Vitaly Mechinsky, Elizaveta Borisevich, Andrei Fedorov
et al.
Binary thin detecting elements on a base of 6Li2O∗2SiO2:Ce/7Li2O∗2SiO2:Ce:Ce glass and Gd1.5Y1.5Al2.5Ga2.5O12:Ce,Mg/Y3Al2.5Ga2.5O12:Ce,Mg ceramic scintillators were evaluated for detection of neutrons. Coupling in the detecting unit of neutron-sensitive and insensitive materials with separate photosensors allows the application of different techniques to discriminate gamma-rays background. Sufficient difference in scintillation kinetics of Gd1.5Y1.5Al2.5Ga2.5O12:Ce and Y3Al2.5Ga2.5O12:Ce,Mg allows pulse shape discrimination of gamma-rays of the same energy in a phoswich detecting unit when one photosensor is utilized.
The present study investigated the effect of D2-N2 (7%) plasma exposure in Magnum-PSI on the D retention and chemical and mechanical properties of a porous W-O (p-W-O) coating. The variation of the chemical composition, crystalline phase and mechanical properties along the sample surface were determined by Nuclear Reaction Analysis (NRA), Rutherford Backscattering Spectroscopy (RBS), nanoindentation and Raman spectroscopy. These changes were compared to the Laser-Induced Breakdown Spectroscopy (LIBS) measurements. LIBS depth profiles of W and Mo were consistent with the profiles determined by NRA and RBS, showing a W-O layer, a thin W adhesion layer and a Mo substrate. Typically, the high D intensity was determined only during the first LIBS laser shot on a measurement spot, while the spatial distribution of D intensity determined by LIBS along the coating surface followed the D concentration determined by NRA. According to the Raman spectra, the investigated p-W-O coating corresponded to nanograins of W-O and the phase composition was relatively uniform along the coating surface. The elastic modulus of p-W-O coating was considerably lower than the modulus of Mo coating or bulk W coating and corresponded to the values found in other studies carried out with W-O mixtures. The elastic modulus of p-W-O coating decreased towards the edge of the coating. The study revealed that the modulus and the background intensity of the LIBS spectra had a negative correlation, suggesting that LIBS may be a suitable method for the estimation of the stiffness of tungsten co-deposits as a similar correlation is shown for other types of W coatings.
Thermophysical properties are reported on ε-HfH2 samples fabricated by powder metallurgy. Samples were heat treated in the range 300–550 °C to transform them from ε-HfH2 to δ-HfH1.6-x, allowing comparison of the properties of both phases. Higher molar heat capacity was found in stoichiometric ε-HfH2 compared to literature data on sub-stoichiometric ε-HfH1.83. The δ-phase undergoes a vacancy order–disorder transformation at ∼130 °C with a transformation enthalpy of ∼1.4 kJ mol−1. The room-temperature thermal diffusivity of the ε and δ phases were 0.11 and 0.09 cm2 s−1 respectively. These values are lower than those for literature bulk hydride materials, which is accounted for by pore-phonon scattering. Thermal expansion of ε and δ phases was measured by high-temperature X-ray diffraction to be 9.2 and 11 x10-6 K−1, respectively. The data on the ε phase is the first known in the literature. The thermal expansion was highly anisotropic, with a negative thermal expansion parallel to the a-axis (Ra = −8.7). Such extreme anisotropy has implications in controlling the microstructure for thermal damage tolerance.
A water calorimeter has been used to establish the measurement standard of absorbed dose to water for 60Co gamma-ray beams. While heat defect and heat conduction have been thoroughly investigated in previous studies, the uncertainty in temperature rise measurement has not received the same level of attention. This work re-evaluated that component, identifying the dominant contributions from type A uncertainty due to repeated irradiation experiments (0.10 %), sensitivity calibration of the bridge circuit (0.075 %), and the extrapolation procedure used to determine signal change (0.07 %). Other sources, such as thermistor calibration and resistance measurements, contributed 0.047 %. As a result, the standard uncertainty of the temperature rise measurement was estimated to be 0.15 %, leading to a combined standard uncertainty of 0.26 % for the absorbed dose to water.
The proposed methodology entails the utilization of surface sterilization using a nanosecond electron beam. This approach has demonstrated efficacy in the sterilization of products characterized by inedible shells, such as eggs, or sterility from pathogens throughout the volume under standard manufacturing or processing conditions (e.g., pieces of meat and meat products, animal feed pellets, etc.). Importantly, the primary product is shielded from direct electron beam irradiation, thereby preventing any adverse alterations, including the embryo which is not affected. The application and successful implementation of the suggested technology are illustrated through specific examples.
Renaud Dejarnac, Jiří Matějíček, Henri Greuner
et al.
Coating Inconel tiles by tungsten is a necessary step towards the full tungsten first wall coverage of the COMPASS-U tokamak. Thin tungsten coatings on Inconel based on physical vapor deposition were successfully produced consequently to a programme of R&D within the COMPASS Upgrade project by three different suppliers. This contribution presents the qualification phase of these tungsten coatings under COMPASS-U relevant high heat fluxes (50 cycles at 10 MW/m2, 100 cycles at 30 MW/m2) in the neutral beam test facility GLADIS. The behavior of the different tungsten coatings during exposures and the main conclusions from the post-mortem analysis are presented. The most important result is that under COMPASS-U relevant heat fluxes, no damage was observed on the front face of all samples, proving the practicability of such coatings for fusion application.
Santiago Bermudez, Furkan Erdogan, Victoria Davis
et al.
Despite their widespread application, FeCrAl alloys face several challenges in maintaining performance under high thermal cycling and extreme oxidation conditions. Following the 2011 Fukushima Daiichi accident, there has been a growing interest on developing of accident tolerant fuel (ATF) cladding materials, as well as modifications to existing ones, for advanced nuclear reactors. This study investigates the role of nickel in enhancing the high-temperature oxidation resistance of FeCrAl alloys, which are being considered as potential replacements for zirconium alloys. Specifically, the oxidation behavior of FeCrAl alloys with 17 wt% chromium and varying nickel contents Fe-17Cr-5.5Al, Fe-17Cr-5.5Al-1Ni, and Fe-17Cr-5.5Al-3Ni were examined under steam environment at 1000 °C for 5000 s. The oxide layer thickness and compositional changes were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM-EDX) and transmission electron microscopy (TEM). The results indicate that low nickel concentrations significantly improve the oxidation resistance of FeCrAl alloys, making them more suitable for accident-tolerant fuel cladding applications in advanced nuclear reactors. This study provides valuable insights in optimizing FeCrAl alloy compositions to improve their oxidation resistance under extreme conditions.
The Neutron Activation System (NAS) is a vital diagnostic component of the Helium-Cooled Ceramic Pebble (HCCP) Test Blanket Module (TBM) under development for the ITER project. This study presents the first detailed RAMI (Reliability, Availability, Maintainability, and Inspectability) analysis specifically applied to the NAS, aiming to ensure it can reliably measure neutron flux and spectrum to support tritium breeding validation and efficiency. By evaluating potential failure modes and their impacts, the analysis identified critical components with high risk, such as the disposal bin, vacuum pump, capsule loader, and transfer station. To address these issues, targeted mitigation strategies, including design improvements and enhanced maintenance protocols, were proposed, which effectively reduced the criticality levels of these components. The study also emphasized the importance of spare parts optimization and proactive maintenance to maintain high system availability over a projected 20-year operation. The results underscore the importance of integrating RAMI analysis in the early design phase to identify and mitigate risks, thereby ensuring long-term stability and reliability of diagnostic systems like the NAS in fusion energy applications.
High-order harmonic techniques can be used to recreate neutron flux distributions in reactor cores using the neutron diffusion equation. However, traditional source iteration and source correction iteration techniques have sluggish convergence rates and protracted calculation periods. The correctness of the implicitly restarted Arnoldi method (IRAM) in resolving the eigenvalue problems of the one-dimensional and two-dimensional neutron diffusion equations was confirmed by computing the benchmark problems SLAB_1D_1G and two-dimensional steady-state TWIGL using IRAM. By integrating Galerkin projection with Proper Orthogonal Decomposition (POD) techniques, a POD-Galerkin reduced-order model was developed and the IRAM model was used as the full-order model. For 14 macroscopic cross-section values, the TWIGL benchmark problem was perturbed within a 20% range. We extracted 100 sample points using the Latin hypercube sampling method, and 70% of the samples were used as the testing set to assess the performance of the reduced-order model The remaining 30% were utilized as the training set to develop the reduced-order model, which was employed to rebuild the TWIGL benchmark problem. The reduced-order model demonstrates good flexibility and can efficiently and accurately forecast the effective multiplication factor and neutron flux distribution in the core. The reduced-order model predicts keff and neutron flux distribution with a high degree of agreement compared to the full-order model. Additionally, the reduced-order model's computation time is only 10.18% of that required by the full-order model.The neutron flux distribution of the steady-state TWIGL benchmark was recreated using the reduced-order model. The obtained results indicate that the reduced-order model can accurately predict the keff and neutron flux distribution of the steady-state TWIGL benchmark.Overall, the proposed technique not only has the potential to accurately project neutron flux distributions in transient settings, but is also relevant for reconstructing neutron flux distributions in steady-state conditions; thus, its applicability is bound to increase in the future.
Negotiating an international disarmament treaty that has as one of its core requirements the concept of “irreversibility” will be a major task, especially so if the aim is to ensure that nuclear weapons and the means of their production and maintenance are irreversibly destroyed. The task exists on several levels: the practical and technical – how to design and implement an effective verification regime, the legal – how to frame necessary treaty definitions, prohibitions and controls; and diplomatic – negotiating and agreeing on the treaty provisions and the temporal factors. The Chemical Weapons Convention’s main objective is the destruction of chemical weapons and their production facilities, but an equally important objective is prevention of their re-emergence. At the heart of the matter is the concept of dual-use where materials and facilities have both legitimate peaceful purposes and actual or potential for hostile purposes, and the basic starting materials required exist in nature. The same applies in the nuclear context. So what can we learn from the CWC? A treaty with nuclear irreversibility as its goal will face multiple challenges. Setting and agreeing treaty language that is clear on scope and enables trouble-free implementation over many decades will not be easily achieved given the record of existing and previous arms control and disarmament treaties. However, there is likely to be one crucial difference: a treaty with nuclear irreversibility as its sole purpose will not be negotiated and implemented in the sort of conflicted world that we saw during the Cold War.
Nuclear engineering. Atomic power, International relations
The purpose of this study was to investigate the effect of the reflector, surface treatment, and length of scintillation crystals on the performance of a time-of-flight and depth-of-interaction (TOF-DOI) PET detector with a dual-ended readout and to determine the best reflector and surface treatment. Various types of crystal arrays with three different reflectors (ESR, BaSO4, and Toray), three different lateral surface treatments (all-polished (AP), all-roughened (AR), and partially roughened (PR, three sides polished, and one side roughened)), and two different lengths (20 and 15 mm) were fabricated. The highest light collection efficiency and best energy resolution were achieved using a crystal with a diffuse reflector (BaSO4 for AP and Toray for AR). In contrast, the best coincidence timing resolution (CTR) was achieved using an AR crystal with a specular reflector (ESR). The best DOI resolution was achieved using an AR crystal with BaSO4. Moreover, the results measured with the 20 mm long crystals were similar to those measured with the 15 mm long crystals. Therefore, we concluded that the dual-ended readout PET detector employing the crystal with AR lateral surface treatment and ESR was a good candidate for TOF-DOI PET because it provided excellent CTR and adequate DOI resolution.
A paradigm shift is underway in Software Engineering, with AI systems such as LLMs playing an increasingly important role in boosting software development productivity. This trend is anticipated to persist. In the next years, we expect a growing symbiotic partnership between human software developers and AI. The Software Engineering research community cannot afford to overlook this trend; we must address the key research challenges posed by the integration of AI into the software development process. In this paper, we present our vision of the future of software development in an AI-driven world and explore the key challenges that our research community should address to realize this vision.
We explore the potential of conducting low-energy nuclear physics studies, including nuclear structure and decay, at the future Electron-Ion Collider (EIC) at Brookhaven. By comparing the standard theory of electron-nucleus scattering with the equivalent photon method applied to Ultraperipheral Collisions (UPC) at the Large Hadron Collider (LHC) at CERN. In the limit of extremely high beam energies and small energy transfers, very transparent equations emerge. We apply these equations to analyze nuclear fragmentation in UPCs at the LHC and $eA$ scattering at the EIC, demonstrating that the EIC could facilitate unique photonuclear physics studies. However, we have also shown that the fragmentation cross-sections at the EIC are about 1,000 times smaller than those at the LHC. At the LHC, the fragmentation of uranium nuclei displays characteristic double-hump mass distributions from fission events, while at the EIC, fragmentation is dominated by neutron emission and fewer few fission products, about 10,000 smaller number of events.
The nuclear charge radius plays a vital role in determining the equation of state of isospin asymmetric nuclear matter. Based on the correlation between the differences in charge radii of mirror-partner nuclei and the slope parameter ($L$) of symmetry energy at the nuclear saturation density, an analysis of the calibrated slope parameter $L$ was performed in finite nuclei. In this study, relativistic and non-relativistic energy density functionals were employed to constrain the nuclear symmetry energy through the available databases of the mirror-pair nuclei $^{36}$Ca-$^{36}$S, $^{38}$Ca-$^{38}$Ar, and $^{54}$Ni-$^{54}$Fe. The deduced nuclear symmetry energy was located in the range 29.89-31.85 MeV, and $L$ of the symmetry energy essentially covered the range 22.50-51.55 MeV at the saturation density. Moreover, the extracted $L_s$ at the sensitivity density $ρ_{s}=0.10~\mathrm{fm}^{-3}$ was located in the interval range 30.52-39.76 MeV.
This contribution discusses a new perception of the structure of compound nuclei by introducing intermediate states of the Feshbach formalism of nuclear reactions in the Interacting Boson Model of nuclear structure. The stake is to explore the manifestation of the unitary limit in heavy, even-even nuclei. Interactions that govern Feshbach resonances of cold and dilute atomic gases suggest the formulation of an IBM-compound Hamiltonian for scattering two neutrons (2n) from a heavy, even-even target (A). The solutions of the corresponding coupled channel equations host a 2n-IBM state resonance. It turns out that the unitary limit is measurable in a heavy A+2n compound nucleus at low temperatures. That measurement is feasible through the fluctuations of the cross-sections that tune the 2n-A scattering length.
Jutta Escher, Kirana Bergstrom, Emanuel Chimanski
et al.
Nuclear reaction data required for astrophysics and applications is incomplete, as not all nuclear reactions can be measured or reliably predicted. Neutron-induced reactions involving unstable targets are particularly challenging, but often critical for simulations. In response to this need, indirect approaches, such as the surrogate reaction method, have been developed. Nuclear theory is key to extract reliable cross sections from such indirect measurements. We describe ongoing efforts to expand the theoretical capabilities that enable surrogate reaction measurements. We focus on microscopic predictions for charged-particle inelastic scattering, uncertainty-quantified optical nucleon-nucleus models, and neural-network enhanced parameter inference.
Christopher Ritter, R. Hays, Jeren Browning
et al.
This case study describes the development of technologies that enable digital-engineering and digital-twinning efforts in proliferation detection. The project presents a state-of-the-art approach to supporting IAEA safeguards by incorporating diversion-pathway analysis, facility misuse, and detection of indicators within the reactor core, applying the safeguards-by-design concept, and demonstrates its applicability as a sensitive monitoring system for advanced reactors and power plants. There are two pathways a proliferating state might take using the reactor core. One is “diversion,” where special fissionable nuclear material—i.e., Pu-239, U-233, U enriched in U-233/235—that has been declared to the International Atomic Energy Agency (IAEA) is removed surreptitiously, either by taking small amounts of nuclear material over a long time (known as protracted diversion) or large amounts in a short time (known as abrupt diversion). The second pathway is “misuse,” where undeclared source material—material that can be transmuted into special fissionable nuclear material: depleted uranium, natural uranium, and thorium—is placed in the core, where it uses the neutron flux for transmutation. Digital twinning and digital engineering have demonstrated significant performance improvement and schedule reduction in the aerospace, automotive, and construction industries. This integrated modeling approach has not been fully applied to nuclear safeguards programs in the past. Digital twinning, combined with machine learning technologies, can lead to new innovations in process-monitoring detection, specifically in event classification, real-time notification, and data tampering. It represents a technological leap in evaluation and detection capability to safeguard any nuclear facility.
Yanjie Zhang, Chaofeng Sang, Changjiang Sun
et al.
Linear plasma devices are the ideal devices to simulate the divertor conditions of tokamak experimentally. The Multiple Plasma Simulation Linear Device (MPS-LD) is under construction at Dalian University of Technology with a focus of studying the plasma-material interactions (PMIs) and edge plasma transport. Before the experiment, numerical modeling plays a crucial role in predicting the main plasma parameters and discharge performance. To this end, simulations are carried out by using scrape-off layer plasma simulation code SOLPS-ITER for the designing studies of MPS-LD in the present work. The effects of particle source simulation method, heating power, and device chamber length on the plasma are investigated systemically. The simulation demonstrates that the direct imposing particle source in the source region is suitable for handling the plasma source. The radiation region, recombination front region and recombination region are formed during plasma transport. Enhancing the plasma source strength can promote the achievement of plasma detachment. The helicon source with a 6 kW radio frequency power source can only obtain the maximum electron density of 5 × 1018 m−3 and electron temperature of 2 eV in the vicinity of the target. Raising the heating power and shortening the distance from the plasma source to the target can significantly increase the plasma parameters at the target.