Hasil untuk "Nuclear engineering. Atomic power"

Marco A.B. Zanoni, Zhe Liang

Jihyun Ahn, Jung-ki Shin, Heekyun Baek et al.

This study developed a Real-time Verifiable Sealing System (RVSS), employing advanced sealing technology to ensure nuclear activities are used only for peaceful purposes. The RVSS meets six design requirements: functionality, reliability, usability, integrity, remote verification and monitoring, and maintainability. It has a self-monitoring system with various tamper-detection sensors, detecting unauthorized access and generating integrity verification data. Additionally, the system alerts users and provides real-time diversion location during abnormal situations. For performance evaluation in intended usage environment, the environmental tests were conducted based on the international standard ISO-18185-3. Other evaluations included gamma and neutron radiation resistance tests, on-site testing at dry storage facilities for spent nuclear fuel in the Republic of Korea, and communication tests through concrete walls at nuclear facilities. The results validated the Remote Verification Sealing System's capacity to withstand significant environmental and radiation challenges and to maintain efficient communication through concrete barriers. The system is expected to significantly enhance the efficiency of safeguards measures through real-time verification.

WANG Fuyang1, ZOU Wenzhong2, WEN Jiming1, 3, , LIANG Xin4, LIU Ziyue1, WANG Shuo1, YU Pei2, , TIAN Ruifeng1, 3, ZHAO Fulong1, 3

Air-cooled microreactor is a highly integrated system with the advantages of easy transportation and reliable operation, which can meet the demand for energy in remote areas. The heat removal capacity of the non-energetic air-cooled waste heat removal system is an important indicator for evaluating the performance and safety of air-cooled microreactors. It uses air as the final heat trap and has the advantages of simple system equipment and reliable long-term operation. Some nuclear power units utilize the air-cooled waste heat removal system to export heat and control the core temperature under the conditions of coolant loss accident and decay heat removal after reactor shutdown. The purpose of this paper is to study the coupled heat transfer characteristics of the natural cycle of the air-cooled waste heat removal system and the influence of different insulation layer structural characteristics on the flow heat transfer capacity of the waste removal system, and to propose an air-cooled waste heat removal system using a horizontal pressure vessel with a double-layer thermal insulation structure, analyze the heat-carrying process of the waste heat removal system, put forward the corresponding assumptions in order to simplify the solving region and the physical model, and determine the masking effect of the radiant heat transfer based on the vectorial method, supplemented by reasonable constitutive equations and mathematical models. The coupling between radiative heat transfer and thermal conductivity, convective heat transfer and heat transfer and flow of the waste heat removal system was realized by supplementing the reasonable constitutive equations and mathematical model to complete the closure of the control equations, and a one-dimensional analysis program was developed to simulate the flow and heat transfer characteristics of the waste heat removal system, and the accuracy of the model was verified by using the experimental data, and based on the program, the outer flow channel closure (thermal insulation) and opening (insulation boundary condition) and the outer flow channel closure (insulation boundary condition) and opening (insulation boundary condition) of the waste heat removal system were discussed in the boundary condition of the fixed-wall temperature of the pressure vessel. Based on this program, the effects of closed (insulation boundary conditions) and open (insulation non-insulation boundary conditions) outer flow channel on the accuracy of the model calculation were discussed, and the relationship between the natural circulation characteristics and the change of the outer wall temperature of the pressure vessel, the emissivity, the width of the annular cavity, the ambient temperature, and the equivalent thermal resistance of the insulation layer were calculated. The results of the study show that appropriately increasing the outer wall temperature of the pressure vessel, the emissivity of the insulation layer and the width of the annular cavity, and appropriately decreasing the equivalent thermal resistance of the insulation layer can help to improve the system’s waste heat removal capacity, and the system’s waste heat removal capacity decreases with the increase in ambient temperature.

Sonja M. Hyrynsalmi, Grischa Liebel, Ronnie de Souza Santos et al.

The discipline of software engineering (SE) combines social and technological dimensions. It is an interdisciplinary research field. However, interdisciplinary research submitted to software engineering venues may not receive the same level of recognition as more traditional or technical topics such as software testing. For this paper, we conducted an online survey of 73 SE researchers and used a mixed-method data analysis approach to investigate their challenges and recommendations when publishing interdisciplinary research in SE. We found that the challenges of publishing interdisciplinary research in SE can be divided into topic-related and reviewing-related challenges. Furthermore, while our initial focus was on publishing interdisciplinary research, the impact of current reviewing practices on marginalized groups emerged from our data, as we found that marginalized groups are more likely to receive negative feedback. In addition, we found that experienced researchers are less likely to change their research direction due to feedback they receive. To address the identified challenges, our participants emphasize the importance of highlighting the impact and value of interdisciplinary work for SE, collaborating with experienced researchers, and establishing clearer submission guidelines and new interdisciplinary SE publication venues. Our findings contribute to the understanding of the current state of the SE research community and how we could better support interdisciplinary research in our field.

WANG Ziqi, GUAN Jingyu, DONG Duo, ZHANG Chenglong, ZHU Siyang, HE Kai, LIU Guoming

The micro gas-cooled reactor is one kind of advanced movable micro nuclear power devices with very high inherent safety, which adopts a new type of dispersed multi-coated particle fuel mainly made of silicon carbide (SiC) in fuel system. As a fuel clad material, SiC plays an important role in transferring heat from fuel to coolant, restrains most of the radioactive fission products within its volume. During the lifetime of reactor, the fuel suffers from neutron irradiation, resulting in a series of radiation damage such as displacement damage, irradiation swelling and transmutation, which leads to permanent changes in microstructure and further affects the performance of the whole fuel system. In order to study the neutron-induced radiation damage of SiC-based material in the reactor core, a core model was established using Monte Carlo program, and the displacement per atom (DPA) of SiC material at typical positions in the core was calculated using SPECTRA-PKA code. The processing code SPECTRA-PKA produces all kinds of primary atomic recoil events for SiC material composition exposed to irradiation spectrum. The calculated result shows that the Si primary knock-on atom (PKA) contributes more radiation damage than the C PKA, and its contribution at the maximum, minimum and average dose level of neutron flux is 55.2%, 56.8% and 54.6%, respectively. The annual radiation damage of SiC with the maximum neutron irradiation dose in core is lower than 1 dpa. Elastic scattering plays a dominant role due to the high cross sections at low neutron energy. In addition, inelastic scattering also makes a small contribution. The additional recoils due to the subsequent decay of radionuclides produced by transmutation reactions were further considered using a self-developed neutron activation analysis code named NIAC. The result indicates that the transmutation elements are mainly produced by Si atoms. Compared to the armour materials of plasma facing materials in fusion reactor such as tungsten, the transmutation of SiC is insignificant. This is mainly attributed to two factors: first, the dose level of neutron flux in fusion reactor is much higher than that in micro gas-cooled reactor, and the average neutron energy of fusion reactor is much higher than that of fission reactor, which is easier to induce transmutation reaction of materials; second, the high-Z tungsten is more susceptible to transmutation, generating transmutation elements such as rhenium, osmium, tantalum and hafnium, resulting in changes in the chemical composition of the material. After 3 years irradiation, the PKA of transmutation elements in SiC only makes up about 0.01% of the total and contributes about 0.24% of the predicted DPA rate.

M.S. Al-Buriahi, Norah Salem Alsaiari, M.U. Baskin et al.

Glass materials are becoming important shielding materials in ionizing radiation applications due to their cost and performance effectiveness. This minireview aims to provide a comprehensive overview of the advancements in radiation shielding glasses, future research and development in the field for common glass groups. The class of glasses covered in this review are limited to borate, phosphate, silicate, tellurite, Pb-Pb-, and Bi-based glasses. The review also covers the analysis, influence, and advantages of different modifying cations or their oxides in shielding glasses investigated within the last two decades. This review is motivated by the need for superior glass shields in different areas of radiation applications, show trend in radiation glass research and application, and providing understanding of how different modifying oxides can be used to tailor glass performance in radiation exposure control. The review concluded that the roles of modifying agents in glasses depends on factors such nature of base glass, amount and density of modifier, and radiation of interest. The use of PbO increases gamma shielding efficiencies of glasses but the fear of Pb-poisoning influenced the use of other heavy metal oxides. However, the use of Pb in shielding glasses is still growing.

M.T. Vigil, S. Faulhaber, M.I. Patino et al.

Bulk targets of W38Ta36Cr15V11 complex concentrated alloy (CCA) were produced by spark plasma sintering at the Vecchio materials research lab at the University of California–San Diego. Targets fabricated were reasonably dense, BCC phase, compositionally close in match to that of El-Atwani et al. (2019), and homogeneous, as measured by electron microscopy, energy dispersive x-ray microanalysis (EDX), EDX mapping, and x-ray diffraction. The targets were exposed to deuterium plasma of associated 100 eV ion fluences of 2×1026 m−2 at 523 K, 773 K and 1023 K in the Pisces-RF high-flux linear plasma device. Plasma exposure is found to produce surface compositional enrichment in W and Ta, as determined by Auger electron spectroscopy and EDX, that is caused by a depletion of surface Cr and V, the former being observed with optical emission spectroscopy in the target plasma. Accompanying the compositional change, transient grating spectroscopy analysis, taken pre- and post-plasma exposure on the 1023 K exposed target, revealed ∼30% reduction in surface thermal diffusivity from 9.4×10−6 m2s−1 to 6.7×10−6 m2s−1. Lastly, D retention in the CCA targets was found to be characterized by a singular thermal release peak at ∼900 K, and retention varied from 2×1023 m−2 to 3×1020 m−2 for exposure in the temperature range 523–1023 K, as measured by thermal desorption spectrometry. This level of D retention is found to be high relative to pure tungsten.

童 阳, 王 城喻, 许 晓锐 et al.

LiCl-KCl共晶熔盐为乏燃料干法后处理中电解精炼过程常用的电解质，其对结构材料的腐蚀主要受熔盐中杂质的影响，通过熔盐纯化降低其腐蚀性是解决干法后处理材料腐蚀问题的重要手段之一。研究中使用电解法对LiCl-KCl盐进行纯化，通过循环伏安电化学方法监测纯化过程，并使用电感耦合原子发射质谱（Inductively Coupled Plasma Mass Spectrometry，ICP-MS）测量LiCl-KCl盐纯化前后杂质元素含量。同时在773 K、氩气环境下开展Inconel 600在纯化前后LiCl-KCl熔盐中500 h的浸泡腐蚀实验，使用扫描电镜（Scanning Electron Microscopy，SEM）、X射线衍射仪（X-ray Diffractometer，XRD）对腐蚀后试样进行表征。结果显示：电解纯化对LiCl-KCl盐内金属离子杂质的去除效果显著，有效减缓了高温熔盐对Inconel 600的腐蚀。

James S. Wheaton, Daniel R. Herber

Traditional requirements engineering tools do not readily access the SysML-defined system architecture model, often resulting in ad-hoc duplication of model elements that lacks the connectivity and expressive detail possible in a SysML-defined model. Without that model connectivity, requirement quality can suffer due to imprecision and inconsistent terminology, frustrating communication during system development. Further integration of requirements engineering activities with MBSE contributes to the Authoritative Source of Truth while facilitating deep access to system architecture model elements for V&V activities. The Model-Based Structured Requirement SysML Profile was extended to comply with the INCOSE Guide to Writing Requirements updated in 2023 while conforming to the ISO/IEC/IEEE 29148 standard requirement statement templates. Rules, Characteristics, and Attributes were defined in SysML according to the Guide to facilitate requirements definition and requirements V&V. The resulting SysML Profile was applied in two system architecture models at NASA Jet Propulsion Laboratory, allowing us to explore its applicability and value in real-world project environments. Initial results indicate that INCOSE-derived Model-Based Structured Requirements may rapidly improve requirement expression quality while complementing the NASA Systems Engineering Handbook checklist and guidance, but typical requirement management activities still have challenges related to automation and support with the system architecture modeling software.

Sayan Chatterjee, Ching Louis Liu, Gareth Rowland et al.

The increasing popularity of AI, particularly Large Language Models (LLMs), has significantly impacted various domains, including Software Engineering. This study explores the integration of AI tools in software engineering practices within a large organization. We focus on ANZ Bank, which employs over 5000 engineers covering all aspects of the software development life cycle. This paper details an experiment conducted using GitHub Copilot, a notable AI tool, within a controlled environment to evaluate its effectiveness in real-world engineering tasks. Additionally, this paper shares initial findings on the productivity improvements observed after GitHub Copilot was adopted on a large scale, with about 1000 engineers using it. ANZ Bank's six-week experiment with GitHub Copilot included two weeks of preparation and four weeks of active testing. The study evaluated participant sentiment and the tool's impact on productivity, code quality, and security. Initially, participants used GitHub Copilot for proposed use-cases, with their feedback gathered through regular surveys. In the second phase, they were divided into Control and Copilot groups, each tackling the same Python challenges, and their experiences were again surveyed. Results showed a notable boost in productivity and code quality with GitHub Copilot, though its impact on code security remained inconclusive. Participant responses were overall positive, confirming GitHub Copilot's effectiveness in large-scale software engineering environments. Early data from 1000 engineers also indicated a significant increase in productivity and job satisfaction.

Piotr Kuwałek

Voltage fluctuations are one of the most common low-frequency disturbances of power quality. Diagnostics of these disturbances are a complex process because voltage fluctuations affect different loads in different ways. Therefore, there is no measure of power quality that allows for the complementary assessment of severity of this disturbance, allow for the identification of sources of voltage fluctuations, and post-factum investigation of their effects. Among the currently used measures of voltage fluctuations, voltage fluctuation indices have the greatest diagnostic capabilities. Many preliminary studies also show the potential possibility of recreation of voltage fluctuations, including: based on voltage fluctuation indices. This paper presents the results of research on methods of recreation of voltage fluctuations from voltage fluctuation indices. The research carried out included a set of data obtained in a real power grid. Moreover, the impact of the discrimination period on the accuracy of recreation of voltage fluctuations has been assessed. The presented research results show, on the one hand, the usefulness of voltage fluctuation indices in the process of recreation of voltage fluctuations and, on the other hand, further challenges in the recreation of voltage fluctuations.

Inga R. Makeyeva, Vasiliy Yu. Pugachev, Olga V. Shmidt et al.

There exist different variants of organizing the closure of nuclear fuel cycle (CNFC) depending on fast reactor type, fuel types, station or centralized allocation of closed nuclear fuel cycle stages. One of the ways to verify and estimate engineering solution is mathematical modeling of radiochemical technology which in the end will allow to optimize composite technological process in order to increase effectiveness and reduce cost. In order to calculate the balance of material flows of process circuits and individual production sections in the stationary and dynamic modes, with taking into account the isotopic composition evolution, a software package VIZART (Virtual Plant of Radiochemical Technologies) was developed, allowing the user to assemble the required sequence of operations for any part of the process scheme and perform the calculation of material balance for all flows of the circuit, as well as to optimize the equipment operating modes and provide the necessary data to justify the safety of certain limits and the entire process circuit. The following capabilities of code VIZART for computational substantiation of CNFC technology design and characteristics are considered: material balance calculation, cyclogram creation, determination of the most loaded parts of processing lines, estimation of fissile materials accumulating in devices and intermediate vessels, optimization of productivity of nodes and devices.

Izabela Gutowska, Robert Kile, Brian G. Woods et al.

The development of the Modular High-Temperature Gas-Cooled Reactor is a significant milestone in advanced nuclear reactor technology. One of the concerns for the reactor’s safe operation is the effects of a loss-of-flow accident (LOFA) where the coolant circulators are tripped, and forced coolant flow through the core is lost. Depending on the steam generator placement, loop or intracore natural circulation develops to help transfer heat from the core to the reactor cavity, cooling system. This paper investigates the fundamental physical phenomena associated with intracore coolant natural circulation flow in a one-sixth Computational Fluid Dynamics (CFD) model of the Oregon State University High Temperature Test Facility (OSU HTTF) following a loss-of-flow accident transient. This study employs conjugate heat transfer and steady-state flow along with an SST k-ω turbulence model to characterize the phenomenon of core channel-to-channel natural convection. Previous studies have revealed the importance of complex flow distribution in the inlet and outlet plenums with the potential to generate hot coolant jets. For this reason, complete upper and lower plenum volumes are included in the analyzed computational domain. CFD results also include parametric studies performed for a mesh sensitivity analysis, generated using the STAR-CCM+ software. The resulting channel axial velocities and flow directions support the test facility scaling analysis and similarity group distortions calculation.

LI Yintao, LIU Dongliang, ZHOU Yuanlin et al.

BackgroundRubber-based nanocomposites have become a research focus in the nuclear industry due to their wide application in wearable radiation protection devices.PurposeThis study aims to explore the γ-ray shielding mechanism of composite material of Bi2WO6 nanoparticles and natural rubber (NR), so as to provide theoretical support for the further materials preparation of low toxicity, light weight and high efficiency radiation shielding.MethodsBismuth tungstate (Bi2WO6) nanoparticles synthesized via hydrothermal process, additionally, WO3 and Bi2O3 particles were prepared by ball milling method. Then, these particles were filled into natural rubber (NR) at the mass fraction of 30% to fabricate three composites: NR/Bi2WO6, NR/WO3 and NR/Bi2O3. Finally, laser particle size analyzer, X-ray diffraction analysis (XRD) and field emission scanning electron microscope (FE-SEM), etc., were employed to access the mechanical properties of NR/Bi2WO6, and the γ-ray shielding effect was evaluated on the basis of the γ-ray shielding effects of Bi2WO6, WO3 and Bi2O3.ResultsThe results show that the NR/Bi2WO6 nanocomposites achieves a γ-ray shielding factor of 13.6% for 59.5 keV (241Am point source), which is significantly higher than NR/WO3 (7.4%) and NR/Bi2O3 (9.2%). Furthermore, a comparison of WO3 and Bi2O3 indicates that the interlayer effect of the Bi2O22+ and WO42- layers in the Bi2WO6 cell is conducive to increasing the probability of collisions between γ photons and extranuclear electrons.ConclusionsThe γ-ray shielding performance of NR/Bi2WO6 composites is significantly improved by the boundary complementary effect of both K and L layer absorption edges of W and Bi elements existed in Bi2WO6 nanoparticles, which enhances the attenuation efficiency of NR/Bi2WO6 to the γ-ray.

Sehrish Malik, Moeen Ali Naqvi, Leon Moonen

There is an increasing need to assess the correct behavior of self-adaptive and self-healing systems due to their adoption in critical and highly dynamic environments. However, there is a lack of systematic evaluation methods for self-adaptive and self-healing systems. We proposed CHESS, a novel approach to address this gap by evaluating self-adaptive and self-healing systems through fault injection based on chaos engineering (CE) [ arXiv:2208.13227 ]. The artifact presented in this paper provides an extensive overview of the use of CHESS through two microservice-based case studies: a smart office case study and an existing demo application called Yelb. It comes with a managing system service, a self-monitoring service, as well as five fault injection scenarios covering infrastructure faults and functional faults. Each of these components can be easily extended or replaced to adopt the CHESS approach to a new case study, help explore its promises and limitations, and identify directions for future research. Keywords: self-healing, resilience, chaos engineering, evaluation, artifact

ZOU Ying;ZHANG Yuhai;TANG Na;LI Jingjing;ZHANG Fengshou

Heavy-ion collisions provide a unique opportunity to study the nuclear equation of state for a wide range of densities, temperatures, and neutron-proton asymmetries in the laboratory. Transport models are the main method to obtain physics information on the nuclear equation of state and in-medium properties of particles from low to relativistic-energy heavy-ion collisions. In this paper, the typical transport models used in heavy ion collisions were introduced, including the phenomenology-type transport model, such as dinuclear system (DNS) model and Langevin equation, Boltzmann-equation and quantum molecular dynamics (QMD) type transport model. Besides, some of their computed results were taken as examples to introduce the progress of transport theory. The difficulties faced by the current transport model were also summarized, and the application of machine learning in heavy ion collisions transport theory was reviewed. In this area, machine learning, especially deep learning, has been widely used as a significant data analysis method. Machine learning could be applied to correct the input of transport model, such as the nuclear equation of state and impact parameter, and constrain the output results, such as fission yields. The convolutional neural networks (CNN), light gradient boosting machine (LightGBM), Bayesian neural network (BNN) were introduced in these studies mentioned. Based on the above, the key problems to be solved possibly using machine learning in transport theory were proposed: Nucleon-nucleon correlations are not included in Boltzmann-type transport model, due to the basic assumptions needed to derive Boltzmann equation from Bogoliubov-Born-Green-Kirkwood-Yvon (BBGKY) equations, which are Rarefied gas hypothesis and Stosszahlansatz; Only two-body collision is considered in Boltzmann equation without N-body collisions, which is unphysical in high density. High order terms of BBGKY equations need to be considered; The fermionic nature of the system should be preserved in the evolution of nuclear reaction system, but is lost rapidly in QMD-type transport model because of fluctuations, even with Fermi statistics implemented at the beginning of the reaction and the Pauli principle enforced in the collision term; The multi-time scale should be used to deal with the evolution from the collision stage to the local equilibrium, which has to be ignored in the current transport theory; Incomplete experimental data are available as input of transport model, which leads to improve the accuracy of the transport model. The solution of above problems is expected to combine machine learning and transport theory. These studies are essential for further developments of precise transport model.