Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-07-25
Abstract：池式研究性反应堆是当前全球多用途研究堆中的重点堆型，因其在安全特性、多用途性和运行维护等方面的突出表现而备受关注。在池式堆中，热功率为1-10MW的小型研究堆方案设计最为成熟，应用场景最为广泛。根据开展RERTR（Reduced Enrichment Research and Test Reactor）低浓化项目并进行堆芯重新设计的全球小型池式研究堆所属不同燃料类型进行区分，介绍了基于 氧化铀、铀铝 、铀硅 、 铀钼合金和 UZrH五种燃料的全球在建和在役的小型池式研究堆重点案例。通过横向对比探究分析得出：未来小型池式研究堆采用紧凑型堆芯设计，高密度低浓铀为燃料，以紧凑可移动式小堆芯为基础，以大水池内中子源应用设施为主体的发展方向。
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-07-23
Abstract： [Background]: The criticality assembly is a device with sufficient fissile materials to maintain the self-sustaining chain fission reactions in a controlled way at low power without cooling system, which is widely used in a variety of reactor physics experiments and measurement methods. The neutron source system is an important system equipment of the criticality assembly. When starting up, the neutron source is transported from the shielding tank to the designated position of the core, and a certain number of neutrons are injected into the core continuously, so that the core can maintain a certain number of fission neutrons in the subcriticality state and play the role of "ignition". At the beginning of start-up, the neutron fluence rate in the core is low and cannot reach the source range of detectors. The method of introducing a neutron source into the core is usually adopted to raise the neutron fluence rate to a high enough level before the reactor reaches the criticality state, so that detectors can better monitor the core state and eliminate monitoring blind spots. [Purpose]: The design and development of this neutron source system were based on years of practical experience operating criticality assemblies and utilizing neutron sources. The system serves two primary functions: providing storage and shielding for the neutron source, as well as ensuring its safe transportation between the shield tank and designated location. [Methods]: The components of this neutron source system include shielding tank, connecting structure, neutron source drive with position monitoring, transportation pipeline, pressure detection device, etc., It can reliably enable the neutron source to move smoothly back and forth between the designated positions in the shielded vessel and the core. Real-time fault detection can be achieved through pressure sensors monitoring wire rope tension changes. Additionally, encoder feedback allows real-time positioning determination while terminal switches signal motor stoppage upon reaching specified positions. Prior to official use, tests using both dummy neutron source resembling actual size/mass characteristics and neutron source were conducted，which including motion tests (up/down), wire rope breakage assessment, accessibility checks along with shielding performance measurements inside tanks and pressure value testing. [Results] After multiple rounds of test which included over one thousand back-and-forth movements during more than one hundred experiments on criticality assembly - it has been verified that this system displays real-time positioning accuracy within ±2mm tolerance limits while maintaining normal functionality for upper/lower terminal switches post-installation. Furthermore，the total dose rate requirements for both gamma rays/neutrons ≤10μSv/h have been met by these systems after installation. This comprehensive validation proves once again that our designed scheme offers simple operation procedures alongside high reliability/repeatability levels; rapid troubleshooting capabilities further enhance its practical value. [Conclusions]: This paper gives full consideration to the design of the neutron source system of the criticality assembly, and focuses on optimizing the installation time of the neutron source and solving the problems of the source blockage. The design scheme of the system can be applied to some similar scenarios in industry, such as the transportation of radioactive items (radioactive sources, small spent fuel assemblies), and effectively solve the problem that radioactive items can not be found in time when they fall/get stuck in the pipeline.
Subjects: Chemistry >> Nuclear Chemistry submitted time 2024-07-22
Abstract： Technetium plays an important role in the vitrification of high level radioactive waste (HLW) and the geological disposal of high level radioactive waste (HLW) in the latter part of the nuclear fuel cycle. In this work, an optimized process for extracting technetium from post-treatment nitric acid medium with NTAamide (C8) as extractant was proposed.Based on the principle of NIAamide (C8) to extract technetium, reverse stem technetium ammonium carbonate and oxalic acid to wash impurity ions, a process for extracting and purifying technetium from post-treatment tailings was designed. The results show that the recovery of technetium is 99.9%, and the purification coefficients of Sr, Cs, Zr and Naphthalene in technetium are 6.9×103, 7.9×104, 4.3×102 and 45 respectively.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-07-19
Abstract： [Background]: Uranium-molybdenum (U-Mo) alloy, which is applied in the heat-pipe cooled reactor (referred to as heat-pipe reactor), has the advantages of high thermal conductivity, high density of uranium and excellent irradiation performance. At the same time, U-Mo alloy as a metal material has significantly thermal expansion and irradiation swelling. And the high temperature will aggravate the irradiation swelling of U-Mo alloy and reduce the performance of the material. Hence research on swelling under high temperature of U-Mo alloy is essential in the design of this fuel. [Purpose]: The aim of this study is to comprehensively evaluate the effect of fuel swelling under high temperature of U-Mo alloy on reactor core structure. [Methods]: First, based on the irradiation data of U-Mo alloy under high temperature, a new type of swelling model considering the effect of high temperature was established. Second, a three-dimensional (3D) thermal-mechanical coupling analysis model of U-Mo alloy fuel had been set up with the use of finite element analysis (FEA) software COMSOL Multiphysics (referred to as COMSOL). Third, in order to verify the validity of the 3D FEA model, a thermal-mechanical coupling analysis was carried out considering the thermal expansion effect. The comparison and analysis with other research results showed that the thermal-mechanical coupling analysis by using COMSOL was reasonable and feasible. Then, this model was used to study the fuel swelling effect of reactor core by considering the irradiation swelling of U-Mo alloy at high temperature. The stress and deformation analysis under different burnup were carried out to evaluate the effect of fuel swelling on the core structural stability. [Results]: Under steady-state operating conditions, the core fuel of 1 kWe Kilopower heat-pipe reactor has a large deformation at the end of life (EOL) due to thermal expansion and irradiation swelling, and the maximum deformation reaches 5.28 mm. The maximum stress caused by deformation is 57.4 MPa, which is concentrated on the wall where the heat pipe is connected to the core fuel. Thermal expansion is the main factor that causes stress and deformation of fuel. As the burnup continues to deepen, the irradiation swelling of U-Mo alloy at high temperature leads to greater deformation and greater stress of the fuel. The maximum deformation of the fuel is 6.63 mm when the burnup is 0.4%, which increases by 1.69 mm compared with the calculation results considering only thermal expansion. The maximum core fuel stress reaches 85.1 MPa, which is close to the yield limit of U-Mo alloy. And the stability of fuel structure may be threatened. [Conclusions]: The results indicate that the swelling effect of U-Mo alloy at high temperature leads to more severe deformation and greater stress on the fuel. The influence of thermal expansion and irradiation swelling on the structural stability of the core at high temperature and high burnup needs to be considered in reactor fuel design. In addition, it is necessary to accelerate the irradiation test of U-Mo alloy at high temperature to optimize the irradiation behavior model.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-07-17
Abstract： The mixing wing plays an important role in reducing the hot spot factor of the reactor core, but there is currently limited research on the influence of the fine structure of the mixing wing on the flow field. In order to gain a deeper understanding of the influence of the characteristics of the mixing wing structure on the thermal and hydraulic performance of the reactor core, a study was conducted on the correlation between the mixing wing structure and the flow field. Firstly, through geometric automation configuration and calculation technology, parameterized and automated construction of a tearing type mixing wing structure and CFD calculation are achieved. Secondly, through orthogonal design and simulation analysis of the parameters of the mixing wing structure, the influence of the mixing wing structure on thermal parameters such as flow field pressure drop and cross flow velocity was clarified. Under the geometric structure of the article, the maximum difference in outlet pressure between different mixing wings is 1.1 kPa, which is 41% of the average pressure drop in the entire computational fluid domain. The maximum difference in cross flow velocity under different mixing wings is 1.1 m/s, which is 173% of the average cross flow velocity. The angle of the mixing wing is strongly correlated with the flow field, followed by the shape and length of the mixing wing, and a better mixing wing has been designed. Provide design basis for subsequent research and engineering application of mixing wing structures.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-07-09
Abstract： Currently ，Uranium molybdenum alloy (U-Mo) is a very popular fuel used in research reactors, space reactors, and small reactors for special purposes. During the irradiation process, the microstructure of the U-Mo fuel will undergo a series of changes, which may affect the fuel performance during reactor operation. These changes mainly include ：the formation of the interaction layer between the U-Mo fuel core and the matrix, the release of fission products (mainly the release of fission gas), and the refinement of the grain size for U-Mo fuel with high burnup. This article summarizes the main characteristics of the above changes and the latest research progress for them. At the same time, it also proposed the development trends in the study of microstructural changes after fuel irradiation in today's world where advanced detection technology has made significant progress.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-06-26
Abstract：在磁性样品环境下小角中子散射谱仪使用非极化中子束能够定量分析样品磁性微结构。本文报道用在CARR堆导管大厅小角中子散射谱仪（SANS）上的磁性样品环境装置的组成、特征和首次实验。该磁性样品环境装置主要由3.00T的电磁铁、高精度电源、支撑台，冷却系统和微机控制系统构成。磁性样品环境装置的主要特征是：磁场均匀；电磁铁的支撑台高度可调；样品位置的气隙在120 mm内可调；样品支架可以旋转，且其高度可调。最后，本文展现在CARR堆小角中子散射谱仪磁性样品环境下测量17-4PH不锈钢纳米析出相的实验结果。这个实验结果标志这套磁性样品环境装置运行正常，满足对小角中子散射用户开放的条件。
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-06-17
Abstract： [Background]: The criticality assembly is a device with sufficient fissile materials to maintain the self-sustaining chain fission reactions in a controlled way at low power without cooling system, which is widely used in a variety of reactor physics experiments and measurement methods. The neutron source system is an important system equipment of the criticality assembly. When starting up, the neutron source is transported from the shielding tank to the designated position of the core, and a certain number of neutrons are injected into the core continuously, so that the core can maintain a certain number of fission neutrons in the subcriticality state and play the role of "ignition". At the beginning of start-up, the neutron fluence rate in the core is low and cannot reach the source range of detectors. The method of introducing a neutron source into the core is usually adopted to raise the neutron fluence rate to a high enough level before the reactor reaches the criticality state, so that detectors can better monitor the core state and eliminate monitoring blind spots. [Purpose]: The design and development of this neutron source system were based on years of practical experience operating criticality assemblies and utilizing neutron sources. The system serves two primary functions: providing storage and shielding for the neutron source, as well as ensuring its safe transportation between the shield tank and designated location. [Methods]: The components of this neutron source system include shielding tank, connecting structure, neutron source drive with position monitoring, transportation pipeline, pressure detection device, etc., It can reliably enable the neutron source to move smoothly back and forth between the designated positions in the shielded vessel and the core. Real-time fault detection can be achieved through pressure sensors monitoring wire rope tension changes. Additionally, encoder feedback allows real-time positioning determination while terminal switches signal motor stoppage upon reaching specified positions. Prior to official use, tests using both dummy neutron source resembling actual size/mass characteristics and neutron source were conducted，which including motion tests (up/down), wire rope breakage assessment, accessibility checks along with shielding performance measurements inside tanks and pressure value testing. [Results] After multiple rounds of test which included over one thousand back-and-forth movements during more than one hundred experiments on criticality assembly - it has been verified that this system displays real-time positioning accuracy within ±2mm tolerance limits while maintaining normal functionality for upper/lower terminal switches post-installation. Furthermore，the total dose rate requirements for both gamma rays/neutrons ≤10μSv/h have been met by these systems after installation. This comprehensive validation proves once again that our designed scheme offers simple operation procedures alongside high reliability/repeatability levels; rapid troubleshooting capabilities further enhance its practical value. [Conclusions]: This paper gives full consideration to the design of the neutron source system of the criticality assembly, and focuses on optimizing the installation time of the neutron source and solving the problems of the source blockage. The design scheme of the system can be applied to some similar scenarios in industry, such as the transportation of radioactive items (radioactive sources, small spent fuel assemblies), and effectively solve the problem that radioactive items can not be found in time when they fall/get stuck in the pipeline.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-05-20
Abstract： Electron beam irradiation has become an important part of the nuclear application industry. Low energy electron beam has been increasingly used in waste water treatment and food preservation, and the measurement parameters of irradiation are crucial to the irradiation quality. Since the relevant standards of electron beam dosimetry below 300keV have not been established, the parameter measurements are traced to the 10MeV electron linear accelerator, and the inconsistency of the measurement objects brings systematic bias. In this paper, for the low energy electrons below 300keV, the method of electron beam energy measurement is studied by combining test and simulation calculation, and the absorption dose measuring device based on calorimetry is developed. The relationship between absorbed dose and beam intensity, displacement velocity and other parameters is investigated. The results show that the energy parameters of low energy electrons are measured by the step stacking dose experiment combined with the energy deposition curve simulation, and the absorbed dose parameters of low energy electrons are measured by calorimetry. The measurement uncertainty is 11% (k=2). This study provides a reliable measurement guarantee for low-energy electron beam irradiation technology.
Subjects: Nuclear Science and Technology >> Nuclear Materials and Techniques submitted time 2024-04-20
Abstract： After decades of research, the problems and behavior of the corrosion of reactor alloy materials are well known. However, some problems in corrosion of reactor materials have not been clarified, including the critical corrosion process of the reactor materials under operational conditions, the role of a single factor in the corrosion process, and the prediction of corrosion behaviors of new materials in extreme environments. The density functional theory, which is based on quantum mechanics, can accurately predict the motion process of atoms and the change in the relevant energy within a very short period. The density functional theory has become an important auxiliary method for investigating the corrosion process of reactor alloy materials in recent years and can help solve the above problems. In this paper, two parts are reviewed. The first part introduces the density functional theory and includes the theoretical basis, development process, and mainstream computing software. In the second part, the research status of the density functional theory in the corrosion of reactor alloy materials is reviewed, including the adsorption, separation, combination, and internal diffusion of the reactor alloy material surfaces in the environments of water-cooled reactor, liquid-metal-cooled reactor, and molten salt reactor.
Subjects: Physics >> Nuclear Physics submitted time 2024-03-11
Abstract： Fusion triple product represents a crucial parameter for evaluating the potential of self-sustained fusion nuclear reactions. It employs the product of three physical properties: the fuel nuclei number density ($n$), plasma confinement time ($τ_ mathrm{E}$) and fuel temperature ($T$) to establish a condition for assessing the feasibility of achieving self-sustained nuclear fusion. This study considers a fusion reaction system using $^{6}$Li-D as nuclear fuel, neglects cyclotron radiation, incorporates the impact of relativistic effects on bremsstrahlung radiation and the impact of recycled energy on the energy gain factor $Q$. Based on this foundation, the minimum triple product ($n_ mathrm{i}Tτ_ mathrm{E}$= SI{4.9e23}{ per cubic meter kilo electronvolt second}) is calculated for the $^{6}$Li-D reaction to yield energy gain of Q=1. These results show that although the $^{6}$Li-D fusion reaction can achieve a positive energy gain but the condition required for the $^6$Li-D fusion reaction is more difficult than the D-T fusion reaction.
Subjects: Physics >> Nuclear Physics submitted time 2024-02-16
LIU Yinshen
YANG Xiaofei
ZHANG Peng
HU Hanrui
BAI Shiwei
WANG Shujing
LIU Yongchao
GUO Yangfan
LIN Zheyang
YAN Zhou
MEI Wencon
CHEN Shaojie
NI Xinyue
XIE Bingqi
YE Yanlin
LI Qite
LI Hongwei
HE Chuangye
YANG Jie
LIU Zuoye
Abstract： The basic properties of atomic nuclei including spins, magnetic moments, electric quadrupole moments and charge radii, are sensitive probes to different aspects of exotic nuclear structure, and are also important to investigate the unrevealed nature of interaction between nucleons. Based on multidiscipline, laser spectroscopy is a unique tool to precisely measure the basic nuclear properties mentioned above in a nuclear-model independent way by measuring the hyperfine structure of atoms, ions, or molecules, which has played an important role in the study of exotic nuclear structures across the different regions of the nuclear chart. Basic principles of laser spectroscopy and various types of experimental devices are expounded after the brief history of the hyperfine structure. Furthermore, advantages of utilizing laser spectroscopy in the study of nuclear structure are briefly introduced by taking the radioactive neutron-deficient Pb region as an illustration. In addition, current condition of collinear laser spectroscopy setup has been systematically reviewed, together with the latest progress on collinear resonance ionization spectroscopy offline devices at Peking University. Finally, the developing status and ongoing plan of laser spectroscopy devices for current and future radioactive ion beam facilities in China have been put forward, and the broad prospects of laser spectroscopy in unstable nuclear properties and the fundamental symmetries based on molecular spectroscopy are interpreted.
Subjects: Physics >> Nuclear Physics submitted time 2024-02-04
Abstract： The nuclear reaction at energies near the Coulomb barrier is an effective way to study the interaction between nuclear structure and dynamics. As more exotic weakly bound nuclei become accessible at new accelerator facilities, it is becoming critically important to understand the influence of weak binding energy on reaction dynamics, including on fusion. At present, a large number of experiments have shown that the complete fusion cross section between stable weakly bound nuclei such as 6,7Li, 9Be and heavy mass target nuclei is suppressed about 30% lower than the fusion cross section calculated by existing theoretical models and the fusion cross section derived from tightly bound nuclear systems. In order to investigate the breakup effect of weakly bound nuclei on the suppression of the complete fusion cross section, studying the breakup reaction and mechanism of weakly bound nuclei has become concerned. This article introduces the recent work on breakup of weakly bound nuclei, including the research of our group.
Subjects: Physics >> Nuclear Physics submitted time 2024-01-12
Abstract： Due to the difficulties of the direct measurement of unstable nuclei neutron capture cross section, the surrogate ratio method had been proved valid in (n, γ) determination. The difference of the spin-parity distribution in compound nuclei that formed by surrogate reaction or neutron capture was discussed in this work. The γ-decay probabilities ratio of 92Zr* and 94Zr* were calculated in various spin-parities up to 8 with TALYS code, and the calculation shows the ratio is insensitive to their spin-parity distribution in high incident neutron energies. The measured γ-decay probabilities ratios of 92Zr* and 94Zr* were compared to the theoretical calculations, it imply that the spin-parity distributions of compound nuclei formed by (18O, 16O) reactions are similar to the one formed by neutron captures.
Subjects: Physics >> Nuclear Physics submitted time 2024-01-09
J. Hu
Z.Y. Han
Y.J. Li
Z.H. Li
G. Lian
Y.P. Shen
S.Q. Yan
S. Zeng
B. Guo
W.P. Liu
Z. Bai
B.L. Jia
S.L. Jin
J.B. Ma
P. Ma
S.B. Ma
S.W. Xu
Y.Y. Yang
N.T. Zhang
X.D. Tang
Abstract： In Orgueil meteorites, an exceptionally high 22Ne/20Ne abundance ratio or even nearly pure 22Ne is ob#2;served, which is the so-called Ne extraordinary problem. Fossil material of extinct 22Na is believed to be the origin of extraordinary 22Ne, these 22Na nuclides were trapped in grains and incorporated into meteorites in stellar explo#2;sive event. Supernovae and neon-rich novae are the primary events, which are responsible for the production of 22Na through the explosive hydrogen burning process. 22Na(p, γ)23Mg and 19Ne(α, p) 22Na are two crucial reactions in the so-called NeNa-MgAl cycle and the rapid-proton process, which lead to the fast nucleosynthesis up to A=100 nuclide region and the outburst of novae and X-ray bursters. Since many proton resonance levels in odd-A compound nucleus 23Mg may be involved at nova temperature, existing measurements can only provide partial effective information on the 22Na(p, γ)23Mg reaction. Large uncertainties still exist in the astrophysical reaction rates of the two reactions at present. Thick target inverse kinematics method is a very effective way to scan the 23Mg proton resonance levels re#2;lated to the 22Na(p, γ)23Mg reaction via the excitation function of 22Na(p, p) elastic scattering, which could be obtained over a large energy range in one-shot measurement with low-intensity radioactive 22Na beam. In the present work, 22Na+p resonance scattering via thick target inverse kinematics was studied at RIBLL1 radioactive beam line in the HIRFL national laboratory at Lanzhou. A high-purity 22Na beam with an intensity of about 2 × 105 pps was produced via the 1H(22Ne,22Na)n reaction with an alcohol-cooled hydrogen gas target. Time-of-Flight by two plastic scintillator detectors and two parallel-plate avalanche counters were used to monitor the 22Na secondary beam before reaching the (CH2 )n target. The timing information is useful for beam particle identification and the position information is essen#2;tial for 22Na(p,p) elastic scattering kinematics reconstruction. Light recoil particles from 22Na+p reaction system were detected by two sets of double-sided silicon strip detector telescopes centered at 𝜃lab = 0° and 14°, respectively, while the heavy recoil particles were stopped in the (CH2 )n thick target. Two-body kinematics reconstruction of 22Na(p,p) elastic scattering is performed on the event-by-event basis, and an excitation function of 22Na(p,p) is obtained in the energy range of 𝐸c.m. = 1.5 to 4 MeV. Obvious proton resonance structure is observed in the 23Mg compound nucleus, which will be further analyzed with R-matrix nuclear theoretical model.
Subjects: Physics >> Nuclear Physics submitted time 2023-12-24
HE Ziyang
WU Xiaoguang
JIANG Wei
LI Congbo
ZHOU Zhenxiang
SUN Qi
GUO Mingwei
WU Hongyi
LI Zhihuan
FAN Ruirui
TANG Jingyu
LI Tianxiao
HU Shouyang
ZHI Yu
SONG Jinxing
LI Peiyu
LUAN Guangyuan
ZHANG Qiwei
WANG Zhaohui
CHEN Xiongjun
Abstract： Isomer with long lifetime and high excitation energy has great significant in the fields of national strategic security and energy storage. Mastering the method of inducing isomer to decay is the key technology. However, this technology has got into trouble in recent years. For mastering the method of inducing isomer to decay, it is beneficial to start the research on the formation, excitation and de-excitation mechanism of isomer from the view of atomic nucleus structure. In terms of experimental technology, we use the white light neutron beams to bombard Hf target. We established a triple coincidence measurement system, whcih consisted of GTAF-II and HPGE, combined with white light neutron time of flight. Through the analysis of experimental data, we found the sign of the $^{178}$Hf isomeric state exciting to the transition level and releasing rapidly.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2023-12-18
Abstract： Gallium oxide, a wide band gap semiconductor, is a focus material in the semiconductor field at present. However, the conventional doping process has not achieved its p-type doping on bulk crystals, which hinders its application. Proton irradiation transmutation doping is realized by using the transmutation products produced by the nuclear reaction between high-energy protons and target materials. Many transmutation products have different doping effects, and it is expected to achieve P-type doping of gallium oxide based on Coulomb coupling effect of various doping elements. In this paper, the transmutation doping of gallium oxide irradiated by 100MeV protons is simulated and analyzed by using the Monte Carlo software FLUKA of ion reaction. The results show that after 100 cooling days after irradiation, the activation activity decreases by about four orders of magnitude, and the element concentration of transmutation products tends to be stable. The analysis of element concentrations of transmutation products with different doping types shows that proton irradiation transmutation can generate net P-type doping. The net P-type doping concentration is different at different depths of the target material. It is the largest at the depth of 0.6-0.9cm, which can reach 4.26×10^{14}cm^{-3} per 10^{16}cm^{-2} irradiation fluence. Compared with the doping of 40MeV proton irradiation and neutron irradiation, 100MeV proton irradiation transmutation doping efficiency is higher.
Peer Review Status:
Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2023-12-06
LI Yun-qiu
LI Cong-bo
ZHENG Yun
LI Tian-xiao
WU Xiao-guang
HONG Rui
WU Hong-yi
ZHENG Min
ZHAO Zi-hao
HE Zi-yang
LI Jin-ze
LI Guang-shun
GUO Cheng-yu
NI Lei
ZHOU Zhen-xiang
HE Chuang-ye
LIU Fu-long
ZHOU Xiao-hong
LIU Min-liang
ZHANG Yu-hu
Abstract： High spin states of 94Nb have been studied with the 82Se(18O, p5n)94Nb fusion evaporation reaction at anincident beam energy of 82and 88 MeV. The level scheme of 94Nbhas been modified and extended with 15 newγrays. Based on γ-γcoincidence relationships，DCO ratios and linear polarization measurements, the new level structures in 94Nb have been interpreted in terms of the shell model calculations performed in the configuration space π(1f5/2, 2p3/2, 2p1/2, 1g9/2 ) for the protons and ν(2p1/2, 1g9/2, 1g7/2, 2d5/2 ) for the neutrons.
Peer Review Status:Awaiting Review
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2023-11-17
Abstract： The diamond-like carbon (DLC) stripper foils with ~5 μg/cm2 in thickness were produced by using the composite technology of the filtered cathodic vacuum arc (FCVA)- alternating current carbon arc (ACCA)-relaxation technique. The uniformity of the DLC foils were measured by the XP2U balance. The results show that the maximum inhomongeneity of DLC foils in the range of Φ100mm is 8.82%. The microstructure of the DLC foils were measured by the scanning electron microscopy (SEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The SEM images show that the DLC foils are smooth, and contain hardly droplets through the double 90° filters. The Raman spectrum indicates that the DLC foils are amorphous carbon films. The X-ray photoelectron spectrum indicates the sp3 bonds of the DLC foils exceed 70%. The irradiation lifetimes of the DLC stripper foils were tested and compared with the heavy ion beams at the Beijing HI-13 Tandem Accelerator. The results indicate that the lifetime of the DLC stripper foils after relaxation is ~3 times of the DLC stripper foils before relaxation. The lifetime of DLC stripper foil is respectively 4 and 13 times of the carbon stripper foil for the 197Au- and 63Cu- ion beams (~9 Mv, ~1 μA). The lifetime of DLC stripper foil is 2.6-10 times of the carbon stripper foil for the 107Ag-、70Ge-、48Ti-、28Si- and 127I-ion beams. The heavier ions and the stronger beam current, the longer lifetime of DLC stripper foil is compared with that of carbon stripper foil. The lifetime of the DLC stripper foils is related to the substrate bias voltage, and increases at first and then decreases with the increasing of the substrate bias voltage. The lifetime reaches the peak value when the substrate bias voltage is -400 V.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2023-08-08
Abstract： Abstract：The testing equipment for boron aluminum alloy neutron absorption materials in spent fuel pool grid of nuclear power plant developed by China Institute of Atomic Energy was upgraded and improved, and the integrated data acquisition system, transmission system and control record analysis system were developed. The detection equipment can be used for multi-point measurement of samples of different sizes. The detection device has the characteristics of continuous, fast, and full area detection, with two modes: fixed point detection and mobile detection. Completed 20cm × 30cm hanging sample, 373cm × 19.5cm long board, 6cm × 6cm square template and Φ 5cm × 0.3cm circular sample plate have been tested and the detection results have been analyzed. The neutron absorption performance testing equipment for boron aluminum alloy materials lays the foundation for conducting non-destructive testing research on domestically produced boron containing neutron absorption materials, and provides strong support for critical safety monitoring of spent fuel pools in nuclear power plants.
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