您选择的条件: 2024-05-08
  • 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。

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