Hasil untuk "Nuclear engineering. Atomic power"

Marino Corrado, Francesca Crivelli, Silvio Cao et al.

The HYPEX^® process is a novel method for conditioning spent ion exchange resins from nuclear power plants, aiming to reduce final waste volume and carbon emissions by stabilizing the resins in metakaolin-based geopolymers. This study addresses the challenge posed by the natural variability of commercial metakaolin and defines a testing strategy to ensure consistent performance of the final matrix. The reactivity of two batches of metakaolin, characterized by comparable chemical composition and BET surface area, was evaluated by monitoring temperature evolution during geopolymerization at varying water-to-solid ratios. The resulting geopolymers were tested for compressive strength, water permeability, and strontium leachability to assess correlations between precursor properties and final matrix performance. Despite similar compositions, the two batches showed marked differences in compressive strength that could be linked to early thermal behavior. These findings demonstrate that conventional precursor characterization is insufficient to guarantee reproducibility and that thermal profiling is useful to predict mechanical performance. The results suggest the implementation of thermal response monitoring as a quality control tool to ensure the reliability of geopolymer wasteforms in nuclear applications. A simplified analytical model for the thermal evolution during geopolymerization was also developed, matching qualitatively the measured evolution, to suggest scale-up rules from laboratory specimens to full-scale drums, which should be achieved while preserving the thermal evolution.

Jungsik Choi, Jeongmin Oh, Taeyoung Ko et al.

Loose parts in the primary systems of nuclear power plants pose a significant safety risk as they can collide with equipment inner surfaces, particularly in high-velocity areas like the steam generator. Such collisions, especially near welded joints in the steam generator tubes, can cause cracks and lead to coolant leakage. To mitigate these risks, nuclear plants use loose parts monitoring systems that trigger alarms based on rule-based algorithms. However, current methods rely on the analyst's proficiency, and timely analysis is challenging. To address these issues, this paper proposes a convolutional neural network (CNN) model to estimate the mass of any detected loose parts and their impact location. The CNN model uses a position-invariant loss function derived from Cartesian coordinates and the Wigner-Ville distribution. The proposed method is validated using impact signals acquired from a quarter-scale testbed specifically designed to simulate a nuclear power plant's primary system steam generator. This study experimentally confirms that the proposed method can estimate the impact location and mass of internal loose parts in three-dimensional structures more accurately and rapidly than existing methods.

赵 正成, 罗 皓天, 赵 亚楠 et al.

兆瓦级核反应堆结合氦氙布雷顿循环系统能有效满足大型深空探测器、星表基地、深海无人潜航器等特种能源动力装置对大功率、小型化、高可靠电源供应的需求，具有广阔的应用前景和研究价值。目前对氦氙混合气体在非理想状态下的物性研究尚不充分，本文构建了非理想状态下氦氙混合气体的物性计算模型，采用浸没式次临界安全空间反应堆氦氙布雷顿循环系统为研究对象，对氦氙混合气体物性模型进行了验证，分析了不同温度、压力和氦气摩尔分数下氦氙混合气体的物性对绝热系数、相对压损和相对对流换热系数等氦氙布雷顿循环系统热力性能关键参数的影响规律及对热力设备选型的影响。

Carlos A. Bertulani

We investigate aspects of low-energy nuclear reactions that could be explored at the forthcoming Electron-Ion Collider (EIC) at Brookhaven National Laboratory and compare them with analogous measurements performed in ultraperipheral collisions (UPCs) at the Large Hadron Collider (LHC) at CERN. The estimated fragmentation cross sections at the EIC are roughly three orders of magnitude smaller than those observed at the LHC. At the LHC, uranium nucleus fragmentation exhibits a distinctive double-peaked mass spectrum arising from fission processes, whereas at the EIC, the breakup pattern is mainly characterized by neutron evaporation and a vastly reduced yield of fission fragments, about four orders of magnitude fewer events in comparison.

G. P. A. Nobre, R. Capote, M. T. Pigni et al.

The ENDF/B-VIII.1 library is the newest recommended evaluated nuclear data file by the Cross Section Evaluation Working Group (CSEWG) for use in nuclear science and technology applications, and incorporates advances made in the six years since the release of ENDF/B-VIII.0. Among key advances made are that the $^{239}$Pu file was reevaluated by a joint international effort and that updated $^{16,18}$O, $^{19}$F, $^{28-30}$Si, $^{50-54}$Cr, $^{55}$Mn, $^{54,56,57}$Fe, $^{63,65}$Cu, $^{139}$La, $^{233,235,238}$U, and $^{240,241}$Pu neutron nuclear data from the IAEA coordinated INDEN collaboration were adopted. Over 60 neutron dosimetry cross sections were adopted from the IAEA's IRDFF-II library. In addition, the new library includes significant changes for $^3$He, $^6$Li,$^9$Be, $^{51}$V, $^{88}$Sr, $^{103}$Rh, $^{140,142}$Ce, Dy, $^{181}$Ta, Pt, $^{206-208}$Pb, and $^{234,236}$U neutron data, and new nuclear data for the photonuclear, charged-particle and atomic sublibraries. Numerous thermal neutron scattering kernels were reevaluated or provided for the very first time. On the covariance side, work was undertaken to introduce better uncertainty quantification standards and testing for nuclear data covariances. The significant effort to reevaluate important nuclides has reduced bias in the simulations of many integral experiments with particular progress noted for fluorine, copper, and stainless steel containing benchmarks. Data issues hindered the successful deployment of the previous ENDF/B-VIII.0 for commercial nuclear power applications in high burnup situations. These issues were addressed by improving the $^{238}$U and $^{239,240,241}$Pu evaluated data in the resonance region. The new library performance as a function of burnup is similar to the reference ENDF/B-VII.1 library. The ENDF/B-VIII.1 data are available in ENDF-6 and GNDS format at https://doi.org/10.11578/endf/2571019.

Lekshmi Murali Rani, Richard Berntsson Svensson, Robert Feldt

The integration of AI for Requirements Engineering (RE) presents significant benefits but also poses real challenges. Although RE is fundamental to software engineering, limited research has examined AI adoption in RE. We surveyed 55 software practitioners to map AI usage across four RE phases: Elicitation, Analysis, Specification, and Validation, and four approaches for decision making: human-only decisions, AI validation, Human AI Collaboration (HAIC), and full AI automation. Participants also shared their perceptions, challenges, and opportunities when applying AI for RE tasks. Our data show that 58.2% of respondents already use AI in RE, and 69.1% view its impact as positive or very positive. HAIC dominates practice, accounting for 54.4% of all RE techniques, while full AI automation remains minimal at 5.4%. Passive AI validation (4.4 to 6.2%) lags even further behind, indicating that practitioners value AI's active support over passive oversight. These findings suggest that AI is most effective when positioned as a collaborative partner rather than a replacement for human expertise. It also highlights the need for RE-specific HAIC frameworks along with robust and responsible AI governance as AI adoption in RE grows.

Daniel Mendez, Paris Avgeriou, Marcos Kalinowski et al.

Empirical Software Engineering has received much attention in recent years and became a de-facto standard for scientific practice in Software Engineering. However, while extensive guidelines are nowadays available for designing, conducting, reporting, and reviewing empirical studies, similar attention has not yet been paid to teaching empirical software engineering. Closing this gap is the scope of this edited book. In the following editorial introduction, we, the editors, set the foundation by laying out the larger context of the discipline for a positioning of the remainder of this book.

Lu Zhang, Xiaoyang Lian, Jie Chen et al.

Objective: The objective of this study was to utilize ultrasonography to measure the movement-related characteristics of the hyoid bone-mandible in patients with dysphagia in order to quantitatively evaluate the clinical efficacy of acupuncture as a treatment for dysphagia following brain infarction. Methods: A total of 63 patients with dysphagia following a brain infarction were randomly assigned into two groups: one receiving meridian point treatments and the other receiving non-meridian and non-point treatments. The meridian point group received routine treatment using the meridian point acupuncture method, and the true acupuncture intervention mode of qi arrival plus swift pricking blood therapy was utilized. The non-meridian and non-acupoint group received conventional treatment using the pseudo-acupuncture mode of non-acupoint without qi arrival. Both groups received treatment once daily, five times per week, for a duration of four weeks. Video fluoroscopic swallowing study (VFSS) was used to diagnose dysphagia in all patients, and FOIS and PAS were also used for clinical assessment. Results: (i) Clinical efficacy comparison: After 4 weeks of treatment, the meridian group showed superior efficacy compared to the non-meridian and non-acupuncture group (P < 0.05). The FOIS score of the meridian acupoint group was also higher than that of the non-meridian and non-acupoint group (P < 0.05). In addition, the dilute fluid food PAS score in the meridian acupoint group was lower than that in the non-meridian and non-acupoint group (P < 0.05). (ii) Comparison of ultrasonography: The hyoid-mandibular comparison of the shortening distance, shortening rate, and movement speed of the bone movement were measured in both groups after 2 weeks and 4 weeks of treatment. The results indicated that the improvement in the meridian group was better than that in the non-meridian and non-acupoint group in all measurements (P < 0.05). Conclusion: Patients with swallowing disorders exhibit impaired hyoid-mandibular movement. However, the implementation of true acupuncture intervention can enhance hyoid-mandibular movement function, ultimately leading to an improvement in swallowing function.

Romano Paul, Tramm John, Shriwise Patrick

The OpenMC Monte Carlo particle transport code has been continuously developed for 13 years by a large community of contributors. In that time span, the codebase has undergone significant changes that have redefined what OpenMC is and made it an enduring presence in the nuclear science and engineering community. In this paper, we discuss the evolution of programming language use in OpenMC, trends in the overall design of the programming interfaces, and implications for the future of the code.

Pikkin Lau, Lingfeng Wang, Wei Wei et al.

In this paper, a novel cyber-insurance model design is proposed based on system risk evaluation with smart technology applications. The cyber insurance policy for power systems is tailored via cyber risk modeling, reliability impact analysis, and insurance premium calculation. A stochastic Epidemic Network Model is developed to evaluate the cyber risk by propagating cyberattacks among graphical vulnerabilities. Smart technologies deployed in risk modeling include smart monitoring and job thread assignment. Smart monitoring boosts the substation availability against cyberattacks with preventive and corrective measures. The job thread assignment solution reduces the execution failures by distributing the control and monitoring tasks to multiple threads. Reliability assessment is deployed to estimate load losses convertible to monetary losses. These monetary losses would be shared through a mutual insurance plan. To ensure a fair distribution of indemnity, a new Shapley mutual insurance principle is devised. Effectiveness of the proposed Shapley mutual insurance design is validated via case studies. The Shapley premium is compared with existent premium designs. It is shown that the Shapley premium has high indemnity levels closer to those of Tail Conditional Expectation premium. Meanwhile, the Shapley premium is nearly as affordable as the coalitional premium and keeps a relatively low insolvency probability.

Jukka Ruohonen, Kalle Hjerppe

Participatory citizen platforms are innovative solutions to digitally better engage citizens in policy-making and deliberative democracy in general. Although these platforms have been used also in an engineering context, thus far, there is no existing work for connecting the platforms to requirements engineering. The present paper fills this notable gap. In addition to discussing the platforms in conjunction with requirements engineering, the paper elaborates potential advantages and disadvantages, thus paving the way for a future pilot study in a software engineering context. With these engineering tenets, the paper also contributes to the research of large socio-technical software systems in a public sector context, including their implementation and governance.

Mehil B Shah, Mohammad Masudur Rahman, Foutse Khomh

Deep learning (DL) techniques have achieved significant success in various software engineering tasks (e.g., code completion by Copilot). However, DL systems are prone to bugs from many sources, including training data. Existing literature suggests that bugs in training data are highly prevalent, but little research has focused on understanding their impacts on the models used in software engineering tasks. In this paper, we address this research gap through a comprehensive empirical investigation focused on three types of data prevalent in software engineering tasks: code-based, text-based, and metric-based. Using state-of-the-art baselines, we compare the models trained on clean datasets with those trained on datasets with quality issues and without proper preprocessing. By analysing the gradients, weights, and biases from neural networks under training, we identify the symptoms of data quality and preprocessing issues. Our analysis reveals that quality issues in code data cause biased learning and gradient instability, whereas problems in text data lead to overfitting and poor generalisation of models. On the other hand, quality issues in metric data result in exploding gradients and model overfitting, and inadequate preprocessing exacerbates these effects across all three data types. Finally, we demonstrate the validity and generalizability of our findings using six new datasets. Our research provides a better understanding of the impact and symptoms of data bugs in software engineering datasets. Practitioners and researchers can leverage these findings to develop better monitoring systems and data-cleaning methods to help detect and resolve data bugs in deep learning systems.

M. Amenomori, S. Asano, Y. Bao et al.

Gamma rays from HESS J1849−000, a middle-aged TeV pulsar wind nebula (PWN), are observed by the Tibet air shower array and the muon detector array. The detection significance of gamma rays reaches 4.0σ and 4.4σ levels above 25 TeV and 100 TeV, respectively, in units of the Gaussian standard deviation σ. The energy spectrum measured between 40 TeV < E < 320 TeV for the first time is described with a simple power-law function of dN/dE=(2.86±1.44)×10−16(E/40TeV)−2.24±0.41TeV−1cm−2s−1 . The gamma-ray energy spectrum from the sub-TeV (E < 1 TeV) to sub-PeV (100 TeV < E < 1 PeV) ranges, including the results of previous studies, can be modeled with the leptonic scenario, i.e., inverse Compton scattering by high-energy electrons accelerated by the PWN of PSR J1849−0001. On the other hand, the gamma-ray energy spectrum can also be modeled with the hadronic scenario in which gamma rays are generated from the decay of neutral pions produced by collisions between accelerated cosmic-ray protons and the ambient molecular cloud found in the gamma-ray-emitting region. The cutoff energy of cosmic-ray protons E p,cut is estimated as log10(Ep,cut/TeV)=3.73−0.66+2.98 , suggesting that protons are accelerated up to the PeV energy range. Our study thus proposes that HESS J1849−000 should be further investigated as a new candidate as a Galactic PeV cosmic-ray accelerator, or “PeVatron.”

H. Choi, D. Leer, M. Virgen et al.

Abstract General Atomics is developing a new 100-MW(thermal) fast modular reactor (FMR) that provides safe, carbon-free electricity and is capable of incremental capacity additions. The modular design allows it to be factory built and assembled onsite to keep the capital cost low, while the use of dry cooling facilitates siting to complement renewables in nearly any location. The FMR uses high-assay low-enriched uranium-dioxide fuel encapsulated by recognized irradiation-resistant silicon carbide composite (SiGA®) cladding that is derisked in the current accident-tolerant fuel program. The FMR fuel assembly is a hexagonal fuel bundle of 120 fuel rods. The total length of the fuel assembly is less than 4 m, with an active fuel length of 1.8 m. The fuel assemblies are configured in an annular core that is located and supported by the reactor internals. The coolant material is helium at a normal operating pressure of 7 MPa. The core is surrounded by zirconium silicide (Zr3Si2) and graphite reflector blocks. The fuel, coolant, internals, and reflectors are contained within a reactor pressure vessel. The preliminary nuclear design and analysis established the arrangement of the active core and reflector blocks. The nuclear design analyses of the FMR defined the design parameters, such as fuel enrichments, excess reactivity, fueling scheme, fuel cycle, power distribution, and control rod worth. The preliminary conceptual design determined the three-batch fueling scheme with the allowable total power peaking factor of 1.5. The average discharge burnup is 100 GW days per ton of uranium.

LIU Haoran, ZHOU Qianqian, LIANG Juncheng et al.

Background55Fe is a low-energy radionuclide that is difficult to measure and decays to a ground state of 55Mn through pure electron capture (EC), accompanied by the emission of Auger electrons and low-energy X-ray. As iron is the main component of nuclear reactor building materials, significant amounts of 55Fe have been produced in nuclear reactors and other neutron-producing nuclear facilities.PurposeThis study aims to develop an 55Fe nuclide standard through the absolute measurement of 55Fe activity and provides activity traceability services for 55Fe measuring instruments to ensure the accuracy and consistency of the measurement results of calibration instruments.MethodsThe liquid scintillation triple-to-double coincidence ratio (TDCR) method was applied to determining the activity of 55Fe. First, based on nuclear and atomic data of 55Fe, the electron deposition spectrum of 55Fe in a scintillator was calculated using a random atomic rearrangement model. Second, the counting efficiency of single-energy electron was computed based on the free parameter model. The total efficiency curve of 55Fe was then obtained by summing the efficiency of all deposited electrons. Finally, the experimental counting efficiency was derived by measuring the TDCR value and combining it with the total efficiency curve to realize an absolute measurement of 55Fe activity.ResultsThe experimental results show that correction factors for the asymmetric effect of photomultiplier tube (PMT) quantum efficiency obtained on test samples are between 1.001 and 1.005. The measured specific activity of 55Fe is 94.15 kBq∙g-1 with a relative standard uncertainty of 0.45%. Experimental efficiency is better than 63% for double coincidence logic sum of liquid scintillation counter.ConclusionsThis study demonstrates that low relative standard uncertainty of 55Fe activity could be achieved using the liquid scintillation TDCR method with high detection efficiency, and more consistent measurement results can be obtained after applying the asymmetry correction of PMT quantum efficiency.

Yaju Zhou, Shengming Yin, Qilai Zhou et al.

This work aims at exploring the irradiation resistance of oxide-dispersion-strengthened reduced-activation ferritic/martensitic (ODS-RAFM) steel prepared by a rapid and cost-efficient method, wire and arc additive manufacturing (WAAM). WAAM ODS-RAFM steel and RAFM steel were prepared using flux cored wires with and without addition of Y2O3, respectively. Both specimens were irradiated with 2.5 MeV Fe ions at 450 °C to a fluence of 1.84 × 1016 ions cm−2, corresponding to a peak damage dose of 20 dpa. The microstructure, hardness and defect structure of WAAM ODS-RAFM steel before and after irradiation were investigated and compared with RAFM steel. It is found that nano-Y2Ti2O7 particles with a high number density (∼10 nm, 1022/m3) are formed in WAAM ODS-RAFM steel, which pin grain boundary and dislocations motion, thus rendering a stable matrix structure after irradiation. The particle size of the stable nano-Y2Ti2O7 slightly increases to ∼ 15 nm while its number density is still high (1022/m3) after irradiation. The grain boundaries, dislocations and nano-Y2Ti2O7 interfaces act as defect sinks to absorb irradiation-induced defects such as self-interstitial atoms and vacancies. Therefore, small dislocation loops (3.6 nm) are found to be the main irradiation defects while no voids are observed. As a result of the inhibited formation and growth of defects, the irradiation hardening is insignificant (ΔH0 = 0.16 GPa), showing great promises of WAAM ODS-RAFM steel as structural components in future fusion reactors.

LIU Yang, MA Haibin, WU Lixiang et al.

BackgroundFeCrAl alloy cladding, as an accident tolerant fuel (ATF) mid-term commercial technology approach, has received extensive attention.PurposeThis study aims to investigate the effect of trace Y on the internal pressure burst and oxidation properties of FeCrAl alloy cladding.MethodsFirstly, the crystalline grain size and micro-morphologies of FeCrAl and FeCrAlY alloy cladding samples were observed by optical microscope. Internal pressure burst and high temperature oxidation tests were carried out by burst test equipment and thermo-gravimetric analyzer with a moisture generator. Then, X-ray diffractometry (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) were employed to analyze the composition of oxidation products, surface and cross-sectional micro-morphologies of FeCrAl and FeCrAlY alloy cladding samples before and after high-temperature stream oxidation and the distribution of elements on the surface oxidation products.ResultsThe results show that trace Y is mainly dissolved in the FeCrAl alloy matrix, and no Fe-Y phase is formed. The inclusion of Y do not change the burst strength and the rupture opening morphology at room temperature (RT) to 1 000 ℃, and the high-temperature steam oxidation resistance of FeCrAl alloy cladding is significantly improved by the trace Y. Under the condition of steam oxidation at 800 ℃, 1 000 ℃ and 1 200 °C for 8 h, the oxidation weight gain of FeCrAlY alloy cladding decrease by 65.1%, 60.0% and 31.5%, respectively. Compared with the single Al2O3 oxide film on the surface of FeCrAl alloy cladding, the Y-containing composite oxide film with lower internal stress, higher compactness and better adhesion with the substrate is formed on the surface of FeCrAlY alloy cladding.ConclusionsTherefore, the addition of trace Y do not change the burst properties of FeCrAl alloy cladding, however, the high-temperature steam oxidation resistance of FeCrAl alloy cladding is significantly improved.

Yaohou Fan, Chetan Arora, Christoph Treude

Stop words, which are considered non-predictive, are often eliminated in natural language processing tasks. However, the definition of uninformative vocabulary is vague, so most algorithms use general knowledge-based stop lists to remove stop words. There is an ongoing debate among academics about the usefulness of stop word elimination, especially in domain-specific settings. In this work, we investigate the usefulness of stop word removal in a software engineering context. To do this, we replicate and experiment with three software engineering research tools from related work. Additionally, we construct a corpus of software engineering domain-related text from 10,000 Stack Overflow questions and identify 200 domain-specific stop words using traditional information-theoretic methods. Our results show that the use of domain-specific stop words significantly improved the performance of research tools compared to the use of a general stop list and that 17 out of 19 evaluation measures showed better performance. Online appendix: https://zenodo.org/record/7865748

Dulaji Hidellaarachchi, John Grundy, Rashina Hoda et al.

Context: Requirements Engineering (RE)-related activities are critical in developing quality software and one of the most human-dependent processes in software engineering (SE). Hence, identifying the impact of diverse human-related aspects on RE is crucial in the SE context. Objective: Our study explores the impact of one of the most influential human aspects, motivation on RE, aiming to deepen understanding and provide practical guidance. Method: By conducting semi-structured interviews with 21 RE-involved practitioners, we developed a theory using socio-technical grounded theory(STGT) that explains the contextual, causal, and intervening conditions influencing motivation in RE-related activities. Result: We identified strategies to enhance motivating situations or mitigate demotivating ones, and the consequences resulting from applying these strategies. Conclusion: Our findings offer actionable insights for software practitioners to manage the influence of motivation on RE and help researchers further investigate its role across various SE contexts in the future.

A. I. Alwaheba, V. I. Surin, T. E. Ivanova et al.

Scanning contact potentiometry (SCP) is used for defects detection and for determine the coordinates of the defects localized in welded joints. Studied samples are welded by manual arc welding of two halves austenitic steel 321H (Chromium-Nickel-titanium stainless Steel) dimension of each 200×110×13.5 mm. Thereafter welding, seam width is about 12 mm. Subsequently welded sample is inspected using X-ray radiographic testing system. In order to compare techniques capabilities, plotted potentiograms and weld radiograph are compared. Experimental outcomes prove that defects can be detected by SCP technique. SCP results are complied with mathematical signal analysis of defects. This method may substitute some destructive or nondestructive methods.