位格架棒束组件、板元组件堆芯的全数全高度燃料组件代表域的CFD计算分析。

  • 基于APROS的核农耦合系统的仿真分析

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-06-06

    摘要: 为缓解气候变暖和实现3060双碳目标,国家优化产业和能源结构,推动煤炭清洁高效利用,大力发展新能源,在确保安全的前提下积极有序发展核电。相较于传统化石能源,核电更清洁、环保、低耗。然后,实际核电站热效率只有约33%,其余热量排放到环境中,造成严重浪费。其中,温排水排放到临近海域,热量对水体环境造成热影响。因此,高效利用温排水余热不仅可以提高核电站能源利用率,还能减少对水体环境的热污染,有助于节能减排。本文采用APROS软件对一套核电余热用于温室大棚和室内海水养殖的增温提产综合系统进行仿真分析,论证核农耦合系统的可行性,为我国核能余热综合利用提供科学依据。

  • 基于D-Be紧凑型快中子源硼中子的慢化整形研究

    分类: 核科学技术 >> 粒子加速器 提交时间: 2024-06-06

    摘要: 硼中子俘获治疗是一种细胞尺度内强靶向性与高传能线密度的二元放射疗法,具有治疗周期短、对周围健康组织损伤小等优势,是一种具有广阔前景的癌症治疗方法。在BNCT装置中,束流整形组件的作用是将中子源产生的快中子束慢化至超热中子能区(0.5 eV< E<10 keV),并保证中子方向性。本文使用蒙特卡罗模拟程序GEANT4以及FLUKA模拟9Be(d,n)10B反应中子源产生及后续中子慢化。采用1.45 MeV、30 mA的氘束轰击9 μm的薄铍靶,由该反应产生的中子作为源项,对BSA进行了可行性方案设计。结果表明:采用45 cm厚的BiF3和5 cm厚的TiF3组合慢化层,12 cm厚的Pb反射层,11 cm厚的Al2O3补充慢化层,以及0.1 mm厚的Cd热中子吸收层,保证出口处的γ成分、快中子成分、Φepi/Φth以及Φepi/Φfast符合IAEA所推荐的建议值。本研究得出了低能氘束与薄铍靶的中子谱及BSA具体设计方案,为D-Be中子源中子的慢化整形提供了数据参考,为D-Be源进一步优化研究提供支持。

  • 弥散核燃料芯体等效弹性性质数值模拟研究

    分类: 核科学技术 >> 核科学与技术 提交时间: 2024-06-05

    摘要: 弥散型燃料弹性性能是反应堆安全分析和燃料元件性能评估中的重要参数。将弥散型核燃料元件视为一种特殊的颗粒复合材料,采用细观力学的方法,对芯体等效弹性性质进行计算。采用通用有限元软件ABAQUS,假设燃料颗粒在芯体中周期性分布,建立有限元计算模型。选取具有代表性的体积元作为研究对象,建立了热-力-裂变气体迁移耦合分析方法,计算得到芯体的等效弹性性能,分析比较了颗粒的体积含量、颗粒大小和燃耗对弥散型核燃料等效弹性性质的影响。研究结果表明,影响芯体等效弹性性质的主要因素是颗粒体积与燃耗。

  • 基于Geant4模拟的41Ar β-γ符合探测器研究

    分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2024-06-03

    摘要: 41Ar是反应堆和加速器运行释放到环境中的主要放射性核素之一,具有半衰期短的特点。由于β-γ符合法能显著降低本底、提高探测器灵敏度,为了实现41Ar高灵敏度测量,设计了由BC404和CsI(Tl)组成的β-γ符合闪烁体探测器,并建立了以最小可探测活度浓度(Minimum Detectable Activity Concentration,MDC)为优化目标的探测器结构优化方法。首先,运用Geant4对β射线在CsI(Tl)中的泄漏率进行模拟,选择BC404厚度为3 mm,此时泄漏率为0.73%;其次,对不同的气体腔尺寸进行模拟,分析计算β探测效率、γ峰效率、气体腔体积和取样时间对MDC的综合影响,完成探测器的结构优化;最后,分析了本底计数率和测量时间对MDC的影响。当测量时间为200分钟、处理时间为30分钟、本底计数率为5×10-3 cps时,优化后的探测器对41Ar的MDC估算值为1.7 Bq/m3。

  • 基于现象模化的安全壳试验适用性分析方法研究

    分类: 核科学技术 >> 核科学与技术 提交时间: 2024-06-03

    摘要: 针对小比例尺度试验数据在安全壳性能分析软件确认过程中的适用性问题,基于安全壳内压力响应过程相似分析提出了试验数据适用性分析方法,并结合试验参数开展了HDR、Battelle和CVTR等安全壳试验数据对华龙一号大破口失水事故(LBLOCA)、主蒸汽管道破裂事故(MSLB)的适用性研究。研究结果表明,事故条件下安全壳内压力响应过程及其关键现象的相似准则数,可用于分析不同安全壳试验对目标电厂的适用性。HDR ISP-16&23、Battelle CASP-1&2和CVTR T3等试验工况的合理组合能够复现LOCA、MSLB等事故条件下HPR1000安全壳内因破口源喷放、安全壳壳体冷凝和壳内构件冷凝导致的压力瞬变过程,模拟失真在可接受范围内或偏保守,适用于HPR1000安全壳热工水力响应分析软件的验证和确认。

  • 氢化物对锆拉伸性能影响的分子动力学研究

    分类: 核科学技术 >> 核科学与技术 提交时间: 2024-06-02

    摘要: 氢化物是锆合金包壳管在核电厂正常运行过程中与一回路冷却剂发生锆水反应而产生的常见缺陷。本文利用分子动力学方法,采用COMB3势函数,构建含氢化物的锆基模型进行单轴拉伸模拟,探究了氢化物密度对锆力学性能的影响。研究结果表明,当氢化物密度在0~1078 µg/g时,随着氢化物密度的增加,屈服强度、应变和杨氏模量降低。在弹性阶段,氢化物密度的增加使应力集中区域增大,有利于位错形核;在塑性变形阶段,随着氢化物密度的增大,初始位错更倾向于在氢化物周围扩展。当氢化物密度在1078 ~ 2311 µg/g时,随氢化物密度的增加,屈服强度、应变和杨氏模量升高,这是由于氢化物密度较高时产生了大量位错并造成位错塞积。

  • Study of the response of 10B-doped MCP to wide-energy range neutrons from eV to MeV

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-05-31

    摘要: Neutron-sensitive microchannel plates (nMCPs) have applications in neutron detection, including energy spectrum measurements, neutron-induced cross-sections, and neutron imaging. 10B-doped MCPs (B-MCPs) have attracted significant attention owing to their potential for exhibiting a high neutron detection efficiency over a large neutron energy range. Good spatial and temporal resolutions are useful for neutron energy-resolved imaging. However, their practical applications still face many technical challenges. In this study, a B-MCP with 10 mol% 10B was tested for its response to wide-energy neutrons from eV to MeV at the Back-n white neutron source at the China Spallation Neutron Source. The neutron detection efficiency was calibrated at 1 eV, which is approximately 300 times that of an ordinary MCP and indicates the success of 10B doping. The factors that caused the reduction in the detection efficiency were simulated and discussed. The neutron energy spectrum obtained using B-MCP was compared with that obtained by other measurement methods, and showed very good consistency for neutron energies below tens of keV. The response is more complicated at higher neutron energy, at which point the elastic and non-elastic reactions of all nuclides of B-MCP gradually become dominant. This is beneficial for the detection of neutrons, as it compensates for the detection efficiency of B-MCP for high-energy neutrons.

  • 10B-doped MCP detector developed for neutron resonance imaging at Back-n white neutron source

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-31

    摘要: Neutron resonance imaging (NRI) has recently emerged as an appealing technique for neutron radiography. Its complexity surpasses that of conventional transmission imaging, as it requires a high demand for both a neutron source and detector. Consequently, the progression of NRI technology has been sluggish since its inception in the 1980s, particularly considering the limited studies analyzing the neutron energy range above keV. The white neutron source (Back-n) at the China Spallation Neutron Source (CSNS) provides favorable beam conditions for the development of the NRI technique over a wide neutron energy range from eV to MeV. Neutron-sensitive microchannel plates (MCP) have emerged as a cutting-edge tool in the field of neutron detection owing to their high temporal and spatial resolutions, high detection efficiency, and low noise. In this study, we report the development of a 10B-doped MCP detector, along with its associated electronics, data processing system, and NRI experiments at the Back-n. Individual heavy elements such as gold, silver, tungsten, and indium can be easily identified in the transmission images by their characteristic resonance peaks in the 1-100 eV energy range; the more difficult medium-weight elements such as iron, copper, and aluminum with resonance peaks in the 1-100 keV energy range can also be identified. In particular, results in the neutron energy range of dozens of keV (Aluminum) are reported here for the first time.

  • 脉冲波形甄别中的最佳特征子集选择与降维研究

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-05-31

    摘要: 随着机器学习在中子-伽马(n-γ)甄别中的广泛应用,脉冲波形甄别中的特征子集选择成为一个值得关注的问题。经验方法、Random Forest分类和Logistic回归特征选择算法较为全面地完善了特征子集选择方法,核主成分分析(KPCA)则将特征子集进一步降维。实验结果表明,特征选择算法在微弱的核信号中表现不佳,错误率均达30%以上。经验方法中的特征子集选取范围则至关重要,特征子集“1-62”的错误率达到49.096%,远高于来自脉冲尾部的特征子集约1%的错误率。最优特征子集与尾积分对应的采样点不完全重合,但差异不大,尾积分对应的采样点可近似为最优特征子集。通过研究目前具有代表性的Random Forest分类、Logistic回归等特征选择算法和细致的经验方法,论文结果具有普适性,为特征子集的选择提供了进一步的理论支持。

  • Geant4 simulation of fast electron bremsstrahlung imaging at the HL-3 tokamak

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-31

    摘要: To further research on high-parameter plasma, we plan to develop a two-dimensional hard X-ray (HXR) imag#2;ing system at the HL-3 tokamak to measure HXRs with energies ranging from 20 to 300 keV. The application of an array-structured detector ensures that this system can measure HXR-radiation spectra from the entire plasma cross section. Therefore, it is suitable for the study of fast-electron physics, such as radio-frequency wave current drives, fast electrons driving instabilities, and plasma disruptions in fusion research. In this study, we develop a simulation for calculating fast-electron bremsstrahlung in the HL-3 tokamak based on the Monte Carlo simulation code Geant4, in which the plasma geometry and forward scattering of fast-electron bremsstrahlung are considered. The preliminary calculation results indicate that the HXR energy deposition on the detector is symmetrically distributed, even though the plasma distribution is asymmetric owing to the toroidal effect. These simulation results are helpful in constructing the relationship between the energy deposition on the de#2;tector and parameter distribution on the plasma cross section during HL-3 experiments. This is beneficial for the reconstruction of the fast-electron distribution function and for optimizing the design of the HXR-imaging system.

  • Cone-beam computed tomography noise reduction method based on U-Net with convolutional block attention module in proton therapy

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-30

    摘要: Cone-beam computed tomography (CBCT) is mostly used for position verification during the treatment pro#2;cess. However, severe image artifacts in CBCT hinder its direct use in dose calculation and adaptive radiationtherapy re-planning for proton therapy. In this study, an improved U-Net neural network named CBAM-U-Netwas proposed for CBCT noise reduction in proton therapy, which is a CBCT denoised U-Net network with con#2;volutional block attention modules. The datasets contained 20 groups of head and neck images. The CT imageswere registered to CBCT images as ground truth. The original CBCT denoised U-Net network, sCTU-Net, wastrained for model performance comparison. The synthetic CT(SCT) images generated by CBAM-U-Net and theoriginal sCTU-Net are called CBAM-SCT and U-Net-SCT images, respectively. The HU accuracies of the CT,CBCT, and SCT images were compared using four metrics: mean absolute error (MAE), root mean square error(RMSE), peak signal-to-noise ratio (PSNR), and structure similarity index measure (SSIM). The mean values ofthe MAE, RMSE, PSNR, and SSIM of CBAM-SCT images were 23.80 HU, 64.63 HU, 52.27 dB, and 0.9919,respectively, which were superior to those of the U-Net-SCT images. To evaluate dosimetric accuracy, the rangeaccuracy was compared for a single-energy proton beam. The γ-index pass rates of a 4 cm × 4 cm scannedfield and simple plan were calculated to compare the effects of the noise reduction capabilities of the originalU-Net and CBAM-U-Net on the dose calculation results. CBAM-U-Net reduced noise more effectively thansCTU-Net, particularly in high-density tissues. We proposed a CBAM-U-Net model for CBCT noise reductionin proton therapy. Owing to the excellent noise reduction capabilities of CBAM-U-Net, the proposed modelprovided relatively explicit information regarding patient tissues. Moreover, it can be used in dose calculationand adaptive treatment planning in the future.

  • 二次侧水位对自然循环蒸汽发生器倒U型管内单相倒流影响的无量纲分析

    分类: 核科学技术 >> 核科学与技术 提交时间: 2024-05-30

    摘要: 核动力装置在自然循环条件下蒸汽发生器内会发生单相倒流,单相倒流对自然循环流动阻力和蒸汽发生器传热能力都产生了很大影响。为了从具有普适性的角度研究蒸汽发生器二次侧水位对单相倒流的影响,本研究建立了无量纲守恒方程。基于无量纲守恒方程,采用微扰理论获得了考虑二次侧水位的单相倒流临界点理论模型,在分析了二次侧水位对倒U型管压降的基础上,进一步分析了不同管长、无量纲阻力数、无量纲传热数条件下二次侧水位对临界点的影响。本文研究结果表明:二次侧水位降低导致倒流发生临界点逐渐接近原点;不同管长条件下二次侧水位影响规律相同;随着水位的降低,无量纲阻力数、无量纲传热数条件下对临界点的影响逐渐减小。本研究结论从理论上证明了二次侧水位对单相倒流的影响不利于倒流的发生,从机理层面解释了原因,可以辅助相关核动力装置的事故分析。

  • Impact of initial fluctuations and nuclear deformations in isobar collisions

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-30

    摘要: Relativistic isobar ($^{96}_{44}$Ru+$^{96}_{44}$Ru and $^{96}_{40}$Zr+$^{96}_{40}$Zr) collisions have revealed intricate differences in their nuclear size and shape, inspiring unconventional studies of nuclear structure using relativistic heavy ion collisions. In this study, we investigate the relative differences in the mean multiplicity ($R_{ langle N_{ rm ch} rangle}$) and the second- ($R_{ epsilon_{2}}$) and third-order eccentricity ($R_{ epsilon_{3}}$) between isobar collisions using Optical and Monte Carlo Glauber models. It is found that initial fluctuations and nuclear deformations have negligible effects on $R_{ langle N_{ rm ch} rangle}$ in most central collisions, while both are important for the $R_{ epsilon_{2}}$ and $R_{ epsilon_{3}}$, the degree of which is sensitive to the underlying nucleonic or sub-nucleonic degree of freedom. These features, compared to real data, may probe the particle production mechanism and the physics underlying nuclear structure.

  • Method for detector description conversion from DD4hep to Filmbox

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-30

    摘要: DD4hep serves as a generic detector de Conversely, Filmbox~(FBX) stands out as a widely used 3D modeling file format within the 3D software industry.In this paper, we introduce a novel method that can automatically convert complex HEP detector geometries from DD4hep de The feasibility of this method was demonstrated by its application to the DD4hep de The automatic DD4hep--FBX detector conversion interface provides convenience for further development of applications, such as detector design, simulation, visualization, data monitoring, and outreach, in HEP experiments. 

  • CF2燃料组件多错对中值下摩擦力与落棒性能试验研究

    分类: 核科学技术 >> 核科学与技术 提交时间: 2024-05-29

    摘要: CF系列燃料组件是中核集团自主研发的先进三代核电反应堆核心部件,为分析CF2燃料组件在多对中值工况下,驱动线运动部件在水和空气中的摩擦力与落棒性能,采用1:1的CF2模拟燃料组件配合自主设计研发的可调节旋转式顶盖首次实现了多个错对中值的集成,能够对多个错对中值进行科学准确的调节。优化了驱动机构性能研究的方法,获取了驱动机构在水和空气两种介质中全行程、多错对中值工况下的摩擦力与落棒性能数据。落棒总时间和棒到缓冲口时间均随着对中值增加而增大,但缓冲时间基本保持一致。燃料组件与控制棒在最大对中值工况下运行良好,摩擦力没有超过允许极限值,也未发生在大对中值工况下的卡棒现象。该研究结果为CF系列燃料组件的设计定型、安全评定与软件开发提供了重要的试验依据,其方法可推广至后续CF3等燃料组件的科研项目中。

  • 基于蒙特卡罗模拟的离子CT图像重建及相对阻止本领误差研究?

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-28

    摘要: 离子束放射治疗(放疗)越来越广泛地被运用于肿瘤治疗,目前使用传统X射线计算机断层扫描(CT)来制定离子放疗治疗计划时存在相对阻止本领(RSP)具有较大误差的问题,理想的方式是直接使用高能离子束对患者成像,生成离子放疗治疗计划设计时所需的医学图像,避免RSP转换从而减小RSP的误差。本研究使用蒙特卡罗程序Geant4/Gate搭建了离子CT模拟平台,设计了理想与现实两种离子CT成像系统探测器,利用最大似然法和ASD-POCS算法实现了图像重建,研究了理想与现实两种设置、多种能量以及不同离子种类对模体内硫、磷、碳和钙四种材料插件重建RSP误差的影响。结果表明,330MeV质子在理想与现实设置两种情况下的RSP相对误差都小于1.547%,理想设置下的RSP相对误差远小于现实设置,现实设置下各材料的RSP重建误差接近理想设置下的三倍;质子的RSP相对误差随着能量的增加而减小,在230MeV时的RSP相对误差最大,在硫、磷、碳和钙四种材料中分别为2.855%、2.468%、1.653%、2.553%。在330MeV时的RSP相对误差达到最小,在硫、磷、碳和钙四种材料中分别为0.181%、0.351%、0.250%和0.245%;在能量330MeV/u下,碳离子在硫、磷、碳和钙四种材料中的RSP相对误差分别为0.060%、0.281%、0.150%、0.082%,误差均在0.281%以内,RSP相对误差小于330MeV的质子。因此,与质子CT相比,碳离子CT能为离子放疗治疗计划设计提供更为精确的RSP数据。

  • 融合到达角的粒子滤波寻源方法研究

    分类: 核科学技术 >> 核科学与技术 提交时间: 2024-05-28

    摘要: 未知放射源搜寻定位是核安检、核应急领域的重要研究课题。为提高寻源效率、适应多源环境探测,提出了一种融合到达角的粒子滤波寻源方法。首先,构建了自主定位与到达角感知相结合的放射源搜寻硬件平台,给探测器引入了位置和角度信息;其次,在粒子滤波基础上考虑到达角信息,动态收缩放射源搜寻区域,进而提高搜寻效率;最后,在自主寻源路径规划中采用到达角引导的机器人姿态调整,增强机器人寻源的灵活度。仿真实验证明此方法可正确有效工作,利用放射源开展的测试进一步验证了该方法对于多源搜寻的实用性。

  • Boron shielding design for neutron and gamma detectors of a pulsed neutron tool

    分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2024-05-27

    摘要: Shielding material is critical for downhole pulsed neutron tool design as it directly influences the accuracy of formation measurements. A well-designed shield configuration ensures that the response of the tool is maximally representative of formation without being impacted by tool and borehole environment. This manuscript investigates the effects of boron-containing materials on neutron and gamma detectors based on a newly designed logging-while-drilling tool, which is currently undergoing manufacturing process. As boron content increases, its ability to absorb thermal neutrons significantly enhances. Through simulation, it is proven that boron carbide (B4C) can be used as an effective boron shielding material for thermal neutrons and therefore employed in this work. To shield against thermal neutrons migrating from mud pipes, the optimal shielding thicknesses for near and far neutron detectors are determined to be 5mm and 4mm. For an example, at a porosity of 25 p.u., the near neutron sensitivity shows a 5.6% increase in response. Furthermore, in order to shield capture gamma generated by thermal neutrons once they enter tool from the mud pipe and formation, the internal and external shields for the gamma detector is evaluated. Results show internal shield needs 75% boron content while the external shield is of 14.2mm thickness and 25% boron content to minimize tool effect.

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