bluuebunny/crossref_metadata_2025 huggingface dataset:
Percutaneous‐endoscopic rendezvous cholangiography with biliary stent placement in a dog with extra‐hepatic biliary duct obstruction
Authors: Work M. , Allerton F. , Griffin S. , Kent A.
Published: October 2021

A middle‐aged male springer spaniel was presented for investigation of acute vomiting, lethargy and icterus. Marked distension of the gall bladder and common bile duct was evident at ultrasound due to obstruction by mineralised intraluminal material. After 48 hours of hospitalisation with intravenous fluid therapy, analgesia and antimicrobial therapy, intervention was deemed necessary to relieve the obstruction. A percutaneous‐endoscopic rendezvous approach was used to achieve placement of a pigtail stent into the distal common bile duct, successfully relieving the obstruction. Serial biochemistry measurements postprocedure confirmed marked improvements in serum bilirubin. The patient remains clinically well 24 months postprocedure, and all hepatic enzyme activities have normalised. Based on the literature search performed, this is the first successful application of this technique in the management of canine extrahepatic biliary duct obstruction.
A review of philopatry and dispersal in felids living in an anthropised world
Authors: de Oliveira Marina E. , Saranholi Bruno H. , Dirzo Rodolfo , Galetti Pedro M.
Published: October 2021

Typically, males of polygamous mammals are responsible for population connectivity and gene flow via dispersal, whereas females, showing stronger philopatry, strengthen local population stability and growth. These expectations can be disrupted by human disturbances; however, this possibility has been poorly examined in wide‐ranging mammals that are important targets for conservation.

By reviewing philopatry and dispersal in felids, we aimed to evaluate: 1) whether the sex‐related patterns of philopatry and dispersal predicted for polygamous mammals are prevalent in felids, 2) possible major causes underlying each of these behaviours, and 3) if, and to what extent, anthropogenic disturbances can alter patterns of philopatry and dispersal in this animal lineage.

We synthesised the available literature (n = 55 papers) comprising 12 species. Puma concolor was the most‐studied species, followed by other large species. Both philopatry and dispersal were heterogeneously defined, depending on the study aim and the method employed (telemetry, camera trapping or molecular tools).

Most species followed the predicted philopatric and dispersal patterns, and most study areas (76%) were under some type of anthropogenic disturbance drivers. Philopatry was linked to females’ higher dependency on the quality and availability of resources, and to their social dynamics, higher reproductive success, inclusive fitness and demographic aspects of population. Dispersal was frequently linked to competition for mates and resources, and inbreeding avoidance. However, some plasticity was observed in both philopatry and dispersal, especially under the presence of anthropogenic drivers. For example, hunting can create open territories, increasing the number of philopatric females and opportunistic philopatric males. Habitat fragmentation can increase population isolation and male dispersal distance, and the presence of anthropogenic or natural barriers can result in unsuccessful dispersal attempts.

We postulate that human activities affect long‐term population persistence in the Felidae, via disruption of sex‐related patterns of spatial dynamics.
Novel use of a Franklin split lens for cycling with hemianopia
Authors: Crossland Michael D , Reuben Mitchel , Bedford Sarah L
Published: October 2021

Purpose

Optical rehabilitation for hemianopia includes the prescription of partial aperture prismatic lenses. Fresnel lenses for this purpose have poor optical quality, while bonded lenses have poor cosmesis and can only be made in glass, creating a potential hazard. Here we present an alternative lens type, which does not reduce contrast sensitivity and which can be made in plastic materials.

Methods

A rotated Franklin split lens was prescribed for the right eye only to provide a full aperture prismatic lens without using a Fresnel prism or bonded lenses. Using different refractive indices in each lens provided a minimal transition in thickness and an acceptable cosmetic appearance. This lens was prescribed to a 34‐year‐old woman with homonymous right hemianopia. Her contemporaneous comments are presented.

Results

The rotated Franklin split lens provided 18Δ over the temporal edge of the lens. The wearer noticed chromatic aberration with this lens, but was able to cycle comfortably when wearing the lens without any reduction in contrast.

Conclusions

A rotated Franklin split lens can be used for the optical rehabilitation of hemianopia. In this case study, cycling was possible with this lens.
Magnetic resonance imaging validation of medial transthyroid ultrasound‐guided stellate ganglion block: A pilot study
Authors: Chung Boo Young , Holfelder Christian , Feldmann Robert E. , Kleinboehl Dieter , Raum Raoul C. , Benrath Justus
Published: October 2021

Objective

Ultrasound‐guided stellate ganglion block (usSGB) facilitates improved accuracy of needle position and application of lesser volumes of local anesthetic (LA). Approaches of usSGB, however, have not fully been optimized with respect to efficacy and technical convenience. This pilot study examined the anatomical position and spatial distribution of a small volume of LA injectate dispensed by medial transthyroid usSGB via magnetic resonance imaging (MRI) and assessment of its effect on cervical sympathetic nerves.

Methods

Twelve healthy males were tested in a double‐blinded within‐subject design. In a total of 37 usSGB, 3 ml of LA and saline 0.9% solution were injected intramuscularly into the longus colli muscle (LCM) preventing uncontrollable spread of LA within cervical structures. Immediately after injection, distribution of injectate was traced by MRI. Twenty‐four out of the 37 usSGB‐injections with 3 ml ropivacaine 1% (verum) and saline 0.9% (placebo) were compared. Efficacy of usSGB was assessed by the appearance of oculosympathetic paresis and increases in skin temperature.

Results

All usSGBs were positioned in the proximity of the LCM muscle belly. Most of the axial injectate was distributed within the transversal plane between the middle section of C5 and the upper section of T1 vertebra. Signs of oculosympathetic paresis and skin temperature increase were found exclusively under verum conditions.

Conclusion

This pilot study demonstrated the feasibility of medial transthyroid usSGB using an out‐of‐plane technique and a volume of 3 ml of LA. Further studies are required to establish the relative value and safety of this technique compared to other published approaches.
Ginsborg’s Reading of Wittgenstein on Rules and Normativity
Authors: Ebbs Gary
Published: October 2021

Hannah Ginsborg argues that according to Wittgenstein, a normal human subject can recognise that a new step is correct without grasping any rule with which the step accords. I argue, on the contrary, that according to Wittgenstein, a normal human subject’s understanding of a series and her capacity to take new steps to be correct continuations of the series are, as Wittgenstein says of “rule” and “accord” (PI §224), “related to one another.” Neither is more fundamental than the other.
Evaluating the contribution of synthetic fungicides to cereal plant health and CO2reduction targets against the backdrop of the increasingly complex regulatory environment in Europe
Authors: Bryson Rosie
Published: October 2021

The global COVID pandemic has impacted the world in ways and at a scale that few could have predicted, with many industries severely disrupted. Despite this, crops were sown and harvested, food was produced and agriculture continued to function, albeit it with many logistical challenges. Plant health lies at the heart of preventing crop losses through a combination of varietal resistance and agronomic practices. In the case of foliar plant diseases in wheat, varietal resistance plays a key role, but the use of synthetic fungicides is essential to minimize crop losses. European arable production faces a dilemma: how to contribute and maintain global food supplies but at the same time decrease emissions of greenhouse gases (GHGs), reduce inputs potentially harmful to biodiversity, society and the environment while ensuring no more land is brought into production. Throughout history, major disruptions in society have led to big steps in agricultural innovation. Presently, the major disruptive forces in Europe are not just a result of the COVID pandemic but the increasingly urgent need to address climate change. Within the European Green Deal, the Farm‐to‐Fork strategy is in place to help achieve climate neutrality by 2050, aiming for a reduction of GHG emissions of 55% by 2030. To achieve this, there will need to be a major adjustment to how food is produced, a realignment in plant health strategies and accelerated innovation across the agricultural sector. This paper aims to evaluate how synthetic fungicides presently contribute to plant health (mainly wheat) and food production as well as the management of GHG emissions. In addition, it explores the future challenges and prospects for their positive contribution in achieving global food security alongside emerging innovative technologies.
Heterogeneous impact of import competition on firm organisation: Evidence from Japanese firm‐level data
Authors: Matsuura Toshiyuki
Published: October 2021

This study empirically investigates the effect of import competition on within‐firm employment reorganisation using a Japanese firm‐level dataset covering the period of 1997–2014. Moreover, this study examines whether the import competition against low‐income countries leads to a shift from a manufacturing activity to non‐manufacturing activity, such as headquarters’ services, wholesale, retail or R&D. Furthermore, this study explored the heterogeneity of the impacts of import competition according to firm size. Findings reveal that competition from Chinese imports induces manufacturing firms to increase the share of service workers, particularly workers that engage in wholesale, retail and other service activities.
'The Technological Sublime': Combining Art and Archaeology in Documenting Change at the Former RAF Coltishall (Norfolk, UK)
Authors:   University of Dundee, Dunlop Gair , Schofield John ,   University of York
Published: October 2021

Since at least the 1990s, archaeologists and artists have been documenting military installations following the withdrawal of service personnel. They have usually embarked on these recording opportunities separately, experiencing these sites as derelict, lifeless places, with stripped buildings devoid of much of their meaning after their occupants have left. Archaeologists have typically created maps and made photographs. Artists have also taken photographs, but in addition made films and created soundworks. Wherever the medium and the motivation, the assumption is usually made that only those closely familiar with the rhythms and rituals of service life can begin to understand the emptiness of what remains. And being secretive military installations, creating a record during their occupation is never an option. Uniquely, in the months leading to the closure of RAF Coltishall (Norfolk) in 2006, the RAF granted the authors unprecedented access to record the base's drawdown and closure. The project brought artists and archaeologists together to see what could be achieved in unison, while still maintaining some degree of research independence. In undertaking this survey, three related themes emerged: the role of art as heritage practice, new thinking on what constitutes landscape, and the notion of a 'technological sublime'. Following an earlier publication, we now reflect again on those themes. In doing so, we offer this collaboration between art and archaeology (traditionally considered two distinct ways of seeing and recording) as an innovative methodology for documentation, not least after the closure and abandonment of such military and industrial landscapes, where occupational communities had once lived. In this article, the words represent our ideas; the images and films are an example of the result.
A Comparative Analysis of Exhaust Gas Temperature Based on Machine Learning Models for Aviation Applications
Authors: Atasoy Vehbi Emrah , Suzer Ahmet Esat , Ekici Selcuk
Published: October 2021

The main objective of this study is to investigate elaborately the relationship between exhaust gas temperature (EGT) and various operational parameters specific to aero-engine for the cruise phase. EGT prediction is performed based on different models, including deep learning (DL) and support vector machine (SVM), using a set of historical flight data, more than 1300. In order to achieve this goal, the EGT is taken as the output parameter while the most key variables for the EGT prediction are taken as the input parameters to the models. Several statistical goodness tests, namely root-mean-square error (RMSE), mean absolute error (MAE), and coefficient of determination (R2), are conducted to make a fair comparison between the efficiency and performance of each model that is developed based on Matrix Laboratory (matlab) and R code. The relative importance for the altitude (ALT) parameter of 11.89% has the highest value while the lowest relatively importance parameter is vibration (VIB) of 5.00%. EGT variation for the actual data is in the range of 459.05 and 607.32 °C. It is observed that the EGT variation of DL and SVM ranges from 457.09 to 604.52 and from 454.64 to 603.23 °C, respectively. Furthermore, the prediction error for DL and SVM fluctuates between a minimum of −21.61 to a maximum of 22.50 °C and a minimum of −13.34 to a maximum of 12.44 °C, respectively. In the light of the statistical test results, it is concluded that the DL model with RMSE of 4.3922, MAE of 3.3981, and R2 of 0.9834 shows more excellent ability in predicting EGT than the SVM model with RMSE of 5.5212, MAE of 4.0527, and R2 of 0.9712. This study may effectively be applied to different aircraft types as a useful roadmap for academic and industrial researchers in this sort of application and it shed the light on optimizing performance for a specific aircraft by thermodynamic methods.
Microflow-Enhanced Bubble Dynamics Along With Gradient Porous Surfaces
Authors: Lin Cheng-Hui , Won Yoonjin
Published: October 2021

Boiling heat transfer has been a popular topic for decades because of its ability to remove a significant amount of thermal energy while maintaining a low wall superheat during the liquid phase change. Such boiling mechanisms can be tailored by engineering new boiling substrates through surface wettability modification and/or microscale feature installation. Here, we create new types of heterogeneous boiling surfaces that integrate vertical gradient micropores on macroscale fins by using a template-free electrodeposition method. The gradient morphology and corresponding gradient wettability simultaneously enable bubble nucleation on the top pores and capillary wicking through the bottom pores. With these unique wetting characteristics, we find that the gradient pores installed at the trench bottom demonstrate the most significant boiling enhancement in critical heat flux and heat transfer coefficients by 160% and 600%, respectively. This enhancement can be attributed to the microflow-enhanced nature of bubble departures around the fins while isolating bubble nucleation and liquid supply through gradient pores. These results provide fundamental insights into boiling mechanisms using porous media and the potential for future works that can optimize the design of multidimensional heterogeneous surfaces to engineer flow patterns and boiling mechanisms accordingly.
Neural Network Soft Sensors for Gasoline Engine Exhaust Emission Estimation
Authors: Tan Qingyuan , Han Xiaoye , Zheng Ming , Tjong Jimi
Published: October 2021

Worldwide research and development programs aim to reduce harmful emissions from transportation vehicles. Soft sensors have shown great potentials to reduce cost and improve onboard diagnosis for vehicle emission control. In this work, two sets of soft sensors are proposed to predict the emissions and exhaust heat flux of a gasoline engine. Extensive steady-state measurement points over the entire engine operating conditions are collected for model training and validation, and the locally linear model tree learning method is adopted. The CO, NOx, hydrocarbon, exhaust temperature, and exhaust heat flux are estimated by the soft sensors under steady-state conditions. Training of CO, exhaust temperature, and exhaust heat flux models has achieved high model accuracy over the entire engine map. Local models are developed for NOx and HC emissions to improve model performance at different engine operating speed/load conditions, especially in the low emission zone. Model validation has shown correlation coefficients ranging 0.983 ∼ 0.999
Study on Local Sub-Cooling Boiling in the Vertical Upward Pipe
Authors: Liu Meng-Meng , Zhang Zhen , Yang Xing-Tuan
Published: October 2021

In the heat transfer pipes of nuclear reactors with complex mass and heat exchange, there exists phenomenon of local sub-cooling boiling. Based on the Eulerian two-fluid model, this paper studied the local sub-cooling boiling phenomenon in the vertical upward pipe at a pressure of 4.5MPa. Firstly, a closed sub-cooling boiling model was built to make comparison with the existing experimental results of Bartolomei, the result of which is in great agreement with the experimental data. What’s more, the parameters of the experimental working conditions were expanded, it helped to analyze data that could not be directly measured in the experiment. The physical mechanism behind data distribution law mainly included the influence of the wall bubble departure diameter, the wall bubble departure frequency, and nucleation density. It is found that the RPI model has a good predictive ability for the liquid temperature field. The nucleation density model corresponding to KI combined with the wall departure diameter model KI can well predict the distribution of the void fractions in the pipe. Finally, the influence on heat and mass transfer of heating power along the pipe was analyzed.

This paper put forward suggestions for the modification of the sub-cooling boiling model to help it predict the distribution of bubbles in the main flow region more precise.
A 3D Numerical Simulation on Heat Transfer Behavior in Eagle ID1 In-Pile Test Using Finite Volume Particle Method
Authors: Zhang Ting , Morita Koji , Liu Xiaoxing , Liu Wei , Kamiyama Kenji
Published: October 2021

The EAGLE in-pile ID1 test was performed by Japan Atomic Energy Agency to demonstrate the effectiveness of fuel discharge from a fuel subassembly with an inner duct structure during a core disruptive accident in a sodium-cooled fast reactor. The experimental results suggested that early duct wall failure observed in the test was initiated by high heat flux from the molten pool of fuel and steel mixture, and the post-test numerical calculation and analyses showed that the high thermal load may be enhanced effectively by molten steel with a rather high thermal conductivity. In this study, to overcome weakness in conventional fluid-dynamic calculations, we adopted a fully 3D Lagrangian approach based on the finite volume particle method to analyze the mechanisms of heat transfer from the molten pool to the duct wall in the ID1 test. A series of behaviors representing pin disruption, molten pool formation, as well as the mixing and separation of molten steel and fuel in the pool was simulated to investigate their effects on molten pool-to-duct wall heat transfer. The present 3D particle-based simulation, which moderated some inherent defects in our previous 2D calculations, clarified that direct contact of the solid fuel with nuclear heat and liquid steel near the duct wall can expose the duct wall to a large thermal load, which led to the duct wall failure in the experiment.
Effect of Annealing Temperature on Dislocation Loop Absorption And Evolution in Fe by Molecular Dynamics Study
Authors: Lin Pandong , Nie Junfeng , Liu Meidan
Published: October 2021

As the basic material in reactor pressure vessel (RPV), Fe endures amounts of irradiation in the entire lifetime. Many irradiation defects such as dislocation loop are generated which affect the macroscopic mechanical properties. In this paper, we use the molecular dynamics method to investigate the effect of annealing temperature on dislocation loop absorption and evolution. The annealing process contains four steps: At first, the temperature increases from room temperature (300K) to annealing temperature. The annealing temperature is set as 600K, 700K, 800K, 900K and 1000K respectively. Then the system maintains at annealing temperature for adequate time to evolve. After that, the temperature recovers to room temperature. Finally, the system evolves at room temperature to get the final configuration. The diameters of 1/2 <111> and <100> dislocation loop are 5.1 nm and 1.2 nm, respectively. The dimension of simulation cell is defined as 29.6nm × 20.2nm × 21.0nm with 1080455 atoms. Based on annealing simulation, we could obtain and analyze the microstructure evolution of dislocation loop. Apart from that, we also investigate the effect of annealing rate (4.29 K/ps, 6.00 K/ps, 10.00 K/ps and 30.00 K/ps) on the number of defect atoms and dislocation length during annealing process. Here under periodic boundary conditions the system is allowed to relax in all three directions independently. Results show that temperature has significant impact on the absorption and evolution of dislocation loop. However, temperature can improve the maximum values of defect atoms and accelerate absorption process from stage II to stage I when temperature is 900 K and 1000 K. In contrast, annealing rate has negligible impact on whether the number of defect atoms or dislocation length during the absorption and evolution of dislocation loop. These results are meaning for understanding the temperature effect on dislocation loop.
Frequency of Plug/Slug Bubbles in Horizontal Air-Water Two-Phase Flow
Authors: Kong Ran , Kim Seungjin
Published: October 2021

The current work performs air-water experiments in three different pipe sizes of 38 mm, 51mm, and 102 mm to investigate the frequencies of plug and slug bubbles in horizontal flows. The local four-sensor conductivity probe is used to establish experimental data for large elongated bubbles. The investigated conditions focus on a relatively high superficial liquid velocity region (1.0 m/s ≤ jf ≤ 4.0 m/s), where limited experimental data are available in the literature. The investigated superficial gas velocity (jg) ranges from 0.19 m/s to 3.0 m/s. In total, 19 conditions are studied. To identify the elongated plugs and slugs, the local four-sensor conductivity probe is located near the top wall. Based on the flow visualization study, the stable plug and slug bubbles cannot be shorter than a pipe diameter. Therefore, a chord length greater than a pipe size is used as a criterion to pick up the elongated plug and slug bubbles. Using the obtained data, the frequencies of plug and slug bubbles are analyzed. For the investigated conditions, the Strouhal number (St) ranges from 0.03 to 1.68, while the St of the existing data in the literature are generally below 0.1. It is found that the frequency of elongated bubbles increases as jf increases, but first increases then decreases as jg increases. This indicates that large elongated bubbles start to coalesce once jg reaches a certain value. This threshold has a higher value of jg than the plug to slug transition point. In addition, the frequency decreases as pipe size increases. The existing correlations in the literature are evaluated using the newly collected data. It is found that the St number-based correlations can predict the data with higher accuracy. New correlations are developed using the new data and they can predict the frequency with an absolute average percentage difference of ±20%.
Preliminary Transient Analysis for LBE-Cooled Fast Reactor BLESS-D
Authors: Xing Mian , Li Linsen , Zheng Gang , Wen Junlang , Liu Chunyuan , Yee Yeoh Eing , Luo Zhen , Sun Peidong , Feng Jinjun
Published: October 2021

Lead-cooled fast reactor is one of the fourth-generation nuclear energy systems, which has great development potential due to good neutronic, thermal-hydraulic characteristics and inherent safety. The lead and bismuth eutectic alloy (LBE) cooled fast reactor BLESS-D (Breeding Lead-Based Economical Safe System) is a small fast reactor developed by the State Power Investment Corporation Research Institute (SPICRI). It is designed as a multi-purpose integrated small reactor system with the characteristics of small power, compact size and inherent safety. In the future, it could be used for electricity consumption for remote areas, polar expedition, island development and etc.

The conceptual design of BLESS-D is described in this paper, including the design criteria, safety features, main parameters and main components. The thermal power of BLESS-D is 300 MW. It is a pool-style reactor with LBE as the coolant, equipped with 8 helical tube steam generators and 4 primary pumps. The safety system consists of passive Decay Heat Removal System (DHR) and RVACS (Reactor Vessel Air Cooling System) outside the reactor vessel. For the preliminary transient analysis, the primary system and secondary boundary of BLESS-D is modeled with SNAP/TRACE. And the steady state simulation results are compared with the design values which shows good agreement. After that, the transient accidents under different conditions are studied to evaluate the feasibility and safety of the current design. In this paper, the results of Unprotected Transient Over Power (UTOP), Unprotected Loss Of Flow (ULOF), and Unprotected Loss Of Heat Sink (ULOHS) are discussed which shows that the current safety system design is sufficient to ensure the reactor safety although some optimizations are still needed.
Development of Digital Twins of PWR Steam Generators: Description of Two Maintenance-Oriented Use Cases
Authors: Deri Enrico , Varé Christophe , Wintergerst Matthieu
Published: October 2021

Physical modelling computation, virtual reality, instrumentation and data analysis have shown great progress in the past years. Thus, the integration of all these disciplines in one unique tool seems now achievable. Within this frame, this communication aims at discussing the extension of the Digital Twin concept to the PWR Steam Generators.

Operating steam generators communicate some information on their health status during inspection outages, and some other during operation. As, generally speaking, a SG fully satisfies its role of safely produce steam, the goal of an in-service DT is to optimize both the maintenance and the operation, namely: provide the best preparation for next outages, avoid SG-caused unscheduled outages and obtain the best performances.

Some general features are outlined with respect to the different roles of Digital Twins both in design and operation. Then the vision of the R&D Division of EDF Company is given for the developed Steam Generators Digital Twin.

Two use cases are presented focusing on maintenance. The first one is about chemical cleaning schedule including how the Digital Twin contributes to the prediction of shell side deposit, and the second one is about periodic hydraulic test preparedness, including how the digital twin contributes to the prediction of crack sizes.
Experimental Study on Measurement of Annular Flow Film Thickness in Vertical Narrow Rectangular Channel
Authors: Liu Antai , Gu Haifeng , Zhu Fuqiang , Yan Changqi
Published: October 2021

As a key physical parameter in annular flow, liquid film thickness is crucial to study the behavior characteristics about gas-liquid interface under annular flow conditions. In this study, the narrow rectangular channel is taken as the research object, and air-water were used as the media to conduct annular flow experiments under atmospheric pressure. The cross-sectional area of the narrow rectangular channel is 70mm × 2mm. The PCB liquid film sensor can realize multi-point measurement of liquid film thickness. A total of 10 × 16 measuring points are arranged in rows and columns on the surface of the channel, with a spatial resolution of 4.4mm × 4.4mm and a measurement speed of 1000 frames per second. The results show the fluctuation of liquid film is dominated by the ripple wave at low superficial liquid velocity. The frequency distribution of film thickness becomes sharper because of the increase of gas flow, i.e. the interfacial surface becomes smoother. The liquid film will become thinner with the increase of gas flow, but the effect is reduced when the gas flow reaches a certain value. The liquid film will thicken and the number of disturbance waves will increase as the increase of the liquid flow.
Study on Dehumidification of Carbon Materials Based on Thermogravimetry
Authors: Yan Da , Shen Kaiyue , Guo Yicheng , Yin Huaqiang , He Xuedong , Ma Tao
Published: October 2021

The high temperature gas cooled reactor contains a lot of carbon materials. Graphite IG-110 and boron-containing carbon (BC) are the main carbon materials. Carbon material is a porous medium, it will absorb water and other impurities. Carbon materials react with these impurities at high temperatures in HTGR. In order to reduce the corrosion of impurities on carbon materials, the HTGR core must be dehumidified before it operats. In this paper, the dehumidification of HTGR is taken as the research background. On the one hand, microscopic geometric parameters such as pore size distribution, porosity and total pore surface area of carbon materials are measured through mercury injection experiments. These parameters are the key parameters to study the macroscopic properties of materials. On the other hand, the research group transformed the original laboratory equipment into a thermogravimetric analysis device for large samples. The modified equipment can widen the volume and mass range of samples in TG experiment. In the experiment, the temperature-mass relationship of carbon materials was measured based on thermogravimetry. Six temperature points were set in the experiment. When the mass change rate of the specimen within ten minutes was less than 0.0003%, the heating furnace temperature was adjusted to the next temperature point. Finally, the mass curves of graphite IG-110 and boron-containing carbon (BC) with temperature were obtained. The results showed that boron-containing carbon (BC) could precipitate some moisture at all temperatures, while graphite IG-110 could not precipitate any moisture at 100°C.
Investigation on Solidification Behavior of Deposited Metal by GTAW With ERNiCrFe-13 Wire
Authors: Guo Xiao , Xu Kai , Lv Xiaochun , Chen Peiyin , Chen Bo , Huo Shubin
Published: October 2021

ERNiCrFe-13 was developed based on ERNiCrFe-7A with Nb and Mo addition with the aim of further improving ductility dip cracking. In addition, solidification cracking susceptibility may increase against a wide solidification temperature range due to Nb and Mo segregation. In this study, the solidification behavior of the deposited metal via gas tungsten arc welding (GTAW) with an experimental ERNiCrFe-13 wire was investigated using JMatPro solidification calculations, differential scanning calorimetry (DSC) analysis, in situ observations by laser confocal scanning microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Both Nb and Mo exhibited segregation toward the liquid phase during solidification, while Fe showed opposite tendency according to the calculated partition coefficients k at the initial solidification stage. The k based on both the solidification calculation and EDS tests showed that Nb had a stronger segregation tendency than Mo. The solidification temperature range (STR) tested by DSC was significantly narrower than the predicted STR, which can be attributed to the overestimated segregation based on the Scheil model. The in-situ observation results showed that the relationship between the liquid phase area fraction f and temperature T followed the Avrami equation well. The solidification process included three stages: initial nucleation stage, rapid growing-up stage, and final solidification stage with rates of 0.015 s−1, 0.15 s−1, and 0.015 s−1, respectively.
Analysis of Flow Resistance Influence on Step-Down Process of the Control Rod Hydraulic Drive System
Authors: Yang Linqing , Qin Benke , Bo Hanliang
Published: October 2021

Control rod hydraulic drive system (CRHDS) is a new type of built-in control rod drive technology which is invented by INET, Tsinghua University. The integrated valve (IV) is the main flow control component of the CRHDS. Flow resistance of IV has a great influence on the control rod dynamic step-down process. The step-down performance experiments of CRHDS with different flow resistance of IV were conducted under room temperature conditions. Meanwhile, the theoretical model of hydraulic cylinder step-down process was established and combined with the relationship of the flow resistance of IV under the experimental conditions to get the dynamic response of the hydraulic cylinder. The calculation results of theoretical model agree well with the experimental data. On this basis, the theoretical model of hydraulic cylinder step-down process was applied to the high temperature working conditions with different flow resistance of IV. The analysis results show that at higher working temperature, with the increase of the flow resistance of IV control rod step-down average velocity decreases and step-down time increases correspondingly. There is an inflection point in the transient pressure curve and the pressure of the inflection point decreases gradually with the increase of the flow resistance. The pressure lag time after step-down also decreases. The research results lay the base for the design and optimization of the flow resistance of the IV for the CRHDS.
Dynamic Modeling of Nuclear Hydrogen Production Using Methane Steam Reforming
Authors: Li Junyi , Dong Zhe , Li Bowen
Published: October 2021

Methane steam reforming (MSR) technology is one of the promising methods of hydrogen production and already available at an industrial scale, in which steam is added to methane to generate hydrogen. MSR carries out at a temperature of 500°C when catalysts and Pd-based membrane reactors are used. The nuclear steam supply system (NSSS) of a modular high-temperature gas-cooled reactor (MHTGR) can provide high-quality steam of around 570°C, which is an excellent heat source for MSR. MHTGR is a typical small modular reactor (SMR), of which the coolant is helium, and the moderator and structural material are graphite. The number of the MHTGR can be decided based on the thermal power required for MSR and electricity generation. In this paper, a six-modular MHTGR nuclear power plant with 1500MW thermal power coupled with the MSR process is designed. The hydrogen production rate is 9.72 tons per hour. The dynamic modeling is based on conservation laws of mass and energy. To examine the dynamic characteristics of the nuclear hydrogen production plant, open-loop responses of the model under different disturbances are presented.
System Design for Ammonia Nuclear Thermal Propulsion
Authors: Mao Chenrui , Ji Yu , Sun Jun , Liang Zhaoyu , Shi Lei
Published: October 2021

Nuclear Thermal Propulsion (NTP) for deep space exploration is promising. Hydrogen is employed as the propellant to enhance the maximized specific impulse of NTP. Whereas, the low boiling point and density of hydrogen lead to several issues related to safety and storage. From the perspective of reactor physics, thermal hydraulics, material compatibility, and experience in the aerospace field, ammonia (NH3) is the alternative propellant to replace hydrogen.

To analyze the specific impulse and system parameters of ammonia NTP, the hydrogen expander cycle NTP system analysis program PANES (Program for Analyzing Nuclear Engine Systems) is improved. The thermophysical properties library of ammonia has been increased in PANES. Based on the same thrust with hydrogen NTP, the design and analysis of ammonia NTP systems are carried out.

This paper improves the PANES program and calculates the NTP performance parameters for potential alternative propellant ammonia, which provides a reference for the design of ammonia NTP system.
Study on Potential Leakage and Electrical Performance for Electrical Penetration Assemblies Under Severe Accident Conditions
Authors: Liu Yu , Liu Jing , Wang Cong , Gao Heng
Published: October 2021

EPAs are the penetrations used to minimize leakage and supply instrumentation or power cables path. Hence, sealing performance of EPA is important to contain radioactive materials and minimize their release without any filtration. Leakage behavior of containment under SAC is also required for the evaluation of mitigation strategies, risk analysis, PSA and emergency planning. In addition, electrical continuity for EPA cables is important for the operation of mitigation systems under different conditions, especially the SAC.

In this paper, it is focused on the review and study on leakage behavior and electrical continuity for EPA under SAC, which consists of the following key issues:

(1) Requirements, criteria and introduction of EPAs.

(2) Study on sealing and electrical performance of EPAs, especially the leakage mechanism, potential leak paths and sealing material performance, electrical degradation under different conditions.

(3) Preparations and plans for the EPA sealing and electrical performance test, introductions of our expectations and methods.

(4) Summary and outlook
Analysis and Research on Sodium Single Droplet Combustion
Authors: Zhao Lei
Published: October 2021

The sodium-cooled fast reactor is one of the preferred reactor types for the fourth-generation nuclear energy system. The sodium-cooled fast reactor uses metallic sodium as the coolant, which has a lot of advantages such as good thermal conductivity, larger heat capacity and lower neutron absorption rate. However, sodium is relatively active in chemical properties, and is prone to chemical reactions with oxygen and cause fires. The sodium fire caused by the sodium leakage of the sodium-cooled fast reactor seriously affected the safe operation of the reactor. The combustion of a single sodium droplet is the basis of sodium fire calculation and analysis. In this paper, by modeling the combustion of a single sodium droplet, a calculation and analysis program for the combustion of a single sodium droplet is developed, and compared and verified with related experiments. Through this program, the factors affecting the combustion of sodium droplets were analyzed and studied. The study showed that the diameter of sodium droplets, the temperature of sodium droplets, and the oxygen concentration have important effects on the combustion of sodium droplets. This work lays the foundation for the analysis of spray sodium fire accidents and is of great significance to the safety of fast reactors.
Analysis of Temperature Field in Hot Leg Piping of Space Nuclear Closed Brayton Cycle
Authors: Ma Wenkui , Ye Ping , Gao Yue , Zhao Gang , Yang Xiaoyong , Wang Jie
Published: October 2021

Direct gas cooled closed Brayton cycle can efficiently convert the fission energy of the reactor into electricity, which is an ideal energy conversion system for space reactor. The pipe between the reactor outlet and turbine inlet is designated as the hot leg piping. To reduce effect of radiation heat dissipation on the cycle performance, the hot leg piping requires unique design features. In this paper, the mathematical models of the space Brayton cycle and the radiation heat dissipation of the hot leg piping are established, and the influence of the heat dissipation on the cycle performance is analyzed. The results show that the heat dissipation of hot leg piping decreases the cycle performance. The turbine inlet temperature decreases by 10K and the cycle efficiency decreases by 1.35%. Based on the numerical simulation method, insulation performance of hot leg piping is studied. The results show that the insulation performance of internal insulation is better than the external insulation. Internal insulation with low thermal conductivity and large thickness of insulation layer decrease the maximum temperature of the hot leg piping, reduce the radiation heat dissipation and improve the cycle performance. The higher the space environment temperature and the lower the emissivity of the coating material reduce the radiation heat dissipation. However, the maximum temperature is easy to exceed the limit of pipe material. The analysis provides a reference for the hot leg piping insulation design of the space closed Brayton cycle in the future.
Numerical Simulation of Added Mass in Narrow Gaps of Multi-Layer Thin-Walled Shell of Fast Reactor
Authors: Duan Dexuan , Lu Daogang , Liu Yu , Li Donghao
Published: October 2021

Sodium-cooled fast reactor is one of the important reactors of the fourth-generation advanced nuclear power technology. Since the pool-type fast reactor has large size and thin wall that its rigidity is usually low. Therefore, the seismic design, analysis and verification of fast reactors are the key concerns of fast reactor safety evaluation. The fluid structure interaction effects of many special structures with narrow gaps under seismic loading need to be more accurately evaluated. At present, the method of added mass in the narrow gap fluid domain and the added mass formula of the infinitely long flexible coaxial cylinder given by the pressure field wave equation is not suitable for direct use. Based on the finite element analysis method, the frequency of different narrow gap annular cylinders such as coaxial three-layer cylinders in different modes is studied. According to the vibration formula, the added mass of narrow gap fluid domain is obtained, and the main pump support in the fast reactor is obtained. And explore the effect of the height of the fluid in the shell gap on the added mass of the shell. The design and inspection of narrow gap watershed structures such as cylinders and stack bodies have reference value.
Hydrodynamic Analysis of Steam Generator Under LOCA Conditions
Authors: He Xiaoqiang , Gao Puzhen , Yuan Weichao
Published: October 2021

Loss of coolant accident (LOCA) is one of most severe accidents of nuclear power plant. The coolant will discharge from the break when this accident occurs, consequently exert large hydrodynamic load on the primary loop system because of the fluid acting force as well as the propagation of pressure wave, then may further influence the pressure boundary of the primary loop. Steam generator (SG) is a crucial device with complex structure, hydrodynamic forces of its U-type tube and plate have been analyzed under various cases in this paper. Firstly, the reactor core and primary loop system of pressurized water reactor nuclear power plant (NPP) was modeled with RELAP5. Then a LOCA was simulated and the thermal hydraulic characteristics such as the pressure and mass flow rate were obtained. Finally, the forces at key positions of SG were calculated with the control volume integral method. The sensitivity analysis was also performed, including the break opening time, number of control volumes as well as the time step chosen in the hydrodynamic force calculation. The results have shown that the break opening time has a great influence on the numerical calculation that should be carefully set before the simulation, and the maximum hydrodynamic force is obtained under the condition that double-ended offset shear break at outlet nozzle of SG, and the pressure difference between the two sides of SG divider plate obviously increases compared with the normal operation condition. Thus, some meaningful suggestions have been provided for the design and safety analysis of SG.
Loss of Main Feedwater ATWS Accident Analysis for Ship Nuclear Power Platform
Authors: Qiu Jinrong , Feifei Song , Longze Li , Xiaofan Hou , Fei Chao
Published: October 2021

In this paper, the complete accident analysis calculation model of the ship nuclear power platform is established by using the developed accident analysis system code SACO (System Analysis Code under Ocean conditons), which is coupled with the ocean condition. Combined with the accident progress of loss of main feedwater ATWS, and on the basis of considering the reasonable assumption of the accident boundary, the main feedwater loss ATWS accident is analyzed. The accident sequence of loss of main feedwater ATWS is given, and the changes of the key thermal safety parameters such as the reactor power, heat removal from the active residual heat removal system, primary circuit pressure, pressurizer water volume, average reactor coolant temperature, peak temperatures of the fuel pellet and cladding are analyzed in detail. The results show the active residual heat removal system, reactor core reactivity feedback and design of the pressurizer safety valve could limit the primary circuit pressure and other key parameters without exceeding the safety limit value in the case of loss of main feedwater ATWS accident for ship nuclear power platform.
Study on Flow Boiling of Refrigerants in Micro/Mini-Channels
Authors: Wen He , Chenru Zhao , Hanliang Bo
Published: October 2021

The flow boiling heat transfer in micro/mini-channels is encountered in many compact heat exchangers such as the once-through steam generator in nuclear reactors due to its high heat transfer efficiency and thus accurately predicting the heat transfer coefficients is of great importance. Nowadays, for the high saturation temperature of water, refrigerants are more widely used in the flow boiling heat transfer experiments and a lot of heat transfer correlations are raised based on the data of refrigerants. Therefore, the accuracy of heat transfer correlations for refrigerants in flow boiling micro/mini-channels are analyzed in this paper. Firstly, five commonly used heat transfer correlations are summarized which can be simply divided into Chen type and Nusselt type and nearly 1000 experimental data of refrigerants conducted in the micro/minichannels are collected from 5 separate experiments. Then, due to the relatively low predicting accuracy of current heat transfer correlations, a new non-dimensional heat transfer correlation has been proposed by analyzing the experimental data with the application of Bond number in the range of 0.42–9.61, liquid Reynold number in the range of 34–8793, Boiling number in the range of 0.55 × 10−4 – 20.66 × 10−4. Finally, this new correlation is applied to water in different working conditions and the predicting accuracy has been analyzed.