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 >> Radiation Physics and Technology submitted time 2024-05-15
Abstract： [Background]Active neutron interrogation (ANI) measurement systems can quantify the fissile mass of special nuclear materials (SNMs) using neutrons and are widely used in nuclear safeguard fields. However, the hydrogen-containing matrix in the waste drum reduces the signal of delayed neutrons and limits the fissile mass measurement precision of the ANI system. [Purpose]It is essential to ensure that the fissile mass evaluation of the SNM is independent of matrix material and to improve the assay performance of the ANI system in nuclear safeguard measurements. [Methods] Therefore, based on the flux monitor response, a new matrix correction method was developed on the basis of traditional correction methods in this work. [Results]It turned out that the effect of various hydrogen densities on the delayed neutron count rate differs. For U3O8 materials with different enrichment and distribution, matrix effect may result in an overestimation of up to ~7 times in the observed mass of 235U. For U3O8 materials with different 235U enrichments and distribution states, both the traditional correction method and the new correction method can effectively reduce the influence of the matrix material on the measurement of SNM mass. But compared with the traditional method, the new method can achieve better correction results. For the case where U3O8 material is located in the center of the matrix, the average relative deviation of 235U mass obtained by the new correction method is 13.6%, while for the case where U3O8 material homogeneous dispersed throughout the matrix, the average relative deviation of 235U mass obtained by the new correction method is 7.78%. [Conclusions]These results confirm the effective performance and practicality of the new correction method.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-05-11
Abstract： Carbon-based nanomaterials have important research significance in various disciplines, such as composite materials, nanoelectronic devices, biosensors, biological imaging, and drug delivery. Recently, the human and ecological risks associated with carbon-based nanomaterials have received increasing attention. However, the biosafety of carbon-based nanomaterials has not been investigated extensively. In this study, we used different types of carbon materials, namely, graphene oxide (GO), single-walled carbon nanotubes (SWCNTs), and multiwalled carbon nanotubes (MWCNTs), as models to observe their distribution and oxidative damage in vivo.
The results of Histopathological and ultrastructural examinations indicated that the liver and lungs were the main accumulation targets of these nanomaterials. SR-μ-XRF analysis revealed that SWCNTs and MWCNTs might be present in the brain. This shows that the three types of carbon-based nanomaterials could cross the gas–blood barrier and eventually reach the liver tissue. In addition, SWCNTs and MWCNTs could cross the blood–brain barrier and accumulate in the cerebral cortex. The increase in ROS and MDA levels and the decrease in GSH, SOD, and CAT levels indicated that the three types of nanomaterials might cause oxidative stress in the liver. This suggests that direct instillation of these carbon-based nanomaterials into rats could induce ROS generation. In addition, iron (Fe) contaminants in these nanomaterials were a definite source of free radicals. However, these nanomaterials did not cause obvious damage to the rat brain tissue. The deposition of selenoprotein in the rat brain was found to be related to oxidative stress and Fe deficiency. This information may support the development of secure and reasonable applications of the studied carbon-based nanomaterials.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-05-08
Abstract： Accurate and efficient online parameter identification and state estimation are crucial for leveraging Digital Twin simulations to optimize the operation of near-carbon-free nuclear energy systems. In previous studies, we developed a reactor operation digital twin (RODT). However, non-differentiabilities and discontinuities arise when employing machine-learning-based surrogate forward models, challenging traditional gradient-based in verse methods and their variants. This study investigated deterministic and metaheuristic algorithms and developed hybrid algorithms to address these issues. An efficient modular RODT software framework that incorpo rates these methods into its post-evaluation module is presented for comprehensive comparison. The methods were rigorously assessed based on convergence profiles, stability with respect to noise, and computational performance. The numerical results show that the hybrid KNNLHS algorithm excels in real-time online applications, balancing accuracy and efficiency with a prediction error rate of only 1% and processing times of less than 0.1 s. Contrastingly, algorithms such as FSA, DE, and ADE, although slightly slower (approximately 1s), demonstrated higher accuracy with a 0.3% relative L2 error, which advances RODT methodologies to harness machine learning and system modeling for improved reactor monitoring, systematic diagnosis of off-normal events, and lifetime management strategies. The developed modular software and novel optimization methods presented offer pathways to realize the full potential of RODT for transforming energy engineering practices.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-05-02
Abstract： [Background] With the development of the nuclear industry, the spent fuel produced by nuclear power plants has attracted people's attention due to its high radioactivity. How to ensure the reliable operation of nuclear facilities and the safety of staff occupies a crucial position. [Purpose] In order to avoid lethal radiation, many functional neutron / γ-ray shielding materials have been developed. [Methods]This paper reviews the research progress of different neutron / γ-ray shielding materials for spent fuel storage, including boride stainless steel, Gd-containing composites, B4C/Al composites, lead-containing and tungsten-containing composites. [Results]The advantages and disadvantages of neutron / γ-ray shielding materials are introduced respectively, and the research and development ideas of neutron / γ-ray shielding materials for subsequent spent fuel storage are proposed.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-05-01
Hua Leiming
Lu Fei
Su Jun
Shen Yangping
Jin Shilun
Yang Guochun
Li Zhihong
Guo Bing
Liu Longxiang
Cao Xiguang
Abstract： The 𝛽-Oslo experimental method provides an important investigative tool for examining the properties of radioactive nuclides in highly excited states and exploring the nucleosynthesis process for elements ranging from iron to uranium. This paper introduces a novel data processing technique designed to eliminate the impact of 𝛽-decay electrons on the detection of nuclear 𝛾 de-excitation within 𝛽-Oslo experiments, accurately unfolding the observed 𝛾-ray spectra. Utilizing a comprehensive detector response function matrix for 𝛾 rays and decay electrons, this method combines column-pivotal elimination and iterative step-by-step inverse solution approaches to determine the true incident 𝛾 spectrum. The reliability and validity of the proposed method have been substantiated through extensive simulations and inverse calculations.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-05-01
Abstract： Abstract [Background]: The defects generated during the working process of metal materials have a significant impact on their performance. For example, the radiation-induced embrittlement and hardening of RPV steels are a factor of concern, which hinders the life extension of the RPV. Annealing treatment is applied to alleviate irradiation-induced precipitates and defects and recover RPV’s mechanical properties in the past few decades to extend the in-service lifetime of the RPV. Unfortunately, this conventional method generally requires a high treatment temperature and long operation time, inevitably wasting considerable energy due to the huge size of the RPV. Recently, as a more convenient and energy-saving method, the repair of metal defects by electropulsing treatment (EPT) has been developed.
[Purpose]: Design and construct a device for EPT processing of samples. The repairs of defects in electron irradiated and deformed iron and RPV steel after EPT has been investigated by using positron lifetime spectroscopy.
[Methods]: Electron irradiated pure iron and RPV steel samples were subjected to multi parameter EPT, and the changes in defects of the samples with EPT were characterized by positron lifetime spectroscopy. In addition, the mechanical properties of pure iron tensile samples were characterized by micro Vickers hardness, and the defect information was characterized by positron lifetime spectroscopy to investigate the relationship between macroscopic properties and microstructure.
[Results]: The defects introduced by electron irradiation in pure iron and RPV steel samples gradually recover after EPT and exhibit similar patterns to annealing treatment. After stretching, the number of defects in pure iron samples increases, leading to an increase in Vickers hardness. EPT can restore defect and reduce Vickers hardness.
[Conclusions]: The EPT equipment and method used in the experiment can indeed recover the defects of metal samples. The samples treated by EPT are characterized by positron lifetime spectroscopy, and defects generated by irradiation or deformation in pure iron and RPV steel can be partially repaired through EPT. The effect of defect repair is not only related to the initial state of the sample, but also to EPT’s parameters. As a new non-destructive testing method, positron annihilation is expected to provide a criterion for material damage or defect repair under the action of pulse current, which can conveniently, quickly, and sensitively detect the defect state of actual working components.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-04-30
Abstract： Transverse mode-coupling instability (TMCI) is a dangerous transverse single-bunch instability that can lead
to severe particle loss. The mechanism of TMCI can be explained by the coupling of transverse coherent
oscillation modes owing to the transverse short-range wakefield (i.e., the transverse broadband impedance).
Recent studies on future circular colliders, e.g., FCC-ee, showed that the threshold of TMCI decreased significantly
when longitudinal and transverse impedances were included. We performed computations for a circular
electron-positron collider (CEPC) and observed a similar phenomenon. Systematic studies on the influence of
longitudinal impedance on the TMCI threshold were conducted. We concluded that the imaginary part of the
longitudinal impedance, which caused a reduction in the incoherent synchrotron tune, was the primary reason
for the reduction in the TMCI threshold. Additionally, the real part of the longitudinal impedance assists in
increasing the TMCI threshold.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-04-29
Abstract： The layout and characteristics of the hard X-ray spectroscopy beamline (BL11B) at the Shanghai Synchrotron Radiation Facility are described herein. BL11B is a bending-magnet beamline dedicated to conventional and millisecond-scale quick-scanning X-ray absorption fine structures. It is equipped with a cylindrical collimating mirror, a double-crystal monochromator comprising Si(111) and Si(311), a channel-cut quick-scanning Si(111) monochromator, a toroidal focusing mirror, and a high harmonics rejection mirror. It can provide 5–30 keV of X-rays with a photon flux of ~5 × 1011 photons/s and an energy resolution of ~ 1.31 × 10-4 at 10 keV. The performance of the beamline can satisfy the demands of users in the fields of catalysis, materials, and environmental science. This paper presents an overview of the beamline design and a detailed description of its performance and capabilities.
Peer Review Status:Awaiting Review
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-04-29
Gao-Long Zhang
Zhen-Wei Jiao
Guang-Xin Zhang
E. N. Cardozo
D. Bazzacco
D. R. Napoli
F. Galtarossa
F. Recchia
A. Illana
S. Bakes
I. Zanon
S. Aydin
G. de Angelis
M. Siciliano
H. Q. Zhang
B. Paes
S. P. Hu
J. Q. Qian
Daniele Mengoni
W. W. Qu
Abstract： One-neutron stripping process between 6Li and 209Bi was studied at 28, 30, and 34 MeV using the in-beam γ-ray spectroscopy method. The γ-γ coincident analysis clearly identified two γ-rays feeding the ground and long-lived isomeric states, which were employed to determine the cross section. The one-neutron stripping cross sections were similar to the cross sections of complete fusion in the 6Li+209Bi system, but the one-neutron stripping cross sections decreased more gradually at the sub-barrier region. A coupled-reaction-channel calculation was performed to study the detailed reaction mechanism of the one-neutron stripping process in 6Li. The calculations indicated that the first excited state of 5Li is critical in the actual one-neutron transfer mechanism, and the valence proton of 209Bi can be excited to the low-lying excited state in (6Li, 5Li) reaction, unlike in the (d,p) reaction.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-04-29
Abstract： The Ultrahard X-ray Multifunctional Application Beamline (BL12SW) is one of the Phase-II Beamline Projects at the Shanghai Synchrotron Radiation Facility. The primary X-ray techniques used at the beamline are high-energy X-ray diffraction and imaging using white and monochromatic light. The main scientific objectives of ultrahard X-ray beamline are focused on two research areas. One is the study of the structural properties of Earth’s interior and new materials under extreme high-temperature and high-pressure conditions, and the other is the characterization of materials and processes in near-real service environments. The beamline utilizes a superconducting wiggler as the light source, with two diamond windows and SiC discs to filter out low-energy light (primarily below 30 keV) and a Cu filter assembly to control the thermal load entering the subsequent optical components. The beamline is equipped with dual monochromators. The first was a meridional bending Laue monochromator cooled by liquid nitrogen, achieving a full-energy coverage of 30–162 keV. The second was a sagittal bending Laue monochromator installed in an external building, providing a focused beam in the horizontal direction with an energy range of 60–120 keV. There were four experimental hutches: two large volume press (LVP) experimental hutches (LVP1 and LVP2) and two engineering material (ENG) experimental hutches (ENG1 and ENG2). Each hutch was equipped with various near-real service conditions to satisfy different requirements. For example, LVP1 and LVP2 were equipped with a 200-ton DDIA press and a 2000-ton dual-mode (DDIA and Kawai) press, respectively. ENG1 and ENG2 provide in-situ tensile, creep, and fatigue tests as well as high-temperature conditions. Since June 2023, the BL12SW has been in trial operation. It is expected to officially open to users by early 2024.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-04-26
Abstract： Small-scale measurements of the radon exhalation rate using the flow-through and closed-loop methods were conducted on the surface of a uranium tailing pond to better understand the differences between the two methods.
An abnormal radon exhalation behavior was observed, leading to computational fluid dynamics (CFD)-based simulations in which dynamic radon migration in a porous medium and accumulation chamber was considered.
Based on the in-situ experimental and numerical simulation results, variations in the radon exhalation rate subject to permeability, flow rate, and insertion depth were quantified and analyzed. The in-situ radon exhalation rates measured using the flow-through method were higher than those measured using the closed-loop method, which could be explained by the negative pressure difference between the inside and outside of the chamber during the measurements. The consistency of the variations in the radon exhalation rate between the experiments and simulations suggests the reliability of CFD-based techniques in obtaining the dynamic evolution of transient radon exhalation rates for diffusion and convection at the porous medium–air interface. The synergistic effects of the three factors (insertion depth, flow rate, and permeability) on the negative pressure difference and measured exhalation rate were quantified, and multivariate regression models were established, with positive correlations in most cases; the exhalation rate decreased with increasing insertion depth at a permeability of 1×10−11 m2. CFD-based simulations can provide theoretical guidance for improving the flow-through method and thus achieve accurate measurements
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-04-26
Abstract： This paper presents a superhydrophobic melamine (ME) sponge (ME-g-PLMA) prepared via high-energy radiation induced in-situ covalent grafting long alkyl chain dodecyl methacrylate (LMA) onto the ME sponge for efficient oil-water separation. The obtained ME-g-PLMA sponge have the excellent pore structure with superhydrophobic (water contact angle is 154°) and super oleophilic properties, can absorb various types of oil up to 66-168 times of its own weight. The obtained ME-g-PLMA sponge can continuously separate oil slick on water by connecting the pump or separate oil under water with a gravity-driven device. The ME-g-PLMA sponge can also maintain its highly hydrophobic properties after long-term immersion in different corrosive solutions and repeated adsorption of oil for many times. The obtained modified ME-g-PLMA sponge has excellent separation properties and has great potential for oil spill cleanup.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-04-26
Abstract： BL02U2 of the Shanghai Synchrotron Radiation Facility (SSRF) is a surface diffraction beamline with a photon flux of 5.5 × 1012 photons/s at 10 keV and a beam size of 160×80 µm2 at the sample site. It is dedicated to studying surfaces (solid–vacuum, solid–gas) and interfaces (solid–solid, solid–liquid, and liquid–liquid) in nanoscience, condensed matter, and soft matter systems using various surface scattering techniques over an energy range of 4.8–28 keV with transmission and reflection modes. Moreover, BL02U2 has a high energy resolution, high angular resolution, and low beam divergence, which can provide excellent properties for X-ray diffraction experiments, such as grazing incident X-ray diffraction, X-ray reflectivity, crystal truncation rods, and liquid X-ray scattering. Diversity of in-situ environments can also be provided for the samples studied. This paper describes the setup of the new beamline and its applications in various fields.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-04-25
Abstract： A Laue microdiffraction beamline (BL03HB) was constructed at the Shanghai Synchrotron Radiation Facility (SSRF). This beamline features two consecutive focusing points in two different sectors within its end station, the first dedicated to protein crystallography and the other tailored to materials science applications. Based on a superbend dipole magnet with a magnetic field of 2.29 T, a two-stage focusing design was implemented with two sets of Kirkpatrick–Baez mirrors to achieve a micro white beam as small as 4.2×4.3 µm 2 at the first sector and 0.9×1.3 µm 2 at the second sector in the standard beamline operation mode at SSRF. The X-ray microbeam in the two sectors can be easily switched between monochromatic and white beams by moving a four-bounce monochromator in or out of the light path, respectively. In the protein crystallography sector, white-beam Laue microdiffraction was demonstrated to successfully determine the structure of protein crystals from only a few images of diffraction data collected by a Pilatus 2M area detector. In the materials science sector, the white-beam Laue diffraction was collected in a reflection geometry using another Pilatus 2M area detector, which could map the microstructural distribution on the sample surface by scanning the samples. In general, the BL03HB beamline promotes the application of Laue microdiffraction in both protein crystallography and materials science. This paper presents a comprehensive overview of the BL03HB beamline, end station, and the first commission results.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-04-19
Lu, Yudong
Zheng, Jinxing
Liu, Xufeng
Wu, Huan
Ge, Jian
Xu, Kun
Li, Ming
Liu, Haiyang
Zhu, Lei
Liu, Fei
Abstract： The superconducting magnet system of a fusion reactor plays a vital role in plasma confinement, a processthat can be disrupted by various operational factors. A critical parameter for evaluating the temperature marginof superconducting magnets during normal operation is the nuclear heating caused by D-T neutrons. This studyinvestigates the impact of nuclear heating on a superconducting magnet system by employing an improvedanalysis method that combines neutronics and thermal hydraulics.In the magnet system, toroidal field (TF) magnets are positioned closest to the plasma and bear the highestnuclear-heat load, making them prime candidates for evaluating the influence of nuclear heating on stability.To enhance the modeling accuracy and facilitate design modifications, a parametric TF model that incorporatesheterogeneity is established to expedite the optimization design process and enhance the accuracy of the computations. A comparative analysis with a homogeneous TF model reveals that the heterogeneous model improvesaccuracy by over 12%. Considering factors such as heat load, magnetic-field strength, and cooling conditions,the cooling circuit facing the most severe conditions is selected to calculate the temperature of the superconductor. This selection streamlines the workload associated with thermal-hydraulic analysis. This approach enablesa more efficient and precise evaluation of the temperature margin of TF magnets. Moreover, it offers insightsthat can guide the optimization of both the structure and cooling strategy of superconducting magnet systems.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-04-12
Abstract： A microscopic method for calculating nuclear level density (NLD) based on the covariant density functional theory (CDFT) is developed. The particle-hole state density is calculated by combinatorial method using the single-particle levels schemes obtained from the CDFT, and then the level densities are obtained by taking into account collective effects such as vibration and rotation. Our results are compared with those from other NLD models, including phenomenological, microstatistical and non-relativistic HFB combinatorial models. The comparison suggests that the general trends among these models are basically the same, except for some deviations from different NLD models. In addition, the NLDs of the CDFT combinatorial method with normalization are compared with experimental data, including the observed cumulative number of levels at low excitation energy and the measured NLDs. Compared with the existing experimental data, the CDFT combinatorial method can give reasonable results.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-04-11
Xian-Lin Yang
Chang-Lin Lan
Yu-Ting Wei
Yi Zhang
Gong Jiang
Bo Xie
Yu Liu
Hong-Tao Shen
Xiao-Jun Sun
Abstract： Aluminum is the primary structural material in nuclear engineering, and its cross-section induced by 14 MeV neutrons is of great significance. To address the issue of insufficient accuracy for the 27Al(n,2n)26Al reaction cross-section, the activation method and accelerator mass spectrometry (AMS) technique were used to determine the 27Al(n,2n)26Al cross-section, which could be used as a D-T plasma ion temperature monitor in fusion reactors. At the China Academy of Engineering Physics (CAEP), neutron activation was performed using a K-400 neutron generator produced by the T(d,n)4He reaction. The 26Al/27Al isotope ratios were measured using the newly installed GYIG 1 MV AMS at the Institute of Geochemistry, Chinese Academy of Sciences. The neutron flux was monitored by measuring the activity of 92mNb produced by the 93Nb(n,2n)92mNb reaction. The measured results were compared with available data in the experimental nuclear reaction database, and the measured values showed a reasonable degree of consistency with partially available literature data. The
newly acquired cross-sectional data at 12 neutron energy points through systematic measurements clarified the divergence, which has two different growth trends from the existing experimental values. The obtained results are also compared with the corresponding evaluated database, and the newly calculated excitation functions with TALYS-1.95 and EMPIRE-3.2 codes, the agreement with CENDL-3.2, TENDL-2021 and EMPIRE-3.2 results are generally acceptable. A substantial improvement in the knowledge of the 27Al(n,2n)26Al reaction excitation function was obtained in the present work, which will lay the foundation for the diagnosis of the fusion ion temperature, testing of the nuclear physics model, and evaluation of nuclear data, etc.
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-04-10
LIN Shen
SONG Luyang
SU Jun
CHEN Xin
SHEN Zhilin
ZHANG Hao
SHENG Yaode
ZHANG Liyong
HE Jianjun
CHEN Size
SHEN Yangping
JIN Shilun
LU Fei
XIAO Dan
ZHANG Yong
NAN Wei
JIANG Yuchen
ZHANG Yuqiang
ZHANG Yang
TIAN Junwen
Abstract： In thermonuclear reactions of nuclear astrophysical interest, some can produce short-lived products that emit positrons. The positrons emitted by these products will annihilate with electrons in the target and then produce a pair of 511 keV γ-rays, which can be used to determine the reaction yield and calculate the cross-section as well as the astrophysical S-factor. Recently, it has been found that the spatial coincidence measurements can be performed basing on the opposite direction of the 511 keV-511 keV γ-ray pair, which can reduce the natural background and enables the in situ measurement of the reaction yield using activity method. In this paper, based on the recently developed large modular BGO detector array LAMBDA-II, this method has been investigated and validated in the ground laboratory, which provides good basis for further application of this method in the nuclear astrophysical investigations in the future.
Peer Review Status:Awaiting Review
Subjects: Nuclear Science and Technology >> Radiation Physics and Technology submitted time 2024-04-09
Abstract： Background Element capture logging can be used to determine the elemental contents of rocks in formations. Purpose This study focused on the BY2 well, the inaugural parameter well for shale gas in the Cambrian Niutitang Formation of the Baojing Block, located in the Middle Yangtze region. The aim is to investigate the developmental and distributional characteristics of shale gas reservoirs in this formation. Methods By interpreting and processing elemental capture logging data, precise elemental compositions of the shale reservoirs were determined. This analysis led to the creation of a comprehensive geochemical index profile for the Niutitang Formation. Additionally, elemental geochemical indicators were used to identify and reconstruct the paleosedimentary environments. Results The analysis revealed that the predominant elements in the Niutitang Formation’s shale were Si, Al, and Fe, accompanied by lower amounts of K, Ca, Mg, and S. The shale featured relatively high concentrations of Si, Fe, and S, which contributed to its enhanced fracturing ability. The sedimentation process of this shale could be categorized as active continental margin sedimentation. The source material for the sedimentary rocks originated from the Kangdian ancient land, located in the northwest. The sedimentation was primarily normal but was influenced by the presence of hydrothermal fluids in the region’s active tectonic zone. Conclusions The upper section of the Niutitang formation was subject to a dry climate during its depositional period, featuring gentle slope sedimentation at the periphery of a stagnant basin and a lack of oxygen. High water salinity, ample land supply, and low water body paleoproductivity characterized this region. Conversely, the lower section experienced a humid climate and served as a deep-water retention basin. Here, the land supply was limited, but water salinity and paleoproductivity were high, leading to the accumulation of organic matter. The aquatic setting was primarily anaerobic, conditions that were conducive to the preservation of organic matter, and provided an optimal sedimentary environment for the generation and concentration of shale gas.
Peer Review Status:Awaiting Review
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