bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic Modeling for Compact Recuperator in Helium Gas Turbine Direct-Cycle System
Authors: Geng Xuyao , Wang Jie 
Published: November 2024

Abstract
The helium gas turbine direct-cycle scheme has the advantages of high operation temperature, simple design, and compact structure. It can serve as an efficient energy conversion system (ECS) and combine with various forms of energy, so it has broad prospects for development. Recuperator is crucial to helium gas turbine direct-cycle system. Its main function is taking advantage of high temperature helium at the outlet of turbine to heat microthermal helium behind the high pressure compressor to improve the power generation efficiency of the system. The accuracy and reusability of recuperator model will affect the system modeling and simulation. It is necessary to explore the appropriate modeling and solving methods for recuperator, and analysis the transient characteristics of recuperator under different operating conditions. In this paper, the plate heat exchanger is selected as the recuperator, and the segmented lumped parameter method is adopted to calculate the dynamic characteristics under the condition of mass flow rate and temperature disturbances. The calculation results are compared with those obtained by CFD methods. It indicates that the segmented lumped parameter model is robust and agree well with the results obtained by the finite volume method. The responses of recuperator to temperature and mass flow disturbance are analyzed. The flow rate has a greater influence on the metal wall temperature distribution shape. In power regulation, changing the flow rate synchronously on both sides of recuperator, the wall temperature is basically unchanged. In load rejection, if the regulating process lasts too long, the wall temperature may suffer from a cold shock.
Features of Space Reactor Brayton Cycle Under Power Regulation by Control Drums
Authors: Ma Wenkui , Ye Ping , Gao Yue , Hao Yadong , Yao Yi , Yang Xiaoyong 
Published: November 2024

Abstract
The development of space exploration technologies such as planetary bases and orbital propulsion has higher requirements for space power systems. The reactor coolant of the space reactor Brayton cycle (SRBC) is also the cycle working fluid, which has the advantages of high power conversion efficiency, compact configuration, small mass and volume. It is the one of the best options for future high-power space power systems. Reactivity insertion by control drums is an effective means of power regulation for the SRBC. In this paper, the dynamic model for the SRBC were established, the safety characteristics of the SRBC under power reduction conditions by control drum insertion were studied. The results indicated that the control drum insertion decreases the output power of the turbine and further leads to speed fluctuations. The bypass valve control can ensure stable shaft speed and balance between power generation and load of the generator, ensuring the safe operation of the SRBC under reactivity insertion conditions. Furthermore, the safety boundary for control drum insertion conditions of the SRBC was investigated. The results indicated that more control drum insertion decreased the output power of the turbine. The speed decreases far from the rated speed and exceeds the safety margin of the bypass valve control. The continuous decrease in speed leads to system shutdown, and there is a safety boundary. The analysis provides a reference for the operation and control of the SRBC in the future.
Depressurization Behavior and Strategy of Automatic Depressurization System for AP1000
Authors: Shang Zhengrun , Lv Dufeng , Meng Zhaoming , Sun Zhongning 
Published: November 2024

Abstract
This article through simulate small-break loss-of-coolant accidents (SBLOCA) specifically in the AP1000 and thoroughly analyze the behavior and strategy of the ADS in such accident scenarios. A comprehensive AP1000 model is constructed using the System Analysis Code, incorporating various components including the reactor coolant system (RCS), secondary system, passive safety injection system (PSIS), and automatic depresurization system (ADS). Five different types of conditions are simulated and evaluated to assess their thermal-hydraulic impact on the RCS, passive core cooling system, core degradation, and the ADS itself. The analysis results show that the design of two sets of independent ADS depressurization pipelines aims to achieve a redundancy level of 2 × 100%. Gradually opening the ADS pipelines increases the inlet pressure of the sprayer and widens its pressure curve, allowing for a sustained stable critical jet state over an extended duration. In the initial stage of the accident, opening the ADS stage with a large area stage can effectively improve the depressurization and cooling rate of the RCS and maintain the critical discharge state of ADS. ADS-4 can reduce the RCS pressure to the start-up pressure of In-containment refueling water storage tank (IRWST) to ensure long-term core cooling. These results hold significant meaning in comprehending the behavior and strategy of the ADS in typical SBLOCA scenarios, thereby contributing to the establishment of an effective theoretical foundation for the design of ADS pipelines and sprayers.
Numerical Investigation on Interphase Interaction and Interplume Effects of Multi-Hole Steam Injection Condensation Based on ADS1-3
Authors: Xu Jibin , Zheng Hao , Shen Xihao , Zhang Yuhao , Lu Daogang 
Published: November 2024

Abstract
Multi-hole jets are commonly employed in most technical applications for cooling and depressurization of high-temperature and high-pressure steam emissions due to their extraordinarily high heat and mass transfer efficiency. Due to the complexity of the micromechanics of steam condensation, in numerical calculations, existing models do not fully satisfy simulation needs, particularly under porous circumstances, past research has concentrated on single-pore steam jet direct contact condensation (DCC). Based on the ADS 1-3 level equipment in IRWST, the development of a model for DCC of multi-hole vapor injection, a three-dimensional transient numerical simulation research of the DCC mechanism and heat transfer characteristics of a multi-hole high-temperature and high-pressure steam jet is undertaken in this work.
The simulation results of the VOF and Mixture multiphase flow models graphically demonstrate the variations in their calculation theories, with the treatment of interphase interpenetration being the most significant difference. Compared to the MIXTURE model, the plume calculated using the VOF model is much larger, with the axial length of the plume being 3 to 4 times that calculated using the MIXTURE model, and the radial length being 2 to 3 times that calculated using the MIXTURE model, which is in gross disagreement with the experimental results. Finally, the Mixture model is better suited for numerical simulations of the steam jet DCC’s non-full Eulerian multiphase flow model. It serves as a data source for future porous steam jet DCC numerical simulation investigations.
The Mission Time Analysis in Level 2 Probabilistic Safety Assessment of the Third-Generation Nuclear Power Plant
Authors: Guo Shujie , Liu Jing , Zhong Yubao 
Published: November 2024

Abstract
Mission times have to be defined for the probabilistic system or equipment failure analysis. Severe accident mitigating systems may need to be in operation for a long time period, thus mission time considered in Level-2 probabilistic safety assessment (L2PSA) is usually longer than in Level-1 probabilistic safety assessment (LIPSA). By simplication, the mission times in the LIPSA are often defined globally as a maximized delay before obtaining a stable state without core damage. A common mission time is often defined as 24 hours for all systems and all accidents in LIPSA. L2PSA has another perspective. In practice, most LIPSAs with the issue of containment challenge due to core concrete interaction which may pressurize the containment or melt through the containment bottom within typical time scales of one to several days. Due to the complexity of the severe accidents and the diversification of the mitigation measures, there is no common time in L2PSA. Different times are used, like 24 hours or 72 hours. Selection principles of the mission time in L2PSA were researched and the modeling methods were developed. As an example of generation III NPP, the mission time was chosen and modeled, and the sensitivity was analyzed.
Numerical Simulation Research on Irradiation-Thermal-Mechanical Behavior of CDM Fuel in Different Types of Reactors
Authors: Tang Changbing , Li Yuanming , Liao Haoyu 
Published: November 2024

Abstract
The ceramic dispersion microencapsulated (CDM) fuels have high tolerance of accidents, and are regarded as promising candidates for the light water reactors. During irradiation, the parts in the CDM fuel may experience extreme irradiation-related irradiation-thermal-mechanical behavior. The buffer layer, which provide free volume for gaseous fission products and absorb kernel swelling, will firstly shrink during the early lifetime, and will re-contact to the IPyC layer. The re-contact of the two layers will cause high circle tensile stress in the IPyC layer, which may lead to the failure of the microencapsulated particle. In order to study the in-pile performance of the CDM fuels, and the possible application of the CDM fuels in other kind of reactors, such as the high flux reactor (HFR), the ADS reactor, and RERTR research and testing reactor, a series of researches are needed. Because of the economic efficiency of in-pile tests, researches of combined with numerical simulation could be an effective method for the study of the in-pile behaviors, the performance evaluation and the optimum design of the CDM fuel. In this research, a 3-D numerical simulation model of the in-pile behaviors of CDM fuel particles with ceramic matrix is built. Different irradiation conditions based on various type of reactors are introduced into the simulation of CDM fuel in-pile irradiation-thermal-mechanical behavior. The simulation results and the failure evaluation of the CDM fuels are discussed.
Modular Structure Selection and Design of ACP1000 Reactor Building
Authors: Xu Man , Tang Minghao , Jia Xiaopan 
Published: November 2024

Abstract
The Chinese nuclear power industry has entered a period of safe and efficient development, facing challenges such as an aging workforce, labor shortages, and significant energy and resource consumption in the construction process. Modular design and construction technology has been proven effective in the latest third-generation nuclear power projects, offering a means to reduce on-site construction, minimize safety hazards, shorten construction periods, and lower overall project costs. There are various structural forms of modular construction. This paper analyzes multiple modular construction technologies, examines the specific characteristics of the ACP1000 Pressurized Reactor, selects a structural modular type suitable for the ACP1000 Pressurized Reactor, and provides a detailed explanation of the modular design calculations for the internal structural buildings within the reactor facility.
Accelerating the implementation of modular internal structure design is of great significance for shortening the main construction period. The main body of the internal structure factory building is a shear wall and thick floor structure, which bear a large and complex load. The traditional reinforced concrete construction site has a large workload and long working time. Comprehensive analysis shows that the steel plate concrete structure is suitable for modular design of the internal structure. The steel plate concrete structure can meet the bearing and construction requirements of the internal structure due to its high construction efficiency and good stress performance. This article focuses on the design and calculation of steel plate concrete walls in practical engineering, and verifies them with reference to the “Technical Specification for Steel Plate Concrete Structures of Nuclear Power Plants “ GB/T 51340-2018, ultimately determining the design scheme of steel plate concrete structures.
The Influences of Key Factors on the Gas Diffusion in the Material Irradiation Test Based on the Regulation of Gas Composition
Authors: Sun Yixiong , Yang Wenhua , Sun Sheng , Zhang Liang , Zhao Wenbin , Jin Shuai , Lei Jin , Cheng Jinkang 
Published: November 2024

Abstract
Material irradiation test requires to design device structure to ensure that the specimen temperature can meet requirements. Gas composition regulation is one of the main temperature control methods. Temperature gradient is established through the gas gap between the specimens and coolant, and the thermal conductivity of gap can be changed by regulating the gas composition, thereby controlling the specimen temperature. The study takes the annular gas gap of a typical material irradiation device as the research object, adopts computational fluid dynamics (CFD) method to simulate the gas diffusion process, and analyzes the influences of key factors such as type of gas inflated, gas inflation rate and volume on gas diffusion behavior during the process of gas composition regulation. Helium floats because of its lower density than the mixed gas, and argon sinks because of its higher density. For the same working conditions, argon will diffuse to a farther location under the action of greater inertial force. The higher the gas inflation rate, the wider the range of gas diffusion to the surroundings at the bottom of the device, the faster the diffusion rate in the gas gap, and the longer the diffusion distance. The volume of only affects the final diffusion state. The higher the gas inflation volume, the mole fraction of the corresponding gas will continue to increase.
Data Sharing and Business Collaboration-the Refined Management Process of Bulk Materials for Nuclear Power Projects
Authors: Jie Wang , Zhuoze Li , Yuan Xin , Xinpei Xia , Yi Zhao , Sen Wang , Yanling Zheng 
Published: November 2024

Abstract
The bulk materials have the characteristics of many varieties, huge quantities, and frequent changes, which have made it difficult to manage the construction of nuclear power projects in the past, and the problem of high residual rate has occurred frequently. The traditional project management mode has the characteristics of focusing on the overall goal of the project and emphasizing the schedule over the cost, which leads to the lack of high requirements for the accuracy, standardization and timeliness of the quantity of bulk materials by the design, procurement and construction parties in the process of project implementation. Based on the principles of data sharing and business collaboration, this paper studies and constructs a set of data-based bulk material refinement management system process. The process is based on design data, compacts the business processes of on-demand procurement and on-demand picking, and loads procurement and construction information. In order to solve the data island phenomenon brought about by traditional form-based management and the problems of difficulty and error rate in manual processing of massive data, a series of software tools and management information systems have been developed to open up the data chain between the three sectors of design, procurement and construction, so as to realize real-time and accurate transparent information transmission.
Effect of Different Temperature Probability Curve Fitting Methods on the System Reliability for PCCS in AP1000
Authors: Yu Yu , Liu Guanyu , Feng Wanxin , Zhao Houjian , Lyu Xuefeng 
Published: November 2024

Abstract
Passive safety systems operating based on natural circulation are widely used in new generation reactor design to improve the safety of nuclear power plant, and functional failure of passive safety system gets more and more attention in recent years. Passive Containment Cooling System (PCCS) in AP1000 nuclear power plant is a typical passive safety system, and atmosphere is used as the heat sink, so air temperature is one of the important factors affecting the system operation. The air temperature probability density curve used in the system reliability evaluation is always gained based on the historical data through fitting ways such as least square method. However, the system always has large safety margin, so for the system failure cases, the air temperatures are so high that have quite low probability. And these values are in the tail of the temperature probability density curve, so the fitting methods may have important effect on the results. In this paper, we calculate the system failure probabilities for PCCS in AP1000 with two temperature probability curves gotten from different fitting ways, and the effect of the air temperature probability curve fitting method is analyzed.
CFD Modeling of a Full Clogging Event in a Pumping Station With Neptune_cfd Solver: A Preliminary Investigation
Authors: Natchez Sebastien , Ceyrolle Romain , Loizeau Vincent , Cordier Hervé 
Published: November 2024

Abstract
The drum screen filters the water upstream of the pumping station of a NPP to protect it from debris entrance. These devices can be damaged in case of full clogging events because of drum deformation or air aspiration in the pumps located downstream of the filter. With climate change and the contingency to face more clogging events, EDF has lately tried to estimate their impact on pumping stations by different manners. The focus was set on passive filtration (static filter with no cleaning system) to reduce the complexity of the modelling and the objective is to determine how long it would take for the water level downstream of the filter to reach a hazardous level. To study such cases numerically, it is necessary to select the appropriate physical models which are able to simulate the physical phenomena while minimizing code developments. In this context, a first attempt with code_saturne highlighted the necessity of a two-phase flow code to simulate an industrial application, which was confirmed by a second attempt with neptune_cfd. In order to ensure the reliability of the results it is now required to validate the code on simpler problems where experimental data are available. This preliminary investigation shows that a development of the deposition model is still necessary to use a lagrangian method for particle transport and deposit in neptune_cfd.
Experimental Study on the Coolability of Molten Core Materials Discharged Into a Depth- and Volume-Limited Sodium Plenum
Authors: Matsuba Ken-ichi , Kato Shinya , Kamiyama Kenji , Akaev Assan S. , Vurim Alexandr D. , Baklanov Viktor V. 
Published: November 2024

Abstract
During a severe accident in sodium-cooled fast reactors, molten core materials could be discharged from the core region toward the lower sodium region of the reactor vessel through coolant channels, such as control rod guide tubes. Typical SFRs have a sodium plenum with limited depth and volume, such as the core inlet plenum located under the core region. Therefore, it is important to evaluate the coolability of molten core materials discharged into a depth- and volume-limited sodium plenum. In the present study, to deepen the understanding on the coolability of molten core materials discharged into such a sodium plenum, conditions under which molten core materials form solidified fragments were discussed based on an experiment discharging a molten fuel simulant (molten Al2O3) into a test vessel filled with liquid sodium. The data obtained in this experiment suggest that the molten Al2O3 formed solidified fragments under a condition beyond the cooling limit (the volume ratio of sodium to molten core materials: more than 10 times) estimated from existing studies, such as M-series experiments performed at the Argonne National Laboratory in the 1970s. Sodium convection flow induced by sodium vaporization (vapor bubble growth) and condensation during the Al2O3 discharge might have contributed to such efficient cooling.
Proposal for Organizing and Understanding Decommissioning Information Using Task Ontology
Authors: Taruta Yasuyoshi , Iguchi Yukihiro , Kawasaki Daisuke , Yanagihara Satoshi , Tomoda Koichi 
Published: November 2024

Abstract
In this study, we propose a hierarchical framework using task ontology, which is used in information science and information engineering, to organize decommissioning information. As background, decommissioning of nuclear facilities generally takes a long time, so it is important to accumulate information and utilize it.
In decommissioning, the operator creates a plan using facility information during construction, subsequent renovations, and contamination distribution and evaluation during operation, and conducts decontamination, demolition, waste management, and waste delivery. It may also include restoring the land on which it was installed to its original condition. In addition, there are several implementation policies for this decommissioning: cases where the operating entity hands over the decommissioning to the decommissioning company, and cases where the operating entity directly carries out the decommissioning. Decommissioning is being carried out in each country and by various organizations, and various knowledge and lessons are being created every day. It is important to utilize these findings. On the other hand, it can be said that it is difficult to simply utilize it in other organizations due to different laws and regulations and different organizational management policies. It is necessary to appropriately utilize precedent cases and information on lessons learned.
Therefore, in this study, we introduce the concept of ontology to decommissioning and propose a conceptual model from the perspective of plant information management and knowledge management. Ontology has guidelines for understanding objects without using language, and is a conceptual structure of knowledge. Previous studies and reports have referred to the importance of ontology in decommissioning, but it cannot be said that its structure and relationships with other ontologies have been specified.
In this study, we propose a structural organization using task ontology as a guideline for information organization to cope with such situations.