Hasil untuk "Nuclear engineering. Atomic power"

WANG Mengqi, ZHENG Zheng, MEI Qiliang, PENG Chao, GAO Jing, ZHOU Yan

This study is dedicated to exploring an advanced intelligent multi-objective shielding optimization method based on the third generation non-dominated sorting genetic algorithm (NSGA-Ⅲ). The program’s functionality was tested and validated to improve the efficiency and effectiveness of shielding design for spent fuel transport ship. The study employed a sophisticated multi-objective intelligent optimization procedure and designed a one-dimensional discrete ordinates scale computational model. The model played a key role in optimizing the shielding structure above the hatch cover, paying particular attention to the dimensions of the concrete and polyethylene layers. This meticulous process resulted in the selection of a series of improved shielding solutions. In addition, a realistic 3D Monte-Carlo computational model was built to rigorously evaluate the shielding effectiveness of these optimized solutions. This model was used for evaluating the effectiveness of the optimized solutions compared to conventional solutions (materials based on concrete, polyethylene or borosilicate-containing resins). The evaluation metrics are comprehensive and include parameters such as shield thickness, total weight, cumulative dose rate and economic cost. The results of the study show that the solutions optimized by the intelligent multi-objective shielding optimization method exhibit unique properties. These solutions stand out from the crowd, providing designers with richer and more varied options. The optimization technique skillfully navigates between ensuring optimal radiation protection and conserving material usage, culminating in a series of Pareto-optimal solutions that demonstrate the effectiveness of the method. The intelligent optimization procedure based on the NSGA-Ⅲ was successfully applied to the optimization of shielding solutions for the hatch region of a spent fuel transport ship. The derived optimization scheme proves a lightweight design concept and does not compromise the strict radiation protection standards. The multi-objective optimization algorithm outperforms traditional radiation shielding design methods in quickly finding a solution that meets the shielding requirements while simultaneously weighing multiple objectives, such as the dose rate, volume and weight of the shielding material. This approach significantly improves the efficiency of shielding design. The methodology described in this paper has broad applicability and is particularly suitable for scenarios involving optimization of photon shielding in major shielding geometries. However, the methodology encounters certain limitations when dealing with complex geometries such as localized shielding challenges with penetrating members, and it is recommended that 3D Monte-Carlo method is used to optimize the design in such cases.

JIN Rui1, ZHONG Wuye1, , LEI Huazhen1, MA Ru1, QI Lijun1, HAN Yongchao2

In the thermionic energy conversion of Cs-charged, the work function of the electrodes, especially the effective work function of the electrode material in the Cs-absorbing state, has a decisive impact on its power generation performance. However, it is difficult to measure the work function in the high-temperature Cs environment for the test method at this stage, so establishing relevant experimental methods to evaluate the work function of the electrode material in the real environment is necessary. Based on the energy balance equation of electron flow between electrodes in thermionic energy conversion, combined with the local characteristics of electrode influence in the thermoelectric conversion process, the indirect measurement method of the effective work function of the emitter and collector was established by processing the current-volt characteristic curves under specific operating parameters. Furthermore, the data processing program was compiled by Matlab language, then the effective work function of the electrode material at different temperatures could be directly output. A series of current-volt characteristic data were obtained by using the current-volt characteristic program in the literature, and the current-volt characteristic data of Ni with only changing the temperature of the collector were tested by using a self-built plate-electrode experimental device. The parameters such as current density, voltage and electrode temperature in the current-volt characteristic results were substituted into the effective work function calculation model. The effective work functions of W emitter and Ni collector under different power generation currents under specific operating conditions subsequently were calculated separately, compared with the test values of the Cs-absorbing work function tested in the literature, which not measured under arc conditions during power generation. The results show that the effective work function of the emitter is approximately positively correlated with the Rasor index, decreasing with the increase of current density, which is caused by the Schottky effect. The changes of the effective work function of the collector with the working condition are consistent with the change trend of the influence of the collector temperature on the output power. Furthermore, there is an optimal collector temperature, in the vicinity of which the effective work function is the lowest. The average relative errors of the effective work functions of the emitter and collector and the literature values of the Cs-absorbing work function are 5.74% and 3.86%, respectively. The indirect measurement results of the effective work function can be consistent with the power generation characteristics of the thermionic energy conversion, which could be reflected in the previous test results of the Cs-absorbing work function.

F. Montupet-Leblond, E. Bernard, S. Feuillastre et al.

The control of tritium inventory and permeation is crucial for the safe operation of fusion reactors. To measure these phenomena, a novel tritium experiment is introduced and used to measure tritium permeation through Eurofer97 at room temperature, with several possibilities for the downstream conditions: air or water and overhead air. A pre-loading condition was shown to be required for this experiment. This direct comparison revealed that tritium is preferentially found in the water phase and secondarily in the air phase.

Vincent Intondi

Since the war in Gaza began, there has been a growing chorus calling for using nuclear weapons. This raises the question: Should those individuals calling for the use of nuclear weapons in Gaza be prosecuted for violating the statute of incitement to genocide under Article III of the Genocide Convention of 1948 or are these statements simply a case of free speech? Are these individuals advocating for nuclear war or inciting? Is calling for the use of nuclear weapons, the same as calling for genocide? This article will attempt to answer these questions focusing on the relationship between nuclear weapons and incitement to genocide.

E. Bogdanova, V. Bolnov, S. Grigoriev et al.

M. A. Agulnik, A. Grol’, V. V. Degtyarev et al.

Megumi Niikura, Shinichiro Abe, Shoichiro Kawase et al.

We plan to develop a new nuclear database for muon-induced nuclear reactions (muon nuclear data). The database will consist of (1) energies and intensities of the muonic X rays, (2) lifetimes of the muonic atom, (3) production branching ratio of the residual nuclei by muon capture, (4) emission probabilities of the particles after muon capture, and (5) energy spectra of the emitted particles after muon capture. In this paper, we review the present status and current investigations for the muon nuclear data.

WANG Chun-li, YANG Xiao-yu, XIAN Dong-fan et al.

The researches on the diffusion of key nuclide Se in Beishan granite, which is the pre-selected surrounding rock of China’s high-level radioactive waste geological repository, were summarized, including research methods, relevant data obtained and work to be carried out. Moreover, the influence of temperature on the diffusion of 75Se(Ⅳ) in Beishan granite and the possible influence mechanism were analyzed emphatically, in order to provide useful references for domestic peers.

Kang-Hee Lee, Heung-Seok Kang, Du-Ho Hong et al.

Experimental study on the fluidelastic instability (FEI) of a curved tube bundle in single phase downward cross flow is investigated for the design qualification and analysis input preparation of helical coiled steam generator tubing. A 6x9 normal square curved tube array with equal and different vertical/horizontal pitch-to-diameter ratio was under-tested up to 6 m/s in term of gap flow velocity to measure the critical velocity for FEI. The critical velocity for FEI was measured at the turning point from the vibration amplitude plot along the gap flow velocity. Our test results were compared with straight tube results and published data in the design guideline. The applicability of the current design guidelines to a curved tube bundle is also assessed. We found that introducing frequency difference in a curved tube array increases the critical velocity for fluidelastic instability.

LIU Hao, XIONG Zhengye, ZENG Caixing et al.

BackgroundDouble perovskites have become a research hotspot in recent years due to their flexible structure, easy doping, and good thermal stability. Photoluminescence (PL) of rare-earth-doped double perovskite materials has been frequently reported, but few studies on thermoluminescence (TL) have been conducted.PurposeThis study aims to investigate the TL characteristics of Y2-x-yBixEuyMgTiO6 (0≤x<1, 0≤y<1) phosphors.MethodBi3+ and Eu3+ co-doped Y2MgTiO6 samples were synthesized by a high-temperature solid phase method, and the X-ray diffraction (XRD), PL, and TL of the samples were measured.ResultsXRD analysis results show that the crystal structures of all samples are monoclinic P21/n, and Bi3+ and Eu3+ are doped into Y2MgTiO6 by substituting Y3+. The PL results show that Y1.79Bi0.01Eu0.20MgTiO6 has a strong red emission near 620 nm (corresponding to the 5D0→7F2 transition of Eu3+), which is accompanied by a long afterglow. The TL curves of the samples doped with different concentrations of Bi and Eu ions show that Y1.79Bi0.01Eu0.20MgTiO6 has the highest TL sensitivity, and the samples exhibits two significant TL peaks near 510 K and 610 K. The TL spectrum is more abundant than the fluorescence spectrum, and the 5D0→7FJ (J =1,2,3,4) transition of Eu3+ can be observed. The TL intensity of the sample has a good linear relationship with the irradiation dose in the range of 2~1 000 Gy. The TL kinetic parameters of the samples are analyzed using two methods under different preheating temperatures (Tm and Tstop) and glow curve deconvolution. The analysis results show that the depth of the TL trap in the sample extends from 0.80 eV to 1.40 eV.ConclusionsThe results of this study indicate that the TL spectrum is richer than the PL spectrum and that Y1.79Bi0.01Eu0.20MgTiO6 may be used as TL dosimeter material for large dose detection.

Yahya Sadeghi

One of the major topic of tokamak research is the determination of the magnetic profile due to magnetic coil fields and plasma current by mean of data from magnetic probes. The most practical approach is to use the current filament method, which models the plasma column with multiple current carrying filaments and the total current of these filaments is equal to the plasma current. Determining the plasma boundary in Alvand-U tokamak is the main purpose of this paper. In order to determine the magnetic field profile and plasma boundary, information concerning the magnetic coils, their position, and current is required in the computing code. Then, the plasma shape is determined and finally the plasma boundary is extracted by the code. In the conducted research, we discuss how to determine the plasma boundary and the performance of the computing code for extraction of the plasma boundary. The developed algorithm shows to be effective by running it in the regular pc machine with characteristics of Intel (R) core (TM) i3-10100 CPU @3.60 GHz and 8.00 GB of RAM. Finally, we present results of a test run for computing code using a typical experimental pulse.

Brian G. Frandsen, Michael Febbraro, Thomas Ruland et al.

Additive manufacturing techniques enable a wide range of possibilities for novel radiation detectors spanning simple to highly complex geometries, multi-material composites, and metamaterials that are either impossible or cost prohibitive to produce using conventional methods. The present work identifies a set of promising formulations of photocurable scintillator resins capable of neutron-gamma pulse shape discrimination (PSD) to support the additive manufacturing of fast neutron detectors. The development of these resins utilizes a step-by-step, trial-and-error approach to identify different monomer and cross-linker combinations that meet the requirements for 3D printing followed by a 2-level factorial parameter study to optimize the radiation detection performance, including light yield, PSD, optical clarity, and hardness. The formulations resulted in hard, clear, PSD-capable plastic scintillators that were cured solid within 10 s using 405 nm light. The best-performing scintillator produced a light yield 83% of EJ-276 and a PSD figure of merit equaling 1.28 at 450–550 keVee.

Mikhail Gorchtein, Chien Yeah Seng

For many decades, the main source of information on the top-left corner element of the Cabibbo-Kobayashi-Maskawa quark mixing matrix $V_{ud}$ were superallowed nuclear beta decays with an impressive 0.01\% precision. This precision, apart from experimental data, relies on theoretical calculations in which nuclear structure-dependent effects and uncertainties play a prime role. This review is dedicated to a thorough reassessment of all ingredients that enter the extraction of the value of $V_{ud}$ from experimental data. We tried to keep balance between historical retrospect and new developments, many of which occurred in just five past years. They have not yet been reviewed in a complete manner, not least because new results are a-coming. This review aims at filling this gap and offers an in-depth yet accessible summary of all recent developments.

Carlotta Giusti, Matteo Vorabbi, Paolo Finelli

We derived microscopic optical potentials (OPs) for elastic nucleon-nucleus scattering within the framework of chiral effective field theories at the first-order term of the spectator expansion of the Watson multiple-scattering theory and adopting the impulse approximation. Our OPs are derived by folding ab initio nuclear densities with a nucleon-nucleon NN t matrix computed with a consistent chiral interaction. The results of our OPs are in good agreement with the experimental data. Recent achievements of our work are reviewed in this contribution.

Afroza Shelley, Mahmud Hasan Ovi

In this research, curium oxide (CmO2) is studied as fuel for VVER-1200 reactor to get an attention to its energy value and possibilities. For this purpose, CmO2 is used in fuel rods or integrated burnable absorber (IBA) rods with and without UO2 and then compared with the conventional fuel assembly of VVER-1200 reactor. It is burned to 60 GWd/t by using SRAC-2006 code and JENDL-4.0 data library. From these studies, it is found that CmO2 is competent like UO2 as a fuel due to higher fission cross-section of 243Cm and 245Cm isotopes and neutron capture cross-section of 244Cm and 246Cm isotopes. As a result, when some or all of the UO2 of fuel rods or IBA rods are replaced by CmO2, we get a similar k-inf like the reference even with lower enrichment UO2 fuels. These studies show that the use of CmO2 as IBA rods is more effective than the fuel rods considering the initially loaded amount, power peaking factor (PPF), fuel temperature and void coefficient, and the quality of spent fuel. From a detailed study, 3% CmO2 with inert material ZrO2 in IBA rods are recommended for the VVER-1200 reactor assembly from the once through concept.

Manpreet Sethi

The nuclear playground in Southern Asia is marked by an exceptional level of complexity. A number of players; their disparate thinking on how to establish deterrence; nuclear dyads that elongate into strategic chains; inter-twining of nuclear issues with conventional, space, cyber realms; disparities in military capabilities; historical animosities accentuated by unresolved territorial conflicts; divides that spawn ideologies, religions and civilizational issues; all make for an immensely complex situation. The consequent regional nuclear dynamics has fair potential for crisis and arms race instability. As a way to address the regional nuclear challenges, the paper explores the character of Pakistan–India and China–India nuclear dyads along three specific axes: drivers of conflict; points of commonalities, similarities and differences; and implications of these for their nuclear stockpiles. Armed with this understanding, it then offers some policy recommendations to address the concomitant dangers.

Shubhchintak, P. Descouvemont

Background: Nuclear transfer reactions are a useful tool to study the structure of a nucleus. For reactions involving weekly bound nuclei, breakup effects can play significant role and theoretical calculations can be computational expensive in such cases. Purpose: To utilize the Lagrange-mesh and R-matrix methods for nuclear transfer reactions. Methods: We use the adiabatic distorted wave approximation (ADWA) method which can approximately treats the breakup effects in a simpler manner. In our approach, we apply the R-matrix method combining it with the Lagrange-mesh method, which is known to provide the fast and accurate computations. Results: As a test case, we calculate the angular distribution of the cross sections for the 54Fe(d, p)55Fe reaction, where deuteron breakup effects play important role. Conclusions: We show that these methods work well in the ADWA framework, and we look forward to applying these methods in coupled channel calculations.

Seyed Alireza Mousavi Shirazi

In this research, a conceptual approach is presented to obtain the neutron flux at a reactor core. A simple spherical reactor core was analyzed by a mathematical model defined by Delphi programming language to derive the neutron flux and visualize the position of neutrons through this approach. This visualization was performed based on the Monte Carlo methods to estimate the position of neutrons. By the presented approach, the neutron flux was computed in all components, and different layers of the spherical reactor core and the traces of collided neutrons were visualized for a wide range of neutron energies as accurately as possible. Besides, this spherical reactor core was simulated by the CITATION nuclear code to obtain the neutron flux. Afterward, the results obtained by the two methods were compared, which showed that the fluxes obtained by the presented approach were in agreement with those of the CITATION code. This simulation can be generalized for every spherical nuclear reactor core having various and optional dimensions, and the neutronic calculations can be performed for it.

Xavière Iltis, Doris Drouan, Thierry Blay et al.

Within the frame of the EMPIrE test, four monolithic mini-plates were irradiated in the ATR reactor. In two of them, the monolithic U(Mo) foil had been PVD-coated with Zr before the plate manufacturing. Extensive microstructural characterizations were performed on a fresh archive mini-plate, using Optical Microscopy (OM), Scanning Electron Microscopy (SEM) combined with Energy Dispersive Spectroscopy (EDS), Electron Backscattered Diffraction (EBSD) and Focused Ion Beam (FIB)/Transmission Electron Microscopy (TEM) with nano EDS. A particular attention was paid to the examination of the U(Mo) foil, the PVD coating, the cladding/Zr and Zr/U(Mo) interfaces.The Zr coating has a thickness around 15 μm. It has a columnar microstructure and appears dense. The cohesion of the cladding/Zr and Zr/U(Mo) interfaces seems to be satisfactory. An almost continuous layer with a thickness of the order of 100–300 nm is present at the cladding/Zr interface and corresponds to an oxidized part of the Zr coating. At the Zr/U(Mo) interface, a thin discontinuous layer is observed. It could correspond to locally oxidized U(Mo).This work provides a basis for interpreting the results of characterizations on EMPIrE irradiated plates.

A. Patriati, A. Insani, N. Suparno et al.

The knowledge of how to avoid crack at high temperature is crucial in fuel fabrication for Experimental Power Reactor or Reaktor Daya Eksperimental (RDE). This knowledge should be established and well-mastered by BATAN. RDE uses uranium dioxide as its nuclear fuel. However, uranium utilization for research purposes is heavily restricted. Therefore, the fabrication of ceria-stabilized zirconia (CSZ) microspheres as nuclear fuel surrogate was studied. In this work, the CSZ was prepared by external gelation with two different washing solutions, i.e. isopropyl alcohol (IPA) and propylene glycol methyl ether (PGME). The morphology in nano- and micro-scale of each CSZ microspheres from both variations was evaluated by small-angle x-ray scattering (SAXS) and optical microscopy. The morphology of the CSZ microsphere after drying at 80 °C and calcination at 200 °C were observed to understand the structural change in those steps and to see the potential crack based on its morphology. There are two parameters that can prevent microspheres from cracking at high temperatures for the next process, i.e., porosity and gel texture. It was observed that IPA solution has a benefit as a washing solution as it can trigger more porosities in the microspheres, but less in gel texture.