bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of Gravity Effect on the Operating Characteristics of High-Temperature Bent Heat Pipes
Authors: Zhang Zhipeng , Wang Chenglong , Guo Kailun , Tian Wenxi , Su Guanghui , Qiu Suizheng 
Published: November 2024

Abstract
As a high-efficiency heat transfer element, heat pipe can be well adapted to the application scenarios of high heat flow density and high safety requirements in the field of nuclear engineering. This paper carries out experiments on a high-temperature sodium heat pipe, and obtains its operating characteristics in the straight pipe state and the bending state respectively. And the operating conditions of the condenser section under different gravity effect was compared. The results show that in the startup process, the temperature difference between the entrance and exit of the bent section increases significantly due to the increase of flow resistance in the bent region. At the same time, even in the bending section of the exit has been started under the conditions of the bending of the temperature difference between the entrance and exit after bending still exists, when the heat pipe into the full start-up state, the temperature difference is gradually reduced to about 10 °C. After bending, the evaporation section to the condenser section of the temperature difference increases, the adiabatic section of the entrance and exit of the obvious temperature difference; and the heat pipe performance of the degree of loss is also related to the bending of the condenser section of the gravity of the orientation.
An Empirical Study of Radionuclides Behavioral Characteristics in Oceanic Biota From Waste Water Ejection
Authors: Oforiwaa Priscilla Obeng , Zhang Xiaole , Su Guofeng 
Published: November 2024

Abstract
The concept of ecosystem changes of radionuclides is important to ensure product management for food safety. The Fukushima nuclear accident which happened in recent years released a massive concentration of radiocesium into the ocean and subsequent water bodies across Japan. In this research, our main mandate is to study the behavior of some radionuclides (Cesium (CS) 137, Strontium (Sr) 90, Carbon (C) 14, and Tritium (H3). These radionuclides transfer occurs through aquatic pathways to aquatic animals as confirmed in a simulation and air monitoring surveys. The decay characteristics and the transfer medium in Pisceverous Fish species, Benthic Fish species, and Forage Fish in the Pacific Ocean; understanding the decay mode, and transfer model is the driving force of the development of systematic policy models for a nuclear emergency. The oceanic study concentration in some sea mammals and herbivores was developed using the exponential double dynamic model. The results indicate that Pisceverous fish species such as octopus and squid are predicted to have a higher concentration at the onset of an emergency.
On the Allometric scale a predicted concentration of 0.766mSv of radioisotope concentration in an oyster fish. The southern belt oysters are observed to contain a higher sediment property, thus the susceptibility of concentration in this fish species is higher than its normal level.
Time-Domain Nonlinear Investigation of Two-Phase Flow Instability in HTGR OTSG Using SIMULINK
Authors: Su Yang , Li Xiaowei , Wu Xinxin 
Published: November 2024

Abstract
Two-phase flow instability may occur in the once-through steam generator (OTSG) of High-Temperature Gas-cooled Reactors (HTGR). A time-domain theoretical model of HTGR OTSG was established to investigate this phenomenon. The heat transfer tube of OTSG was divided into three regions, namely the subcooled water region, the saturated two-phase region and the superheated steam region. The influence of inlet resistance coefficient could not be accurately predicted by a single-node model of the saturated two-phase region. Consequently, the saturated two-phase region was subdivided into several regions, each experiencing the same enthalpy increase. The dimensionless one-dimensional partial differential governing equations were transformed into nonlinear ordinary differential equations (NODE) using integration and the Leibniz formula under constant pressure drop boundary conditions. The physical parameters characterizing flow instability were dimensionless inlet flow velocity and the dimensionless length between the entrance and different nodes. These NODE were solved using SIMULINK (a toolbox of MATLAB). The typical characteristic of DWO was captured by NODE and SIMULINK, where the phase of dimensionless inlet and outlet mass flow rates are opposite. The multi-nodes (in the saturated two-phase region) time-domain theoretical model can accurately predict the stability boundary of High-Temperature Gas-cooled Reactor-Pebble bed Module (HTR-PM) OTSG. This multi-nodes model was used to predict stability boundary at start-up conditions further, and there is enough safety margin for HTR-PM OTSG.
Effects on a Bending Pipe Behaviour via Simple Pre-Loading for Considering Functional Limitations of Piping in Industrial Facilities
Authors: Sugiura Ayumu , Takito Kiyotaka , Furuya Osamu , Nakamura Izumi , Okuda Yukihiko 
Published: November 2024

Abstract
This paper investigates the effect of initial plastic deformation on the load-displacement relationship of elbow piping of different wall thicknesses made of elastoplastic material The same conditions are applied in the finite element analysis (FEA). Load tests results and FEA of elbow piping made of carbon steel were conducted when three cycles of sinusoidal input with frequency of 0.02 Hz were applied to one end of the piping. Analyses were performed for three types of piping with different wall thicknesses before and after plastic deformation. The effect of initial displacement on the load-displacement relationship was confirmed by loading test, and analytical investigations were also summarized. Then, Comparison of the test and analytical results confirmed that the basic load-displacement relationship could be expressed qualitatively, such as a decrease in yield load due to a decrease in primary stiffness caused by the amount of initial plastic deformation, but from a quantitative standpoint, errors were observed in the loads. The error rate of the maximum load when the specimen was pulled in the in-plane bending direction tended to decrease as the wall thickness increased, but the error rate of the compression of the specimen in the in-plane bending direction showed a completely different trend from that of the pulling.
Criticality and Burnup Analysis of NuScale Reactors With Various Burnable Absorber Designs and Fuel Isotopes
Authors: Luo Yu-Chen , Wu Shin-Rong , Hong Jhao-Yang , Chao Der-Sheng , Liang Jenq-Horng 
Published: November 2024

Abstract
Burnable absorber (BA) crucial components of specific fuel rods, playing a vital role in managing excess reactivity throughout the entire cycle. This substance not only reduces the initial demand for soluble boron at the beginning of the cycle, thus preventing the occurrence of positive moderator temperature coefficient (MTC) during the initial power operation phase, but also mitigates power differences within the assembly. This study models the reactor design of the NuScale small modular reactor according to the original manual and simulates the neutron physics characteristics of the NuScale small modular reactor with different burnable absorbers (BA) and nuclear fuel isotopes. Two designs of burnable absorbers were employed: one involves coating a layer of burnable absorber directly onto the fuel pellets, while the other involves uniformly mixing the burnable absorber into the fuel pellets. Fuel rods containing burnable absorbers were arranged differently. This study using Monte Carlo N-Particle Transport Code (MCNP6.2) [3] computer code with ENDF/B-VII continuous energy library to calculate. Effective multiplication factor (Keff), burnup, and the residual mass of Gd-157 from first cycle to 730 days.
Liquid Lead-Bismuth Oxygen Sensors Performance Study
Authors: Li Hui , Wu Weihao , Zhu Yuqi , Zhu Huiping , Niu Fenglei 
Published: November 2024

Abstract
Liquid Lead-Bismuth Eutectic (LBE) has become the preferred coolant material for Lead Fast Reactors (LFR) due to its outstanding physical and chemical properties. However, the severe corrosion of structural materials by LBE restricts the development of Lead Fast Reactors. Research indicates that maintaining the dissolved oxygen concentration in LBE within the range of 10−6 – 5 × 10−8 wt.% effectively mitigates corrosion on structural materials. In this process, the measurement and control of oxygen concentration are crucial technologies that urgently need implementation. Oxygen sensors, as key devices for measuring internal oxygen concentration in LBE, are essential for dynamically adjusting the circuit’s oxygen concentration. Based on the Nernst principle, oxygen sensors utilize the high oxygen ion conductivity and low electron conductivity of solid electrolytes, assembled into the form of an electrochemical cell for oxygen concentration measurement. Currently developed oxygen sensors are primarily designed for high-temperature environments, and the Pt/air and Bi/Bi2O3 oxygen sensors used exhibit shortcomings in low-temperature testing performance, making it challenging to meet the oxygen concentration measurement requirements below 300°C in LFR’s cold section. Therefore, there is an urgent need to develop wide-temperature-range LBE oxygen sensors suitable for low-temperature operation. To meet low-temperature measurement requirements, we conducted tests on a water-cooled lead-bismuth platform to evaluate the performance of three reference electrode oxygen sensors: Cu/Cu2O, LSM/air, and LSCF/air. The applicable temperature lower limit of the oxygen sensor depends on the performance of the reference electrode. Experimental data indicate that, within the low-temperature range of 250°C to 300°C, Cu/Cu2O, LSCF/air, and LSM/air reference electrodes perform well, meeting the low-temperature measurement requirements of LFR. The Cu/Cu2O reference electrode exhibits good accuracy within the experimental temperature range after adding correction values. LSM/air and LSCF/air reference electrodes maintain good accuracy across the entire testing temperature range. Compared to metal/metal oxide reference electrodes, air-type reference electrode systems generally exhibit better accuracy. However, all three types of reference electrodes demonstrate excellent stability within the experimental temperature range.
Evaluation of Coolant Mixing Characteristics in the Lower Plenum of a Scaled PWR With OpenFOAM
Authors: Djebara Lilia , Wei Hongyang , Yang Cheng , Tan Sichao , Tian Ruifeng 
Published: November 2024

Abstract
In the realm of nuclear reactor design, ensuring uniform flow rates at the core inlet of Pressurized Water Reactors (PWR) is vital for safety, impacting cooling functions and “fuel hot spot” criteria. This intricate balance is influenced by fluid dynamics in the reactor pressure vessel’s lower plenum, essential for both hydraulic and structural plant design.
The geometric configuration of the lower plenum significantly influences the hydraulic characteristics of the Pressurized Water Reactor (PWR). The flow behavior at lower plenum and downcomer (closer to reactor core) has influences on the distribution of the flow entering the reactor core.
To reach a comprehensive understanding of the thermal hydraulic phenomena in the downcomer and plenum of a scaled PWR reactor pressure vessel, numerical investigations was pursued, employing 3D computational fluid dynamics (CFD) simulations, with a thorough comparative analysis against experimental data obtained through Particle Image Velocimetry (PIV), this PIV analysis allow the visualization and understanding of flow mixing characteristics providing valuable insights into the suspended particles’ behavior.
The geometric model with a 3-loop configuration was meticulously developed, and subsequent meshing and simulations were executed employing OpenFOAM. The selected test case emulated a scaled Pressurized Water Reactor (PWR) reactor pressure vessel, solving a 3D Navier Stokes equations. The simulation incorporated a transient flow algorithm coupled with a standard k-epsilon turbulence model. Explicit meshing was applied throughout. Due to the computational complexity, the utilization of high-performance computing resources was imperative to ensure expedited and accurate results.
The results offer a clear representation of flow patterns within the lower plenum of a PWR, significantly augmenting considerations related to nuclear safety. The computational capability of CFD facilitates the evaluation of various flow distribution device concepts, providing engineers with advanced tools for nuanced insights into their advantages and disadvantages in reactor design.
An Effect of Damage Rate on Mechanical Property Change and Microstructural Evolution in Proton-Irradiated Fe-Cu Alloys
Authors: Noshi Yusuke , Fukumoto Ken-Ichi , Ishigami Ryoya , Uda Kinji 
Published: November 2024

Abstract
Damage rate effects have been recognized as being important for understanding the correlation between mechanical property changes and microstructural evolution in neutron-irradiated commercial reactor pressure vessel steels. In this study, the correlation between the irradiation hardening behavior and defect cluster formation in proton-irradiated Fe-Cu model alloy is investigated using nanoindentation tests and transmission electron microscopy with a variety of damage rates for the proton irradiations. A wide range of damage rates across three orders of magnitude is adopted for the proton flux in a single irradiation experimental system. The hardness in the low damage rate case is higher than in the high damage rate case in the initial stage of damage level when hardening behavior was not saturated. From transmission electron microscopy observations, it is found that a low density of large dislocation loops is formed under lower damage rate conditions. According to the irradiation hardening estimation based on the classical dispersed barrier hardening model, it is indicated that the damage rate effects on the hardening contribution are weak for dislocation loops but dominant for Cu-rich precipitates.
Analysis of Water Hammer in the Reactor Coolant System Based on Wave Tracking Method
Authors: Zhang Qianping , Dong Shubiao , Zhang Xiaoyu 
Published: November 2024

Abstract
To investigate the pressure wave propagation process caused by water hammer in the reactor coolant system, a simulation model of the three-loop main coolant system, consisting of the reactor core, steam generator, main pump, and pressurizer, has been established. The reactor core and steam generator are simplified with equivalent pipes, the pressurizer model is established using a two-phase canister, and the friction torque model of the main pump’s anti-reversal device has been developed. Unlike existing studies, this paper employs the wave tracking method (WTM) for water hammer simulation. Finally, the accuracy of the model is verified by idling experiments after the power failure of the three main pumps (case 1). And the restart of a single main pump after power failure (case 2) and the shaft stuck of the main pump (case 3) are simulated. The results indicate that the simulation results in case 1 are in good agreement with the experimental results, and the pressure wave fluctuates slightly in case 2. In case 3, water hammer occurred in the main pump, the maximum pressure reached 16.66MPa (amplitude 1.47Mpa), and the minimum pressure dropped to 14.97MPa (amplitude −0.94Mpa). The simulation results provide support for the safe operation of the reactor coolant system.
Effect of Nanostructures of Different Sizes on Boiling and Nucleation: A Molecular Dynamics Study
Authors: Gao Deyang , Ma Yue , Bo Hanliang 
Published: November 2024

Abstract
With the development of technology, the energy needs of today’s society are gradually increasing, and methods that can improve heat transfer efficiency within limited volumes are becoming increasingly important. Among various heat transfer methods, boiling is considered an effective way to improve spatial heat transfer efficiency due to its ability to fully utilize phase change latent heat. The design of nanostructures enables further enhancement of boiling heat transfer efficiency, and numerous studies indicate that nanostructures facilitate bubble nucleation and growth during boiling, thereby increasing critical heat flux (CHF). However, existing studies mostly analyze the influence of surface nanostructures on bubbles independently of the heat transfer and potential energy aspects. Possible synergistic or mutually inhibiting effects between the two are hardly taken into account. In addition, boiling heat transfer in a reactor not only improves the efficiency of heat transfer, but can also affect the reactivity and safety of the reactor due to the uneven distribution of bubbles in time and space. Therefore, it is also necessary to consider the influence of nanostructures on the bubble nucleation positions. The entire bubble growth process was directly observed by using molecular dynamics simulations. Furthermore, a detailed discussion was conducted on the influence of nanostructures on nucleation positions, nucleation times, and CHF. The results suggested that not all nanostructures contribute to bubble nucleation; Instead, when the nanostructure size is smaller, bubble nucleation was delayed and CHF is reduced. The mechanism of this phenomenon is revealed by the inhibitory effect between heat transfer and potential energy.
Comparative Analysis of Loss of Coolant Accidents for GEN-III PWRs Based on ACME and ATLAS Facilities
Authors: Huang Yuhang , Zhang Xueyan , Yang Jun 
Published: November 2024

Abstract
ISP-51 and ISP-50 are two recent international cooperation projects organized by OECD/NEA, with the aim of comparing and evaluating the capability of best estimate system codes. ISP-51, led by HUST, is based on ACME (Advanced Core Cooling System Mechanism Experiment) facility scaled from the CAP1400 in China. ISP-50, led by the KAERI, is based on ATLAS (Advanced Thermal-Hydraulic Test Loop for Accident Simulation) facility scaled from the APR1400 in Korea. Both ISPs simulated Loss of Coolant Accident (LOCA) scenarios in the passive thermal-hydraulic facilities and followed the international ISPs practice of conducting blind test and open test. ISP-51 aimed to simulate CAP22 (a small 2-inch break at the cold leg and a failure of one of the four ADS4 valves on the non-PZR side) for the open phase, and CAP16 (a double ended break of direct vessel injection) for the blind phase. ISP-50 aimed to simulate a 50% direct vessel injection line break accident. Both ISPs are based on the LOCA transients on integral test facilities mocked from the representing GEN-III PWRs with similar power level and passive safety features. Since CAP1400 and APR1400 are both of GEN-III PWRs with passive safety features and similar power level, it would be of interest to study these two ISPs, comparatively, by cross-checking and analyzing the prototypic reactors and test facility. This study further enhances the understanding of typical GEN-III PWR technologies, provides us insightful view about the overall design characteristics and passive safety features.
Reducing Variance in Nuclear Monte Carlo Simulations Through Deep Learning Post-Processing Techniques in the Gaming Domain
Authors: Guo Haoxuan , Li Wei , Sang Yaodong , Chen Haizheng , Zhang Qingmin 
Published: November 2024

Abstract
In nuclear science and engineering, Monte Carlo simulation, a critical tool for solving complex physical problems, faces significant computational costs and challenges in achieving high precision due to the extensive time and hardware resources required. Drawing inspiration from the gaming industry, which has developed advanced deep learning techniques for denoising and super-sampling in raster graphics rendering, this study investigates the adaptation and integration of these techniques into Monte Carlo simulations to enhance precision and reduce computational demands. By incorporating deep learning super-sampling and denoising techniques, such as Intel OIDN, NVIDIA OptiX, SRCNN, and waifu2x, as post-processing steps in simulations of nuclear events, the study demonstrates a notable reduction in variance and improvement in accuracy. This novel approach not only presents a promising avenue for improving the efficiency of Monte Carlo simulations in nuclear science and engineering but also opens up possibilities for applying these advanced techniques to a broader range of complex issues in the field.
Ways to Solve the Safe Operation of VVER-1000 Reactors in Case of Loss of Original Rod Cluster Control Assemblies Supply
Authors: Mazurok Oleksandr , Zuyok Valeriy , Ivanov Vadym , Tretyakov Mykhaylo 
Published: November 2024

Abstract
The article briefly presents the results and experience of lifetime extension of operating RCCAs manufactured in RF. It is shown that by reducing conservatism, until the criteria for maintaining the integrity of the fuel cladding are achieved, it is possible to extend the lifetime of almost all RCCAs currently operating at Ukrainian NPPs from 25500 to 38000 hours in the control group and from 75600 to 113500 hours in the shutdown groups. However, the substantiation should be carried out for each RCCA separately, since each one has its own individual history of operation in the reactor core.
The main part of the article is devoted to the ways of increasing the efficiency and extension of RCCA lifetime, and to the development of control rods with improved characteristics. Among the proposed absorbers, the most acceptable neutron absorption efficiency is provided by metallic hafnium with an absorbing part diameter of 8.2 mm (without a cladding) and Dy2O3·HfO2 in the pellet version of filling the lower part of the control rod (up to 300 mm). In the upper part of the rod (from 300mm to 3500mm), Eu2O3·HfO2 composition can be used instead of B4C. Europium hafnate with a density of 8.0 g/cm3 and a tablet filling (6.85 mm) will exhibit an initial neutron absorption efficiency of 95.6% of B4C. The high neutron absorption efficiency will make it possible to use less efficient (n,y) absorbers with extended lifetime (Dy2O3·HfO2, Hf) with a length of more than 300 mm in the lower part without violating the neutron-physical criteria for the performance of the control rod.
Analysis of the Acceleration Effect of Anderson’s Fixed-Point Acceleration Method in Core Neutronics Calculations
Authors: An Ping , Lu Wei , Liu Rui , Li Zhigang , Tang Qifen , Shen Jie 
Published: November 2024

Abstract
Fixed-point iteration is the most widely used iterative format in numerical calculations. The Seidel iterative method is a traditional acceleration method, which is generally used in the source iteration process of core neutronics calculations. During the fixed-point iteration process, the Anderson acceleration method is using the least squares method to find the direction that converges the fastest, based on previous iteration values. The Anderson acceleration method can replace the Seidel iteration directly. So, it can be easily implemented in existing numerical software iteration.
In this paper, the Anderson method with depth n is derived, where depth n represents the value of the previous n iterations. The Anderson acceleration formats with depths of 1 and 2 are used to calculate neutron flux of the reactor core. We calculate Boron critical searching calculation of the first-cycle loading. The calculation results show that the Anderson method reduces the number of iterations by 20% and the calculation time by about 15% on average compared with the source Seidel iteration while ensuring the same convergence accuracy. This improves the efficiency of neutronics calculations and provides a theoretical basis for subsequent transport calculations or other fixed-point iteration acceleration methods.