Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-05-30
Abstract： Cone-beam computed tomography (CBCT) is mostly used for position verification during the treatment pro#2;
cess. However, severe image artifacts in CBCT hinder its direct use in dose calculation and adaptive radiation
therapy re-planning for proton therapy. In this study, an improved U-Net neural network named CBAM-U-Net
was proposed for CBCT noise reduction in proton therapy, which is a CBCT denoised U-Net network with con#2;
volutional block attention modules. The datasets contained 20 groups of head and neck images. The CT images
were registered to CBCT images as ground truth. The original CBCT denoised U-Net network, sCTU-Net, was
trained for model performance comparison. The synthetic CT(SCT) images generated by CBAM-U-Net and the
original sCTU-Net are called CBAM-SCT and U-Net-SCT images, respectively. The HU accuracies of the CT,
CBCT, and SCT images were compared using four metrics: mean absolute error (MAE), root mean square error
(RMSE), peak signal-to-noise ratio (PSNR), and structure similarity index measure (SSIM). The mean values of
the MAE, RMSE, PSNR, and SSIM of CBAM-SCT images were 23.80 HU, 64.63 HU, 52.27 dB, and 0.9919,
respectively, which were superior to those of the U-Net-SCT images. To evaluate dosimetric accuracy, the range
accuracy was compared for a single-energy proton beam. The γ-index pass rates of a 4 cm × 4 cm scanned
field and simple plan were calculated to compare the effects of the noise reduction capabilities of the original
U-Net and CBAM-U-Net on the dose calculation results. CBAM-U-Net reduced noise more effectively than
sCTU-Net, particularly in high-density tissues. We proposed a CBAM-U-Net model for CBCT noise reduction
in proton therapy. Owing to the excellent noise reduction capabilities of CBAM-U-Net, the proposed model
provided relatively explicit information regarding patient tissues. Moreover, it can be used in dose calculation
and adaptive treatment planning in the future.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-05-30
Abstract： [Background]: The single-phase reversed flow in inverted U-tubes of steam generator (SG) leads to increasing flow resistance and decreasing heat transfer area, so it is meaningful to study this phenomenon. [Purpose]: The water level of the secondary side in SG can influence the single-phase reversed flow, it is necessary to clarify its influence mechanism from a more general viewpoint. [Methods]: The dimensionless conservation equations were derived first, and the extreme point was obtained based on the equations. Then the effect of the water level of the secondary side under conditions of different lengths, dimensionless resistance number, and dimensionless heat transfer number was analyzed. [Results]: The decrease in the water level leads to the critical point of the single-phase reversed flow gradually approaching the origin, the influence law of the water level is the same under different pipe length conditions. As the water level decreases, the influence of the dimensionless resistance number and dimensionless heat transfer number on the critical point gradually reduces. [Conclusions]: This study theoretically proves that the effect of secondary water level on single-phase reversed flow is not conducive to the occurrence of backflow, and explains the reasons from a mechanistic perspective, which can assist in accident analysis of related nuclear power plants.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-05-30
Abstract： Relativistic isobar ($^{96}_{44}$Ru+$^{96}_{44}$Ru and $^{96}_{40}$Zr+$^{96}_{40}$Zr) collisions have revealed intricate differences in their nuclear size and shape, inspiring unconventional studies of nuclear structure using relativistic heavy ion collisions. In this study, we investigate the relative differences in the mean multiplicity ($R_{ langle N_{ rm ch} rangle}$) and the second- ($R_{ epsilon_{2}}$) and third-order eccentricity ($R_{ epsilon_{3}}$) between isobar collisions using Optical and Monte Carlo Glauber models. It is found that initial fluctuations and nuclear deformations have negligible effects on $R_{ langle N_{ rm ch} rangle}$ in most central collisions, while both are important for the $R_{ epsilon_{2}}$ and $R_{ epsilon_{3}}$, the degree of which is sensitive to the underlying nucleonic or sub-nucleonic degree of freedom. These features, compared to real data, may probe the particle production mechanism and the physics underlying nuclear structure.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-05-30
Abstract： DD4hep serves as a generic detector de Conversely, Filmbox~(FBX) stands out as a widely used 3D modeling file format within the 3D software industry. In this paper, we introduce a novel method that can automatically convert complex HEP detector geometries from DD4hep de The feasibility of this method was demonstrated by its application to the DD4hep de The automatic DD4hep--FBX detector conversion interface provides convenience for further development of applications, such as detector design, simulation, visualization, data monitoring, and outreach, in HEP experiments.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-05-28
Abstract： Ion beam radiotherapy is increasingly being used for tumor treatment. Currently, the use of traditional X-ray computed tomography (CT) for treatment planning of ion-beam radiotherapy has significant relative stopping power (RSP) errors. A more ideal approach is to directly use ion beams to generate patient images for treatment planning so as to avoid RSP conversion and reduce RSP errors. In this study, the Monte Carlo program Geent4/Gate was adopted to establish an ion-CT simulation platform, designed two sets of ion CT systems, ideal and real, and reconstructed images using the maximum likelihood method and ASD-POCS algorithm. The effects of the ideal and real settings, multiple energies, and different ion types on the RSP error of phantom reconstruction were investigated. The results show that the relative error of RSP for 330MeV protons in both the ideal and real settings was less than 1.547%, and the RSP reconstruction error in the ideal settings was much smaller than that in the real settings. The RSP reconstruction error of each material under realistic settings is close to three times that under ideal settings. The relative errors of RSP for protons decrease with the increase of incident energy. The relative errors of RSP were the biggest at 230MeV, and were2.855%、2.468%、1.653%、and 2.553% in sulfur, phosphorus, carbon, and calcium materials. The RSP relative error reached its minimum at 330MeV, with 0.181%, 0.351%, 0.250%, and 0.245% in sulfur, phosphorus, carbon, and calcium materials. At energy of 330MeV/u for carbon ions , the RSP relative errors in sulfur, phosphorus, carbon, and calcium materials were 0.060%, 0.281%, 0.150%, and 0.082%, respectively, all within 0.281%. And the RSP relative errors were much smaller than those of protons under the same conditions. Thus, compared with proton CT, carbon ion-beam CT seems more possible to provide accurate RSP data for treatment planning for ion-beam radiotherapy..
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-05-28
Abstract： The search and localization of unknown radioactive sources is an important research topic in the field of nuclear security inspection and nuclear emergency response. In order to improve the source finding efficiency and adapt to the multi-source environment detection, a particle filtering source finding method integrating the angle of arrival is proposed. Firstly, a hardware platform combining autonomous localization and angle-of-arrival sensing is constructed to introduce position and angle information to the detector; secondly, the angle-of-arrival information is taken into account on the basis of particle filtering, which can dynamically shrink the source searching area and improve the searching efficiency; lastly, the angle-of-arrival-guided robot attitude adjustment is adopted in the path planning of the autonomous source searching, which can enhance the flexibility of the robot in searching for the source. Simulation experiments prove that this method can work correctly and effectively, and tests using radioactive sources further verify the practicality of this method for multi-source search.
Subjects: Nuclear Science and Technology >> Nuclear Detection Technology and Nuclear Electronics submitted time 2024-05-27
Abstract： Shielding material is critical for downhole pulsed neutron tool design as it directly influences the accuracy of formation measurements. A well-designed shield configuration ensures that the response of the tool is maximally representative of formation without being impacted by tool and borehole environment. This manuscript investigates the effects of boron-containing materials on neutron and gamma detectors based on a newly designed logging-while-drilling tool, which is currently undergoing manufacturing process. As boron content increases, its ability to absorb thermal neutrons significantly enhances. Through simulation, it is proven that boron carbide (B4C) can be used as an effective boron shielding material for thermal neutrons and therefore employed in this work. To shield against thermal neutrons migrating from mud pipes, the optimal shielding thicknesses for near and far neutron detectors are determined to be 5mm and 4mm. For an example, at a porosity of 25 p.u., the near neutron sensitivity shows a 5.6% increase in response. Furthermore, in order to shield capture gamma generated by thermal neutrons once they enter tool from the mud pipe and formation, the internal and external shields for the gamma detector is evaluated. Results show internal shield needs 75% boron content while the external shield is of 14.2mm thickness and 25% boron content to minimize tool effect.
Peer Review Status:
Awaiting Review
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-05-26
Abstract： The Very Large Area gamma-ray Space Telescope (VLAST) is a mission concept proposed to detect gamma#2;
ray photons through both Compton scattering and electron-positron pair production mechanisms, thus enabling
the detection of photons with energies ranging from MeV to TeV. This project aims to conduct a comprehensive
survey of the gamma-ray sky from a low-Earth orbit using an anti-coincidence detector, a tracker detector
that also serves as a low-energy calorimeter, and a high-energy imaging calorimeter. We developed a Monte
Carlo simulation application of the detector using the GEANT4 toolkit to evaluate the instrument performance,
including the effective area, angular resolution, and energy resolution, and explored specific optimizations of
the detector configuration. Our simulation-based analysis indicates that the current design of the VLAST is
physically feasible, with an acceptance above 10 m2 sr which is four times larger than that of the Fermi-LAT,
an energy resolution better than 2% at 10 GeV, and an angular resolution better than 0.2 ◦ at 10 GeV. The
VLAST project promises to make significant contributions to the field of gamma ray astronomy and enhance
our understanding of the cosmos.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-05-26
Abstract： [Background]: CF series fuel assemblies are the key reactor-core components of the advanced third-generation nuclear power, which are independently developed by China National Nuclear Corporation(CNNC). [Purpose]: The purpose is to analyze the friction force and rod drop performance of CF2 fuel assembly combined control rod drive line moving parts in water and air under different eccentricity. [Methods]: a 1:1 simulated fuel assembly was used in the test with an independently-developed rotatable top cap. The integration of multiple eccentric was initially implemented for scientific and accurate regulation. [Results]: The friction force and rod drop performance data in water and air at different heights and under different eccentric conditions were obtained. The total rod drop time and the time for rod reaching the buffer increased with the increase of eccentricity while the buffer time was basically constant. The fuel assembly and control rod functioned properly under the maximum eccentricity. The friction did not exceed the allowable limit. And no jamming of control rod occurred under large eccentric condition. [Conclusions]: The experimental results provide an important experimental basis for the design optimization , safe evaluation and software development of CF fuel assembly. The method can be extended to the subsequent CF3 and other fuel assembly scientific research projects.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-05-25
Abstract： Due to only extracting a single feature of the vibration signal of the nuclear power unit, the detection effect of the vibration fault detection method for nuclear power units is poor. Therefore, a vibration fault detection method for nuclear power units based on DBN and multi-sensor data decomposition was designed. Obtain vibration signal data of nuclear power units, smooth and fuse the obtained multi-sensor data, extract multiple features of the vibration signal of nuclear power units under the action of DBN, calculate the sensitivity index and fuzzy entropy of different features, analyze the characteristics of the vibration signal, construct a corresponding vibration fault detection model, and solve the vibration fault signal of nuclear power units. The experimental results show that in the practical application of this method, the AUC-ROC curve area is closer to 1, and the detection effect is better.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-05-24
Abstract： [Objective] In order to solve the problem that the existing R&D level of mobile reactors cannot meet the relevant requirements of the GB11806-2019 Regulations for the Safe Transport of Radioactive Materials, and cannot obtain transportation permits under the domestic regulatory system, [Method] In this study, according to the relevant requirements of 10 CFR 71 and §12 of the United States, the types of accidents that may be encountered in the transportation of mobile reactors were sorted out, and the most serious accident impact with the tanker truck was used as the design benchmark accident. The accident risk of a mobile reactor with an assumed power of 20 MWt under the design baseline accident is calculated. [Result] It was calculated that the probability of the design benchmark accident of the mobile reactor was 9.7×10-6/year under the condition of annual transportation, and the irradiation dose to the staff under the design benchmark accident after the reactor was cooled for one year was 810mSv. After 5 years of cooling, the radiation dose to workers under the design baseline accident was 590 mSv. [Conclusion] The accident consequences of mobile reactors under the design benchmark accident far exceed the irradiation dose limits for workers in SSG-26 Advisory Material for the IAEA Regulations For the Safe Transport of Radioactive Material and the GB18871 Safety Standards for Protection against Ionizing Radiation and Radiation Sources. Moreover, the probability of occurrence of design benchmark accidents does not meet the screening requirements of 10-7 years of over-design benchmark accidents in China. Therefore, it is necessary to take management measures, including armed escort and route planning, during the transportation of mobile reactors, to reduce the probability of design baseline accidents, and take corresponding protective measures to mitigate the consequences of design baseline accidents to meet the regulatory requirements of the nuclear safety department.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-05-23
Abstract： In-situ leaching is the main process of natural uranium production in China. The environmental protection problems in the process of construction, operation and decommissioning have been widely concerned. The production of wastes was introduced in this paper, and ten issues of concern were raised, included bleed ratio, drilling mud disposal, monitoring well setting, groundwater baseline determination, abnormal data determination of monitoring well, wastewater treatment, evaporation pool operation, target value determination of groundwater restoration, groundwater remediation and waste minimizaton. the present situation of technology and management was discussed, and the main task and research direction in the field of environmental protection of in-situ leaching of uranium mining were pointed out, in order to provide some suggestions for the sustainable development of in-situ leaching of uranium mining。
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-05-23
Abstract： With the development of digital control technology, the traditional instrument and control system based on analog quantity in nuclear power plant is gradually replaced by full digital technology, and it is possible to use more complex and efficient advanced control technology. Making full use of the advantages of system information in the process of digitization of the whole plant to improve the automation level of nuclear power plant has gradually become the focus of research on pressurized water reactor control system. The control systems of Pressurizer Water Reactor (PWR) nuclear power plant are based on traditional Proportional Integral Derivative (PID) controller. Although there are studies on improving the control performance of PWR NPP control systems by advanced control algorithms, such as neural network control, fuzzy control and model predictive control, most of them only focus on the control system itself without considering the interconnection and coupling among multiple control systems. The operation task of PWR nuclear power plant needs to be coordinated by multiple control systems at the same time, and the effect of improving the overall performance by simply improving the performances of the controllers are limited. [Purpose]: To comprehensively consider the coupling effect amonge control systems, coordinate multiple control systems from the top level to optimize the overall control performances and achieve better task execution results, a setpoint decision optimization system is proposed. [Methods]: The intelligent decision system for PWR control system was optimized based on particle swarm optimization (PSO) method. The decision objective function and operation constraint conditions of the intelligent decision system were proposed. Considering the actual operation of PWR, the system optimized the setpoint offline and the intelligent decision operation was performed online according to the operation condition to provide the directions and amplitudes of the control targets for the underlying control systems. The typical operation process of the PWR NPP was taken as an example to carry out the simulation of the deigned intelligent decision-making system, and the simulation results were analyzed. [Results]: Compared with the control scheme using traditional setpoints, the ITSE (Integral of Time multiplied by the Square Error) of average coolant temperature, pressurizer level, pressurizer pressure and steam generator level decreased by 58.9%, 67.7%, 99.9% and 83.3%, respectively. The peak value decreased by 62.4%, 3.0%, 100% and 66.3% respectively. The simulation results show that the system proposed in this paper can effectively reduce the ITSE and peak value of the system. The overall control performances and safety margin of the control systems of PWR NPP are improved. In practical engineering practice, it can be combined with digital twin technology to use the characteristics of the twin that can synchronously reflect the real state of the system for more accurate online setpoint optimization, so as to achieve better control performance.
Subjects: Nuclear Science and Technology >> Other Disciplines of Nuclear Science submitted time 2024-05-22
Abstract： As a candidate material for fusion reactors, the main components of low activation ferrite steel (martensitic steel) are Fe and Cr. In actual working conditions, helium produced by fusion reactions will enter the material, causing microscopic defects and radiation damage, affecting the material's resistance to radiation (helium embrittlement phenomenon) and other physical properties. This article simulates the interface of Fe Cr alloy, the main material of the reactor, through first principles calculations. He atoms are doped at different substitution and interstitial sites, and the formation energy of each structure is calculated after optimizing its structure. The stability of He atoms at different positions on the Fe Cr interface is obtained. At the same time, by calculating the volume, it was found that He would cause significant lattice distortion at the Fe octahedral gap near the interface. Based on the analysis of electronic density of states, it is inferred that this is the result of the hybridization of He, Fe, and Cr atoms at specific positions, provide a theoretical basis for the next research on the microscopic defects and physical and chemical properties of nuclear grade stainless steel.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-05-22
Abstract： Light Gradient Boosting Machine (LightGBM) and Random Forest (RF) algorithms were used to predict the apparent diffusion coefficient of Se(IV) in compacted bentonite. Seven instances of Se(IV) were measured using through-diffusion method. LightGBM (R2 = 0.98 and RMSE = 0.025) exhibited superior predictive accuracy with a training dataset consisting of 956 instances and eight input features from Japan Atomic Energy Agency (JAEA-DDB). Shapley Additive Explanation and Partial Dependence Plots analyses revealed valuable insights into the diffusion mechanism of adsorbed anion obtained by evaluating the relationships between the apparent diffusion coefficient and the dependency of each input feature.
Peer Review Status:Awaiting Review
Subjects: Nuclear Science and Technology >> Nuclear Detection Technology and Nuclear Electronics submitted time 2024-05-21
Abstract： The cooling storage ring (CSR) external-target experiment (CEE) is a spectrometer used in construction to study the properties of nuclear matter in high-baryon density regions at the Heavy-Ion Research Facility in Lanzhou (HIRFL). This study presents the design, simulation, manufacturing, and testing of a half-size prototype of a multi-wire drift chamber (MWDC) for the CEE. First, the performance of the MWDC connected to home-made electronics was simulated. The results demonstrated that an energy resolution of 18.5% for 5.9-keV X-rays and a position resolution of 194 um for protons can be achieved by the current design. Because the size of the largest MWDC reached 176 × 314 cm, a set of 98 × 98 cm prototypes was built using the new techniques. The positioning accuracy of the anode wires in this prototype exceeded 20 um. After optimization using commercially available electronic devices, the prototype achieved an energy resolution of 19.7% for a 55Fe X-ray source. The CEE-MWDC detector and electronics were simultaneously tested. An energy resolution of 22% was achieved for the 55Fe source; the track residuals were approximately 330 um for the cosmic rays. The results demonstrate that the current design and techniques meet the requirements of the CEE-MWDC array.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-05-21
Abstract： [Background]:Neural networks, with their powerful fitting capabilities, can learn the relationships between input and output variables based on large amounts of data, often serving as proxy models for physical programs in the field of engineering calculations, including nuclear engineering calculations. Neutron transport calculations, as one of the core links in neutronics simulations, often suffer from lengthy computational times. However, this issue can also be addressed by utilizing neural network models. Nevertheless, neural network models have a series of hyperparameters that need to be set, but manually adjusting these hyperparameters is laborious, repetitive, and reliant only on experience. Moreover, these hyperparameters are not reusable when solving different problems. [Purpose]: By seeking a surrogate model for VITAS, the research can provide some reference for the application of artificial intelligence in core physics calculation theory.[Methods]:This paper proposes the use of the bayesian optimization algorithm to adjust neural network hyperparameters, combined with learning rate decay and loss function optimization methods. [Results]: By fitting the key core parameters obtained from VITAS's calculation of the TAKEDA benchmark problem, the results show that the average error of the effective multiplication factor is within 150pcm, and the average error rate of the regional integral flux on the TAKEDA1 dataset is 1.72%, with a maximum error rate of 7.56%. [Conclusions]: This approach can automatically search for the optimal combination of hyperparameters for different datasets to achieve the best performance, demonstrating high flexibility, efficiency, and strong generalization.
Subjects: Nuclear Science and Technology >> Nuclear Detection Technology and Nuclear Electronics submitted time 2024-05-21
Abstract： [Background]: In order to apply in different scenarios of silicon-photomultiplier-coupled scintillator detector, Preamplifiers need to fulfill different requirements. [Purpose]: This study aims to design high-bandwidth, low-noise preamplifiers to cater for different output modes of silicon-photomultiplier-coupled scintillator detector. [Methods]: Based on OPA855 and consideration of bandwidth and noise, a transimpedance amplifier (TIA) and a voltage feedback amplifier (VFB) were designed. The amplifier circuits were simulated and analysed using PSpice for TI software to obtain circuit parameters. Finally, the signal response and noise baseline level were measured, and signals of 241Am source were analysed using a silicon-photomultiplier-coupled Cerium-doped Gadolinium Aluminum Gallium Garnet (GAGG(Ce)) detector. [Results and Conclusions]: These preamplifiers have good gain stability. TIA's bandwidth is 101MHz lower than VFB's 381MHz, but its baseline noise level σnoise≅ 448.32μV is better than the VFB's σnoise≅ 680.96μV . In addition, TIA is suitable for energy measurements and small-area SiPM applications, while VFB is more suitable for time measurements and large-area SiPM arrays.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2024-05-20
Abstract： Electron beam irradiation has become an important part of the nuclear application industry. Low energy electron beam has been increasingly used in waste water treatment and food preservation, and the measurement parameters of irradiation are crucial to the irradiation quality. Since the relevant standards of electron beam dosimetry below 300keV have not been established, the parameter measurements are traced to the 10MeV electron linear accelerator, and the inconsistency of the measurement objects brings systematic bias. In this paper, for the low energy electrons below 300keV, the method of electron beam energy measurement is studied by combining test and simulation calculation, and the absorption dose measuring device based on calorimetry is developed. The relationship between absorbed dose and beam intensity, displacement velocity and other parameters is investigated. The results show that the energy parameters of low energy electrons are measured by the step stacking dose experiment combined with the energy deposition curve simulation, and the absorbed dose parameters of low energy electrons are measured by calorimetry. The measurement uncertainty is 11% (k=2). This study provides a reliable measurement guarantee for low-energy electron beam irradiation technology.
Subjects: Nuclear Science and Technology >> Nuclear Detection Technology and Nuclear Electronics submitted time 2024-05-18
Abstract： [Background] Due to the independence of traditional neutron and density measurement instruments, in order to improve the safety and efficiency of geological information.[Purpose]Integrate the design of existing neutron and density instruments to merge the neutron density components And analyze in detail the gamma influencing factors in integrated design.[Methods] In order to investigate the influence of the distance between neutron and gamma sources on detector measurements, Monte Carlo simulation was used to analyze detector counts and energy spectra at different distances between neutron and gamma sources, and the results were validated under different rock and density conditions.[Results] Keeping the true instrument source distance, neutron source intensity and other parameters unchanged, the neutron radiation field has no significant impact on the density measurement results when the neutron and gamma sources are 410mm apart, and the absolute error of the inversion density is less than 0.015g/cm3. By changing the neutron source intensity to explore the impact of source intensity on integrated research, and simulating multiple neutron sources with different intensities, it can be found that as the neutron source intensity gradually increases, the optimal distance between the neutron source and gamma source gradually increases and presents a quadratic function relationship.[Conclusions] Based on such findings, the distance between the two sources can be flexibly determined based on the strength of the neutron source, enabling rapid performance evaluation of on-site instrument testing and providing theoretical guidance for integrated design.
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