Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-07-08
Abstract： [Background]Active neutron interrogation (ANI) measurement systems can quantify the fissile mass of special nuclear materials (SNMs) using neutrons and are widely used in nuclear safeguard fields. However, the hydrogen-containing matrix in the waste drum reduces the signal of delayed neutrons and limits the fissile mass measurement precision of the ANI system. [Purpose]It is essential to ensure that the fissile mass evaluation of the SNM is independent of matrix material and to improve the assay performance of the ANI system in nuclear safeguard measurements. [Methods] Therefore, based on the flux monitor response, a new matrix correction method was developed on the basis of traditional correction methods in this work. [Results]It turned out that the effect of various hydrogen densities on the delayed neutron count rate differs. For U3O8 materials with different enrichment and distribution, matrix effect may result in an overestimation of up to ~7 times in the observed mass of 235U. For U3O8 materials with different 235U enrichments and distribution states, both the traditional correction method and the new correction method can effectively reduce the influence of the matrix material on the measurement of SNM mass. But compared with the traditional method, the new method can achieve better correction results. For the case where U3O8 material is located in the center of the matrix, the average relative deviation of 235U mass obtained by the new correction method is 13.6%, while for the case where U3O8 material homogeneous dispersed throughout the matrix, the average relative deviation of 235U mass obtained by the new correction method is 7.78%. [Conclusions]These results confirm the effective performance and practicality of the new correction method.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-07-04
Abstract： Under severe Ocean environment, the liquid level inside the in-vessel pressurizer will fluctuate greatly, threatening the safe operation of the reactor. To study the response characteristics of the liquid level inside the in-vessel pressurizer under severe ocean conditions, the fluctuation forms of the liquid level pressure under various motion forms are analyzed by means of experiments. The results show that the swinging motion affects the pressure signal because the linear distance between the liquid surface and the measuring point changes during the swinging process. The swaying(surging) motion that influence the pressure measurement are derived from the tendency that the fluid will periodically impact the wall and liquid surface due to inertia. The influence of heaving motion on pressure measurement mainly comes from the acceleration change in the vertical direction, which periodically causes the phenomenon of weightlessness.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-06-27
Abstract： [Background]Active neutron interrogation (ANI) measurement systems can quantify the fissile mass of special nuclear materials (SNMs) using neutrons and are widely used in nuclear safeguard fields. However, the hydrogen-containing matrix in the waste drum reduces the signal of delayed neutrons and limits the fissile mass measurement precision of the ANI system. [Purpose]It is essential to ensure that the fissile mass evaluation of the SNM is independent of matrix material and to improve the assay performance of the ANI system in nuclear safeguard measurements. [Methods] Therefore, based on the flux monitor response, a new matrix correction method was developed on the basis of traditional correction methods in this work. [Results]It turned out that the effect of various hydrogen densities on the delayed neutron count rate differs. For U3O8 materials with different enrichment and distribution, matrix effect may result in an overestimation of up to ~7 times in the observed mass of 235U. For U3O8 materials with different 235U enrichments and distribution states, both the traditional correction method and the new correction method can effectively reduce the influence of the matrix material on the measurement of SNM mass. But compared with the traditional method, the new method can achieve better correction results. For the case where U3O8 material is located in the center of the matrix, the average relative deviation of 235U mass obtained by the new correction method is 13.6%, while for the case where U3O8 material homogeneous dispersed throughout the matrix, the average relative deviation of 235U mass obtained by the new correction method is 7.78%. [Conclusions]These results confirm the effective performance and practicality of the new correction method.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-06-23
Abstract： [Background] As a typical representative of passive safety technology, the automatic depressurization system ( ADS ) accelerates the reactor primary loop depressurization after the accident, connects the high-pressure, medium-pressure and low-pressure safety injection systems, and maintains the core cooling. [Purpose] In order to study the opening and closing characteristics of the pressure relief valve of the automatic depressurization system and its influence on the reactor systems. [Methods] Based on the system analysis program, China Advanced Pressurized Water Reactor is taken as the research object, and the typical ADS trigger accident is taken as the initial event. The different opening speeds of the first three valves of ADS and the closing conditions of the fourth pressure relief valve of ADS are simulated, and the response of each system under different working conditions is analyzed. [Results] The results show that, the opening speed of the ADS1-3 valve cannot significantly affect the pressure relief characteristics of the primary loop; the ADS-1 pressure relief valve uses a quick opening method which helps the sprinkler reach the stable critical jet state faster; the ADS-2/3 pressure relief valve uses a slow opening method which is helpful to avoid "sharp" peak points in the pipeline flow curve and reduce the impact of the spraying process on the pipeline and sprinklers while satisfying the economic principle; ADS-4 is crucial for small break LOCA accident and also necessary for the injection of pressure tank at the later stage of the accident. [Conclusions] Through the simulation analysis of the opening and closing characteristics of the ADS pressure relief valve, it provides a reference for the design of the automatic depressurization system, and also provides theoretical and data support for the safety analysis of advanced nuclear power plants.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-06-17
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 >> Radiation Physics and Technology submitted time 2024-06-13
Abstract： [Background]Active neutron interrogation (ANI) measurement systems can quantify the fissile mass of special nuclear materials (SNMs) using neutrons and are widely used in nuclear safeguard fields. However, the hydrogen-containing matrix in the waste drum reduces the signal of delayed neutrons and limits the fissile mass measurement precision of the ANI system. [Purpose]It is essential to ensure that the fissile mass evaluation of the SNM is independent of matrix material and to improve the assay performance of the ANI system in nuclear safeguard measurements. [Methods] Therefore, based on the flux monitor response, a new matrix correction method was developed on the basis of traditional correction methods in this work. [Results]It turned out that the effect of various hydrogen densities on the delayed neutron count rate differs. For U3O8 materials with different enrichment and distribution, matrix effect may result in an overestimation of up to ~7 times in the observed mass of 235U. For U3O8 materials with different 235U enrichments and distribution states, both the traditional correction method and the new correction method can effectively reduce the influence of the matrix material on the measurement of SNM mass. But compared with the traditional method, the new method can achieve better correction results. For the case where U3O8 material is located in the center of the matrix, the average relative deviation of 235U mass obtained by the new correction method is 13.6%, while for the case where U3O8 material homogeneous dispersed throughout the matrix, the average relative deviation of 235U mass obtained by the new correction method is 7.78%. [Conclusions]These results confirm the effective performance and practicality of the new correction method.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-06-12
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 >> 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 >> 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 >> Radiation Physics and Technology submitted time 2024-05-15
Abstract： [Background]Active neutron interrogation (ANI) measurement systems can quantify the fissile mass of special nuclear materials (SNMs) using neutrons and are widely used in nuclear safeguard fields. However, the hydrogen-containing matrix in the waste drum reduces the signal of delayed neutrons and limits the fissile mass measurement precision of the ANI system. [Purpose]It is essential to ensure that the fissile mass evaluation of the SNM is independent of matrix material and to improve the assay performance of the ANI system in nuclear safeguard measurements. [Methods] Therefore, based on the flux monitor response, a new matrix correction method was developed on the basis of traditional correction methods in this work. [Results]It turned out that the effect of various hydrogen densities on the delayed neutron count rate differs. For U3O8 materials with different enrichment and distribution, matrix effect may result in an overestimation of up to ~7 times in the observed mass of 235U. For U3O8 materials with different 235U enrichments and distribution states, both the traditional correction method and the new correction method can effectively reduce the influence of the matrix material on the measurement of SNM mass. But compared with the traditional method, the new method can achieve better correction results. For the case where U3O8 material is located in the center of the matrix, the average relative deviation of 235U mass obtained by the new correction method is 13.6%, while for the case where U3O8 material homogeneous dispersed throughout the matrix, the average relative deviation of 235U mass obtained by the new correction method is 7.78%. [Conclusions]These results confirm the effective performance and practicality of the new correction method.
Subjects: Library Science，Information Science >> Library Science submitted time 2023-12-08
Abstract： Smart service is the transformation and upgrading of university library services, and it is an inevitable choice for the sustainable development of university libraries. This report focuses on university libraries as the main research object. Starting from our library's reader behavior data (including borrowing data, spatial utilization data, access control data, WeChat platform data, etc.), we analyze the current situation of library smart services in several aspects such as borrowing services and resource construction, personalized services, and spatial services. We delve into the existing problems and attempt to explore the methods, content, and forms of library smart services, Provide relevant suggestions for creating a good service environment for smart libraries.
Peer Review Status:
Awaiting Review
Subjects: Digital Publishing >> New Media submitted time 2023-10-08 Cooperative journals: 《中国传媒科技》
Abstract：【目的】元宇宙以其强大的仿真能力为用户带来真实的沉浸式体验。近年来，由于人工智能、区块链技术和数字孪生等技术的快速发展，元宇宙技术逐渐显露出其在产业界、学术界的发展前景。文章旨在探讨基于6G网络的元宇宙应用技术研究。【方法】详细介绍元宇宙技术的发展脉络，分析元宇宙在演进过程中的若干关键技术。【结果】通过介绍6G网络技术的指标特点和优势，论述6G技术对加强元宇宙应用中多源异构数据稳定性、提升传输速度和扩展覆盖范围的重要意义。【结论】文章对6G网络环境下元宇宙的发展进行展望，强调在新一轮技术革新下我国基于在5G网络布局优势基础上，应加强对元宇宙关键技术的研发。
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： Due to the special strategy role and the trends of global warming, the Arctic region attracts many interests. The underwater acoustics play a very important role in the ocean research work of Arctic region and its neighborhood. The research work of underwater signal processing in polar region is relative late than the other field of underwater acoustics. It focuses on polar region especially the Arctic ocean environment, studies the effects of underwater acoustic environment and its adaptive signal processing methods. In this paper, the outline of research work, since WWII, of underwater acoustics in Arctic region and its neighborhood is introduced. The specific research issues and results different from the traditional underwater acoustics in this special region are discussed. It is shown that the characteristics of Arctic ocean environment has more important role in underwater signal processing and sonar design, , some special treatments must be taken in matching the requirement of Arctic underwater acoustics.
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