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  • 熔盐堆用U型管壳式换热器的传热与流动特性模拟分析

    分类: 核科学技术 >> 核科学与技术 提交时间: 2024-05-12

    摘要: 为更好的理解和掌握熔盐换热器的运行特征,并给熔盐堆中换热器的设计和运行累积经验,本文以美国橡树岭国家实验室10MWt熔盐实验堆(MSRE)用的主换热器为研究对象,基于该换热器的设计参数,应用管壳式换热器的理论计算方法(包括Kern方法和Bell-Delaware方法)、换热器设计软件HTRI Xchanger Suite和计算流体力学方法(Computational Fluid Dynamics, CFD)对换热器的关键性能指标(如换热系数、压降和换热功率)分别进行了计算分析,并与MSRE主换热器的实验数据进行比较分析。结果表明:两种理论计算方法(Kern方法、Bell-Delaware方法)、HTRI软件及CFD仿真模拟的结果与实验结果的差异均在可接受范围内,其中Kern方法与MSRE实验所得的换热量相差最大、约为15%,HTRI软件模拟与MSRE实验所得的总换热系数相差最小、为0.16%;理论计算方法、换热器设计软件及CFD仿真均不同程度适用于熔盐-熔盐换热器设计,且CFD仿真还可对换热器内部传热和流动细节进行直观描述。

  • HL-3装置ECRH天线系统研制

    分类: 核科学技术 >> 核聚变工程技术 提交时间: 2024-05-12

    摘要: 根据HL-3装置电子回旋共振加热(ECRH)系统的需求,完成了天线系统的设计与研制,并对天线进行了测试与安装。HL-3装置ECRH天线系统由三个天线组成,包含一个中平面天线和两个上斜天线,三个天线位于装置弱场侧的同一扇段,可协同完成加热、新经典撕裂模(NTM)控制等功能。目前已经完成其中两个天线的设计、制造和测试,另外一个天线完成了发射光路的设计。测试结果表明,中平面天线和上斜一号天线控制精确、快速,达到了装置实验使用的要求。

  • 动态刻棒方法在田湾VVER的应用研究

    分类: 核科学技术 >> 核科学与技术 提交时间: 2024-05-12

    摘要: 在物理试验中准确测量控制棒价值对于反应堆安全运行有着非常重要的意义。开展基于六角形几何的多群时空动力学计算方法研究,基于此,开展适用于六角形几何的先进动态刻棒方法研究。该方法适用范围广,测量精度高且测量过程快。利用田湾VVER动态刻棒试验数据对该方法进行了验证,结果表明基于该方法所测量的控制棒价值与理论值偏差在10%以内,计算精度较高,且该方法计算时间较短,计算效率高。

  • 基于超级电容储能的HL-3装置中性束逆变型高压电源模块设计

    分类: 核科学技术 >> 核聚变工程技术 提交时间: 2024-05-12

    摘要: 高压电源是中性束注入加热系统的重要组成部分,决定着束能量和引出束流的品质。随着电压等级的逐步提高,PSM高压电源无法满足实验要求。为了实现中性束调制注入功率的快速切换,提出一种基于超级电容储能的逆变型高压电源。采用超级电容储能方式,降低所需电网容量,减小对电网的冲击。采用软开关技术的DC-DC谐振变换器结构,提高电源的响应速度,减小开关器件的开关损耗。设计电源模块电路拓扑,根据电源性能指标完成系统建模计算。建立充电电路和主回路PSIM仿真模型,对电源性能指标进行仿真验证。搭建逆变电源模块测试样机,完成相关性能指标测试。经仿真及实验验证,电源模块能够实现1600V/50A的稳定输出,满足6MW/120kV设计要求。

  • The Dynamics Beamline at SSRF

    分类: 核科学技术 >> 核科学与技术 提交时间: 2024-05-11

    摘要: The Dynamics beamline (D-Line), which combines synchrotron radiation infrared spectroscopy (SR-IR) and energy-dispersive X-ray absorption spectroscopy (ED-XAS), is the first beamline in the world to realize concurrent ED-XAS and SR-IR measurements at the same sample position on a millisecond time-resolved scale. This combined technique is effective for investigating rapid structural changes in atoms, electrons, and molecules in complicated disorder systems, such as those used in physics, chemistry, materials science, and extreme conditions. Moreover, ED-XAS and SR-IR can be used independently in the two branches of the D-Line. The ED-XAS branch is the first ED-XAS beamline in China, which uses a tapered undulator light source and can achieve approximately 2.5 × 1012 photons/s•300 eV BW@7.2 keV at the sample position. An exchangeable polychromator operating in the Bragg-reflection or Laue-transmission configuration is used in different energy ranges to satisfy the requirements for beam size and energy resolution. The focused beam size is approximately 3.5 μm (H) × 21.5 μm (V), and the X-ray energy range is 5–25 keV. Using one- and two-dimensional position-sensitive detectors with frame rates of up to 400 kHz enables time resolutions of tens of microseconds to be realized. Several distinctive techniques, such as the concurrent measurement of in-situ ED-XAS and infrared spectroscopy, time-resolved ED-XAS, high-pressure ED-XAS, XMCD, and pump–probe ED-XAS, can be applied to achieve different scientific goals.

  • Reliable calculations of nuclear binding energies by the Gaussian process of machine learning

    分类: 物理学 >> 核物理学 提交时间: 2024-05-11

    摘要: Reliable calculations of nuclear binding energies are crucial for advancing the research of nuclear physics. Machine learning provides an innovative approach to exploring complex physical problems. In this study, the nuclear binding energies are modeled directly using a machine-learning method called the Gaussian process. First, the binding energies for 2238 nuclei withZ >20andN >20are calculated using the Gaussian process in a physically motivated feature space, yielding an average deviation of 0.046 MeV and a standard deviation of 0.066 MeV. The results show the good learning ability of the Gaussian process in the studies of binding energies. Then, the predictive power of the Gaussian process is studied by calculating the binding energies for 108 nuclei newly included in AME2020. The theoretical results are in good agreement with the experimental data, reflecting the good predictive power of the Gaussian process. Moreover, theα-decay energies for 1169 nuclei with50≤Z≤110are derived from the theoretical binding energies calculated using the Gaussian process. The average deviation and the standard deviation are, respectively, 0.047 MeV and 0.070 MeV. Noticeably, the calculatedα-decay energies for the two new isotopes204Ac M. H. Huanget al.,Phys. Lett. B834, 137484 (2022) and207Th H. B. Yanget al.,Phys. Rev. C105, L051302 (2022) agree well with the latest experimental data. These results demonstrate that the Gaussian process is reliable for the calculations of nuclear binding energies. Finally, theα-decay properties of some unknown actinide nuclei are predicted using the Gaussian process. The predicted results can be useful guides for future research on binding energies andα-decay properties.

  • Carbon-based nanomaterials cause toxicity by oxidative stress to the liver and brain in Sprague–Dawley rats

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-11

    摘要: Carbon-based nanomaterials have important research significance in various disciplines, such as compositematerials, nanoelectronic devices, biosensors, biological imaging, and drug delivery. Recently, the human andecological risks associated with carbon-based nanomaterials have received increasing attention. However, thebiosafety of carbon-based nanomaterials has not been investigated extensively. In this study, we used differenttypes of carbon materials, namely, graphene oxide (GO), single-walled carbon nanotubes (SWCNTs), and multiwalledcarbon nanotubes (MWCNTs), as models to observe their distribution and oxidative damage in vivo.The results of Histopathological and ultrastructural examinations indicated that the liver and lungs were the mainaccumulation targets of these nanomaterials. SR-μ-XRF analysis revealed that SWCNTs and MWCNTs mightbe present in the brain. This shows that the three types of carbon-based nanomaterials could cross the gas–bloodbarrier and eventually reach the liver tissue. In addition, SWCNTs and MWCNTs could cross the blood–brainbarrier and accumulate in the cerebral cortex. The increase in ROS and MDA levels and the decrease in GSH,SOD, and CAT levels indicated that the three types of nanomaterials might cause oxidative stress in the liver.This suggests that direct instillation of these carbon-based nanomaterials into rats could induce ROS generation.In addition, iron (Fe) contaminants in these nanomaterials were a definite source of free radicals. However,these nanomaterials did not cause obvious damage to the rat brain tissue. The deposition of selenoprotein inthe rat brain was found to be related to oxidative stress and Fe deficiency. This information may support thedevelopment of secure and reasonable applications of the studied carbon-based nanomaterials.

  • 基于TMSR-PNS的宽能区中子束流监测器的模拟研究

    分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2024-05-11

    摘要: 针对钍基熔盐堆白光中子源(TMSR-PNS)在运行过程中出现中子束流掉束或打火导致的束流不稳定的问题,有必要设计研发一种具有高计数率、低中子束流影响、高中子/伽马甄别性能的中子束流监测器。基于蒙特卡洛模拟软件Geant4系统研究了薄膜塑料闪烁中子束流监测器的中子转换层厚度、闪烁体厚度、以及外壳材料等关键参数对薄膜闪烁体的影响规律,分析结果表明:闪烁体中子转换层厚度约为2 um时具有相对合适的本征探测效率,闪烁体厚度为2 mm、甄别阈值为0.1 MeV时监测器具备伽马射线不灵敏性能。同时,通过对比不同外壳材料对于γ射线产生电子的影响,选取电子产生较少的铁作为外壳材料。研究结果可为后续的中子束流监测器实物制备提供理论依据。

  • HL-3装置ECRH天线系统研制

    分类: 核科学技术 >> 核科学与技术 提交时间: 2024-05-10

    摘要: 根据HL-3装置电子回旋共振加热(ECRH)系统的需求,完成了天线系统的设计与研制,并对天线进行了测试与安装。HL-3装置ECRH天线系统由三个天线组成,包含一个中平面天线和两个上斜天线,三个天线位于装置弱场侧的同一扇段,可协同完成加热、新经典撕裂模(NTM)控制等功能。目前已经完成其中两个天线的设计、制造和测试,另外一个天线完成了发射光路的设计。测试结果表明,中平面天线和上斜一号天线控制精确、快速,达到了装置实验使用的要求。

  • 核电机组蒸发器水位调节机构适配技术研究及应用

    分类: 核科学技术 >> 核科学与技术 提交时间: 2024-05-10

    摘要: 核电机组在高负荷工况下,给水泵转速调节系统与主/旁路阀调节系统形成耦合,导致控制系统出现调节震荡情况,对执行机构的可靠性和耐久性带来挑战,同时对核电机组的安全稳定运行带来影响。故如何解决高负荷工况下控制系统耦合震荡问题至关重要。深入分析多基地波动曲线,发现执行机构响应特性慢,不能及时跟随控制系统的响应速度,是造成调节波动的主要原因。通过执行机构响应特性曲线评估,优化阀门执行机构参数,实施比例增益、速度增益、最小回路增益匹配设置,实现小信号跟随性好、大信号超调性低、时间响应特性快三方面的响应特性优化,提升执行机构兼具小信号、大信号时良好的响应和控制特性。从执行机构调节特性的角度提升高负荷下蒸发器水位控制的稳定性。

  • 中国散裂中子源上的一种双束团数据解析方法

    分类: 物理学 >> 核物理学 提交时间: 2024-05-10

    摘要: 中国散裂中子源(CSNS)可提供0.3 eV至300 MeV的白光中子束流,总束流强度可达107n/s/cm2,为中子俘获反应截面的测量提供了一个优秀的实验平台。CSNS在正常的运行模式下会由加速器产生两个间隔410 ns的质子束团先后打靶,因此产生的中子束流也由间隔为410 ns的两个束团混合而成。为避免两个束团的效应相互干扰,影响中子俘获截面的能量精度,需要对实验数据进行解析和重构,还原单个束团的效应。现有的解析方法可以得到非常精细的解谱结果,但相对复杂,具有一定使用门槛。本工作提出了一种简化的双束团解谱方法,在保证中子能量精度的情况下适用于中子能量低于1.2 MeV的数据,为同类型的实验工作提供一种新的数据处理思路。

  • HL-3装置二号中性束注入束线量热靶研制

    分类: 核科学技术 >> 核科学与技术 提交时间: 2024-05-09

    摘要: 在中性束注入器中,量热靶是非常重要的水冷部件之一,承担着接收和测量束功率的任务。除此之外,利用内置热电偶阵列的方式,可以即时的监测靶板不同位置的温升,进而获得引出离子束或中性束的功率密度分布。在HL-3装置二号中性束注入束线上,量热靶的设计采用了一种利用直线推杆机构实现升降,并采用“W”字型靶板结构实现中性束能量的吸收。此外,利用Ansys Workbench的流体计算模块对量热靶在满功率运行状态下的温度分布做了模拟计算,结果显示量热靶的设计满足二号中性束注入束线的使用要求。

  • On the accuracy and efficiency of the reactor operation digital twin for parameter identification and state estimation

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-08

    摘要: Accurate and efficient online parameter identification and state estimation are crucial for leveraging Digital Twin simulations to optimize the operation of near-carbon-free nuclear energy systems. In previous studies, we developed a reactor operation digital twin (RODT). However, non-differentiabilities and discontinuities arise when employing machine-learning-based surrogate forward models, challenging traditional gradient-based in verse methods and their variants. This study investigated deterministic and metaheuristic algorithms and developed hybrid algorithms to address these issues. An efficient modular RODT software framework that incorpo rates these methods into its post-evaluation module is presented for comprehensive comparison. The methods were rigorously assessed based on convergence profiles, stability with respect to noise, and computational performance. The numerical results show that the hybrid KNNLHS algorithm excels in real-time online applications, balancing accuracy and efficiency with a prediction error rate of only 1% and processing times of less than 0.1 s. Contrastingly, algorithms such as FSA, DE, and ADE, although slightly slower (approximately 1 s), demonstrated higher accuracy with a 0.3% relative L2 error, which advances RODT methodologies to harness machine learning and system modeling for improved reactor monitoring, systematic diagnosis of off-normal events, and lifetime management strategies. The developed modular software and novel optimization methods presented offer pathways to realize the full potential of RODT for transforming energy engineering practices. 

  • 高放废液贮存厂房的系统与布置设计

    分类: 核科学技术 >> 核科学与技术 提交时间: 2024-05-08

    摘要: 高放废液贮存厂房是乏燃料后处理厂中必不可少的重要设施,其稳定运行关系到整个厂区的生产安全。文章依据设计标准并结合工程实践,阐述了高放废液贮存厂房的工艺系统设计,包括高放废液贮存及输送系统、循环冷却水系统、高放废液搅拌系统、工艺尾气处理及贮槽稀释空气系统等等。以实际工程项目为例,介绍了高放废液贮存厂房的整体布置形式、工艺设备及管道的布置特点,可为后续高放废液贮存厂房的设计及其他核化工项目的设计工作提供借鉴和参考。

  • Efficient and selective removal of Pb(II) from landfill leachate using L-serine-modified polyethylene/polypropylene nonwoven fabric synthesized via radiation grafting technique

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-05-08

    摘要: In this study, to efficiently remove Pb(II) from aqueous environments, a novel L-serine-modified polyethylene/polypropylene nonwoven fabric sorbent (NWF-serine) was fabricated through the radiation grafting of glycidyl methacrylate and subsequent L-serine modification. The effect of the absorbed dose was investigated in the range of 5–50 kGy. NWF-serine was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Batch adsorption tests were conducted to investigate the influences of pH, adsorption time, temperature, initial concentration, and sorbent dosage on the Pb(II) adsorption performance of NWF-serine. The results indicated that Pb(II) adsorption onto NWF-serine was an endothermic process, following the pseudo-second-order kinetic model and Langmuir isotherm model. The saturated adsorption capacity was 198.1 mg/g. NWF-serine exhibited Pb(II) removal rates of 99.8% for aqueous solutions with initial concentrations of 100 mg/L and 82.1% for landfill leachate containing competitive metal ions such as Cd, Cu, Ni, Mn, and Zn. Furthermore, NWF-serine maintained 86% of its Pb(II) uptake after five use cycles. The coordination of the carboxyl and amino groups with Pb(II) was confirmed using X-ray photoelectron spectroscopy and extended X-ray absorption fine structure analysis.

  • 重离子辐照CMOS图像传感器导致的永久损伤效应

    分类: 物理学 >> 核物理学 提交时间: 2024-05-08

    摘要: 互补型金属氧化物半导体(Complementary Metal Oxide Semiconductor, CMOS)图像传感器有着体积小,质量轻,功耗低,高集成度等特点正逐步取代CCD图像传感器,在空间辐射环境中有着质子,重粒子,γ射线,电子等大量的高能粒子,CMOS图像传感器会受到重离子的辐射效应并对其有着永久损伤的影响。本文主要是针对CMV4000在重离子辐照下的永久损伤机制。CMV4000在经过重离子辐照过后其图像有着明显的热像素(暗电流尖峰高于其他像素暗电流尖峰数倍通常表现为该像素的灰度值是其他正常像素的数倍),在下一帧图像以及后续图像中热像素也并不会消失,因此热像素并不是暂时的。本文还将考虑 CMOS图像传感器在辐照前后各像参数的对比并揭示各项参数的退化机理。

  • Fe-Cr合金界面氦掺杂的第一性原理研究

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-05-08

    摘要: Fe-Cr合金作为聚变反应堆候选材料中低活化铁素体钢(马氏体钢)的主体成分,在实际工况下,聚变反应产生的氦会进入材料中,产生微观缺陷,从而引起辐照损伤,影响材料的抗辐照能力及其他物理化学性能。本文通过第一性原理计算,模拟得出反应堆主体材料Fe-Cr合金的界面,并在不同的间隙位置和替代位置掺杂He原子,结构优化后计算形成能,得出He原子在不同位置的稳定性。与此同时,通过对体积的计算得出He在靠近界面的Fe八面体间隙位时会引起较大的晶格畸变,这是He、Fe、Cr三种原子在特定位置相互杂化影响的结果。

  • 超细X射线密度测井仪器优化设计与测量验证

    分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2024-05-07

    摘要: 随着油气开采的深入,作为新一代可控源,X射线密度测井仪器设计和测量方法的研究受到广泛关注。以超细伽马仪器为原型,将伽马源更改为X射线源,具体内容包括:1)X射线源能谱模拟匹配;2)通过探测效率、地层灵敏度、探测深度等指标综合指导仪器关键参数正向设计;3)基于多变量正反演方法开展X射线密度测量,并与伽马测井进行对比。结果显示:X射线仪器的近、远探测器源距设置为110mm和290mm时可达到比伽马仪器更高的探测指标。相较于伽马测井,X射线测井具有更佳的地层灵敏度、垂直分辨率和地层测量准度。地层密度和Pe分别满足0.015g/cm3和0.2b/e以内,尤其在重泥饼场景中,Pe测量准度提升了47%。这些研究为仪器正向设计以及X射线密度测量提供了参考。

  • 基于流固耦合的蒸汽发生器传热管结构应力分析

    分类: 核科学技术 >> 核科学与技术 提交时间: 2024-05-07

    摘要: 蒸汽发生器传热管是压水堆核电站一回路的关键压力边界,正常运行及事故条件下的系统运行参数,直接影响着传热管结构的完整性。为进一步对传热管的结构响应特性进行研究,建立了两种主流排列方式的传热管局部模型,并分别进行了正常运行和典型事故参数下的流固耦合计算和对比分析,获得了一、二次侧流体共同作用下的传热管关键部位的载荷变化规律。结果表明,在相同的流动条件下,传热管叉排模型的应力和变形均大于顺排模型;传热管根部横截面的等效应力沿壁厚方向先减小再增大,中部横截面的等效应力沿壁厚方向呈现近似线性降低;在传热管根部区域,内、外壁面的等效应力沿轴向高度先迅速降低而后快速升高,并形成应力平台。

  • 基于碎片云运动模型的缓发γ射线电离大气蒙特卡罗模拟

    分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-05-07

    摘要: 高空核爆炸碎片云释放出的缓发γ射线在高空非均匀大气的输运过程中电离大气,使得电离层中电子数密度剧增,进而影响途径电离层的无线电通信链路。为了准确描述随时空演化的缓发γ射线源电离大气过程,首先建立高空核爆炸碎片运动演化的流体力学模型,然后根据碎片云运动参数建立缓发γ射线分层等效体源模型,最后采用蒙特卡罗方法模拟缓发γ射线在高空大气中输运并电离大气的过程。针对碎片云形状随时间不断演化特性,采用辐射源分层抽样的方法得到缓发γ射线的初始位置。针对大气密度随高度指数衰减的特性,采用质量厚度抽样方法简化计算模型。结果表明:碎片云形状对缓发γ射线电离大气范围和强度存在明显影响。兆吨级高空核爆炸缓发γ射线电离大气范围可达千公里以上。当爆高不变当量增加时,碎片云高度和水平半径增大,缓发γ射线电离大气范围和强度有所增大。当当量不变爆高增加时,碎片云高度和水平半径增大,缓发γ射线电离大气范围增大,但强度有所降低。

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