Hasil untuk "Nuclear engineering. Atomic power"

Corina Andreoiu, Svetlana Barkanova, Gregory Christian et al.

The Canadian subatomic physics community establishes its scientific, and thus funding, priorities through periodic Long-Range Plans (LRP). The community is now putting together a new LRP, which will be in effect from 2027 through 2034, with its scope extending through 2041. As part of this process, the Canadian Institute of Nuclear Physics (CINP) has put together a strategic report, following an extensive consultation process. The report describes the broad and ambitious research program undertaken by the Canadian nuclear physics research community, both onshore and abroad, touching on key questions regarding the origin, evolution, and structure of visible matter in the universe. This document provides a grid of different Canadian nuclear physics projects undertaken now and in the future, and their associated timelines. It concludes with specific recommendations for maximizing Canadian scientific output in nuclear physics.

Bo Zhang, Xin Lei, Feifei Huang et al.

Jun Zhang, Ke Wu, Xuanchen Zhang et al.

The bilateral control method serves as the primary means of interaction for remote handling (RH) in CFETR, effectively enhancing operations performance during interaction with the environment. However, traditional control methods excessively rely on the system's inherent performance and the operator skill, making it necessary to introduce the admittance control strategy to further enhance operational safety. This paper adopts the Naturally-Switching Velocity and Admittance Control (NSVAC) method, ensuring operational safety through a combination of velocity and admittance control. In this study, an analysis was conducted on the variations in interaction forces at different positions during the RH process. When the force is below a predetermined value, velocity control was applied; otherwise, admittance control was used. In order to naturally and smooth switching between the two modes, the control law and switch function were provided. Subsequently, the system behavior using NSVAC is analyzed and the stability analysis based on passivity control theory is conducted. Finally, the effectiveness of the NSVAC method is validated through simulation and experiments. The results strongly indicate that NSVAC not only meets practical operational requirements but also effectively guarantees the safety of operations throughout the process.

Bashir Garba Aminu, Yong-Kuo Liu, Hanan Akhdar et al.

This study investigates the radiation-shielding abilities of PS-WO3 composites across a range of energies, from 0.46 MeV to 2 MeV. The main objective is to discover the gamma mass attenuation (μ/ρ) and linear attenuation (μ) coefficients, along with the fast neutron removal cross section, for tungsten (VI) oxide with varying weight fractions (0 % wt, 10 % wt, 20 % wt, 30 % wt, 40 % wt, and 50 % wt). The methodology includes simulations using Geant4 by shooting a photon using a point source, passing the investigated samples while a NaI detector was used to detect the un-attenuated photons, and EpiXS was used to validate the key parameters, such as half-value layers and effective atomic numbers. Simulations using a Geant4-designed female phantom validated the results. Findings indicate that the PS-WO3 50 % sample exhibits the highest dose absorption and scattering ability, making it the most effective shielding material among the samples. This research provides valuable insights for applications in radiation protection, particularly in occupational exposure scenarios.

K. Hagino

We discuss recent theoretical developments in low-energy heavy-ion reactions. To this end, we put emphasis on a viewpoint of probing nuclear shapes with heavy-ion reactions. We first discuss a single-channel problem with an optical potential model. We particularly discuss a microscopic modeling of the imaginary part of an optical potential as well as a visualization of quantum interference phenomena observed in heavy-ion elastic scattering. We then discuss multi-channel scattering problems, and demonstrate that heavy-ion fusion reactions at energies around the Coulomb barrier are sensitive to the shape of colliding nuclei, providing a powerful tool to probe nuclear shapes. We finally point out that relativistic heavy-ion collisions have large similarities to low-energy heavy-ion reactions in the context of nuclear shape dynamics.

Ruicong Xu, Avadhesh Kumar Sharma, Erdal Ozdemir et al.

Guo-Liang Ren, Wei-Hsing Huang, Hsin-Kai Chou et al.

This study investigates the creep behavior of bentonite-sand mixtures as potential buffer materials for low-level radioactive waste (LLW) repositories, with a specific case study in Taiwan. To assess the long-term hydro-mechanical properties, constant-volume swelling pressure, hydraulic conductivity, strain-controlled shear, and stress-controlled shear tests were conducted on MX80 and KV1 bentonite-sand mixtures. The experimental results indicate that MX80-sand 70/30 mixtures are prioritized as the buffer materials with 2.10 MPa swelling pressure and 1 × 10−13 m/s hydraulic conductivity. However, the shear strength of mixtures was reduced by almost 50 % when fully saturated. Furthermore, this study proposed a novel stress-controlled direct shear apparatus to retrieve the creep model parameters. The numerical method based on the creep model efficiently supports and simulates the saturation process and creep displacement. The finite element method (FEM) result predicts that the buffer of both bentonite-sand mixtures will achieve an average degree of saturation of 95 % at the end of three decades and full saturation in 100 years. The simulated creep displacement results at key nodes suggest that both top and bottom parts in the buffer, assembled from MX80-sand 70/30 mixtures or KV1-sand 70/30 mixtures, will have almost equivalent values of 4 mm in the horizontal and 2 mm in the vertical directions eventually.

Emine Gülden Erkılıç, Songül Gürel, Çiğdem Yıldız et al.

One of the techniques used to develop drought-tolerant varieties in wheat is mutation breeding. The strong mutant genotypes that emerge in this way create specific responses that provide adaptation to drought. In this study covering the M1 and M2 generation periods, a small number of bread wheat (Triticum aestivum L.) mutant genotypes developed some adaptation mechanisms in response to stress. During M1 generation period, seedlings of Kınacı 97 and Doğu 88 varieties, whose seeds were treated with 0, 200, 300 and 400 Gy gamma rays, were exposed to drought (−1.03 MPa). As mutation dose applied to seeds in both varieties increased, amounts of chlorophyll and other parameters affecting yield of seedlings that developed from these seeds and were exposed to drought decreased, while amounts of proline increased. In terms of drought tolerance and yield, a small number of M1 mutant seeds obtained by 300 Gy mutation application to Kınacı 97 achieved the best performance. Thus, M2 generation period continued through seeds of 19 different mutant ears (mutant genotypes) developed from M1 mutant seeds. Seedlings developing from seeds of these 19 mutant ears were also exposed to the same level of drought. It was observed that proline amounts were lowest, TaMYB, TaMAPK, TaDHN, TaMIP, TaP5CS gene expressions and some yield criteria were highest in study groups 5, 16 and 19. Therefore, according to the data, it was determined that the most drought tolerant groups were 5, 16 and 19.

LU Xiaojun, LIU Jiayu, HU Chongqing et al.

BackgroundWith the development of nuclear medicine, the amount of medical radioactive waste increase rapidly. The radioactivity of nuclides in medical radioactive liquid waste must be monitored to meet the relevant standards before discharge of the radioactive liquid waste. The volume of the waste sample and its distribution around the detector have a direct impact on the detection efficiency.PurposeThis study aims to explore the variation law of the size parameters of the optimal Marlin cup sample box and provide a basis for subsequent monitoring methods.MethodsThe LaBr3(Ce) crystal was applied to the detection of nuclide activity in medical radioactive waste liquid. Geant4 tool was employed to establish a LaBr3(Ce) crystal detection model. The changing rules of the optimal Marin cup sample box size parameters were explored using a Ø25.4 mm×25.4 mm LaBr3(Ce) detector, and 3D printed photosensitive resin samples were used in the laboratory box for verification experiments.ResultsExperimental results show that simply increasing the sample volume cannot improve the detection efficiency, and the change trend of the detection efficiency in the depth direction of the annular part of the sample container tends to be flat with increase of the sample volume. The optimal size ratio of the Marinelli beaker is that the depth of the annular portion (h2) and the radius (r) are approximately two times the length of the detector crystal and the diameter of the hollow cavity, respectively, and the ratio of the radius (r) to the height of the sample container (H) is approximately 0.5. The experimental results of the full energy peak detection efficiency with optimized sample container size are consistent with the simulation results, and the relative deviation is better than 2.5%.ConclusionsThe results of the study provide an important technical reference for detector selection, sampling container design, and processing and traceability methods of medical radioactive liquid waste monitoring devices.

Michaël Montout, Christophe Herer, Joonas Telkkä

Nuclear accidents such as Fukushima Daiichi have highlighted the potential of passive safety systems to replace or complement active safety systems as part of the overall prevention and/or mitigation strategies. In addition, passive systems are key features of Small Modular Reactors (SMRs), for which they are becoming almost unavoidable and are part of the basic design of many reactors available in today’s nuclear market. Nevertheless, their potential to significantly increase the safety of nuclear power plants still needs to be strengthened, in particular the ability of computer codes to determine their performance and reliability in industrial applications and support the safety demonstration.The PASTELS project (September 2020–February 2024), funded by the European Commission “Euratom H2020” programme, is devoted to the study of passive systems relying on natural circulation. The project focuses on two types, namely the SAfety COndenser (SACO) for the evacuation of the core residual power and the Containment Wall Condenser (CWC) for the reduction of heat and pressure in the containment vessel in case of accident.A specific design for each of these systems is being investigated in the project. Firstly, a straight vertical pool type of SACO has been implemented on the Framatome’s PKL loop at Erlangen. It represents a tube bundle type heat exchanger that transfers heat from the secondary circuit to the water pool in which it is immersed by condensing the vapour generated in the steam generator. Secondly, the project relies on the CWC installed on the PASI test loop at LUT University in Finland. This facility reproduces the thermal-hydraulic behaviour of a Passive Containment Cooling System (PCCS) mainly composed of a CWC, a heat exchanger in the containment vessel connected to a water tank at atmospheric pressure outside the vessel which represents the ultimate heat sink. Several activities are carried out within the framework of the project. Different tests are conducted on these integral test facilities to produce new and relevant experimental data allowing to better characterize the physical behaviours and the performances of these systems for various thermo-hydraulic conditions. These test programmes are simulated by different codes acting at different scales, mainly system and CFD codes. New “system/CFD” coupling approaches are also considered to evaluate their potential to benefit both from the accuracy of CFD in regions where local 3D effects are dominant and system codes whose computational speed, robustness and general level of physical validation are particularly appreciated in industrial studies. In parallel, the project includes the study of single and two-phase natural circulation loops through a bibliographical study and the simulations of the PERSEO and HERO-2 experimental facilities. After a synthetic presentation of the project and its objectives, this article provides the reader with findings related to the physical analysis of the test results obtained on the PKL and PASI installations as well an overall evaluation of the capability of the different numerical tools to simulate passive systems.

Arthur Pilone, Paulo Meirelles, Fabio Kon et al.

A central challenge for ensuring the success of software projects is to assure the convergence of developers' and users' views. While the availability of large amounts of user data from social media, app store reviews, and support channels bears many benefits, it still remains unclear how software development teams can effectively use this data. We present an LLM-powered approach called DeeperMatcher that helps agile teams use crowd-based requirements engineering (CrowdRE) in their issue and task management. We are currently implementing a command-line tool that enables developers to match issues with relevant user reviews. We validated our approach on an existing English dataset from a well-known open-source project. Additionally, to check how well DeeperMatcher works for other languages, we conducted a single-case mechanism experiment alongside developers of a local project that has issues and user feedback in Brazilian Portuguese. Our preliminary analysis indicates that the accuracy of our approach is highly dependent on the text embedding method used. We discuss further refinements needed for reliable crowd-based requirements engineering with multilingual support.

Jiaqi Hu, Zhaopeng Qiao, Lunhe Fan et al.

MgF2 as a moderator material has been extensively used in the beam shaping assembly (BSA) that plays an important role in the boron neutron capture therapy (BNCT). Regarded as important for applications, the thermal neutron scattering data of MgF2 were calculated, based on the phonon expansion model. The structural properties of MgF2 were researched by the VASP code based on the ab-initio methods. The PHONOPY code was employed to calculate the phonon density of states. Furthermore, the NJOY code was used to calculate the thermal neutron scattering data of MgF2. The calculated inelastic cross sections plus absorption cross sections are in agreement with the available experimental data. The neutron transport in the BSA has been simulated by using a hybrid Monte-Carlo-Deterministic code NECP-MCX. The results indicated that compared with the calculation of the free gas model, the thermal neutron flux and epithermal neutron flux at the BSA exit port calculated by using the thermal neutron scattering data of MgF2 were reduced by 27.7% and 8.2%, respectively.

Ugur Korkut Pata, Mustafa Tevfik Kartal

This study investigates the impacts of nuclear energy consumption on environmental quality from a different perspective by focusing on carbon dioxide (CO2) emissions, ecological footprint, and load capacity factor. In this context, the South Korea case, which is a leading country producing and consuming nuclear energy, is investigated by considering also economic growth, and the 1997 Asian crisis from 1977 to 2018. To this end, the study employs the autoregressive distributed lag (ARDL) approach. Different from previous literature, this study proposes a load capacity curve (LCC) and tests the LCC and environmental Kuznets curve (EKC) hypotheses simultaneously. The analysis results reveal that (i) the LCC and EKC hypotheses are valid in South Korea; (ii) nuclear energy has an improving effect on the environmental quality; (iii) renewable energy does not have a significant long-term impact on the environment; (iv) the 1997 Asian crisis had an increasing effect on the load capacity factor; (v) South Korea has not yet reached the turning point, identified as $55,411, where per capita income improves environmental quality. Overall, the results show the validity of the LCC and EKC hypotheses and prove the positive contribution of nuclear energy to South Korea's green development strategies.

CHEN Qidong, GAO Fuhai

BackgroundUranium dioxide fuel elements of fast neutron reactor operate under the conditions of high burnup, high neutron fluence rate, high line power and high temperature. Complex physical chemical interactions occur between fuel and the cladding materials. The establishment of fuel element chemical interaction model is very important for the design of high burnup fast reactor fuel element.PurposeThis study aims to establish a chemical interaction model between fast reactor fuel and cladding materials under high burnup.MethodsEmphasis was placed on the chemical interaction phenomenon of the oxide fuel elements of fast neutron reactors. Firstly, the chemical interaction models of uranium dioxide interacted with austenitic stainless steel and ferritic-martensitic steel cladding materials were established by using a dynamic model. Then, special fuel element performance analysis program FIBER-Oxide, developed by China Institute of Atomic Energy (CIAE), was employ to verify these chemical interaction models by experimental data.ResultsThe corrosion model of fast reactor uranium dioxide fuel and austenitic stainless steel can successfully predict the cladding corrosion with maximum burnup of 10.8at% and irradiation damage of 87.5 dpa. The corrosion model of fast reactor uranium dioxide fuel and ferritic-martensitic steel can successfully predict the cladding corrosion with maximum burnup of 9.3at% and irradiation damage of 76.6 dpa.ConclusionsThe results of this study provide important reference value for the design and performance prediction of high burnup uranium dioxide irradiation elements and fuel elements of demonstration fast reactor.

Yue-Lin Liu, Lu Wang, Kun Jie Yang et al.

Mo has been applied to nuclear material, in which H and carbon impurities are unavoidable. In view of this, we have studied the effect of carbon on the H retention in Mo using first-principles simulations. In perfect Mo, there is always repulsion between H and carbon, and impurity carbon cannot capture H atoms. With the appearance of vacancy in Mo, vacancy and carbon-vacancy cluster trap seven and six H atoms, respectively. This means that impurity carbon has little effect on the H vacancy capturing. Finally, we explore the H diffusion by considering the presence of one Mo-carbon layer in Mo. Away from the Mo-carbon layer, H jumps along the optimal route with a diffusion barrier of 0.12 eV. As H moves close and passes through the Mo-carbon layer, the H diffusion barrier is increased to 0.73 eV. Therefore, the repulsive interaction between H and carbon can increase the H energy barrier in the vicinity of the Mo-carbon layer, which prevent the H diffusion and permeation in Mo. The current results can explain the promoting mechanism of bubble formation due to impurity carbon implantation and help us design future Mo-based nuclear material.

Hyungjoo Seo, Moon Hee Choi, Sang Wook Park et al.

Marine reactor systems experience platform movement, and therefore, the system thermal-hydraulic analysis code needs to reflect the motion effect on the fluid to evaluate reactor safety. A moving reactor model for MARS-KS was developed to simulate the hydrodynamic phenomena in the reactor under motion conditions; however, its applicability does not cover the MULTID component used in multidimensional flow analyses. In this study, a moving reactor model is implemented for the MULTID component to address the importance of multidimensional flow effects under dynamic motion. The concept of the volume connection is generalized to facilitate the handling of the junction of MULTID. Further, the accuracy in calculating the pressure head between volumes is enhanced to precisely evaluate the additional body force. Finally, the Coriolis force is modeled in the momentum equations in an acceleration form. The improvements are verified with conceptual problems; the modified model shows good agreement with the analytical solutions and the computational fluid dynamic (CFD) simulation results. Moreover, a simplified gravity-driven injection is simulated, and the model is validated against a ship flooding experiment. Throughout the verifications and validations, the model showed that the modification was well implemented to determine the capability of multidimensional flow analysis under ocean conditions.

S. A. Kuzin, N. A. Boldyreva, S. B. Kravets

The paper analyses the main factors affecting the reliability indicators of plate heat exchangers used at NPPs of various factors, namely: materials of heat exchange plates and gaskets, types of working media, loading modes (temperature and pressure), and resistance of sealing elements to ionizing radiation. There are no regulatory methods for thermal and hydraulic calculations for plate heat exchangers used for nuclear power plants. Only separate test methods for plate heat exchangers are proposed. The main failures are identified: external leaks, internal leaks and cases of clogging of heat exchangers. In the conclusions of the work it is proposed to analyze information on the failures of plate heat exchangers operated at LNPP-2, NVNPP-2 and supplied by foreign and domestic firms for more accurate prediction of the operation of plate heat exchangers during operation at NPPs.

CAO Qiong;JIANG Heyuan;DING Xiao;LU Daogang;LI Zhen;WANG Xiaotian

After the Fukushima nuclear accident, the safety of spent fuel pool has attracted much attention. Under extreme accident conditions, the spent fuel pool may lose make-up water and cooling for a long time, causing the water level in the spent fuel pool to drop, resulting in excessive temperature of spent fuel rods, even damage to fuel assemblies and leakage of radioactive substances, come into being serious safety problems. In order to avoid this safety problem, the third generation nuclear power plants, such as AP1000 and CAP1400, introduced spray cooling system. Under the condition of spraying, the liquid film flow characteristics on spent fuel rods is an important factor affecting the cooling effect, which has not been studied in detail by domestic and foreign scholars. Too large or too small spray flow rate may lead to the rupture of the liquid film on the spent fuel rod. Therefore, it is necessary to study the flow characteristics of the liquid film on the spent fuel rod. In this paper, optical method was used to study the time and space variation of liquid film thickness formed by spray cooling of single spent fuel rod at different Reynolds numbers. The liquid film image was captured by CCD camera, and the clear liquid film thickness image and good coincidence data were obtained after processing. Using the obtained data, the fluctuation images of liquid film at different Reynolds numbers at fixed positions of spent fuel rod and at different positions of spent fuel rod at fixed Reynolds numbers were drawn. In addition, the variation trend of time-averaged liquid film thickness on spent fuel rod at different Reynolds numbers was obtained. The experimental results show that when Reynolds number is in the range of 608-7 538, the maximum value of transient liquid film thickness is 2.36 mm, which occurs when Reynolds number is 7 085. With the increase of Reynolds number, the time mean liquid film thickness will increase, and the amplitude of liquid film fluctuation will also increase. Along the rod direction, with the increase of the distance from the top of the rod, the liquid film thickness will gradually decrease and become stable, and as the Reynolds number increases, the stable part will appear farther from the top of the rod. The research on the flow characteristics of single rod coolant film of spent fuel lays a foundation for determining the minimum spray flow rate with effective cooling capacity.

Qianliang Deng, Songyang Li, Dingqu Wang et al.

Solid Microencapsulated Fuel (SMF) is a type of solid fuel rod design that disperses TRISO coated fuel particles directly into a kind of matrix. SMF is expected to provide improved performance because of the elimination of cladding tube and associated failure mechanisms. This study focused on the neutronics and some of the fuel cycle characteristics of SMF by using OpenMC. Two kinds of SMFs have been designed and evaluated - fuel particles dispersed into a silicon carbide matrix and fuel particles dispersed into a zirconium matrix. A 7x7 fuel assembly with increased rod diameter transformed from the standard NHR200-II 9x9 array was also introduced to increase the heavy metal inventory. A preliminary study of two kinds of burnable poisons (Erbia & Gadolinia) in two forms (BISO and QUADRISO particles) was also included. This study found that SMF requires about 12% enriched UN TRISO particles to match the cycle length of standard fuel when loaded in NHR200-II, which is about 7% for SMF with increased rod diameter. Feedback coefficients are less negative through the life of SMF than the reference. And it is estimated that the average center temperature of fuel kernel at fuel rod centerline is about 60 K below that of reference in this paper.

Jie Liu, Ping Song, Dalin Zhang et al.

Abstracts: The research on the flow and heat transfer characteristics of lead bismuth(LBE) is significant for the thermal-hydraulic calculation, safety analysis and practical application of lead-based fast reactors(LFR). In this paper, a new CFD model is proposed to solve the thermal-hydraulic analysis of LBE. The model includes two parts: turbulent model and turbulent Prandtl, which are the important factors for LBE. In order to find the best model, the experiment data and design of 19-pin hexagonal rod bundle with spacer grid, undertaken at the Karlsruhe Liquid Metal Laboratory (KALLA) are used for CFD calculation. Furthermore, the turbulent model includes SST k−ω and k−ε; the turbulent Prandtl includes Cheng-Tak and constant (Prt =1.5,2.0,2.5,3.0). Among them, the combination between SST k−ω and Cheng-Tak is more suitable for the experiment. But in the low Pe region, the deviation between the experiment data and CFD result is too much. The reason may be the inlet-effect and when Pe is in a low level, the number of molecular thermal diffusion occupies an absolute advantage, and the buoyancy will enhance. In order to test and verify versatility of the model, the NCCL performed by the Nuclear Thermal-hydraulic Laboratory (Nuthel) of Xi'an Jiao tong University is used for CFD to calculate. This paper provides two verification examples for the new universal model.