Hasil untuk "Nuclear engineering. Atomic power"

Karina Kohl, Luigi Carro

Software Engineering (SE) faces simultaneous pressure from AI automation (reducing code production costs) and hardware-energy constraints (amplifying failure costs). We position that SE must redefine itself around human discernment-intent articulation, architectural control, and verification-rather than code construction. This shift introduces accountability collapse as a central risk and requires fundamental changes to research priorities, educational curricula, and industrial practices. We argue that Software Engineering, as traditionally defined around code construction and process management, is no longer sufficient. Instead, the discipline must be redefined around intent articulation, architectural control, and systematic verification. This redefinition shifts Software Engineering from a production-oriented field to one centered on human judgment under automation, with profound implications for research, practice, and education.

Kristina D Launey, Grigor H. Sargsyan, Alexis Mercenne et al.

In this review, we discuss recent applications of the ab initio symmetry-adapted no-core shell-model (SA-NCSM) theory for study and prediction of structure and reactions of stable and unstable nuclei from light to medium mass range. We explore structure properties of neutron-rich He, Mg, and Li isotopes, with a focus on nuclear collectivity, clustering, and spectroscopic factors, as well as multi-particle excitations of utmost significance in the proximity of the drip lines. In addition, we present extensions of the SA-NCSM with continuum for determining the microscopic structure of reaction fragments, which enables calculations of reaction cross sections for targets from the lightest $^{4,6}$He to $^{40}$Ca, rooted in first principles. We illustrate this for neutron and proton elastic scattering, deuteron and alpha capture reactions, and alpha knock-out reactions. Furthermore, we discuss microscopic optical potentials with uncertainty quantification, a critical ingredient in many reaction models, and reaction observables with uncertainties that stem from the underlying chiral potential. We also discuss the impact of alpha clustering on reactions of significance to nuclear astrophysics, as well as on beta decays and beyond-the-standard-model physics.

Se-Hwan Park, Byung-Hee Won, Seong-Kyu Ahn

We develop a deep learning model employing a semi-supervised learning approach, which can detect automatically safeguards-related events in nuclear facility from surveillance video. Our model is designed after a comprehensive analysis of the trends in artificial intelligence-based models to identify abnormal events in video. Our model incorporates a reconstruction module and a prediction module independently. The reconstruction module is trained to generate video frames within a sliding window, while the prediction module is trained to predict future motion feature based on the motion features within the video frames in a sliding window. Each module utilizes an autoencoder with a memory module positioned between an encoder and an decoder of the autoencoder. We evaluate the model's performance using a benchmark dataset and a self-produced dataset obtained from facility related to pyroprocessing. Our model's performanace is comparable to or superior to that of the prevous models from the benchmark dataset analysis, and all the abnormal events can be detected without false positive error from the self-produced dataset analysis.

Yoshihiro Kubo, Akifumi Yamaji

The SiC cladded fuel is being developed as a candidate for the accident tolerant fuel of light water reactors, in which the cladding wall consists of the inner SiC/SiC layer and the outer monolithic (mSiC) layer. The FEMAXI-ATF fuel performance modeling code is being developed based on the experience of FEMAXI-7 with the focus on evaluation of the pellet-cladding mechanical interaction (PCMI). In the preceding study, the capability of FEMAXI-ATF to show the PCMI failure limit of the SiC cladded fuel was successfully demonstrated by modeling the SiC/SiC layer with a continuum finite calculation element and reducing Young's modulus of the failed element to practically zero, so that the stress on the cladding wall is redistributed among the remaining cladding wall elements. In this study, FEMAXI-ATF has been further developed to consider pseudo-ductility of SiC/SiC and improvement to the temperature dependent SiC swelling model. The new FEMAXI-ATF was applied in the BWR normal operation conditions to show a possible scenario. That is, the SiC cladded fuel may experience partial failure of the SiC/SiC layer during the reactor shutdown depending on the swelling characteristics of SiC. Consequently, PCMI may induce large mechanical load on the mSiC layer in the subsequent operation.

Teva Meyer

This paper explores the role of intellectual property (IP) in the geopolitics of nuclear energy, addressing the growing importance of patents and technological control in shaping international power dynamics. It investigates two main research questions: how IP rights allocate power in the context of nuclear technologies, and how this power reshapes geopolitical relations in the nuclear industry. Using a mixed-method approach, the study first conducts interviews with nuclear industry stakeholders to identify the geopolitical dimensions of IP in nuclear technologies. This is complemented by a quantitative analysis of 56,310 nuclear energy-related patents, providing insights into the geographic distribution, value, and impact of IP rights. Qualitative results indicate that (1) IP rights allocate power through technological interdependencies, (2) the US can weaponize these interdependencies by using counter-proliferation regulations, (3) IP rights serve strategies to penetrate new geographic markets and as assets to secure funding, (4) patents sustain soft-power narratives. Finally, patenting data nuances previous research on nuclear geopolitics. Russia's dominance appears weaker than expected while the narrative over the supposed decline of Europe and the US is less clear-cut. Simultaneously, China's growing leadership in nuclear patenting activity sustains soft power narratives but fails to translate into geopolitical power as it lacks internationalization.

TAO Yajun, DONG Yongqi, SUN Zhe et al.

BackgroundThe oxygen octahedral rotation (OOR) in perovskite oxides is closely related to its physical properties. The recent development of synchrotron radiation three-dimensional diffraction provides opportunities for efficient characterization of the superlattice half-order peaks corresponding to OOR, but quantitative analysis is still difficult.PurposeThis study aims to provide guidance for the measurement of OOR half-order peaks and lay a foundation for their quantitative analysis through a theoretical simulation of the half-order peak intensity.MethodsFirstly, a universal calculating formula for coordinates of all the oxygen ions in an OOR super cell was provided. Then, starting from the calculation formula of structure factor of a lattice unit cell, a quantitative formula for calculating the half-order peak intensity of lattice with OOR was deduced according to the basic theory of crystal diffraction kinematics. Subsequently, the half-order peak intensity distribution patterns corresponding to the 27 rotation modes were simulated and exhibited by programming, and the appearance rules were summarized. Finally, two typical examples were used to verify the consistency between the simulation results and the measured results.Results & ConclusionsTwo typical examples show that the simulation results are in good agreement with the measured results. Based on these results, the OOR half-order peak pattern can be predicted beforehand and their origins may be verified after hand for experimental measurement of half-order peak. This work may promote the application of synchrotron radiation diffraction in the characterization of perovskite OOR.

Vladimir Ermolaev

Gianfranco Federici, M. Siccinio, C. Bachmann et al.

High temperature superconductors (HTSs) offer the promise of operating at higher magnetic field and temperature. Recently, the use of high field magnets (by adopting HTS) has been promoted by several groups around the world, including new start-up entries, both to substantially reduce the size of a fusion power reactor system and as a breakthrough innovation that could dramatically accelerate fusion power deployment. This paper describes the results of an assessment to understand the impact of using high field magnets in the design of DEMO in Europe, considering a comprehensive list of physics and engineering limitations together with the interdependencies with other important parameters. Based on the results, it is concluded that increasing the magnetic field does not lead to a reduction in device size with relevant nuclear performance requirements, because (i) large structures are needed to withstand the enormous electromagnetic forces, (ii) thick blanket and n-shield structures are needed to protect the coils from radiation damage effects, and (iii) new divertor solutions with performances well beyond today’s concepts are needed. Stronger structural materials allow for more compact tokamaks, but do not change the conclusion that scalability is not favourable when increasing the magnetic field, beyond a certain point, the machine size cannot be further reduced. More advanced structural support concepts for high-field coils have been explored and concluded that these solutions are either unfeasible or provide only marginal size reduction, by far not sufficient to account for the potential of operating at very high field provided by HTS. Additionally, the cost of high field coils is significant at today’s price levels and shows to scale roughly with the square of the field. Nevertheless, it is believed that even when not operated at high field and starting within conventional insulated coils, HTS can still offer certain benefits. These include the simplification of the magnet cooling scheme thanks to increased temperature margin (indirect conduction cooling). This in turn can greatly simplify coil construction and minimize high-voltage risks at the terminals.

M. Gilbert

Abstract Modern nuclear physics software is well validated, providing advanced capabilities to support the engineering of the future generations of fission and fusion reactors. Transport simulators can model the transport of neutrons through reactor geometries, and inventory codes can accurately predict transmutation and activation. Meanwhile, material modeling applies a variety of techniques to understand how structural damage and composition changes will alter the properties of materials, ultimately limiting their usable lifetime in a reactor. Bridging the gap between nuclear simulation tools and materials modeling is a necessary step if these lifetimes are to be accurately predicted, which, for fusion, is critical to provide the necessary assurance of commercial viability. SPECTRA-PKA is a tool developed to compute the rates of structural damage source events, i.e. the primary knock-on atoms (PKAs), using the same nuclear data as used by transport and inventory simulations. Now, it has been interfaced with the binary collision approximation code SDTrimSP, allowing those PKA events, distributed spatially and temporally in an atomic system, to be converted into damage cascades. This computational infrastructure provides insight into the variation in damage distributions between different materials under the same nuclear environment. Example simulations for materials under fusion reactor conditions demonstrate how the rich detail of the nuclear environment can be applied directly to modeling, without the need for integral-average measures that omit those details.

M. V. Supotnitskiy

Currently, there are practically no people left who have seen the consequences of the use of nuclear weapons. This is the reason for certain frivolous statements about the advisability of using tactical nuclear weapons to solve certain tactical problems. The purpose of this work is to remind, using the example of the consequences of the atomic bombings of the cities of Hiroshima and Nagasaki, how does the nuclear war looks like in reality. Materials and Methods. Open sources from the Cold War era and more recent reviews of the consequences of the use of nuclear weapons were analyzed. The analysis was carried out from general to specific, i.e. from the understanding of physical processes underlying a nuclear explosion and determining the design of the nuclear devices, to the specific consequences of their use. Discussion. The article analyses the history of the creation of the «Gadget», «Fat Man» and «Kid» bombs, their design, preparation and the results of the use. Detailed descriptions of nuclear explosions and the consequences of their use, made both by those who used nuclear weapons and by those against whom they were used, are provided. Being imperfect in design and ineffective in using fissile matter, they showed stunning power even for the present time, destroying two densely populated cities and at least 106 thousand people at once. Real examples show the features of the destruction of engineering objects and the impact on people of the damaging factors of a nuclear explosion. Attention is drawn to the fact that the power of the bombs used was 15 and 22 kt, respectively. According to modern NATO classification, these are tactical nuclear weapons. It is designed to destroy targets in the tactical depth of enemy troop deployment (up to 300 km). The maximum power of tactical ammunition according to NATO standards is up to 100 kt. It means that the yield of the tactical ammunition used in battle will depend on the tactical mission, and not be limited to a few kilotons. Conclusions. The use of tactical nuclear weapons without escalating their power, causing large casualties among the population and the risk of being drawn into a global nuclear war is impossible. Currently, the world is oversaturated with nuclear and thermonuclear weapons. Some countries possess them secretly, others have the potential to create such weapons. Therefore, any use of nuclear weapons by anyone will lead to the lowering of the threshold of nuclear deterrence. It will become a common thing during the resolution of military conflicts.

A. Rodríguez-López, B. Savoini, M.A. Monge et al.

This work investigates the influence of composition on the thermal properties of the high entropy alloy family Cu5Cr35Fe35V20-X5 (at. %), where X  = Ti, Ta, W or Mo in the framework of acting as a thermal barrier between the W-based plasma-facing elements and the CuCrZr or Cu-based heat sink components of the fusion reactor. The alloys were produced by arc melting and their microstructure and mechanical properties were previously characterized by XRD, SEM, and Vickers hardness measurements. Thermal properties have been measured on as-cast at thermally treated alloys using the laser flash method in the temperature range 25 °C to 600 °C to determine the thermal diffusivity, α, thermal conductivity, λ, and specific heat, Cp. Dilatometry experiments were also carried out to obtain the linear thermal expansion coefficient, CTE, as a function of temperature.For all materials, the thermal conductivity increases with temperature from 15 W/m·K at RT to 28 W/m·K at 600 °C and does not significantly depend on the thermal treatment for the Mo-HEA and W-HEA, but increases after aging for the Ta-HEA and Ti-HEA. These values are lower than those of W (∼122 W/m·K at 600 °C) and much lower than for CuCrZr-IG (∼354 W/m·K at 400 °C). The thermal expansion coefficients of these HEAs, ∼10 × 10−6 °C−1 at RT and ∼ 2 × 10−6 °C−1 at 650 °C are between those of CuCrZr and the W for the entire operative temperature range. These results indicate that the Cu5Cr35Fe35V20-X5 (X = Ti, Ta, W, Mo) HEAs have a promising combination of the thermophysical properties, λ, Cp and CTE, to act as thermal barrier in plasma-facing components that require the union of W- and Cu-based materials.

R. Nishimura, T. Oishi, I. Murakami et al.

Tungsten (W) is one of the major impurities in ITER and future DEMO reactors. However,diagnosing the ion density, temperature, and spatial distribution of tungsten ions in intermediate charge states, such as W8+-W27+, is difficult because of the lack of spectral line data. In this study, we observed a tungsten Unresolved Transition Array (UTA) spectrum, which has a pseudo-continuum structure, around W20+ in the Extreme Ultraviolet wavelength region in the Large Helical Device (LHD). We conducted Collisional-Radiative (CR) modeling for W17+-W25+. Two pseudo-continuum peaks corresponding to 5 s-5p transition and transition between doubly excited states of 5 s2-5s5p, are strongly emitted around 200 Å for each ion. The synthesized spectrum of W17+-W25+ ions reproduced the observed LHD spectrum near 200 Å. From the electron temperature dependence of the UTA spectral shape, the UTA shifted toward longer wavelength region with several pseudo-continuum peaks appearing for ions in lower charge states, with decreasing electron temperature from 0.4 keV to 0.2 keV. This result qualitatively explained the observed time evolution of the spectrum.

Donkoan Hwang, Soon Ho Kang, Nakjun Choi et al.

In nuclear thermal-hydraulic system codes, most correlations used for vertical pipes, under downward two-phase flow, have been developed considering small pipes or pool systems. This suggests that there could be uncertainties in applying the correlations to accident scenarios involving large vertical pipes owing to the difference in the characteristics of two-phase flows, or flow conditions, between large and small pipes. In this study, we modified the Multi-dimensional Analysis of Reactor Safety KINS Standard (MARS-KS) code using correlations, such as the drift-flux model and two-phase multiplier, developed in a plant-scale air-inflow experiment conducted for a pipe of diameter 600 mm under downward two-phase flow. The results were then analyzed and compared with those based on previous correlations developed for small pipes and pool conditions. The modified code indicated a good estimation performance in two plant-scale experiments with large pipes. For the siphon-breaking experiment, the maximum errors in water flow for modified and original codes were 2.2% and 30.3%, respectively. For the air-inflow accident experiment, the original code could not predict the trend of frictional pressure gradient in two-phase flow as ⟨jg⟩/⟨j⟩ increased, while the modified MARS-KS code showed a good estimation performance of the gradient with maximum error of 3.5%.

A. Šagátová

This university textbook provides the first part of basic knowledge in nuclear physics and technology. It focuses on the correct understanding of the problematics of radioactivity of atomic nuclei. The textbook describes the structure and forces of atomic nuclei with background in standard model of elementary particles. It discusses the radioactive decay law as well as the activation of atomic nuclei. It offers the overview of stabilisation of radioactive nuclei via radioactive decay, gamma emission or spontaneous fission. At the end of individual chapters, students will find exercises for practicing their correct understanding of the discussed topics: the atomic nuclei, the radioactivity and the radioactive decays. All exercises are based on real examples with actual parameters of nuclei. The correct answers to problems can be found in the rear part of the textbook. The textbook also responds to the recent methods and knowledge in the field of nuclear physics and encourages the students to use the global databases involving latest results of world leading research centres in nuclear physics and technology. The textbook is primary dedicated to the students of nuclear power engineering and nuclear technology, but it can also enrich students of other study fields of natural science and technology, as well as the employees in the nuclear power engineering with a different background than nuclear.

J. Elbez-Uzan, Laurence Williams, Sarah M Forbes et al.

The discussion in the international community on how fusion power plants (FPPs) will be licenced and regulated is ongoing. As such, there is a concerted drive from the European stakeholders to understand the requirements from such a framework and how to best establish it with the aim of easing the licensing process of FPPs. Initiated by the EUROfusion consortium, a group of European experts were convened to produce a set of recommendations on the regulatory framework for the safety and licensing of FPPs. To do so effectively, the group assessed lessons learned from existing fusion facilities, reports by International Atomic Energy Agency and European Commission on FPP safety and the on-going work by the UK government, US Nuclear Regulatory Commission and Canadian Nuclear Safety Commission, as well as the licensing process of ITER. As a result, commonalities between fusion and fission were identified in terms of fundamental safety objectives which could facilitate parity in certain framework aspects. However, significant differences to any such implementation were also identified, particularly with respect to the lower hazard potential inherent to FPPs and how to remain proportionate to the associated safety challenges and the physical principles behind these two types of reactors together with their associated technologies. The recognition of the differences in the safety challenges in FPPs and fission-based nuclear power plants (NPPs) is paramount to future regulatory framework development. Ultimately, regulatory frameworks depend upon a country’s legal framework, therefore it is apparent that a common global regulatory framework for FPPs is not possible. However, as with present-day NPP regulation, efforts could be made to develop harmonised approaches to FPP regulation to provide common levels of protection. In view of this objective, 12 recommendations are presented across 4 topics: regulations, international databases, codes and standards, safety demonstration rules and regulatory approaches. These recommendations are provided to inform and advise potential future actions on FPP regulatory framework and licencing process principles.

R. Stewart, T. Palmer, Bryony DuPont

Abstract Problems in nuclear engineering – such as reactor core design – involve a multitude of design variables including fuel or assembly configurations; all of which require careful consideration when constrained by a set of objectives such as fuel temperature or assembly power density. Reactor design is one facet of nuclear engineering, where many nuclear engineers often face large multi-objective problems to solve. These types of problems can be solved by relying upon experts to aid in reducing the design space required for multi-objective optimization, however, computational optimization algorithms have been used to generate optimal solutions with reproducibility and quantitative evidence for designs. We present a review of multi-objective optimization literature including an introduction to optimization theory, commonly used multi-objective optimization algorithms, and current applications in nuclear science and engineering. From this review, researchers will glean an understanding of multi-objective optimization algorithms that are currently available, and gain a fundamental understanding of how to apply these techniques to a wide variety of problems in the fields of nuclear science and engineering.

V. Telnov, Y. Korovin

The paper deals with issues of designing and creating knowledge bases in the field of nuclear science and technology. The authors present the results of searching for and testing optimal classification and semantic annotation algorithms applied to the textual network content for the convenience of computer-aided filling and updating of scalable semantic repositories (knowledge bases) in the field of nuclear physics and nuclear power engineering and, in the future, for other subject areas, both in Russian and English. The proposed algorithms will provide a methodological and technological basis for creating problem-oriented knowledge bases as artificial intelligence systems, as well as prerequisites for the development of semantic technologies for acquiring new knowledge on the Internet without direct human participation. Testing of the studied machine learning algorithms is carried out by the cross-validation method using corpora of specialized texts. The novelty of the presented study lies in the application of the Pareto optimality principle for multi-criteria evaluation and ranking of the studied algorithms in the absence of a priori information about the comparative significance of the criteria. The project is implemented in accordance with the Semantic Web standards (RDF, OWL, SPARQL, etc.). There are no technological restrictions for integrating the created knowledge bases with third-party data repositories as well as metasearch, library, reference or information and question-answer systems. The proposed software solutions are based on cloud computing using DBaaS and PaaS service models to ensure the scalability of data warehouses and network services. The created software is in the public domain and can be freely replicated.

A. F. Fantina, F. Gulminelli

In this contribution, we briefly present the equation-of-state modelling for application to neutron stars and discuss current constraints coming from nuclear physics theory and experiments. To assess the impact of model uncertainties, we employ a nucleonic meta-modelling approach and perform a Bayesian analysis to generate posterior distributions for the equation of state with filters accounting for both our present low-density nuclear physics knowledge and high-density neutron-star physics constraints. The global structure of neutron stars thus predicted is discussed in connection with recent astrophysical observations.

C.A. Johnson, E.A. Unterberg, D.A. Ennis et al.

Current spectroscopic based erosion diagnostics require both Te and ne measurements in addition to detailed atomic physics and collisional radiative (CR) modeling. Machine Learning (ML) techniques are used to address the temperature measurement requirement for erosion diagnosis. ML techniques are combined with tungsten spectroscopic diagnosis trained with co-located Langmuir probe measurements in the Compact Toroidal Hybrid (CTH) to obtain a spectroscopic based local electron temperature diagnostic. Initial analysis using synthetic data and a Neutral Network (NN) suggests a temperature diagnostic obtained with experimental data is feasible. ML methods have the potential to bypass sources of error in traditional tungsten erosion diagnosis by taking the place of required atomic and CR modeling which introduce inherent uncertainties. Temperature diagnosed could be used as input to current erosion diagnosis techniques (the S/XB method).

P. Muscente, P. Innocente, J. Ball et al.

One of the major problems for future tokamak devices are ELMs (Edge Localized Modes) as they can lead to large, uncontrolled heat fluxes at the machine targets. For this reason, different techniques and alternative magnetic configurations are under study to mitigate or avoid these phenomena. One of the most promising among these studies is the Negative Triangularity (NT) configuration, which exhibits a global confinement comparable with H-Mode operation and, staying in L-mode, could enable an easier power exhaust dissipation due to a possible bigger heat flux decay length with respect to the conventional Positive triangularity (PT) H-mode. In this work, the fluid code SOLEDGE2D-EIRENE is used to study edge transport. Studies are made on discharges performed in the TCV device (Tokamak à configuration variable), which can create a variety of different plasma geometries thanks to 16 independently powered poloidal field coils and its open vacuum vessel. In order to understand if and how power and particle exhaust in NT differs with respect to those of the PT shape, four discharges in single null magnetic divertor configuration with fixed lower triangularity (δbot = +0.5) but with different upper triangularity (from δup = −0.28 to δup = +0.45) have been modelled. All of them are ohmically heated, L-mode deuterium plasmas, and in the high recycling regime. Moreover, these discharges were previously used in [4] to measure the heat flux decay length by IRT (Infrared Thermography), allowing us to make comparisons with modelling results.