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The online core monitoring system (CMS) is a crucial system for ensuring the safe operation of nuclear power plants. Its primary function is to real-time monitor the key parameter changes within the reactor core, in order to timely detect potential abnormal conditions and provide subsequent operational recommendations. The mathematical modeling of the main functions of online CMS was conducted, and its core modeling forward problem was clearly defined as well as the inverse problems of monitoring, diagnosis, and operational control. Through analyzing the research status of typical online CMS systems, the solution approaches for the aforementioned forward and inverse problems were identified, providing references for resolving specific engineering issues of online CMS in the future. The reactor core modeling mainly involves high and low-fidelity mechanistic models, as well as various machine learning models and model order reduction techniques. Solving the detector placement, physical field reconstruction, and uncertainty quantification problems using diverse types of detectors and data assimilation algorithms is the core of the monitoring inverse problem. The diagnosis inverse problem primarily relies on in-core and ex-core neutron detector information to analyze the causes of control rod drop, self-powered neutron detector anomalies, and vibration abnormalities. Utilizing the theoretical models of core tracking, various types of reactivity or power distribution control constitute the main tasks of the operational support inverse problem. Furthermore, this paper points out the existing issues in current online CMS technology research, such as multi-source information fusion, uncertainty quantification, and operational procedures. Particularly, considering the influence of various uncertainty factors within the framework of digital twins and numerical reactors, to enhance the plant operating capability, is one of the future development directions for online CMS and its underlying technologies.

Difference from the movable neutron detector for CPR1000 reactor can only be used periodically, HPR1000 and other Gen-Ⅲ reactor innovatively use self-powered neutron detector (SPND) to continuously measure the in-core neutron flux. This paper provided detailed design and implementation of the high-precision core surveillance system for the first HPR1000 reactor. Firstly, a novel SPND signal processing method was proposed, which not only solved the limitation of traditional design software for high-precision SPND current calculation, but also enabled high-precision signal processing of measured SPND. Based on this, a high-precision core 3D power reconstruction method was established. Subsequently, the online monitoring system SOPHORA for the HPR1000 reactor core designed based on this theoretical model was described, and its uncertainty analysis method was explained in detail. The uncertainty analysis results indicate that the accuracy of the key parameters of the system can meet the needs of high-precision core monitoring. Finally, in order to confirm the performance of the system, a comparative analysis was conducted on the deviation between the measurement and theoretical prediction of SPND current during the start-up process of the HPR1000 reactor, as well as the deviation of component power distribution. The results show that the deviation is much smaller than the regulatory requirements for initiating physical tests. The double validation of the uncertainty analysis results and the component power deviation analysis results during the start-up process indicates that SOPHORA achieves high-precision core monitoring, and its use of SPND signal processing and core 3D power reconstruction methods has significant accuracy and reliability.

China is currently facing a critical period of economic transformation and social development, with land use being under tremendous pressure, facing multiple challenges. The imbalance in land use structure is becoming increasingly prominent and conflicts over various land uses are becoming more intense, thereby attracting an increasing focus. Land use conflict refers to the inconsistent and disharmonious land use methods and quantities among stakeholders in the process of land resource utilization, as well as the conflicting states between various land use methods and environmental aspects. The study of land use conflicts can provide important references for stabilizing land use structures, alleviating land use conflicts, and optimizing the allocation of national spatial resources. Identifying the spatial range and intensity of land use conflicts is a prerequisite for alleviating regional land use pressure. However, existing research has thus far provided insufficient characterization of the negative ecological and environmental effects of land use. The concept of ecosystem service trade-offs is advantageous regarding expressing the negative effects of land use conflicts and their inherent causes. Therefore, based on the perspective of ecosystem services, this study identifies the intensity and spatial distribution characteristics of land use conflicts in the Guangdong-Hong Kong-Macao Greater Bay Area in different types of space using ecosystem service trade-off analysis. Results show that from 2010 to 2020, land use change in the Guangdong-Hong Kong-Macao Greater Bay Area was relatively drastic, with a decrease of 1,440.90 km2 (8.20%) in arable land area and an increase of 1,649.92 km2 (28.01%) in urban land area. During the study period, carbon fixation, soil retention, and water production services exhibited increasing trends, whereas food supply and habitat quality services exhibited decreasing trends. High-gain areas of food supply and carbon fixation, as well as high-loss areas of water production and soil retention, were mainly distributed in the southwest and northwest of the study area. The land use conflict index of the study area was 1.05, indicative of strong land use conflict. This was mainly because the study area had a large number of service types to balance, with the balance relationships being strong. Among them, the balance relationships between water production and food supply, habitat quality, and carbon fixation were the dominant factors in land use conflicts in the study area. The intensity of land use conflicts in each subregion ranged from strong to weak in the following order: natural or semi-natural area (1.10) > semi-natural semi-artificial area (0.97) > artificial area (0.77) > semi-natural area (0.45). Natural or semi-natural area was the main area of land use conflicts, mainly because this area had many service types to balance, with the balance relationships being strong. In terms of spatial distribution characteristics, the spatial distribution range of land use conflicts in the study area was mainly characterized by weak and moderate conflict areas; however, land use conflicts were more severe in some local areas. The spatial distribution structure of land use conflicts in the study area showed a medium-weak-medium pattern from the periphery to the central part. Strong and extremely strong conflict areas were concentrated in natural or semi-natural areas.

Artificial simulated communication networks inspired by molecular communication in organisms use biological and chemical molecules as information carriers to realize information transmission. However, the design of programmable, multiplexed and general simulation models remains challenging. Here, we develop a DNA nanostructure recognition-based artificial molecular communication network (DR-AMCN), in which rectangular DNA origami nanostructures serve as nodes and their recognition as edges. After the implementation of DR-AMCN with various communication mechanisms including serial, parallel, orthogonal, and multiplexing, it is applied to construct various communication network topologies with bus, ring, star, tree, and hybrid structures. By the establishment of a node partition algorithm for path traversal based on DR-AMCN, the computational complexity of the seven-node Hamiltonian path problem is reduced with the final solution directly obtained through the rate-zonal centrifugation method, and scalability of this approach is also demonstrated. The developed DR-AMCN enhances our understanding of signal transduction mechanisms, dynamic processes, and regulatory networks in organisms, contributing to the solution of informatics and computational problems, as well as having potential in computer science, biomedical engineering, information technology and other related fields. Artificial simulated communication networks use biological and chemical molecules as information carriers to realize information transmission, but their design is challenging. Here, the authors report a DNA nanostructure recognition-based artificial molecular communication network, in which rectangular DNA origami nanostructures serve as nodes and their recognition as edges, and use it to construct various communication network topologies. [ABSTRACT FROM AUTHOR]

The challenge for future nuclear fuel management research is to deal with the problems caused by the high nuclear fuel burnup, high power factor, and high enrichment of fuel assemblies. On the other hand, the increasingly strict license safety review of design methods and design limits also place ever more demanding requirements. This makes the traditional lowdimensional analysis method that introduces too conservative assumptions seem inadequate. Therefore, it is necessary to develop a new three-dimensional method so that all global and local parameters of the nuclear steam supply system (NSSS) can be coupled in the simulation of the accident transient, including neutrons parameters, thermal hydraulic and system parameters of primary and secondary loop, etc. As an essential physical and thermal part of the numerical reactor, a three-dimensional coupling analysis code was developed. Through the dynamic link library technology and based on the independently developed system thermal hydraulic code GINKGO and three-dimensional core code COCO, coupling code GINKGO/COCO was developed. The coupling code is verificated by benchmark TMI-MSLB exercise 2. By comparing the parameters of steady-state core parameters, transient power and reactivity, the results show that the coupled calculation model of the developed code is correct, and the calculation has good accuracy and reliability. In this paper, three dimension of the rod drop accidents were analyzed by coupling code. Based on the developed GINKGO/COCO coupling code, the effect of two sets of rod drop calculation on the core power distribution of the control rod group was studied, and the stable power of the two sets of rod drop after the automatic adjustment of the R rod was compared and analyzed. Through the numerical analysis, it can be observed that the noncenter symmetric rod groups drop accident will lead to the core power center asymmetry, and the center asymmetric rod group will lead to the core power center asymmetry, which makes the core outlet loop temperature different. The rod drop value of R rod group is small, but the adjustment range of R rod group is large. The larger reactivity value of the rod drop is, the larger the steady-state power recovery after adjustment is compared with the initial steadystate difference. The variation trend of DNBR calculated by W3 coorelation formula in the rod drop accident example shows that the opposite law with the power, and the local fine DNBR calculation can be carried out in the future combined with the more fine sub-channel coupling analysis.

BackgroundUnder the condition of sub-cooled nucleate boiling (SNB), corrosion products in primary coolant of nuclear reactor will deposit on the outer surface of fuel cladding, which is commonly called fuel crud. Previous literature shown, zinc injection in primary coolant is an important method to inhibit the fuel crud deposition on the fuel cladding surface.PurposeThis study aims to investigate the influence of zinc concentration on the behavior of fuel crud deposition, and eventually provide guidance for zinc injection in primary coolant of nuclear power plant.MethodsThe fuel crud deposition tests of domestic zirconium alloy fuel cladding in different zinc concentrations were carried out by using a self-made fuel crud deposition device. Tubular crud deposition test specimen with built-in heating unit was designed and prepared for simulation study. After the tests, stereo microscope (SM) and scanning electron microscope (SEM) were employed to observe the macro and micro morphology of fuel crud whilst the composition of of fuel crud was observed and analyzed by the energy dispersive spectroscopy (EDS) with SEM, and X-ray photoelectron spectroscopy (XPS) was used to analyze the contents of Zn and B elements in the crud phase and inside the crud.ResultsObservation results show that the chimney-like crud formed on the fuel cladding surface becomes less obvious with increasing the zinc concentration in the coolant and the crud surface becomes flatter. Simutabeously, the crud thickness, the ratio of Ni/Fe and the boron precipitation mass within the crud are decreasing with increase of the zinc concentration. When the zinc concentration increases to 100 μg‧L-1, new Zn-containing phases precipitate within the crud.ConclusionsWithin the zinc concentration of 0~100 μg‧L-1, zinc injection in primary coolant of reactor can significantly inhibit the crud deposition on the fuel cladding surface.

Federated learning is a distributed learning framework designed to protect user privacy, widely applied across various domains. However, existing federated learning algorithms face challenges, including slow convergence, significant loss fluctuations during aggregation, and imbalanced client sampling. To address these issues, this paper introduces a high-performance federated learning aggregation algorithm. This algorithm combines a cyclic adaptive learning rate adjustment strategy with client-weighted random sampling, addressing the aforementioned problems. Weighted random sampling assigns client weights based on their sampling frequency, balancing client sampling rates and contributions to enhance model aggregation. Additionally, it adapts the learning rate based on client loss variations and communication rounds, accelerating model convergence and reducing communication costs. To evaluate this high-performance algorithm, experiments are conducted using well-known datasets MNIST and CIFAR-10. The results demonstrate significant improvements in convergence speed and loss stability. Compared to traditional federated learning algorithms, our approach achieves faster and more stable convergence while effectively reducing training costs. [ABSTRACT FROM AUTHOR]

Seismic monitoring data for the past 50 years in the Three Gorges Reservoir area show that the reservoir head area is a typical weak seismic region with low seismicity before impoundment and that the epicenters were concentrated in the east and west sides of the Zigui Basin, most of which were natural tectonic earthquakes. After impoundment, the seismic activity shifted to the segment between Badong and Zigui along the Yangtze River, mainly within 5 km of the reservoir bank. The seismogenesis was categorized into four types; Karst collapse earthquakes, earthquakes caused by Karst gas explosion, mining tunnel collapse earthquakes, and rock (terrane) slip earthquakes, all of which are related to the lithology, structure, and tectonics of near-surface geological bodies of the area. Compared with the seismicity before impoundment, the seismic frequency increase was remarkable, with most of the magnitudes below Ms2. 0. Therefore, the intensity of the earthquakes remained at a low level. On November 22, 2008, a magnitude 4. 1 earthquake, the largest earthquake recorded since impoundment, occurred in Quyuan Town, Zigui County. The intensity and PGA of reservoir-induced earthquakes are higher than those of tectonic earthquakes with equal magnitude, but the peak intensity of reservoir-induced earthquakes is not likely to go beyond that of the estimated range from earlier studies.

The spatial and temporal slip distribution of the Lushan earthquake was estimated using teleseismic body wave data. To perform a stable inversion, we applied smoothing constraints and determined their optimal relative weights on the observed data using an optimized Akaike’s Bayesian Information Criterion (ABIC). The inversion generated the source parameters. Strike, dip and slip were 218°, 39° and 100. 8°, respectively. A seismic moment (M0) was 2. 1 × 1020 Nm with a moment magnitude (Mw) of 6. 8, and a source duration was approximately 30 second. The rupture propagated along the dip direction, and the maximum slip occurred at the hypocenter. The maximum slip was approximately 2. 1 m, although this earthquake did not cause an apparent surface rupture. The energy was mainly released within 10 second. In addition, the Lushan earthquake was apparently related to the 2008 Wenchuan earthquake. However, the question of whether it was an aftershock of the Wenchuan earthquake requires further study.

The seismic intensities, lithologic characteristics and terrain features from a 3000 km2-region near the epicenter of the Lushan earthquake are used to analyze earthquake-induced geological disaster. The preliminary results indicate that secondary effects of the earthquake will affect specific areas, including those with glutenite and carbonate bedrock, a seismic intensity of IX, slopes between 40° and 50°, elevations of less than 2500 m, slope change rates between 20° and 30°, slope curvatures from –1 to –0. 5 and 0. 5 to 1, and relief between 50 and 100 m. Regions with susceptibility indices greater than 0. 71 are prone to landslides and collapses. The secondary features are mainly distributed on both sides of the ridges that extend from Baosheng to Shuangshi and from Baosheng to Longxing. Other features are scattered on both sides of the ridges that extend from Qishuping to Baosheng and from Masangping to Lingguan. The distribution of the earthquake-related features trends in the NE direction, and the area that was most affected by the Lushan earthquake covers approximately 52.4 km2.

A M6.6 earthquake occurred on July 22, 2013 at Dingxi Basin in Gansu Province within the tectonially expanding northeastern margin of the Qinghai-Tibet Plateau. We analyzed the geomorphological features of the Dingxi Basin by using remote sensing technology and compared them with local seismic activity. We found that most of the river basins are at the robust stage of development and that the major local rivers and the development of some basins boundaries are controlled by the seismic faults. Among four zones identified to have significant tectonic activities, the northwestly-oriented one located in the south has the highest seismic activity, and it is where the M6. 6 earthquake occurrred.