Tulkki Ville, Sanchez-Espinoza Victor Hugo, Sobecki Nicolas
Small modular reactors are being developed globally with first new builds being planned within a decade. The most near-term designs are based on light water reactor technologies. While the fundamental technology is well known, the designs aim to utilize passive safety functions and simplifies systems to drive down costs. The correct operation of these functions must be ensured for these new nuclear reactors to be licensed in Europe. This paper discusses three projects funded by Euratom Research and Training programme: ELSMOR, McSAFER, and EASI-SMR.
In this paper, the main goals and selected outcomes of two European research projects that finished some months ago will be presented and discussed. In addition, the main goals and the research program of the EASI-SMR project will be described.
GAO Jin1, WU Shi1, DOU Yankun1, ZHANG Chonghong2, HE Xinfu1, YANG Wen1
Austenitic stainless steels are widely used as the structural materials in reactors. However, due to its face centered cubic structure, austenitic stainless steels are highly susceptible to irradiation swelling. Swelling resistance is one of the most important topics for austenitic stainless steels used in nuclear reactors. In order to investigate the effect of helium on the evolution of bubbles and swelling, 316L stainless steel was first pre-implanted with 1 000 appm He at room temperature. And then it was irradiated by self-ion of 3.5 MeV Fe at 550 ℃ to a nominal dose of 26-65 dpa. He bubbles are not observed after helium irradiation at room temperature and after annealing at 550 ℃ for 90 h. The self-ion irradiation contributes to the bubble nucleation and growth. It is observed that high density of helium bubbles distributes in a depth of 300-1 000 nm after Fe-ion irradiation. Distribution of He bubbles is consistent with helium implantation plateau calculated by SRIM. No obvious He bubbles are observed in depth ＜300 nm and ＞1 000 nm, demonstrating the effect of helium atoms on bubble nucleation. The average size and number density of He bubbles in 100 nm depth bin were investigated. The average size increases in depth of 400-700 nm and reaches maximum in depth of 600-700 nm. In depth 700-900 nm He bubbles size decreases. The number density shows a slight decrease in depth of 400-900 nm. Meanwhile, the bubble size shows a unimodal distribution in depth of 400-500 nm and bimodal distribution in depth of 500-800 nm. The corresponding swelling increases in depth of 400-700 nm and decreases in depth of 700-900 nm, which is similar to the bubble size. As for the effect of radiation dose, the average size of He bubbles increases with increasing radiation dose, while the number density decreases slightly first and then increases. The average He bubble size increases from 3.3 nm to 9.7 nm when the irradiation dose increases from 26 to 52 dpa, and further increases to 11.9 nm when the irradiation dose increases up to 65 dpa. While bubble density decreases from 1.5×1022/m3 to 0.8×1022/m3 first and then increases to 2.0×1022/m3. Pre-implanted helium accelerates the nucleation of He bubbles with density increasing and size decreasing. As a result, 316L stainless steel swells at a rate of 0.03%/dpa from 26 to 57 dpa, while swelling rate deviates to 0.26%/dpa when radiation dose increases from 57 to 65 dpa. The swelling behavior of 316L stainless steel after ion irradiation is consistent with neutron irradiation.
Significance of the chiral symmetry restoration is studied by considering the role of the modification of the nucleon mass in nuclear medium at finite density and temperature. Using the Korea-IBS-Daegu-SKKU density functional theory, we can create models that have an identical nuclear matter equation of state but different isoscalar and isovector effective masses at zero temperature. Effect of the effective mass becomes transparent at non-zero temperatures, and it becomes more important as temperature increases. Role of the effective mass is examined thoroughly by calculating the dependence of thermodynamic variables such as free energy, internal energy, entropy, pressure and chemical potential on density, temperature and proton fraction. We find that sensitivity to the isoscalar effective mass is several times larger than that of the isovector effective mass, so the uncertainties arising from the effective mass are dominated by the isoscalar effective mass. In the analysis of the relative uncertainty, we obtain that the maximum uncertainty is less than 2% for free energy, internal energy and chemical potential, but it amounts to 20% for pressure. Entropy shows a behavior completely different from the other four variables that the uncertainty is about 40% at the saturation density and increases monotonically as density increases. Effect of the uncertainty to properties of physical systems is investigated with the proto-neutron star. It is shown that temperature depends strongly on the effective mass at a given density and substantial swelling of the radius occurs due to the finite temperature. Equation of state is stiffer with smaller isoscalar effective mass, so the effect of the effective mass appears clearly in the mass-radius relation of the proto-neutron star, larger radius corresponding to smaller effective mass.
Brachytherapy can kill cancer cells more effectively and make the normal tissues around the tumor free or less irradiated. It has become an effective means for the treatment of malignant tumors. 103Pd has a half-life of 16.96 days and a significant advantage in the field of brachytherapy due to its unique decay properties. In order to achieve the large-scale production of 103Pd, the preparation process based on Cyclone-30(C30) cyclotron was studied. The rhodium metal was electroplated on the copper target base by pulse electroplating method. The rhodium-plated target was transferred to C30 solid target station for irradiation with beam energy of 16-18 MeV, and the beam current was 200 μA. In order to obtain Curie-level 103Pd, the beam integral should be more than 10000 μA•h. After irradiation, the target was transferred to the separation and purification hot cell, the rhodium plating was separated from the target base first, then was ground into powder, and dissolved by high temperature melting of potassium bisulfate. The rhodium was converted into soluble rhodium sulfate, and the 103Pd nuclide was separated and purified by AG1-X8 resin. The impurities of Rh, Fe, Cu and Zn were rinsed with 6 mol/L hydrochloric acid and 0.03 mol/L hydrochloric acid, respectively. At last, 103Pd was desorbed with a mixed solution of ammonium chloride-ammonia mixed solution(volume ratio 1∶1). The radioactive activity, radionuclide purity and specific activity of 103Pd were measured respectively. The preparation of sealed seed core was studied by using the prepared 103Pd feed solution. The results show that the rhodium plating layer is smooth and dense, and firmly bonded with the copper plate, the rhodium layers mass thickness is greater than 150 mg/cm2. The production capacity of 103Pd is greater than 37 GBq, the radionuclide purity is greater than 99.9%, and the specific activity is greater than 875 GBq/mg, and activity concentrations greater than 6.2 GBq/mL. The preparation field of 103Pd brachytherapy sources is more than 90%, it can meet the requirements. The 103Pd preparation process is stable, and the quality is controllable. The large-scale production capacity has been reached, and it provides a stable source for the research of 103Pd brachytherapy sources.
Nuclear engineering. Atomic power, Chemical technology
BackgroundCAT-1 (China Astro-Torus 1) is a levitated dipole field magnetic confinement device, which mainly used for dipole plasma physics experiments, requiring a central floating superconducting coil to be stably levitated for at least 5 h without cooling or power supply.PurposeThis study aims to design a levitation control system of coupling superconducting levitation coil and floating coil for CAT-1 dipole device.MethodsAccording to the design parameters of the suspension magnet system of the CAT-1 device, Simulink model of the control system was established and applied to the simulation. Based on Routh-Hurwitz stability criterion, the influence of PID (Proportion-Integral-Derivative) control strategy on stability control was studied. The selection range of stability control parameters was determined to ensure the stable levitation of 1 200 kg, 5 MA floating magnet.ResultsSimulation results show that under ideal conditions, delay time of the PD (Proportion-Derivative) control system is 0.046 3 s, rise time is 0.154 5 s, peak time is 0.628 3 s, adjustment time is 0.084 8 s, and overshot δ=1.6. It means that PD can restore the levitated superconducting ring to the preset balance position in a short time, and the load of the circuit can be greatly reduced by adopting the appropriate starting mode.ConclusionThe results provide key technical support for the design and development of levitated superconducting dipole field devices.
Traditional text-based system engineering, which has been used in the design and application of passive residual heat removal system (PRHRS) for lead-cooled fast reactors, is prone to several problems such as low development efficiency, long iteration cycles, and model ambiguity. This study aims to effectively address the above-mentioned problems by adopting a model-based system engineering (MBSE) method, which has been preliminarily applied to meet the design requirements of a PRHRS. The design process has been implemented based on the preliminary design of the system architecture and consists of three stages: top-level requirement analysis, functional requirements analysis, and design requirements synthesis. The results of the top-level requirements analysis and the corresponding use case diagram can determine the requirements, top-level use cases, and scenario flow of the system. During the functional requirements analysis, the sequence, activity, and state machine diagrams are used to develop the system function model and provide early confirmation. By comparing these sequence diagrams, the requirements for omissions and inconsistencies can be effectively checked. In the design requirements synthesis stage, the Analytic Hierarchy Process is used to conduct preliminary trade-off calculations on the system architecture, after which a white box model is established during the system architecture design. Through these two steps, the analysis and design of the system architecture are ultimately achieved. The resulting system architecture ensures the consistency of the design requirements. Ultimately, a functional hazard analysis was conducted for a specific incident to validate case requirements and further refine the system architecture. Future research can further reduce the design risk, improve the design efficiency, and provide a practical reference for the design and optimization of PRHRS in digital lead-cooled fast reactors.
Objective: To investigate the involvement of the circadian clock gene BMAL1 in regulating radiosensitivity in nasopharyngeal carcinoma (NPC). Methods: The regulatory role of BMAL1 in NPC radiotherapy was investigated using 44 NPC cases and the NPC cell line CNE2, which had been genetically modified to either overexpress or silence BMAL1. Infected CNE2 cells were divided into four groups, including those with BMAL1 overexpression and BMAL1 RNA interference (RNAi), as well as their respective control groups. The group responses to different doses of radiotherapy were examined. Results: The 5-year survival rates of the BMAL1 overexpression group demonstrated a significant increase compared to those of the low expression group (p < 0.05). Furthermore, the BMAL1 overexpression group exhibited a higher tumor-growth inhibition rate (p < 0.001) and apoptotic rate (p = 0.004) following radiotherapy; a decreased proportion of S-phase cells (p < 0.001) but an increased proportion of G2/M-phase cells (p = 0.001) after 24 h of 8Gy irradiation; reduced number of cell colonies (p = 0.042), and a lower survival score (p = 0.037). Conclusions: Our findings demonstrate a positive correlation between BMAL1 expression and NPC survival, suggesting that BMAL1 promotes NPC radiosensitivity.
Medical physics. Medical radiology. Nuclear medicine, Nuclear engineering. Atomic power
BackgroundThe use of controlled X-ray sources instead of 137Cs radioactive sources in density logging has become a new trend. The intensity of the X-ray source is substantially influenced by the high voltage on the target substrate, and the density measurement uncertainty can be maintained at 0.01 g·cm-3 when the high voltage is 350 kV.PurposeThis study aims to analyze the parameters of the shielding material and thickness suitable for the 350 kV high-voltage X-ray density logging instrument.MethodsThe Monte Carlo method was used to analyze the energy spectrum and counting rate of X-rays passing through different materials and thicknesses. By comparing the correlation between the 0~0.15 MeV and 0.15~0.35 MeV energy windows, the reasons for the difference between the X-ray attenuation and detector count rate in different energy windows were determined. In addition, combined with the actual instrument model construction of the four-detector X-ray density logging instrument, the influence of the three parts of particles on the detector was primarily considered. The placement mode and optimal thickness of each part of the shield for detectors were analyzed and designed using Monte Carlo N-particle (MCNP) simulation.ResultsThe simulation results show that the attenuation of X-rays in high- and low-energy windows increases with increase of atomic number and thickness of shielding materials. When tungsten nickel iron alloy is selected as the shielding material for the four-detector X-ray density logging instrument model, the suitable thickness of the shield between the base and the near-source detector is 1.75 cm. Meanwhile, to maintain the high voltage of X-ray generator at 350 kV, a shield layer with a thickness of 0.2 cm is placed between each detector, and a shield layer with a thickness of 0.35 cm is added to the back of the detector.ConclusionsThis study provides the design theory and key parameters for shielding materials and structures in the development of X-ray density logging tool.
Ranim Khojah, Mazen Mohamad, Philipp Leitner
et al.
Large Language Models (LLMs) are frequently discussed in academia and the general public as support tools for virtually any use case that relies on the production of text, including software engineering. Currently there is much debate, but little empirical evidence, regarding the practical usefulness of LLM-based tools such as ChatGPT for engineers in industry. We conduct an observational study of 24 professional software engineers who have been using ChatGPT over a period of one week in their jobs, and qualitatively analyse their dialogues with the chatbot as well as their overall experience (as captured by an exit survey). We find that, rather than expecting ChatGPT to generate ready-to-use software artifacts (e.g., code), practitioners more often use ChatGPT to receive guidance on how to solve their tasks or learn about a topic in more abstract terms. We also propose a theoretical framework for how (i) purpose of the interaction, (ii) internal factors (e.g., the user's personality), and (iii) external factors (e.g., company policy) together shape the experience (in terms of perceived usefulness and trust). We envision that our framework can be used by future research to further the academic discussion on LLM usage by software engineering practitioners, and to serve as a reference point for the design of future empirical LLM research in this domain.
Nuclear coherent population transfer (NCPT) plays an important role in the exploration and application of atomic nuclei. How to achieve high-fidelity NCPT remains so far challenging. Here, we investigate the complete population transfer of nuclear states. We first consider a cyclic three-level system, based on the mixed-state inverse engineering scheme by adding additional laser fields in an open three-level nuclear system with spontaneous emission. We find the amplitude of the additional field is related to the ratio of the pump and Stokes field amplitudes. As long as an appropriate additional field is selected, complete transfer can be achieved even when the intensities of the pump and Stokes fields are exceedingly low. The transfer efficiency exhibits excellent robustness with respect to laser peak intensity and pulse delay. We demonstrate the effectiveness through examples such as $^{229}$Th, $^{223}$Ra, $^{113}$Cd, and $^{97}$Tc, which have a long lifetime excited state, as well as $^{187}$Re, $^{172}$Yb, $^{168}$Er and $^{154}$Gd with a short lifetime excited state. Focusing on the case without additional coupling, we further reduce the three-level system to an effective two-level problem. We modify the pump and Stokes pulses by using counterdiabatic driving to implement high-fidelity population transfer. The schemes open up new possibilities for controlling nuclear states.
Abstract Tokamak edge (scrape-off layer (SOL)) plasmas can exhibit non-local transport in the direction parallel to the magnetic field due to steep temperature gradients. This effect along with its consequences has been explored at equilibrium for a range of conditions, from sheath-limited to detached, using the 1D kinetic electron code SOL-KiT, where the electrons are treated kinetically and compared to a self-consistent fluid model. Line-averaged suppression of the kinetic heat flux (compared to Spitzer-Härm) of up to 50% is observed, contrasting with up to 98% enhancement of the sheath heat transmission coefficient, γ e . Simple scaling laws in terms of basic SOL parameters for both effects are presented. By implementing these scalings as corrections to the fluid model, we find good agreement with the kinetic model for target electron temperatures. It is found that the strongest kinetic effects in γ e are observed at low-intermediate collisionalities, and tend to increase (keeping upstream collisionality fixed) at increasing upstream densities and temperatures. On the other hand, the heat flux suppression is found to increase monotonically as upstream collisionality decreases. The conditions simulated encompass collisionalities relevant to current and future tokamaks.
BackgroundThe performance of solid oxide fuel cells (SOFCs) can be promoted by optimizing cathode materials.PurposeThis study aims to boost the electrochemical performances of cathodes for SOFCs by doping transition metal at the B-site of double perovskite.MethodsFirstly, a series of B-site doped PrBa0.8Ca0.2Co2O5+δ (PBCC) oxides as cathodes for SOFCs were prepared by sol-gel. The effects of B-site doped content and doped elements on the crystalline structure of the cathodes were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). Then, the trends of conductivity and thermal expansion coefficient with B-site doped PBCC oxides were investigated. Finally, the electrochemical performances of cathodes with different B-site doped PBCC oxides were tested to find optimal doping element type and content.ResultsTest results show that polarization is reduced and the electrochemical catalytic activity is improved when 5 mol% of Fe is doped on the B-site of the PBCC cathode. Compared to the PBCC cathode, the max power density of the full cell with a 5-mol% Fe-doped cathode increases from 988 mW∙cm-2 to 1 259 mW∙cm-2 at 700 ℃.ConclusionsThe electrochemical performances of SOFCs can be boosted by modifying the B-site of double perovskite using transition metal.
Low activation ferritic martensitic steel is considered as one of the candidate structural materials for the fourth generation reactor and fusion reactor. Low activation ferritic martensitic steel is based on Fe-Cr alloy, in which W is an important solute element. Irradiation embrittlement at low temperature is one of the important problems limiting the service of low-activation ferrite martensitic steels. The precipitated clusters during the service process cause hardening and embrittlement of the material due to the obstruction of dislocation movement by the precipitated clusters. An in-depth understanding of cluster precipitation behavior during service is helpful to understand the irradiation embrittlement of low-activation ferrite martensitic steels at low temperature. In order to simulate the precipitation kinetics of Fe-Cr alloy, by introducing composition-dependent pair potential, some improvements were made on the MIET_AKMC software developed by ourselves. The precipitation kinetics of coherent Cr-rich precipitates/clusters in Fe-Cr(8%, 10%, 16%, 20%)-W(0%, 1%, 2%) alloys during thermal ageing was simulated using the atomic kinetic Monte Carlo (AKMC) method. After thermal ageing, Cr precipitate into clusters to form Cr-rich precipitates/clusters, while W is still in a solid solution state. At the beginning of coarsening process, the radius of clusters, which was about (0.57±0.03) nm, was independent on simulation temperature and the initial Cr content in the box. The precipitation process of Cr cluster can be divided into three stages: nucleation, growth and coarsening. The Cr concentration in box and simulation temperature have an influence on the precipitation rate of Cr clusters. The presence of W can delay the precipitation kinetic process and the effect is most significant when Cr content is about 10%. This is due to that when Cr content is about 10%, the absolute value of the short-range order parameter for Fe-Cr has a maximum, quite independent of the composition and the temperature. The delay effect of W was related with the stronger binding energy between W and vacancy. For the binding energy between Cr and vacancy is 0.06 eV, while the binding energy between W and vacancy is 0.14 eV. From the simulation results, it can be deduced that W is benefit for materials performance, expect for solution strengthening, it can delay the precipitation process of Cr-rich clusters, which is harmful for materials performance.
LI Kunfang1,2,3;FENG Jie1,2,*;WANG Haichuan1,2;LI Yudong1,2,*;WEN Lin1,2;LI Zhenzhe4;GUO Qi1,2
The γ-rays are widely and abundantly present in strong nuclear radiation environments, and when they act on the camera equipment used to obtain environmental visual information on nuclear robots, radiation effects will occur, which will degrade the performance of the camera system, reduce the imaging quality, and even cause catastrophic consequences. Color reducibility is an important index for evaluating the imaging quality of color camera, but its degradation mechanism in a nuclear radiation environment is still unclear. In this paper, the γ-ray irradiation experiments of CMOS cameras were carried out to analyse the degradation law of the camera’s color reducibility with cumulative irradiation and reveal the degradation mechanism of the color information of the CMOS camera under γ-ray irradiation. The results show that the spectral response of CMOS image sensor (CIS) and the spectral transmittance of lens after irradiation affect the values of a* and b* in the LAB color model. While the full well capacity (FWC) of CIS and transmittance of lens affect the value of L* in the LAB color model, thus increase color difference and reduce brightness, the combined effect of color difference and brightness degradation will reduce the color reducibility of CMOS cameras. Therefore, the degradation of the color information of the CMOS camera after γ-ray irradiation mainly comes from the changes in the FWC and spectral response of CIS, and the spectral transmittance of lens.
Broadband quantum memory is critical to enabling the operation of emerging photonic quantum technology at high speeds. Here we review a central challenge to achieving broadband quantum memory in atomic ensembles -- what we call the 'linewidth-bandwidth mismatch' problem -- and the relative merits of various memory protocols and hardware used for accomplishing this task. We also review the theory underlying atomic ensemble quantum memory and its extensions to optimizing memory efficiency and characterizing memory sensitivity. Finally, we examine the state-of-the-art performance of broadband atomic ensemble quantum memories with respect to three key metrics: efficiency, memory lifetime, and noise.
The digitization of engineering drawings is crucial for efficient reuse, distribution, and archiving. Existing computer vision approaches for digitizing engineering drawings typically assume the input drawings have high quality. However, in reality, engineering drawings are often blurred and distorted due to improper scanning, storage, and transmission, which may jeopardize the effectiveness of existing approaches. This paper focuses on restoring and recognizing low-quality engineering drawings, where an end-to-end framework is proposed to improve the quality of the drawings and identify the graphical symbols on them. The framework uses K-means clustering to classify different engineering drawing patches into simple and complex texture patches based on their gray level co-occurrence matrix statistics. Computer vision operations and a modified Enhanced Super-Resolution Generative Adversarial Network (ESRGAN) model are then used to improve the quality of the two types of patches, respectively. A modified Faster Region-based Convolutional Neural Network (Faster R-CNN) model is used to recognize the quality-enhanced graphical symbols. Additionally, a multi-stage task-driven collaborative learning strategy is proposed to train the modified ESRGAN and Faster R-CNN models to improve the resolution of engineering drawings in the direction that facilitates graphical symbol recognition, rather than human visual perception. A synthetic data generation method is also proposed to construct quality-degraded samples for training the framework. Experiments on real-world electrical diagrams show that the proposed framework achieves an accuracy of 98.98% and a recall of 99.33%, demonstrating its superiority over previous approaches. Moreover, the framework is integrated into a widely-used power system software application to showcase its practicality.
Hiroyuki Tajima, Hajime Moriya, Wataru Horiuchi
et al.
Neutron star observations, as well as experiments on neutron-rich nuclei, used to motivate one to look at degenerate nuclear matter from its extreme, namely, pure neutron matter. As an important next step, impurities and clusters in dilute neutron matter have attracted special attention. In this paper, we review in-medium properties of these objects on the basis of the physics of polarons, which have been recently realized in ultracold atomic experiments. We discuss how such atomic and nuclear systems are related to each other in terms of polarons. In addition to the interdisciplinary understanding of in-medium nuclear clusters, it is shown that the quasiparticle energy of a single proton in neutron matter is associated with the symmetry energy, implying a novel route toward the nuclear equation of state from the neutron-rich side.
BackgroundThe Shanghai high repetition rate XFEL and extreme light facility (SHINE) accelerates electrons up to 8 GeV using cryogenic-superconducting high-frequency cavity. Wire scanner system is applied to the beam profile measurement of SHINE due to its advantages such as fewer secondary particles generation compared with that of complete beam block, hence reduce the risk of superconducting cavity.PurposeThis study aims to design data acquisition system for wire scanner system and realize synchronous acquisition of beam loss signal and relative position between the wire and beam.MethodsThe data acquisition system for wire scanner was designed to include radio frequency (RF) daughter board with analog signal digitizer, digital motherboard, firmware, data processing software. A Zynq-UltraScale+ based system on chip (SoC) was employed as system central component, and a field programmable gate array (FPGA) was used for system control and data transmission whilst the advanced RISC machine (ARM) integrating Linux was implemented for data acquisition and communication. Finally, experimental test of this data acquisition system was performed on the testbed to verify its feasibility and functionalities.ResultsThe data acquisition system can correctly read back position of grating ruler, and achieve synchronous acquisition of sample beam loss signal and signal of cavity beam position monitor.ConclusionsThe data acquisition system meets the requirements of SHINE wire scanner system. It will be applied to the prototype of SHINE wire scanner system.
Background: Requirements changes (RCs) are inevitable in Software Engineering. Research shows that emotional intelligence (EI) should be used alongside agility and cognitive intelligence during RC handling. Objective: We wanted to study the role of EI in-depth during RC handling. Method: We conducted a socio-technical grounded theory study with eighteen software practitioners from Australia, New Zealand, Singapore, and Sri Lanka. Findings: We found causal condition (software practitioners handling RCs), intervening condition (mode of work), causes (being aware of own emotions, being aware of others' emotions), direct consequences (regulating own emotions, managing relationships), extended consequences (sustaining productivity, setting and sustaining team goals), and contingencies: strategies (open and regular communication, tracking commitments and issues, and ten other strategies) of using EI during RC handling. We also found the covariances where strategies co-vary with the causes and direct consequences, and ease/ difficulty in executing strategies co-vary with the intervening condition. Conclusion: Open and regular communication is key to EI during RC handling. To the best of our knowledge, the framework we present in this paper is the first theoretical framework on EI in Software Engineering research. We provide recommendations including a problem-solution chart in the form of causes, direct consequences, and mode of work against the contingencies: strategies for software practitioners to consider during RC handling, and future directions of research.