This paper gives a clear, practical summary of how vacuum drying and small amounts of residual water can influence the integrity of spent nuclear fuel (SNF) cladding in dry storage. It also proposes a practical R&D priorites and recommendations for Korea that fits licensing and routine operations. We reorganize the lessons from major U.S. efforts (CSFM, DCSC, ESCP) to show what they can and cannot answer for Korea today. We review inspection methods based on gas sampling. We explain how rupture and fracture are assessed and how data on crack sizes contribute to assessing safety margins. Rather than estimating the likelihood of various accident events, we focus on specific conservative cases regarding residual water. Within these cases, we apply probabilistic analysis to assess material integrity, considering the variability in corrosion or fracture. Historical campaigns largely validated safety empirically via sipping/gas sampling, while quantitative margins (e.g., the comparison of applied stress intensity factors against critical values under handling loads) remain under-constrained due to limited and not-fully-public post-irradiation examination (PIE) datasets.
This paper investigates the Single Event Upset (SEU) sensitivity, system-level hardening effectiveness, and potential applications of high-performance 16 nm Field Programmable Gate Arrays (FPGAs) in radiation environments. Representative circuits incorporating flip-flops and configured arithmetic logic units were specifically designed using FPGA internal resources. This integration introduces extra upset errors due to the additional utilization of arithmetic logics, contributing to a better understanding of SEU sensitivity in FPGA-based circuits within actual application designs. The irradiation tests were conducted to evaluate the SEU sensitivity of D flip-flops (DFFs) and Configuration Memories (CRAMs) under various application conditions. The results indicate that Fine-Grained (FG) Triple Modular Redundancy (TMR) circuits play a critical role in achieving high SEU tolerance, whereas general TMR hardening circuits often prove ineffective in most experiments, even with triplicated flip-flops. FG TMR circuits were developed to address the limitations of general TMR circuits, achieving SEU tolerance improvements by three orders of magnitude for output protection. Notably, FG TMR circuits showed no global signal-induced failures during proton irradiation tests. Furthermore, these system-level radiation tolerance designs present promising applications for Commercial Off-The-Shelf (COTS) devices in spaceflight and ground accelerator facility.
The discussion around AI-Engineering, that is, Software Engineering (SE) for AI-enabled Systems, cannot ignore a crucial class of software systems that are increasingly becoming AI-enhanced: Those used to enable or support the SE process, such as Computer-Aided SE (CASE) tools and Integrated Development Environments (IDEs). In this paper, we study the energy efficiency of these systems. As AI becomes seamlessly available in these tools and, in many cases, is active by default, we are entering a new era with significant implications for energy consumption patterns throughout the Software Development Lifecycle (SDLC). We focus on advanced Machine Learning (ML) capabilities provided by Large Language Models (LLMs). Our proposed approach combines Retrieval-Augmented Generation (RAG) with Prompt Engineering Techniques (PETs) to enhance both the quality and energy efficiency of LLM-based code generation. We present a comprehensive framework that measures real-time energy consumption and inference time across diverse model architectures ranging from 125M to 7B parameters, including GPT-2, CodeLlama, Qwen 2.5, and DeepSeek Coder. These LLMs, chosen for practical reasons, are sufficient to validate the core ideas and provide a proof of concept for more in-depth future analysis.
Conventional neutron spectrum calculation methods are difficult to achieve both high resolution and high efficiency. This paper presents a high-resolution rapid calculation method of neutron spectrum. This method processes nuclear data library to generate high-resolution energy transfer probability matrices for various nuclides. The neutron spectrum of a specific region is rapidly calculated by the direct response between the initial spectrum and the energy transfer probability matrices. This method is capable of the complex geometry and material compositions in localized regions, enabling rapid calculations of neutron spectrum with high resolution. Verification with the Monte Carlo results under different geometry and material compositions demonstrates the precision of this method is comparable to that of Monte Carlo simulation. In addition, the application of this method is demonstrated through neutron spectrum calculations of isotope production targets in HFIR, and the stability of the method is proved in dealing with material perturbations.
This paper presents experimental measurements of the location of the impurity flow stagnation point in the scrape-off-layer (SOL) of a tokamak plasma. Coherence imaging of carbon-2+ emission (465 nm) is used to track the main-chamber impurity velocity of DIII-D L-mode plasmas with B×∇B out of the divertor. The C2+ flow stagnates near the top or crown of the plasma when an open divertor (no baffling) is used. In contrast, with matched conditions and using a divertor with baffling, the C2+ flow stagnates near the outer divertor leg (X-point). The C2+ poloidal emission is hollow, peaking near the divertor legs, in the open configuration. In contrast, in the closed configuration, the C2+ emission is flat through most of the main-chamber SOL. Changing divertor dissipation from attached to detached conditions had only a minor effect on the main-chamber midplane impurity velocity. Numerical simulations using the multi-fluid edge transport code UEDGE including cross-field drifts show qualitative agreement with the open divertor experimental result.
Using a reduced MHD model, extended to include field-aligned thermal conduction, we present numerical simulations of the churning mode (CM): a toroidally symmetric, non-linear plasma vortex in the vicinity of the null points in a snowflake (SF) divertor (Ryutov et al., Phys. Scr. 89 088002, 2014). Simulations are carried out across a range of inter-null separations, $d_{xx}$, and inter-null orientations, $θ$, primarily in conditions relevant to the MAST-U tokamak. We find that, when $d_{xx}$ is small, the CM induces additional transport across the X-points when $β_{pm} \gtrsim 8$ %, where $β_{pm}$ is the ratio of the plasma pressure in the null region to poloidal magnetic pressure at the midplane. This transport also increases approximately linearly as $d_{xx}$ is reduced. A diffusive model of this transport is shown to predict the total transport across the null points, where diffusion coefficients of up to $\sim 10^2$ m$^2$s$^{-1}$ centred on a small region around the X-points are used. However, the CM also results in significant changes to the flux surfaces in the null region which is not captured by this diffusive model. The changes in magnetic geometry mean the fractional exhaust power delivered to each divertor leg is highly sensitive to $β_{pm}$, $d_{xx}$ and $θ$. For small values of $θ$, the CM can induce a change in topology, redirecting exhaust power from a secondary divertor leg on the high field side to one on the low field side. Similar behaviour is found in the fraction of exhaust power going to the inner and outer divertor. Such changes in the flux surfaces may not be captured by Grad-Shafranov solvers and so may be a source of error in the magnetic reconstruction of SF experiments. We consistently find that the fractional exhaust power going to a secondary divertor leg on the high field side is small, consistent with SF experiments.
This paper explores how generative AI can help automate and improve key steps in systems engineering. It examines AI's ability to analyze system requirements based on INCOSE's "good requirement" criteria, identifying well-formed and poorly written requirements. The AI does not just classify requirements but also explains why some do not meet the standards. By comparing AI assessments with those of experienced engineers, the study evaluates the accuracy and reliability of AI in identifying quality issues. Additionally, it explores AI's ability to classify functional and non-functional requirements and generate test specifications based on these classifications. Through both quantitative and qualitative analysis, the research aims to assess AI's potential to streamline engineering processes and improve learning outcomes. It also highlights the challenges and limitations of AI, ensuring its safe and ethical use in professional and academic settings.
V.A. Soukhanovskii, S.L. Allen, M.E. Fenstermacher
et al.
Experimental data from NSTX and DIII-D discharges with the snowflake (SF) divertor configurations are analyzed toward the development of the X-point radiator (XPR) concept. The XPR divertor regime was recently realized in standard divertor configurations in several tokamaks The SF divertor configuration, with an additional poloidal field null nearby the main X-point, could provide additional benefits for the XPR: a higher flux expansion inside the separatrix and an extended private flux region. This may lead to lower temperatures and higher neutral and electron densities, which are thought to be essential for XPR stability, initiation, and impurity containment. In this work, 4 MW NBI-heated H-mode NSTX discharges and 3–5 MW NBI-heated H-mode DIII-D discharges with SF-minus and SF-plus divertors, with the ion B×∇B drift toward the lower divertor, with and without D2 and CD4 seeding, were analyzed. Many experimental XPR features were found, including good or slightly degraded H-mode confinement, significant ELM size reduction, nearly complete divertor power detachment and a significant divertor radiated power loss. However, evidence of the XPR extending into the confined region was inconclusive in the NSTX tokamak, while in DIII-D, a number of discharges demonstrated a stable MARFE-like structure inside the separatrix over a wide operating space. The present analysis supports the SF divertor as a good candidate for further XPR scenario development in DIII-D and NSTX-U.
Technologies for manipulating single atoms have advanced drastically in the past decades. Due to their excellent controllability of internal states, atoms serve as one of the ideal platforms as quantum systems. One major research direction in atomic systems is the precise determination of physical quantities using atoms, which is included in the field of precision measurements. One of such precisely measured physical quantities is energy differences between two energy levels in atoms, which is symbolized by the remarkable fractional uncertainty of $10^{-18}$ or lower achieved in the state-of-the-art atomic clocks. Two-level systems in atoms are sensitive to various external fields and can, therefore, function as quantum sensors. The effect of these fields manifests as energy shifts in the two-level system. Traditionally, such shifts are induced by electric or magnetic fields, as recognized even before the advent of precision spectroscopy with lasers. With high-precision measurements, tiny energy shifts caused by hypothetical fields weakly coupled to ordinary matter or by small effects mediated by massive particles can be potentially detectable, which are conventionally dealt with in the field of nuclear and particle physics. In most cases, the atomic systems as quantum sensors have not been sensitive enough to detect such effects. Instead, experiments searching for these interactions have placed constraints on coupling constants, except in a few cases where effects are predicted by the Standard Model of particle physics. Nonetheless, measurements and searches for these effects in atomic systems have led to the emergence of a new field of physics.
A developed tungsten (W) grade was prepared by powder metallurgy technology plus multi-step low-temperature rolling. The relative density, thermal conductivity, microstructure, tensile properties of original and high-temperature annealed states, micro-hardness and transient thermal shock resistance were characterized. The results of tensile test with a strain rate of 2 × 10-4 s−1 show that the ductile–brittle transition temperature (DBTT) of rolled-W in the original and recrystallized state are 150–200 °C and 250–300 °C, respectively. The rolled-W presents high strength and great plasticity simultaneously. For example, the maximum ultimate tensile strength (UTS) below DBTT is as high as ∼ 1189 MPa, and the maximum total elongation (TE) above DBTT reaches 28.9 %. In particular, the TE of recrystallized W achieves an incredible 81.4 % at 500 °C, which is the highest value among all the published literatures so far. The results of transient thermal shock tests indicate that the rolled-W has an outstanding transient thermal shock resistance. It can withstand the thermal bombardment at an absorbed power densities (APD) of 0.33 GW·m−2 without causing any surface damages, and still no cracks are observed as the APD rises to 0.88 GW·m−2. Moreover, the failure mechanism of rolled-W was also studied in details. This work plays an important role in establishing a dependable China Fusion Engineering Test Reactor (CFETR) data-library on a unitary W grade, which can provide an effective reference for the identification of material performance under the high heat flux and subsequent numerical simulation.
With the rapid development of nuclear energy and space technology, application of high-voltage power devices based on SiC, especially the SiC MOSFET, is increasing. The problems of single event effect (SEE) caused by high-energy particle radiation in the radiation environment, such as, single event burnout (SEB) and single event gate rupture (SEGR), are becoming more and more prominent. In order to systematically understand the research progress of SiC MOSFET SEE, and accelerate the research of SiC MOSFET SEE mechanism and its radiation hardening technologies, the advantages of SiC MOSFET and the key problems in its radiation application are first demonstrated. Then, the simulation calculation, irradiation experiment and corresponding research results of SiC MOSFET SEE at home and abroad are comprehensively reviewed, and the main focus of related research is summarized. In addition, the possible reasons for the high sensitivity of SiC MOSFET to SEE is analyzed. Finally, possible future research directions of SiC MOSFET SEE are discussed according to current existing problems in this field. By systematically summarizing the research progress of SiC MOSFET SEE worldwide, it is expected to provide valuable reference for fully revealing the physical mechanism of SiC MOSFET SEE, and even further improving the radiation hardening technologies of SiC MOSFET to prevent the problem from SEE.
FU Pengtao;LU Shengbo;LIANG Shan;YANG Xiaohuan;XU Jiehao;ZHOU Wenzhong;HAN Song
During the normal operation of pressurized water reactor, fission products activity in the primary coolant will increase when failure of fuel rods happens. The prediction of the status of fuel failure has been paid great attention from industry for the long term with respect to radiological protection, radioactive consequence and the economy. The iodine isotope activity ratio 131I/133I is one of the most important indicators to evaluate fuel reliability in nuclear power industry. In this paper, the production and release of fission products in fuel rods and the primary coolant were simulated by the kinetic model and the typical 131I/133I in the primary coolant were theoretically estimated at the equilibrium conditions for the intact fuels, fuel failure with small defect and large defects, respectively. The radiochemical data in the primary loops were gathered and compiled from thirty six cycles in operating CPR1000 PWR units. The statistical results of these operation data show that the higher volume activities of radio-iodine in the primary loops may result from the dissemination of actinides due to secondary hydriding from the previous cycles and the 131I/133I can be used to well identify the fuel reliability in comparison of the radio-iodine activities. In the cycles with fuel failure, the radio-iodine activities and 131I/133I according to the operation data distribute much wider than the expected because the actual status of fuel failure are more complicated during operation than expected, e.g. changes of fuel failure size, the discrepancy of the location of fuel failure and the relative power of the defective fuel rods. In some cases, it is difficult to distinguish the fuel failure by radio-iodine owing to its low release rate from defective fuel rods. In addition, the size of fuel failure in the specific cycles can be illustrated by the significant change of 131I/133I. It shows that the predictions by the model and the statistical results in operating CPR1000 PWR units are qualitatively in agreement for both intact fuel and fuel failure. It also indicates that the conventional threshold 131I/133I≥0.1 for fuel failure may make the misjudgment due to the overlap of distributions and 131I/133I≥0.15 can distinguish 97% operation date for the fuel failure and 98% operation date for intact fuel rods. The method used and the results in the paper can help to make better understanding of the release of iodine for fuel failure and identity the defective fuel rods during unit operation.
In recent years, beryllium oxide has been widely utilized in multiple compact nuclear reactors as the neutron moderator, the neutron reflector or the matrix material with dispersed nuclear fuels due to its prominent properties. In the past 70 years, beryllium oxide has been studied extensively, but rarely been systematically organized. This article provides a systematic review of the application history, thermal properties, mechanical properties, corrosion behavior and fabrication methods of beryllium oxide. Data from previous literature are extracted and sorted out, and all of these original data are attached as the supplementary material, so that subsequent researchers can utilize this paper as a database for beryllium oxide research in reactor design or simulation analysis, etc. In addition, this review article also attempts to point out the insufficiency of research on beryllium oxide, and the possible key research areas about beryllium oxide in the future.
The dissolution process of oxides is a key step in the pyrochemical process of spent oxide fuel by electrolyzing in molten salt. The dissolved products will provide feeds for subsequent separation and recovery of U and Pu. The solubility and dissolution rate of oxides in molten salt systems are generally low. In order to meet process requirements, it is usually necessary to introduce chlorinating reagents. With different chlorinating reagents, the dissolution mechanism is quite different. Through extensive literature investigation, the related principles and characteristics of various chlorinating reagents in the chlorination process were analyzed and compared, which provided guidance for the research on chlorination and dissolution of U and Pu oxides in China.
Nuclear engineering. Atomic power, Chemical technology
Siyuan Ji, Michael Wilkinson, Charles E. Dickerson
In this third decade of systems engineering in the twenty-first century, it is important to develop and demonstrate practical methods to exploit machine-readable models in the engineering of systems. Substantial investment has been made in languages and modelling tools for developing models. A key problem is that system architects and engineers work in a multidisciplinary environment in which models are not the product of any one individual. This paper provides preliminary results of a formal approach to specify models and structure preserving transformations between them that support model synchronization. This is an important area of research and practice in software engineering. However, it is limited to synchronization at the code level of systems. This paper leverages previous research of the authors to define a core fractal for interpretation of concepts into model specifications and transformation between models. This fractal is used to extend the concept of synchronization of models to the system level and is demonstrated through a practical engineering example for an advanced driver assistance system.
In this study, tissue equivalency (TE) of a newly developed epoxy-based phantom to 3–5 years child's tissue was investigated in paediatric energy range. Epoxy-based TE-phantoms were produced at different glandular/adipose (G/A) ratios of 17/83%, 31/69%, 36/64% and 10/90%. A procedure was developed in which specific amounts of boron, calcium, magnesium, sulphur compounds are mixed with epoxy resin, together with other minor substitutes. In paediatric energy range of 40–60 kVp half-value layer (HVL) values were measured and then Hounsfield Units (HU) were determined from Computed Tomography(CT) scans taken in the X-ray energy range of 80-120kVp. It is found that radiation absorption properties of these phantoms in terms of the measured HVL values related to linear attenuation coefficients (μ) are very well mimicking a 3 years child's soft tissue in case a ratio of 10/90%G/A. Additionally, the HU values of phantoms were determined from the CT scans. The HU = 47.8 ± 4.8 value was found for the epoxy-based phantom produced at a ratio of 10/90%G/A. The obtained HVL and HU values also support the suitability of the new epoxy based-phantom produced at a ratio of 10/90%G/A for a satisfactory mimicking a 3 years child's soft tissue by 5%. Thus they can have a potential use to perform the quality controls of medical X-ray systems and dose optimization studies.
A.I.W.S. Ramadani, N.S. Pamungkas, N.A. Putrisetya
et al.
Ordered pores structureanalysis of mesoporous silica materials using a template of poly(ethylene oxyde)-poly(propylene oxide)-poly(ethylene oxide), PEO-PPO-PEO, triblock copolymer or Pluronics in numerous synthesis conditions has been conducted. Two different length of hydrophilic chain of Pluronics, i.e., P123 (EO20PO70EO20) and F127 (EO106PO70EO106), produced two different fine pore structures, which were basically hexagonal and cubic. A highly ordered pore structure, confirming with many Bragg peaks, was clearly obtained with the lattice parameters in nanometer scale from analyzing the synchrotron small angle X-ray scattering (SAXS) data. Meanwhile, the surface area and pores size of mesoporous silica determined by nitrogen absorption clearly support the analysis of SAXS data, presenting a complete information of pore order characteristics. This paper shows how the synthesis parameters,such as length of hydrophilic chains, silica precursor concentration, Al:Si ratio and synthesis methods, are related to the structure and order of the pores formed. The SAXS patterns show that the pore orderincreases with increasing concentration of sodium silicate and decreases with longer sonication time.