Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-06-07
Abstract： 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。
Peer Review Status:
Awaiting Review
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-06-07
Abstract： Computational Fluid Dynamics (CFD) technology can be used for nuclear reactor core to understand and predict the fine thermal-hydraulic status, to obtain the optimizing design and operation, and improve the safety. However, CFD analysis of reactor core faces challenges such as difficulty in modelling huge amount of meshes, large amount of calculations, time consuming and resource requirements, etc. Moreover, the universality of CFD technology for reactor types is poor so that it requires the whole analysis process again when the reactor type is changed. Based on the characteristics of reactor structure and coolant flow feature, this paper develops a CFD supporting technology that is "specific" to the reactor core and "common" to different reactor types, which can decompose the CFD computing burden and effectively reduce the fine mesh modelling and calculation analysis. It has been successfully applied to the CFD analysis of the reactor cores with full number and whole height of fuel assemblies, such as the reactor core with wire-wound rod bundle assemblies, spacer grid rod bundle assemblies and plate element assemblies.
Subjects: Nuclear Science and Technology >> Other Disciplines of Nuclear Science submitted time 2024-06-06
Abstract： In order to mitigate climate warming and achieve the 3060 goal, the state optimizes the industrial and energy structure. The efficient and clean utilization of coal is promoted and new energy is vigorously developed. On the premise of ensuring safety, nuclear power is actively and orderly expanded. Compared with traditional fossil energy, nuclear power has the advantage of clean, environmental protection and low consumption. However, the actual thermal efficiency of nuclear power plant is only about 33%. The rest heat is discharged into the environment, resulting in serious waste. Among them, the thermal discharge is discharged into the adjacent sea area and its heat has a thermal impact on the water environment. Therefore, the efficient utilization of thermal discharge residual heat can not only improve the energy utilization rate of nuclear power plants, but also reduce the thermal pollution to the water environment, which is conductive to energy conservation and emission reduction. In this paper, APROS software is used to simulate and analyze a comprehensive system for increasing temperature and production of greenhouse and indoor marine culture by using nuclear residual heat. The possibility of nuclear power and agricultural coupling system is demonstrated, which provides a scientific basis for the comprehensive utilization of nuclear residual heat in China.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-06-06
Abstract： [Background]: Boron Neutron Capture Therapy (BNCT) is a binary radiation therapy with strong targeting and high energy transfer line density at the cellular scale.It has the advantages of short treatment cycle and minimal damage to surrounding healthy tissues,making it a promising cancer treatment method. [Purpose]: This study aims to design beam shaping assembly(BSA)to make the neutron beam of D-Be neutron source suitable for BNCT and ensure neutron directionality. [Methods]: This article uses Monte Carlo simulation programs GEANT4 and FLUKA to simulate the generation of 9Be(d,n)10B reaction neutron sources and subsequent neutron moderation.A feasible scheme design for BSA was carried out using a 1.45 MeV,30 mA deuterium beam to bombard a 9 μm thin beryllium target,and set a basis BSA model with a cylindrical structure as a whole. [Results]: The results show that using a 45 cm thick BiF3 and 5 cm thick TiF3 combined slowing layer,a 12 cm thick Pb reflector layer,an 11 cm thick Al2O3 supplementary slowing layer,and a 0.1 mm thick Cd thermal neutron absorption layer,the outlet is ensured to γ and fast neutron composition,Φepi/Φth, Φepi/Φfast meets the recommended values of the IAEA. [Conclusions]: This study obtained the neutron spectra and BSA specific design scheme of low-energy deuterium beams and thin beryllium targets,providing data reference for the slowing shaping of neutrons in D-Be neutron sources and supporting subsequent research on D-Be sources.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-06-05
Abstract： [Background]:The elastic properties of dispersed fuel serve as crucial parameters in the safety analysis of reactors and the performance assessment of fuel components.[Purpose]:This study considers dispersed nuclear fuel elements as a special type of particulate composite material and employs micromechanics methods to calculate the equivalent elastic properties of the fuel element.[Methods]:Using the universal finite element software ABAQUS and user-defined subroutines, assuming the periodic distribution of fuel particles in the core, a finite element calculation model is established. A representative volume element was selected as the research object, and a thermal mechanical fission gas migration coupling analysis method was established to calculate the equivalent elastic performance of the core. [Results]: The equivalent elastic properties of the fuel element were determined. The effects of particle volume content, particle size, and burnup on the equivalent elastic properties of dispersed nuclear fuel were analyzed and compared. [Conclusions]: The results indicate that the main factors influencing the equivalent elastic properties of the fuel element are particle volume and burnup.
Subjects: Nuclear Science and Technology >> Nuclear Detection Technology and Nuclear Electronics submitted time 2024-06-03
Abstract： [Background] As one of the main radionuclides released into the environment by the operation of reactors and accelerators, the measurement of 41Ar activity concentration is of great significance for ensuring public health. In the field of radioactive gas measurement, the β-γ coincidence method is widely used because it can significantly reduce the background and improve the sensitivity of the detector. However, at present, there is little study on β-γ coincidence detectors for 41Ar measurement. [Purpose] In order to realize high sensitivity measurement of 41Ar, a detector composed of plastic scintillator and CsI(Tl) scintillator is designed, and an optimization method of detector structure based on minimum detectable activity concentration (MDC) is proposed. [Methods] The optimization process of the detector is realized based on Geant4 simulation. Firstly, the energy deposition of β-rays in CsI(Tl) with different thicknesses of BC404 was simulated. Secondly, the peak efficiency of 1293.6 keV γ-ray in CsI(Tl) scintillator with different thicknesses was simulated. Thirdly, assuming that the sampling time of argon is proportional to the volume of the detector’s gas chamber, by simulating with different gas chamber volume, the comprehensive effects of β detection efficiency, γ peak efficiency, gas chamber volume and sampling time on MDC were analyzed. Finally, the influence of measurement time on MDC under different background counting rates was analyzed. [Results] It is concluded that the particle number percentage of the energy deposited by 41Ar decay β-rays in CsI(Tl) is about 0.74% when the thickness of BC404 is 3 mm. The γ peak efficiency increases with the increase of CsI(Tl) scintillator thickness. With the argon sampling rate of 600 mL/h, the optimal detector size parameters that minimize MDC are completely determined. When the background count rate is 1×10-3 ~1 cps, the recommended measurement time for 41Ar is about 200 minutes. [Conclusions] When the measurement time is 200 minutes, the sample cooling time is 30 minutes and the background count rate is 5×10-3 cps, the MDC of the optimized β-γ coincidence detector for 41Ar measurement is about 1.7 Bq/m3.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-06-03
Abstract： [Background]: The volume of the nuclear power plant containment is huge, making it difficult to conduct equal-scale or large-scale thermal-hydraulic tests. Currently the test data mainly come from small-scale tests. [Purpose]:To address the applicability of small-scale containment test data in validation process of the containment performance analysis code, the analysis method for applicability of experimental data is proposed and developed on the basis of similarity analysis of the pressure response process in the containment. [Methods]: The applicability study of the test data, which are produced by some scaled containment facilities such as the HDR, Battelle and CVTR, is carried out in combination with the test parameters. The applicability of each test case are obtained respectively when they are applied to validate the containment code in case of the Large Break Loss of Coolant Accident (LBLOCA) and Main Steam Line Break Accident (MSLB) of HPR1000 nuclear power plant. [Results]:The results show that the similarity criteria for pressure response process and key phenomena within the containment vessel under accident conditions can be used to analyze the applicability of different containment tests to the target power plant. [Conclusions]:The proper combination of test cases including HDR ISP-16&23, Battelle CASP-1&2, and CVTR T3 can represent the pressure transient process, results of coupling phenomena such as mass and energy release at the break, condensation near the containment shell and internals, within the HPR1000 containment in case of LOCA or MSLB. The distortion is either within the acceptable range or conservative for design limits of containment pressure, so that the small-scale containment test data are suitable for the verification and validation of the HPR1000 containment thermal hydraulic response analysis code.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-06-02
Abstract：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。
Subjects: Nuclear Science and Technology >> Other Disciplines of Nuclear Science submitted time 2024-05-31
Abstract： 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.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-05-31
Abstract： 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.
Peer Review Status:Awaiting Review
Subjects: Nuclear Science and Technology >> Other Disciplines of Nuclear Science submitted time 2024-05-31
Abstract：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。
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-05-31
Abstract： 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.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-05-30
Abstract： 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 radiation
therapy re-planning for proton therapy. In this study, an improved U-Net neural network named CBAM-U-Net
was 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 images
were registered to CBCT images as ground truth. The original CBCT denoised U-Net network, sCTU-Net, was
trained for model performance comparison. The synthetic CT(SCT) images generated by CBAM-U-Net and the
original 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 of
the 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 range
accuracy was compared for a single-energy proton beam. The γ-index pass rates of a 4 cm × 4 cm scanned
field and simple plan were calculated to compare the effects of the noise reduction capabilities of the original
U-Net and CBAM-U-Net on the dose calculation results. CBAM-U-Net reduced noise more effectively than
sCTU-Net, particularly in high-density tissues. We proposed a CBAM-U-Net model for CBCT noise reduction
in proton therapy. Owing to the excellent noise reduction capabilities of CBAM-U-Net, the proposed model
provided relatively explicit information regarding patient tissues. Moreover, it can be used in dose calculation
and adaptive treatment planning in the future.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-05-30
Abstract： [Background]: The single-phase reversed flow in inverted U-tubes of steam generator (SG) leads to increasing flow resistance and decreasing heat transfer area, so it is meaningful to study this phenomenon. [Purpose]: The water level of the secondary side in SG can influence the single-phase reversed flow, it is necessary to clarify its influence mechanism from a more general viewpoint. [Methods]: The dimensionless conservation equations were derived first, and the extreme point was obtained based on the equations. Then the effect of the water level of the secondary side under conditions of different lengths, dimensionless resistance number, and dimensionless heat transfer number was analyzed. [Results]: The decrease in the water level leads to the critical point of the single-phase reversed flow gradually approaching the origin, the influence law of the water level is the same under different pipe length conditions. As the water level decreases, the influence of the dimensionless resistance number and dimensionless heat transfer number on the critical point gradually reduces. [Conclusions]: This study theoretically proves that the effect of secondary water level on single-phase reversed flow is not conducive to the occurrence of backflow, and explains the reasons from a mechanistic perspective, which can assist in accident analysis of related nuclear power plants.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-05-30
Abstract： 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.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-05-30
Abstract： 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.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-05-29
Abstract： [Background]: CF series fuel assemblies are the key reactor-core components of the advanced third-generation nuclear power, which are independently developed by China National Nuclear Corporation(CNNC). [Purpose]: The purpose is to analyze the friction force and rod drop performance of CF2 fuel assembly combined control rod drive line moving parts in water and air under different eccentricity. [Methods]: a 1:1 simulated fuel assembly was used in the test with an independently-developed rotatable top cap. The integration of multiple eccentric was initially implemented for scientific and accurate regulation. [Results]: The method to study the performance of the driving mechanism was optimized. The friction force and rod drop performance data of the driving mechanism in water and air at different heights and under different eccentric conditions were obtained. The total rod drop time and the time for rod reaching the buffer increased with the increase of eccentricity while the buffer time was basically constant. The fuel assembly and control rod functioned properly under the maximum eccentricity. The friction did not exceed the allowable limit. And no jamming of control rod occurred under large eccentric condition. [Conclusions]: The experimental results provide an important experimental basis for the design optimization , safe evaluation and software development of CF fuel assembly. The method can be extended to the subsequent CF3 and other fuel assembly scientific research projects.
Key words CF2 fuel assembly, Rod Drop Performance, Friction
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-05-28
Abstract： Ion beam radiotherapy is increasingly being used for tumor treatment. Currently, the use of traditional X-ray computed tomography (CT) for treatment planning of ion-beam radiotherapy has significant relative stopping power (RSP) errors. A more ideal approach is to directly use ion beams to generate patient images for treatment planning so as to avoid RSP conversion and reduce RSP errors. In this study, the Monte Carlo program Geent4/Gate was adopted to establish an ion-CT simulation platform, designed two sets of ion CT systems, ideal and real, and reconstructed images using the maximum likelihood method and ASD-POCS algorithm. The effects of the ideal and real settings, multiple energies, and different ion types on the RSP error of phantom reconstruction were investigated. The results show that the relative error of RSP for 330MeV protons in both the ideal and real settings was less than 1.547%, and the RSP reconstruction error in the ideal settings was much smaller than that in the real settings. The RSP reconstruction error of each material under realistic settings is close to three times that under ideal settings. The relative errors of RSP for protons decrease with the increase of incident energy. The relative errors of RSP were the biggest at 230MeV, and were2.855%、2.468%、1.653%、and 2.553% in sulfur, phosphorus, carbon, and calcium materials. The RSP relative error reached its minimum at 330MeV, with 0.181%, 0.351%, 0.250%, and 0.245% in sulfur, phosphorus, carbon, and calcium materials. At energy of 330MeV/u for carbon ions , the RSP relative errors in sulfur, phosphorus, carbon, and calcium materials were 0.060%, 0.281%, 0.150%, and 0.082%, respectively, all within 0.281%. And the RSP relative errors were much smaller than those of protons under the same conditions. Thus, compared with proton CT, carbon ion-beam CT seems more possible to provide accurate RSP data for treatment planning for ion-beam radiotherapy..
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-05-28
Abstract： The search and localization of unknown radioactive sources is an important research topic in the field of nuclear security inspection and nuclear emergency response. In order to improve the source finding efficiency and adapt to the multi-source environment detection, a particle filtering source finding method integrating the angle of arrival is proposed. Firstly, a hardware platform combining autonomous localization and angle-of-arrival sensing is constructed to introduce position and angle information to the detector; secondly, the angle-of-arrival information is taken into account on the basis of particle filtering, which can dynamically shrink the source searching area and improve the searching efficiency; lastly, the angle-of-arrival-guided robot attitude adjustment is adopted in the path planning of the autonomous source searching, which can enhance the flexibility of the robot in searching for the source. Simulation experiments prove that this method can work correctly and effectively, and tests using radioactive sources further verify the practicality of this method for multi-source search.
Subjects: Nuclear Science and Technology >> Nuclear Detection Technology and Nuclear Electronics submitted time 2024-05-27
Abstract： 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.
Peer Review Status:Awaiting Review
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