Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-07-01
Abstract： [Background]: As the commercial application of sodium-cooled fast reactors continues to develop, there is a need to develop an integrated analysis code for sodium-cooled fast reactors in order to enhance the capability for safety assessment. [Purpose]: Sodium boiling is a critical phenomenon prior to severe accidents in sodium-cooled fast reactors, and accurate prediction of thermodynamic parameters of the coolant at the onset of sodium boiling is essential for accident analysis. [Methods]: This paper introduces the development of the integrated analysis code ISAA-Na for sodium-cooled fast reactors, focusing on the core thermal-hydraulic model. The ISAA-Na code was used to simulate and analyze the loss-of-flow experiment CABRI-BI1. [Results]: Comparison with experimental data shows that ISAA-Na provides more accurate predictions of coolant temperature and pressure prior to boiling compared to other codes such as SAS4A, ASTEC-Na, and SIMMER. However, after the onset of boiling, overestimations of bubble growth rate and two-phase interface movement were observed due to the lack of fuel melting and cladding failure models. [Conclusions]: Overall, the application of the multi-bubble liquid slug boiling model in ISAA-Na for the analysis of the CABRI-BI1 experiment is deemed reasonable and reliable.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-07-01
Abstract： Background : The quantification of uncertainty has become a common requirement in reactor physics analysis, with the covariance data of nuclear data serving as the foundational data for conducting uncertainty quantification. Purpose : This study aims to develop a covariance data generation module, covar_calc, in the nuclear data processing software NECP-Atlas to produce continuous energy covariance data for Monte Carlo programs and multi-group covariance data for deterministic programs. Methods : Covar_calc module was developed to process all covariance data provided in evaluated nuclear databases, according to the different storage formats of nuclear data and different computational methods. This included the covariance data of various parameters such as average fission neutron multiplicities, cross sections, angular distributions of secondary particles, fission spectrum, resonance parameters, and neutron activation cross-sections. Results : A comparative verification is carried out with the covariance data production module in the nuclear data processing software NJOY21 to demonstrate the accuracy of the multi-group covariance databases produced by NECP-Atlas and the maximum bias is less than 0.1%. Utilizing Monte Carlo calculation code NECP-MCX and uncertainty analysis code NECP-UNICORN, sensitivity coefficients for different benchmarks are calculated. By incorporating both continuous energy covariance databases and multi-group covariance data, and utilizing the Sandwich formula, the final uncertainties are computed. The results indicate that the uncertainties calculated using the multi-group covariance data generated by NECP-Atlas exhibit comparable accuracy to those obtained with NJOY21. Conclusions : The precision in creating both continuous energy covariance and multi-group covariance meets the requirements for usage in Monte Carlo programs and deterministic programs, validating the efficacy of covar_calc module within NECP-Atlas for uncertainty quantification in reactor physics analysis.
Subjects: Nuclear Science and Technology >> Other Disciplines of Nuclear Science submitted time 2024-07-01
Abstract： [Background]: Uranium polymetallic ores are strategic emerging industry minerals, and the quantitative analysis of uranium (U) in ores is a crucial step in the development process of such ores. [Purpose]: In this paper, a quantitative analysis of U in uranium polymetallic ores using femtosecond laser-induced breakdown spectroscopy (LIBS) combined with partial least squares regression (PLSR) modeling was conducted. [Methods]: Initially, the concentrations of U in six samples were measured by high-purity germanium gamma spectrometer and set as reference values, and then femtosecond lasers were employed to ablate the samples to obtain LIBS spectra. Subsequently, two normalization methods were applied to preprocess the raw spectra, and the impact of the preprocessed spectra on PLS model prediction analysis was compared with that of the raw spectra. Subsequently, the spectral data from five sets of samples were utilized as a training dataset to construct a quantitative model, enabling the analysis and prediction of U concentration in sample 3# [Results]: The results indicate that the relative standard deviation (RSD) and mean relative error (MRE) of 10 predicted values for sample 3# are merely 5.94% and 4.73%, respectively. [Conclusions]: This demonstrates that the combination of PLSR algorithm and femtosecond LIBS exhibits high analytical accuracy and stability for samples. This finding can provide significant reference for practical applications of femtosecond LIBS technology in the quantitative analysis of U content in uranium polymetallic ores.
Subjects: Mathematics >> Mathematics （General） submitted time 2024-07-01
Abstract： By considering the spectrum of the Cesaro operator on the Hilbert-Polya space, we proved the Riemann hypothesis for Riemann zeta function and Dirichlet L-function.
Peer Review Status:
Awaiting Review
Subjects: Energy Science >> Energy Science （General） Subjects: Nuclear Science and Technology >> Engineering Technology of Fission Reactor Subjects: Nuclear Science and Technology >> Particle Accelerator Subjects: Nuclear Science and Technology >> Reprocessing Technology of Spent Nuclear Fuel submitted time 2024-06-30
Huan Jia
Xunchao Zhang
Yuanshuai Qin
Xiaobo Li
Yuan He
Neng Pu
Hanjie Cai
Haihua Niu
Yulu Huang
Guirong Huang
Wei Wu
Xiaochong Zhu
Xiaoqiang Wei
Jonathan C. Wong
Abstract： Accelerator Driven sub-critical System (ADS) is considered to be the most important candidate for nuclear waste transmutation. We propose a Multi-Target Accelerator Driven System (MTADS) to resolve two longstanding challenges of ADS, namely heat removal and the associated target lifetime, and inhomogeneous power distribution that affects burn-up of the reactor. An 18 mA, 1 GeV proton beam is split into 12 beams by radio frequency cavities and injected to 12 compact targets inside the reactor. With beam power of 18 MW, the sub-critical reactor is driven to 1500 MW thermal power. The peaking factor of the reactor is reduced to 1.7 by optimization of targets number and position for Multi Target Accelerator Driven System. The maximum beam current density is also reduced to 18.5 μA/cm2, which prolongs the beam window lifetime to 12 months with T91 steel. Towards the next generation ADS, the concept of MTADS simplifies the sub-critical system and increases the transmutation efficiency.
Peer Review Status:Awaiting Review
Subjects: Nursing >> Nursing submitted time 2024-06-30
Abstract： This paper summarizes the therapeutic effect and nursing experience of a case of acute mastitis in the lactation period of primipara with multi-step psychological nursing combined with Chinese ointment rubbing technology. Nursing evaluation, nursing diagnosis, nursing plan, nursing measures, effect evaluation, life and diet guidance were mainly carried out through the method of syndrome differentiation and nursing, and psychological nursing was also emphasized. The application of traditional Chinese medicine (TCM) and multi-step psychological nursing mode for the first time resulted in lower VAS pain score, higher Barthel index, lower SPBS scale score and lower SAS scale score. The combination of Chinese and western medicine can relieve pain, relieve anxiety and improve the quality of life of patients. To provide reference for more similar cases.
Peer Review Status:Awaiting Review
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-06-30
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 >> Other Disciplines of Nuclear Science submitted time 2024-06-30
Abstract：在核辐射测量中，受限于测量系统本身以及测量环境的干扰，脉冲畸变不可避免，如果无法准确估计这类脉冲的参数将会降低能谱的分辨性能。本文提出将六种轻量级神经网络模型用于畸变脉冲的参数预测，预测对象包括脉冲幅度参数和畸变时间参数。以预定义的数学模型生成的畸变脉冲为基础数据集，经数字三角整形得到模型训练所需的数据集。模型性能评估结果表明，传统的数字整形法虽然在时间参数预测上具有绝对优势，但在幅度参数预测中却受到脉冲畸变的限制，无法获得准确的幅度预测结果。在对包括UNet在内的六种神经网络模型进行参数预测性能评估时，UNet模型在测试集上获得了最低的相对误差，其中幅度参数的相对误差约为0.57%，时间参数的相对误差为3.51%。在信噪比实验中，探讨噪声对具有优秀参数预测性能的UNet模型与CNN-LSTM模型的影响，进一步证明了UNet模型优秀的抗噪性能。
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-06-29
Abstract： [Background]:Neural networks, with their powerful fitting capabilities, can learn the relationships between input and output variables based on large amounts of data, often serving as proxy models for physical programs in the field of engineering calculations, including nuclear engineering calculations. Neutron transport calculations, as one of the core links in neutronics simulations, often suffer from lengthy computational times. However, this issue can also be addressed by utilizing neural network models. Nevertheless, neural network models have a series of hyperparameters that need to be set, but manually adjusting these hyperparameters is laborious, repetitive, and reliant only on experience. Moreover, these hyperparameters are not reusable when solving different problems. [Purpose]: By seeking a surrogate model for VITAS, the research can provide some reference for the application of artificial intelligence in core physics calculation theory.[Methods]:This paper proposes the use of the Bayesian optimization algorithm to adjust neural network hyperparameters, combined with learning rate decay and loss function optimization methods. [Results]: By fitting the key core parameters obtained from VITAS's calculation of the TAKEDA benchmark problem, the results show that the average error of the effective multiplication factor is within 150×10-5, and the average error rate of the regional integral flux on the TAKEDA1 dataset is 1.72%, with a maximum error rate of 7.56%. [Conclusions]: This approach can automatically search for the optimal combination of hyperparameters for different datasets to achieve the best performance, demonstrating high flexibility, efficiency, and strong generalization.
Subjects: Information Science and Systems Science >> Methodology of System Engineering Subjects: Engineering and technical science >> Engineering Cybernetics submitted time 2024-06-29
Abstract： An urban overpass and its construction method, in the fields of traffic science, traffic rules, traffic engineering, and technical management. After studying the 3D mathematical model of transportation and examining the construction of urban transportation facilities in Beijing in recent years, the inventor proposed an optimized combination scheme for the transportation system of mega cities; The present invention provides a highly optimized and economical design and construction scheme for overpasses based on the characteristics of urban transportation. The scheme effectively reduces traffic flow and pedestrian vehicle intersections, improves exchange rates, has road buffering and high applicability capabilities, and is suitable for upgrading and renovating large flow complex traffic nodes such as intersections and five forks. While improving performance, it can also reduce the overall complexity of transportation facilities. The present invention only requires partial modifications to existing urban roads and overpasses, reducing the difficulty of implementation and is one of the important combination solutions for improving urban congestion.
Peer Review Status:Awaiting Review
submitted time 2024-06-29
Abstract： A new sub-critical reactor concept is proposed as one accelerator splitting into multiple beams to drive the subcritical reactor in this work, which is so called Multi-Beam Accelerator Driven System (MB-ADS). The spallation target is designed as a unit similar to the fuel assembly. The high current proton beam is divided into multiple parts and injected into different targets located in the core to improve beam efficiency and flatten the spatial power distribution of the core. Based on different MB-ADS schemes, neutronics were conducted on the effects of beam splitting number, target assembly arrangements, fuel partitioning, and neutron data libraries. The results show that a reasonable multi-beam scheme can significantly improve the efficiency of the proton beam and flatten the power distribution of the reactor compared to the one target ADS scheme. Due to the improved beam efficiency, the beam density on the target window is greatly reduced.
Peer Review Status:Awaiting Review
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-06-29
Abstract： As nuclear energy is developed on a large scale, traditional uranium resources from mines have shown a trend of shortage, and uranium extraction from seawater is likely to be one of the most viable ways to obtain large-scale uranium resources in the future. Photocatalysis, with its advantages of low pollution, low energy consumption, and high material recycling rate, has become an important direction in the research of uranium extraction from seawater in recent years, focusing on the preparation and selection of photocatalysts. Graphite phase carbon nitride photocatalyst is relatively inexpensive and stable, making it an ideal photocatalyst; titanium dioxide photocatalyst can effectively reduce hexavalent uranium in radioactive wastewater to stable tetravalent uranium, with high activity, good stability, and environmental friendliness. This project combines the photocatalytic advantages of the several materials to prepare a magnetic composite photocatalyst made from graphite phase carbon nitride and titanium dioxide, with magnetism added to better control the catalyst in the solution and for use in seawater uranium extraction experiments. The results show that the composite catalyst has an efficiency of up to 76% in photocatalytic extraction of uranium from seawater, offering a promising new pathway for the development of uranium resources.
A nursing case report on a patient with chronic non-specific low back pain of spleen kidney yang deficiency type treated with Du meridian moxibustion
Subjects: Other Disciplines Subjects: Other Disciplines submitted time 2024-06-29
Abstract：
This article summarizes the experience of traditional Chinese medicine nursing for a patient with chronic non-specific low back pain of spleen-kidney yang deficiency type. Based on the theory of syndrome differentiation and nursing of traditional Chinese medicine, moxibustion along the governor vessel, a traditional Chinese medicine nursing technique, was used. The pain visual analog scale (VAS), Pittsburgh sleep quality index (PSQI), and Hamilton anxiety scale (HAMA) were used to evaluate the curative effect. The nursing achieved the effect of relieving low back pain, reducing anxiety, and improving sleep quality of the patient. The patient's symptoms improved significantly, and the nursing effect was remarkable.
Peer Review Status:Awaiting Review
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-06-29
Abstract：随着化石燃料逐渐枯竭，研制商业化的聚变反应堆成为解决能源问题的途径之一，而为了实现聚变堆氚自持运行，从聚变堆增殖包层中提取氚的技术有着重要研究意义。从经济性和可实现性角度出发，液态锂铅包层具有很大的优势和发展前景。本文对国际热核聚变实验堆（ITER）以及欧盟聚变示范堆（DEMO）所提出的液态锂铅包层中的氚提取技术，包括真空渗透法（PAV）、气液接触法（GLC）、真空筛板法（VST）三种氚提取工艺进行了综述，归纳总结了各个工艺的优劣势、所需辅助系统、技术问题等，并对其进行了性能比对，以期对聚变堆氚提取系统的设计研究提供思路和参考。
Subjects: Nursing >> Nursing submitted time 2024-06-28
Abstract： To explore the nursing experience of ear scraping and bone bi exercise in a patient with osteoarthritis. After two weeks of treatment and nursing for a patient with right hip pain with ear scraping and bone pain, the patient’s pain score decreased significantly, his anxiety was significantly relieved, and his daily living ability was significantly improved. Ear scraping and bone pain operation are characteristic therapies of traditional Chinese medicine, which has a positive auxiliary effect on relieving pain and improving joint function in patients with osteoarthritis, and have no obvious side effects. This method is worth applying in clinical care.
Peer Review Status:Awaiting Review
Subjects: Computer Science >> Other Disciplines of Computer Science Subjects: Biology >> Molecular Biology Subjects: Mathematics >> Logic submitted time 2024-06-28
Abstract： Polymer aggregates and molecular polymers are written as computable numbers, realizing the unity of cells and universal Turing machines with the Entscheidungsproblem. However, whether the Entscheidungsproblem of cells really exists remains elusive. Alan Turing found universal Turing machines read only computable numbers written by humans who further differentiate transcendental numbers from the set of computable numbers by Georg Cantor’s diagonal process. It follows that the decidability of the Entscheidungsproblem derived from humans eliminates the independence of computable numbers from each other and enables computable numbers to be fused with each other into the set of computable numbers, with the result that humans are endowed with a capacity to read of the fusion of computable numbers with each other into the set of computable numbers by humans to read the set of computable numbers bearing computable numbers by being endowed with a capacity to write computable numbers. Accordingly, it is shown here how humans are invited to write cell backbones as complex numbers read by artificial intelligence machines emulated by cells by writing polyribonucleotides as computable numbers read by universal Turing machines emulated by extracellular ribosomes to extend Georg Cantor’s continuum hypothesis by being invited to extend Alan Turing’s work on the Entscheidungsproblem, realizing the unity of humans, cells, and artificial intelligence machines without the Entscheidungsproblem.
Peer Review Status:Awaiting Review
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-06-28
Abstract： Microchannel heat exchanger is a promising candidate intermediate heat exchanger design for applications in high temperature reactors. In high temperature reactors, internal pressure and high temperature are the main loading sources. In order to ensure the safety of high temperature microchannel heat exchanger, the heat exchanger macroscopic and microscopic finite element model was established. According to ASME III-5 standard, systematic stress evaluation, strain evaluation, and fatigue strength and life prediction of a customized microchannel heat exchanger were carried out under cyclic conditions. The results show that the studied high temperature microchannel heat exchanger meets the requirements of ASME III-5 and Code Cases N-898, and the maximum fatigue strength was obtained to predict the maximum safe service life.
Subjects: Medicine, Pharmacy >> Clinical Medicine submitted time 2024-06-28 Cooperative journals: 《中国全科医学》
Abstract： Background Intra-abdominal infection is a common etiology of sepsis，and older patients with intra#2;abdominal sepsis have a high mortality rate. Therefore，it is significant to evaluate the prognosis accurately. Currently，the measurement of skeletal muscle mass derived from computed tomography（CT）has become a research hotspot. Whereas theprognostic value of skeletal muscle mass in older patients with abdominal sepsis is rarely reported. Objective To investigate the prognostic value of the skeletal muscle index（SMI）at the midpoint of the third lumbar vertebra（L3）along with sequential organ failure assessment（SOFA）score or acute physiology and chronic health evaluation Ⅱ（APACHE Ⅱ）in older patients diagnosed with intra-abdominal sepsis. Methods This study was conducted at the emergency medicine center of Beijing Chao#2;Yang Hospital from January 1，2022 to July 31. A total of 335 older patients with intra-abdominal sepsis were recruited. The participants were divided into survival group （250 cases） and non-survival group（85 cases）based on their survival status during hospitalization. Clinical characteristics and L3 SMI derived from abdominal CT were compared between survival and non-survival groups. Multivariable Logistic regression analysis was used to identify the risk factors of in-hospital mortality in older patients with intra-abdominal sepsis. The receiver operating characteristic （ROC） curves of L3 SMI，SOFA score，APACHE Ⅱ score，and combined variables for predicting in-hospital mortality were drawn，and the area under the curve（AUC）were calculated and subsequently compared. Results 335 older patients with intra-abdominal sepsis were included，of whom 85（25.4%）died. There were statistically significant differences in age，BMI，albumin，creatinine，procalcitonin，L3 SMI，nutritional risk screening 2002 （NRS2002），sepsis shock proportion，SOFA score，APACHE Ⅱ score between the two groups （P<0.05）. Multivariable Logistic regression analysis revealed that decreased L3 SMI（OR=0.924，95%CI=0.886-0.964，P<0.001），increased NRS2002 score（OR=1.312，95%CI=1.086-1.585，P=0.005），increased SOFA score（OR=1.170，95%CI=1.053-1.300，P=0.004），and increased APACHE Ⅱ score（OR=1.052，95%CI=1.003-1.103，P=0.038）were independent risk factors for in-hospital mortality in older patients with intra-abdominal sepsis. The AUCs of L3 SMI，SOFA score，and APACHE Ⅱ score for predicting the risk of in-hospital mortality were 0.711，0.740，and 0.742，respectively. L3 SMI combined with SOFA score，or APACHE Ⅱ score could improve their predictive ability，with AUCs of 0.795 and 0.792，respectively. Conclusion Decreased L3 SMI was an independent risk factor for in-hospital mortality in older patients with intra-abdominal sepsis，The skeletal muscle mass based on abdominal CT combined with critical illness scoring systems could effectively evaluate the prognosis of these patients.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-06-28
Abstract： As a candidate heat exchanger for the high temperature reactor, printed circuit heat exchanger (PCHE) operates in a very demanding environment and its technological readiness level is very low. In this work, a 20 kW PCHE is designed and the possible life-limiting factors are analyzed, a partitioned homogenization method of the heat exchanger core is proposed, and the heat exchanger high-temperature and high-pressure operating environment of the heat exchanger core is simulated. Finally, through the theoretical and preliminary numerical simulation analyses, predictions of possible failure parts, failure modes and consequences of the PCHE were made. This work provides further research directions for the safety assessment of PCHE heat exchanger.
Subjects: Nuclear Science and Technology >> Nuclear Detection Technology and Nuclear Electronics submitted time 2024-06-28
Abstract： Abstract Background : Radioactivity measurement is widely used in various fields of nuclear technology application. The measurement uncertainty, confidence interval and detection limit are important parameters of radioactivity measurement. Different calculation methods may get different results, and the calculation results directly affect some important and relevant decisions. Purpose : It is important to analyze whether the calculation method is used properly. Methods : The important parameters of α particle activity concentration measurement were studied by partial derivative method and Monte Carlo method. In this study, based on the measurement of α activity concentration, the sources of uncertainty for the measurement results were analyzed. The measurement uncertainty, confidence limits, decision threshold and detection limit of α particle activity concentration under different input modes were derived and calculated by partial derivative and MC methods. Results : The results show that when the input uncertainty is higher than 10%, the relative deviation between confidence interval and uncertainty results obtained by the two calculation methods is greater than 15%. When the relative uncertainty of the input is small, the detection limit is about 2 times of the decision threshold. Conclusions : The partial derivative method is widely used, but it does not consider the probability distribution of the input, and it is not suitable for complex and special input models. Under the circumstances, Monte Carlo method can be used to obtain more reliable calculation results. The two approaches can be applied in complementary ways.
Peer Review Status:Awaiting Review
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