The modular high temperature gas-cooled reactor (mHTGR) adopts helium as coolant, graphite as moderator and structural material, and TRISO particle-based fuel elements. The HTR-PM is the world's first multi-modular high temperature gas-cooled reactor power plant, having successfully entered to its commercial operation. To ensure inherent safety, the two reactors of HTR-PM are designed with the features of low power density, strong negative temperature feedback and large surface-to-volume ratio, giving a rated reactor thermal power of 200MWt. To enlarge plant power rating, the scheme of two reactor modules driving a common steam turbine is deployed. Since the modules are coupled by the turbine, the coordinated control is key in providing a stable and efficient operation. In this paper, the design of implementing coordinated control laws on distributed control system (DCS) is given. Then, the response of key process variables under power step conditions is analyzed This work manifest the feasibility of multi-modular nuclear power plant (NPP) scheme for the first time, showing the promising future in building large-scale NPPs by small modular reactors (SMRs).
The steam-water separator is the core component of a pressurized water reactor (PWR) steam generator, and its performance has a direct impact on the safety and economy of a nuclear power plant. This paper presents a systematic review of the numerical simulation methods for steam-water separators. It is shown that the Euler-Lagrange model is suitable for sparse droplet trajectory tracking, with low computational cost, but ignores the inter-phase coupling effect; the Euler-Euler two-fluid model can efficiently simulate inter-phase interactions in a complex flow field through the assumption of continuous medium; the Euler-DPM-EWF model can describe droplet-liquid film interactions in fine detail by combining discrete-phase tracking and liquid-film simulation and is suitable for analyses of liquid-film re-entrainment phenomena; and the Popu-lation Balance Model (PBM) can effectively predict the multi-scale droplet distribution and its aggregation/fragmentation process. Among the turbulence models, the Realizable k-ε model performs well in high strain rate flows, the RNG k-ε model is suitable for strong cyclonic fields, and the SST k-ω model is more robust in near-wall flows and free shear flows. In this paper, the Euler-DPM-EWF model is suggested to be coupled with the VOF method to extend the liquid film thickness simulation range, and the SST k-ω model is preferred to optimize the near-wall flow prediction.
Esteban Parra, Sonia Haiduc, Preetha Chatterjee
et al.
Peer review is the main mechanism by which the software engineering community assesses the quality of scientific results. However, the rapid growth of paper submissions in software engineering venues has outpaced the availability of qualified reviewers, creating a growing imbalance that risks constraining and negatively impacting the long-term growth of the Software Engineering (SE) research community. Our vision of the Future of the SE research landscape involves a more scalable, inclusive, and resilient peer review process that incorporates additional mechanisms for: 1) attracting and training newcomers to serve as high-quality reviewers, 2) incentivizing more community members to serve as peer reviewers, and 3) cautiously integrating AI tools to support a high-quality review process.
Erick Martinez-Loran, Daisuke Nishijima, Marlene Patino
et al.
We demonstrate a new renewable boron aggregate material that can withstand heat loads of 40MWm-2 without cooling and featuring low sublimation of below 100Torr-L/s/m2 and sputtering yield of 0.04 from 40eV D, similar to solid boron. The retention of deuterium (D) is 3.2 × 1020D/m2, 200× less than solid boron, 100× less than carbon, and comparable to tungsten at similar fluence and energy. The material sheds under high heat loads, at a rate of 0.35cm/s, exposing the cool surface to the plasma, allowing heat removal and tritium extraction away from the plasma and eliminating the need for cooling channels. This recession rate can be compensated for, as the material can be extruded from a paste at a rate of 1cm/s.
Power line infrastructure is a key component of the power system, and it is rapidly expanding to meet growing energy demands. Vegetation encroachment is a significant threat to the safe operation of power lines, requiring reliable and timely management to enhance the resilience and reliability of the power network. Integrating smart grid technology, especially Unmanned Aerial Vehicles (UAVs), provides substantial potential to revolutionize the management of extensive power line networks with advanced imaging techniques. However, processing the vast quantity of images captured by UAV patrols remains a significant challenge. This paper introduces an intelligent real-time monitoring framework for detecting power lines and adjacent vegetation. It is developed based on the deep-learning Convolutional Neural Network (CNN), You Only Look Once (YOLO), renowned for its high-speed object detection capabilities. Unlike existing deep learning-based methods, this framework enhances accuracy by integrating YOLOv8 with directional filters. They can extract directional features and textures of power lines and their vicinity, generating Oriented Bounding Boxes (OBB) for more precise localization. Additionally, a post-processing algorithm is developed to create a vegetation encroachment metric for power lines, allowing for a quantitative assessment of the surrounding vegetation distribution. The effectiveness of the proposed framework is demonstrated using a widely used power line dataset.
Lead-cooled fast reactors (LFRs) have a wide range of application scenarios, which require the thermal-hydraulic characteristics of LFRs to be reliable. In the present paper, the Lead-cooled fast reactor Thermal-Hydraulic Analysis Code LETHAC was developed, including the models of pipe, heat exchanger, and pool. To verify the correctness of LETHAC, two experimental facilities and three experimental cases were selected, including GFT and PLOFA tests for NACIE-UP and Test-1 for CIRCE. The calculated results show the same and consistent trend with the experimental data, but there are some discrepancies. It can be found that LETHAC is suitable and reliable in predicting the transient behavior of lead-cooled system.
Jowi Rapha P. Cruz, Alvie A. Astronomo, Gil Nonato Santos
et al.
Since 1988, the Philippines lacked local access to a nuclear facility, creating a significant void in this field of study for Filipinos. However, after a hiatus of 34 years, this gap was addressed with the recent authorization granted to Philippine Research Reactor 1 (PRR-1) Subcritical Assembly for Training, Education, and Research (SATER), allowing it to resume operations. In this work, a PHITS-based computational model was developed for the recently commissioned PRR-1 SATER. The model utilized a simplified model of the Training, Research, Isotope, General Atomics (TRIGA) fuel that releases photons with 0.6617 MeV energy from the Cs-137 fission product in the fuel. Compared to previous works on photon transport mapping, which utilized average source definition, this study employed individually defined fuel intensities and compared them with the averaged source definition for the fuel. The two fuel source definitions showed noticeable differences inside the reactor tank which is relevant for mixed-field irradiation applications of a research reactor. However, defining the fuel rods by their average strength is sufficient for radiation protection purposes. Simulations were also performed for fuel source definitions based on the average and ±1 standard deviation of the gamma intensity. Gamma doses received by cylindrical phantoms positioned at 0.5 m from the surface of the reactor tank for 500 h were found to be 1 % of the radiation dose limits per year and 4 % of the average dose limit for 5 years as stipulated by the Code of Philippine Nuclear Research Institute (PNRI) Regulations. Loss of water accident was also analyzed based on a conservative exposure time of 500 h. This resulted in a dose value that is only 45.5 % of the dose identified as the emergency turnback guidance of the IAEA. Lastly, PHITS calculated values of gamma doses were found to agree well, with 0.98 ratio, when compared with gamma doses measured at specified locations in the reactor. Results of this study confirm the inherent safety of the PRR-1 SATER in terms of radiological shielding for Cs-137 photons.
Yichen Zou, Ken-ichi Fukumoto, Ryoya Ishigami
et al.
V-Cr-Ti alloys with reduced Ti contents are expected to be good candidates as recyclable structural materials for fusion reactors. Herein, He irradiation was applied to V-4Cr-xTi (x = 0 to 4) alloys to investigate the additional effect of Ti and gas interstitial impurities on their microstructural evolution and irradiation hardening. Following He irradiation of the specimens at 700 °C with a maximum damage depth of 0.5 dpa, transmission electron microscopy and nanoindentation hardness tests were conducted. The microstructural evolution of the titanium-oxycarbonitride (Ti(CON)) precipitates formed during He ion irradiation was observed. The behavior of irradiation hardening is explained by the formation process of Ti(CON) precipitates and the magnitude of irradiation hardening depends on the amount of gas interstitial impurities that contribute to precipitate formation.
This study introduces a transient analysis module developed for RAST-V and validates it using the Kalinin-3 benchmark problem. For the benchmark analysis, RAST-V standalone and STREAM/RAST-V calculations were performed. STREAM supplies the few-group constants and RAST-V conducts a 3D core simulation utilizing few-group cross-sectional data. To improve accuracy, the main solver was developed based on the advanced semi-analytic nodal method. To evaluate the computational capability of the transient analysis module in RAST-V, Kalinin-3 benchmark is employed. Kalinin-3 represents a coolant transient benchmark that offers experimental data during the deactivation of the Main Circulation Pumps. Consequently, the transient calculations reflected the changes in the reactor flow rate. Benchmark comprising steady-state and transient calculations. During the steady state, the STREAM/RAST-V combination demonstrated a 30 ppm root mean square difference from 0 to 128.50 EFPD. For the transient calculations, STREAM/RAST-V showed power differences within ±7 % over a range of 0–300 s. Axial offset differences were within ±3 %, and the RMS difference in radial power ranged within 2.596 % at both 0 and 300 s. Overall, this study effectively demonstrated the newly developed transient solver in RAST-V and validated it using the Kalinin-3 benchmark problem.
M.S. Al-Buriahi, Z.A. Alrowaili, Sultan J. Alsufyani
et al.
Glasses with nominal compositions of (68-x) SiO2–25Na2O–2Al2O3- xCaO-5CaF2 (x = 0, 5, 10, 20, representing SiNAlCF1, SiNAlCF2, SiNAlCF3, and SiNAlCF4, respectively) were reported for their gamma-photon shielding and dosimetry functions using theoretical calculations starting with the use of the NIST cross-section library. Several parameters (including the mass attenuation (MAC) and energy absorption coefficient (MEAC), effective atomic number and electron density (Zeff and Neff), gamma exposure constant (Γ), exposure rate (Dr) and exposure buildup factor (EBF) among others) were estimated for energies within 0.015–15 MeV. The range of MAC for SiNAlCF1, SiNAlCF2, SiNAlCF3, and SiNAlCF4 is 0.0208–5.9944, 0.0210–6.7179, 0 0.0212–7.4460, and 0.0217–8.9164 cm2/g, respectively. The values of Zeff and Neff vary within the ranges 10.13–12.74 and 2.98–3.74 (1023 electron/g) for SiNAlCF1, 10.27–13.42 and 2.98–3.89 (1023 electron/g) for SiNAlCF2, 10.41–14.03 and 2.98–4.01 (1023 electron/g) for SiNAlCF3, and 10.71–15.07 and 2.98–4.19 (1023 electron/g) for SiNAlCF4. The glass with the higher CaO content interacts more with gamma rays and attenuates and absorbs photons better. For 15 mm thick SiNAlCF1-SiNAlCF4, Dr is about 3.66, 4.10, 4.56, and 5.47 MR/h, respectively. The addition of CaO thus improves the shielding efficacy of the SiNAlCF glasses in the narrow and broad beam geometry situations. The SiNAlCF glasses, in comparison to some conventional and recently recommended glass shields, contain nontoxic component, are cheaper, and effective (especially at higher gamma-photon energies). they are thus recommended for gamma-ray protection applications in narrow and broad beam shielding scenarios.
Medical physics. Medical radiology. Nuclear medicine, Nuclear engineering. Atomic power
The article discusses the issues of increasing the accuracy of measurements which is especially important in the installation and operation of technological equipment. The paper presents a technique for studying the accuracy of determining the rectangular coordinates of the controlled points measured by an electronic tacheometer. It is proposed to use a precision laser tracker for metrological standardization of high-precision electronic tacheometers at short distances (up to 60 m). The results of practical testing of the proposed method of metrological standardization of a high-precision electronic tacheometer are presented.
Tungsten (W) erosion and edge transport are investigated for EAST L-mode discharges with different gas injection. It is found that W erosion can be suppressed or mitigated by Ne or D2 seeding when divertor detachment is achieved. Compared to edge D2 fueling, Ne seeding from the divertor target is favorable for full detachment condition and thus W erosion suppression. Increasing the upstream plasma density by edge D2 fueling can affect the divertor condition, which may lead to a W erosion mitigation. D2 puffing at divertor target is less effective on increasing the upstream plasma density than OMP D2 puffing, and thus it is less effective on reduction of W erosion rates. W gross erosion profiles with different amount of injected D2 at the divertor are reproduced by a mixed material W erosion model, which indicates that there exist a Li-C overlayer on the W surface of EAST divertor. Ne and D2 injection are also found to have different impact on the normalized core W density. For the attached divertor condition, divertor Ne seeding will increase W leakage, but a suitable D2 fueling from divertor target can strengthen the edge W screening. After the divertor detachment, although the W source is dramatically reduced, the W core density is kept in a high level for the Ne seeding discharges, and even increased for the D2 fueling discharges.
We review the theory of nuclear collective vibrations evolved over decades from phenomenological quasiclassical picture to sophisticated microscopic approaches. The major focus is put on the underlying microscopic mechanisms of emergent effects, which define the properties of giant resonances and soft modes. The response of atomic nuclei to electromagnetic and weak fields is discussed in detail. Astrophysical implications of the giant resonances and soft modes are outlined.
The finite nuclear thickness affects the energy density $ε(t)$ and conserved-charge densities such as the net-baryon density $n_B(t)$ produced in heavy ion collisions. While the effect is small at high collision energies where the Bjorken energy density formula for the initial state is valid, the effect is large at low collision energies, where the nuclear crossing time is not small compared to the parton formation time. The temperature $T(t)$ and chemical potentials $μ(t)$ of the dense matter can be extracted from the densities for a given equation of state (EOS). Therefore, including the nuclear thickness is essential for the determination of the $T$-$μ_B$ trajectory in the QCD phase diagram for relativistic nuclear collisions at low to moderate energies such as the RHIC-BES energies. In this proceeding, we will first discuss our semi-analytical method that includes the nuclear thickness effect and its results on the densities $ε(t), n_B(t), n_Q(t)$, and $n_S(t)$. Then, we will show the extracted $T(t), μ_B(t), μ_Q(t)$, and $μ_S(t)$ for a quark-gluon plasma using the ideal gas EOS with quantum or Boltzmann statistics. Finally, we will show the results on the $T$-$μ_B$ trajectories in relation to the possible location of the QCD critical end point. This semi-analytical model provides a convenient tool for exploring the trajectories of nuclear collisions in the QCD phase diagram.
BackgroundHeavy water moderated molten salt reactor (HWMSR) adopts heavy water as moderator and heavy metal elements dissolved in fluoride salt as the fuel, which has high neutron economy. But large temperature difference of fuel salt outlet will lead to the thermal fatigue of piping components at the top of the core.PurposeThis paper aims to optimize the core design of HWMSR to minimize the fuel salt outlet temperature.MethodsBy using the developed codes of neutron-thermal hydraulic coupling calculation and core critical search calculation, the power density distribution, outlet temperature distribution, initial 233U loading and breading ratio (BR) were analyzed for the cores with different size of molten salt channels.ResultsThe calculation results demonstrate that increasing the radius of molten salt channels in the inner core zone (correspondingly decreasing the radius of molten salt channels in the outer core zone) will decrease the peak of power density and the maximum outlet temperature of molten salt while the influence on BR and 233U initial loading.ConclusionsThis study provides a valuable foundation for core optimization of HWMSR.
Coarse Mesh Finite Difference (CMFD) is a widely-used iterative acceleration method for neutron transport problems in which nonlinear terms are introduced in the derivation of the low-order CMFD diffusion equation. These terms, including the homogenized diffusion coefficient, the current coupling coefficients, and the multiplicative prolongation constant, are subject to numerical instability when a scalar flux estimate becomes sufficiently small or negative. In this paper, we use a suite of contrived problems to demonstrate the susceptibility of CMFD to failure for each of the vulnerable quantities of interest. Our results show that if a scalar flux estimate becomes negative in any portion of phase space, for any iterate, numerical instability can occur. Specifically, the number of outer iterations required for convergence of the CMFD-accelerated transport problem can increase dramatically, or worse, the iteration scheme can diverge. An alternative Linear Diffusion Acceleration (LDA) scheme addresses these issues by explicitly avoiding local nonlinearities. Our numerical results show that the rapid convergence of LDA is unaffected by the very small or negative scalar flux estimates that can adversely affect the performance of CMFD. Therefore, our results demonstrate that LDA is a robust alternative to CMFD for certain sensitive problems in which CMFD can exhibit reduced effectiveness or failure.
BackgroundHigh energy physics (HEP) experiments aimed at studying elementary particles and their interactions need to acquire and analyze large amount of experimental data to discover new particles or measure the properties of known particles. With the development of HEP experiments, the energy and luminosity of accelerators are increasing, the scale of experiments is expanding, and consequently the acquisition, processing and analysis of large amount of data will be more challenging.PurposeThis study aims to design and implement a more advanced or effective distributed data acquisition framework to acquire and process the huge amount of data generated by tracking detectors for future HEP experiments where the number of channels and data volume of tracking detectors is extremely large.MethodsThe distributed data acquisition framework in HEP experiment divided into data flow software and online software was redesigned by using Hadoop big data framework, mainstream open source big data processing components was adopted to develope a new data acquisition framework—BigDataDAQ. Finally, this framework was applied to the prototype of the time projection chamber for verification.Results & ConclusionsResults of performance test show that the framework has high performance in data throughput and data processing, and can be easily deployed and managed. It provides a feasible solution for the future data acquisition system of high energy physics experiment.
The study of liquid-gas phase transition in heavy ion collisions has generated a lot of interest amongst the nuclear physicists in the recent years. In heavy ion collisions, there is no direct way of measuring the state variables like entropy, pressure, energy and hence unambiguous characterization of phase transition becomes difficult. This work proposes new signatures of phase transition that can be extracted from the observables which are easily accessible in experiments. It is observed that the temperature dependence of the first order derivative of the order parameters in nuclear liquid gas phase transition exhibit similar behavior as that of the variation of specific heat at constant volume Cv which is an established signature of first order phase transition. This motivates us to propose these derivatives as confirmatory signals of liquid-gas phase transition. The measurement of these signals in easily feasible in most experiments as compared to the other signatures like specific heat, caloric curve or bimodality. Total multiplicity, size of largest cluster are some of the order parameters which have been studied. Statistical Models based on canonical ensemble and lattice gas model has been used for the study. This temperature where the peak appears is designated to be the transition temperature and the effect of certain parameters on this has also been examined. The multiplicity derivative signature proposed in this work has been further confirmed by other theoretical models as well as in experimental study.