bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on the Water Wall Material Selections of USC Boiler With 700°C Steam Parameter
Authors: Chongbin Wang , Xueyuan Xu , Danhua Yao , Zhengran Lu , YuFeng Zhu , Bo Zhang , Yongqiang Jin , Wangyu  , Xiaoli Lu
Published: December 2017

This paper discusses the materials properties of candidate water wall materials for USC boiler with 700°C steam parameter, and analyzes the serviceability of water wall panels made of different tubes, such as T12, 12Cr1MoVG, T23, T24, T91, T92, T122(HCM12A), VM12, 617 and 617 mod. In addition, some suggestions and optimization measures on the material selection have been proposed.

Paper published with permission.
Predicting Remaining Life Using Damage Mechanics Principles
Authors: Le May Iain
Published: December 2017

Continuum damage principles have been used to characterize damage occurring in pressurized components operating under creep conditions. Following a review of the concepts of damage and its measurement, analysis has been presented to show how damage can be estimated using continuum damage concepts and how the remaining life can be estimated in terms of the current creep rate of a component. It is shown how such damage can be estimated using measurements of the local creep rate.

Paper published with permission.
Simulated Fireside Corrosion of Ni-Base Alloys in Oxy-Fired Conditions at 700°–800°C
Authors: Pint Bruce A.
Published: December 2017

One future objective for coal-fired power generation is to develop advanced ultrasupercritical (A-USC) boilers that incorporate oxy-firing to facilitate carbon capture. The steam condition goals of 760°C/34.5 MPa will require major materials changes throughout the boiler, including Ni-base alloys in the hottest sections. Solution hardened alloys such as 740 and 282 are needed to meet the strength requirements for 760°C. In previous work, little difference in corrosion rate was found between air- and oxy-firing for alloy 740 at 600°–800°C so laboratory testing focused on the “worst case” oxy-firing conditions with higher CO2, H2O and SO2 than expected with air-firing. Model alloys were made to investigate the roles of Cr, Al, Ti, Co and Mo on the fireside corrosion behavior. Exposures conducted for 500h at 700° and 800°C found that Al and Ti additions typically reduced the extent of attack under these conditions. As expected, the alloy Cr content had a substantial effect between 18 and 22%. Additions of 4% and 8%Mo to Ni-20Cr-(0-20)Co alloys increased the metal loss at 800°C and Ni-20Cr-20Co-(0-8%)Mo showed the highest attack at 700°C. The much higher attack of alloy 282 at 800°C can likely be attributed to its lower Cr content compared to alloy 740, which was developed to have excellent fireside corrosion resistance.

Paper published with permission.
Materials Selection and Design Issues for Supercritical Carbon Dioxide (CO2) Power Systems
Authors: Stein Arthur , Perkins Carl
Published: December 2017

Current materials and designs limit the service life of key components in supercritical CO2 power cycles. There are few economical materials which have a long term track record operating in the creep range that can support a practical and economical plant design. This paper outlines some of the specific materials and design limitations that challenge the economical implementation of this technology and proposes design approaches that may be more practical and economical.

Paper published with permission.
Application of Performance-Based Fire Protection Design in Pipe Gallery of Nuclear Power Plant
Authors: Zhou Cai
Published: December 2017

Performance-based fire protection design (PFPD), a new method to solve complex/special fire engineering problem, satisfy the safety requirements of fire protection goals based on these specific data from the characteristics of the combustible objects and building, and make satisfied evaluation and verification of the fire prevention design, by analyzing the fire scene and calculating the fire risk. When the project is complicated, and the design standard or code has implementation difficulties or the fire protection goals are really special, the method of PFPD can be an alternative way which is reasonable and scientific to the fire protection design and evaluation.
Effect of Spray System on in Containment Fission Product Washout During In-Vessel Release Phase
Authors: Mehboob Khurram , Aljohani Mohammad. S.
Published: December 2017

The response of containment sprinkles during the in-vessel release phase of low-pressure loss of coolant accident (LOCA) has for two-loop PWR been simulated. Cleaning and wash out of radioactive isotopes is essential to limit the risk of radioactive exposure. An uncontrolled LOCA has been selected for this study. In this work, numerical simulation of spray system with its parameter has been carried out to study the sensitivity analysis of airborne radioactive isotopes on spray system parameters. Therefore, we have developed a kinetic model and implemented in MATLAB which used the ORIGEN 2.2 as a subroutine code. The sensitivity analysis and airborne isotopes and removal rate has been carried out for spray activation time, droplet size. It has been seen that the droplets mean size plays an important role in containment washout. The droplet absorption ratio indicates that the smaller droplet size has higher absorption efficiency.
The Resonance Effect of External Vertical Vibration on a Single Nuclear-Coupled Boiling Channel System With Forced Flows
Authors: Lin Yuh-Ger , Lee Jin-Der , Chen Shao-Wen , Peir Jinn-Jer
Published: December 2017

The present study adopts the single nuclear-coupled boiling channel model integrated with oscillating vertical seismic accelerations to investigate the seismic-induced effect on a single nuclear-coupled boiling channel system. The nonlinear dynamics and stabilities of a single nuclear-coupled boiling channel are investigated through nonlinear analyses. The void-reactivity feedback would destabilize the system as that reported in the literatures. The natural frequencies of the stable states are widely explored. The results indicate that the natural frequency of initial state could depend on the parameters of phase change number and subcooling number. It tends to increase as the increase in the phase change number (operating power) or the decrease in the subcooling number (inlet subcooling). Notably, the system natural frequencies distributed in the stable region are located within the common range of seismic vibration frequency. For the concern of reactor safety, the present study investigates the seismic-induced resonance effect on a nuclear-coupled boiling channel system. The results illustrate that the resonance oscillations could be triggered if the external vibration frequency is the same as the system natural frequency. Moreover, the strength of resonance effect may depend on the inherent stability characteristics of the initial states.
Structural Integrity Test of Steel Containment Vessel at the First AP1000 Unit of China
Authors: Kai Li , Zhimin Zhong , Xianhong Ma
Published: December 2017

This paper briefly introduces the design functions, structure of steel containment vessel (CV) of AP1000 unit and its related design, fabrication, examination, and testing codes and standards. It focuses on the practices of Structural Integrity Test (SIT), of CV in Sanmen unit 1, which is the first steel CV in China. Its SIT aim and testing process, including pretest, baseline measurements, pressurization and depressurization process, displacements and strains measurement method and measurement point positions, Visual Testing and Leakage examination activities are discussed in detail. Some important feed backs or lessons learned from this testing also are discussed. The CV SIT results of Sanmen Unit 1 showed that the containment vessel behaved elastically and no cracks and leakage were observed during the test. After the containment vessel SIT, the Integrated Leak Rate Test ( ILRT ) was successfully completed. Therefore, it was confirmed that the tested CV had adequate structural integrity against the test pressure, its leak tight boundary met the design requirements, the testing system work well and the testing activities and its organization were successful.
The Airflow Analysis for CAP1400 Control Rod Drive Mechanisms Cooling System
Authors: Yu Hao , Zhang Xingliang , Zhang Wei , Hao Guofeng
Published: December 2017

The CAP1400 nuclear power plant (NPP) reactor integrated head package (IHP) refers to the assembly of all of the equipment and structures that are either mounted to the reactor closure head or provide services to the reactor head assembly. One of the main functions of the IHP in the reactor is to provide cooling for the control rod drive mechanism (CRDM) magnetic coils. The IHP cooling system is realized by axial fans connected to the vent tubes of the CRDM cooling shroud. Under normal operating conditions, two of four fans are required to be in operation. The IHP cooling system shall meet the requirements of “keeping the coil temperature within the magnetic coil component below 200°C”. This requirement is achieved by ensuring that the average flow velocity around the CRDM coil assembly is above 15 m/s and that the minimum flow velocity at any location on the outer surface of the coil assembly is not less than 9 m/s. The main purpose of this paper is to study the flow characteristics of the IHP cooling system under various operating conditions. The CFD method is used to obtain the flow field and temperature field in the IHP and to support the rationality of IHP design.
Comparison and Reference Between RSE-M and ASME Section XI Regulations on In-Service Inspection for China Nuclear Power Plant
Authors: Haitao Sun , Qinghua Zhang , Panpan Jia , Ligong Ling , Chen Wang , Yunhe Lv
Published: December 2017

RSE-M and ASME Section XI regulations are currently recognized as NPP ISI regulations which are most extensively used, most detailed in content and most mature in technology in the world. In China, RSE-M or ASME section XI regulations are used to guide the ISI program preparation, ISI activities implementation and management. There are many differences between RSE-M and ASME Section XI regulations, such as application of regulation, scope of application, main frame and content, basic requirements of ISI, acceptance and evaluation of ISI results, repairing and change. At the same time, some technical clauses can be used for reference by each other, such as qualification and inspection items.

By comparison of RSE-M and ASME Section XI regulations for in-service inspection rules of China pressurized water reactor power plant, the technical differences between the two rules are analyzed. Combined with application and engineer practices for in-service inspection of China nuclear power plant, some technical terms used for mutual reference are summarized to provide assistance for establishing the in-service inspection program and specific implementation.

During ISI activity, applicable regulation should be chosen according to the requirements of design in consideration of inspection items, examination methods, defect acceptance criteria and evaluation. Meanwhile, implementation of RSE-M and ASME Section XI regulations should be combined with the design features, experience feedback and aging management of mechanical equipment, and draw lessons from mature technical clauses of other regulations.
Research on Testing Adequacy Criterion of Reactor Physics Code of NESTOR
Authors: Meng Li , Li-Jun Wang , Yu-Yan Li , Xiao-Hua Yang
Published: December 2017

In view of the characteristics of the physical code Nestor the focus is on the correctness of calculation for which the test adequacy criterion has been established. This is based on structural coverage and the input domain.

According to such test adequacy criterion, testing strategies have been applied on the entire testing process. They consist of unit static, unit dynamic, integration, system and regression test strategy. Each strategy is composed of test target, test range, technology and method, entry criterion, completion criterion, test focus and priority.

After compared with 11 basic benchmarks from nuclear power plants and calculation result of benchmark programs, the ELEMENT program result is correct and credible; the relative error of result is less than three percent.

The ELEMENT testing is adequacy. Its test cases covers fuel grid element types, fuel types, non-combustible grid element types, and control rod computational models. Furthermore, it puts forward a research direction in the future.
An Image-Based Micro-Scale Fracture Model for Weld Zone in Nuclear Pipe and Component
Authors: Bai Xiaoming , Zheng Liangang , Wang Xinjun , Lv Xi
Published: December 2017

The mechanical analysis of weld zone is a significant problem during the nuclear power plant design due to the fact that the material property of weld zone is complex. In most of the standards and codes, the weld zone is assumed as an effective homogeneous material. However, the weld zone is non-homogeneous at micro-scale, and the microstructure has great effect on the mechanical property, especially the fracture behaviors. Therefore, how to propose an accurate and convenient model to analyze fracture behavior of the weld zone of nuclear pipe or components becomes a major issue.

The objective of present work is to develop an accurate method to investigate the fracture behavior of weld zone from the microstructure of weld zone. To achieve the objective, a double smoothed image based reconstruction method is developed to generate the finite element mesh from digital image of weld zone directly. Then a cohesive finite element framework is utilized to simulate the initiation and propagation of micro-cracks in weld zone. Moreover, a damping boundary condition is used to apply the complex loading case on the micro-scale model.
Numerical and Experimental Analysis of the Control Rod Hydraulic Deceleration Device for the Control Rod Hydraulic Drive System
Authors: Benke Qin , Leishi Li , Hanliang Bo
Published: December 2017

Control rod hydraulic drive system (CRHDS), which is invented by INET, Tsinghua University, is a new type of internal control rod drive technology. Control rod hydraulic deceleration device (CRHDD), which consists of the plug, the hydraulic deceleration cylinder, the hydraulic buffer, etc., is one of the main components of the CRHDS. The plug is connected with the top of the control rod driving shaft and moves along with the control rod inside the hydraulic deceleration cylinder. The CRHDD performs the rod dropping deceleration function through the interworking of the plug and the deceleration cylinder which is filled with water, and reduces the rod dropping peak acceleration and the impact force acting upon the control rod to prevent the control rod cruciform blade from being deformed or damaged. The working mechanism of the CRHDD is presented and analyzed. The rod dropping performance of the CRHDS was tested experimentally under room temperature. The theoretical model of the control rod dropping process, which is composed of the three dimensional flow field analysis and flow resistance calculation of the hydraulic deceleration cylinder, the kinematics and dynamics model of the control rod, is built whose results are compared and validated by the CRHDS scram test results under room temperature. Then the model takes into account of the influence of the fuel assembly box on the control rod scram process under high temperature working conditions, and is used to analyze the influence of the key parameters, including the helical spring stiffness inside the deceleration cylinder and the working temperature on the CRHDD working performance. The research results can give guidance for the design and optimization of the CRHDD.
The Study of Nanosized Cu-Mn Precipitates Contribution to Hardening in Bcc Fe Matrix
Authors: Dou YanKun , He XinFu , Wang DongJie , Shi Wu , Jia LiXia , Yang Wen
Published: December 2017

In order to study the contribution of Mn atoms in Cu precipitates to hardening in bcc Fe matrix, the interactions of a (111){110} edge dislocations with nanosized Cu and Cu-Mn precipitates in bcc Fe have been investigated by using of molecular dynamics. The results indicate that the critical resolved shear stresses (τc) of the Cu-Mn precipitates are larger than that of Cu precipitates. Meanwhile, τc of the Cu-Mn precipitates show a much more significant dependence on temperature and size, compared to Cu precipitates. Mn atoms exhibit strong attractive interaction with <111> crowdion and improve the fraction of transformed atoms from body centred cubic (bcc) phase to face centred cubic (fcc) phase for big size precipitates. Those all lead to the higher resistance to the dislocation glide. The increasing temperature can assist the Cu atoms rearrange back towards a bcc structure, resulting in the rapid decline of τc. Similar to Cu precipitate, Cu-Mn precipitate with equator planes on the dislocation glide plane is proved to be the strongest obstacle. Eventually, these features are confirmed that the appearance of Mn atoms in Cu precipitates greatly facilitates the hardening in bcc Fe matrix.
Stress Corrosion Behaviors of Three Typical Materials (304L, 2205, Alloy 825) in Boiling Magnesium Chloride Solution
Authors: Zhao Liang , Luo Kunjie
Published: December 2017

According to YB/T 5362-2006 “stainless steel stress corrosion test method in boiling magnesium chloride solution”, the sensitivity of the stress corrosion of three typical materials (304L, 2205, Alloy 825) was investigated in boiling magnesium chloride solution (experimental temperature is 143±1 °C, concentration of magnesium chloride is 43%). The results show that under the condition of constant strain, the corrosion resistant performance of 825 material is far better than 304L, and the corrosion resistance of dual phase steel may not be superior than that of austenitic stainless steel.
Study on Cycle-Based Fatigue Monitoring Technique
Authors: Wang Xin-jun , Ai Hong-lei , Lu Xi-feng , He Feng
Published: December 2017

According to NUREG/CR-6909, the coolant environments have great influence on the fatigue resistance of the nuclear piping and equipment. As there are many conservatives in the cycle number and temperature/pressure scope of design transient, the fatigue usage factor of some main equipment may exceed the design requirement if the environmentally-assisted fatigue (EAF) is considered in the design phase. In order to solve this problem, the fatigue usage factor may be calculated by using real transient cycle and sequence based on cycle-based fatigue monitoring technique in nuclear power plant. Using this method the conservatives of design transients will be deleted and the life of main equipments should not be influenced by considering EAF. The method flow and key technologies for cycle-based fatigue monitoring technique were studied. Four steps were needed to get fatigue usage factor: transient statistics, stress reconstruction, fatigue calculation and EAF correction. Plant signals needed for the fatigue monitoring system were provided based on in service nuclear power plant. Transient statistics (include transient detection, classification and statistics) was the most important and difficulty of the four steps and it could not only benefit the fatigue life, but also can benefit the aging management, design and operating improvement. Transient statistics was done according to reactor power level, the initial state and causes of the transient, the protection actions and some of other important plant signals. According to reactor power which is the most important signal, the transient can be divided into four types: transients during reactor at no-load, full-power, power varying and reactor trip. The initial and final state of the transient and rate of change were used to classify the no-load transients. At full power state, only two transients were included. Power varying transients can be classified by initial and final power level. Reactor trip signals, pump state, pressure, temperature and other operating signals were used to classify reactor trip transients. A stress sequence was built according to transient sequence. The extremal stress of the sequence was selected and fatigue usage factor was calculated. The environmental correction factor Fen mentioned in NUREG/CR-6909 was used to modify the fatigue usage factor in order to consider the influence of EAF. The method was verified by assumption events and the result shows that the method could detect and classify operating transients accurately. The cycle-based fatigue monitoring technique should be improved by using the real plant parameters and can be programmed and used in plant fatigue monitor.
Dynamic Seismic Response Analysis of Nuclear Storage Tank Based on Fluid-Structure Coupling Method
Authors: Weng Yu , Liu Lang , Jiang Yang , Gu Hongfang , Wang Haijun
Published: December 2017

The storage tanks in nuclear facilities has a significant impact on the safety of the reactor and the radiation shielding, so its mechanical property analysis has been widely concerned in the field of engineering and scientific research. Meanwhile, the storage tank is usually filled with gas and liquid medium. In the presence of external disturbances (such as external force, displacement, earthquake etc.), the position and structure of the vessel changes, that lead to changing of the gas-liquid interface. This characteristic can make the storage tank system as a tightly fluid-structure coupling system.

In this paper, a storage tank which stored radioactive gas liquid medium is choosing to study such fluid-structure coupling system phenomenon, and a typical dynamic seismic condition is assumed. A two-way fluid-structure coupling method is used with CFD (Computational Fluid Dynamics) and FEM (Finite Element Method) numerical method. The study considered interaction between structure and two phase turbulent fluid. In FEM calculation, the time history seismic acceleration load is applied to the support of tank, and the flow loading coming from fluid medium is applied to the wall of tank which is send from CFD code. Then, the structure displacement which is calculate by FEM is transferred to CFD code. In CFD calculation, multiphase fluid numerical model is applied to simulate the flow characteristics of gas-water two phase fluid, and the turbulent properties are also considered in the calculation. Mesh deformation method is used to simulate the displacement of flow passage boundary which is send by FEM code. After CFD calculation, flow loading is transferred to the tank wall of FEM code again. Such loop of FEM and CFD calculation continues to go on with the seismic time history, the response characteristics of the tank will be solved.

In order to evaluate the difference between the above method and the traditional analysis method. An independent calculation used added mass approach is carrying out, in which the effect of steady state water is applied to the wall of the vessel, and this load will not change with the earthquake. All others load and constraint mode are same with the above method.

According to the two-way fluid-structure coupling analysis, the detailed characteristics of liquid free surface distribution and structural response of the vessel are obtained. The results show that the response vibration amplitude of the tank structure increases with the earthquake, and the response is mainly affected by the liquid sloshing. According to comparative analysis, the advantages of coupling method are proved. The method from this study can be used for the same type of analysis.
The Durability Design of the Technical Specifications for Nuclear Building Concrete of ACP1000
Authors: Dan Chen , Yulin Liu , Weiguo Zhang
Published: December 2017

For the continuous improvement of nuclear power plants safety standards, the actual requirements of the plant’s long service life, and the diversification of the plant site conditions, the durability design of nuclear building concrete structure has attracted widespread attention gradually. ACP1000, the third generation class nuclear power plant, is developed by China independently, and it may locate in different site conditions. Taking an ACP1000 nuclear power plant under construction as an example, this paper provides the technical requirements of concrete and concrete raw materials used in nuclear building. And by comparing with AP1000, the third generation class nuclear power plant imported from the United States, the advance and reasonableness of technical requirements of concrete and concrete raw materials used in nuclear building are provided further evidence.
Methodology for Assessing Shock Effect due to Aircraft Impact Considering the Nonlinear of Impact Zone and Soil-Structure Interaction
Authors: Sun Yugang , Cheng Shujian , Ge Honghui , Wang Xiaowen , Yuan Fang , Li Shuaixi
Published: December 2017

Based on the shock damage propagation distances and the median fragility limit of the equipments, the NEI 07–13 employs the shock damage rules for determining the potential for affecting safe shutdown and fuel cooling equipments. However, the NEI 07–13 does not provide more detailed guidance for performing the shock damage assessments, because both the shock damage distances and the methodology for developing the median fragility limit are not provided in NEI 07–13.

This paper discussed methodology developed for performing simplified assessments for shock effects considering the material nonlinearity of the impact zone and the soil-structure interaction. Three different models (i.e., linear model, nonlinear mode, and SSI model) were developed to calculate the in-structure shock response. The results of the linear model show the shock response due to aircraft impact would completely propagate from the center of initial impact zone and then along a structure pathway (e.g. wall, floor, basemat) to the in-structure without any energy dissipation. As a result, the in-structure shock response spectra are considerably higher than the spectra associated with the design-basis earthquake in the high frequency range.

In order to reduce the shock effects on the in-structure safety-related systems and equipments, the material nonlinearity of the impact zone and the soil-structure interaction were incorporated in the dynamic analysis.

The numerical results show that both the material nonlinearity and the soil-structure interaction would obviously absorb the energy of the shock waves, so the in-structure shock response spectra were reduced due to these two factors. Finally, the representative shock response spectra were compared with those used in the seismic margin assessment in order to assess specific equipment survival.
Nonlinear Analysis Method Research of Multi-Bolt Connection Structure of Primary Equipment Support
Authors: Zou Jianrong , Zhou Shaochong
Published: December 2017

The main equipments of the reactor coolant system include the steam generator, the reactor coolant pump, the pressurizer and the reactor coolant loop. The reactor coolant system is equipped with a steam generator for each of the two loops, and pressurizer is connected with the hot leg of loop 1 using the surge line. The main loop support system design of AP series greatly simplifies the RCS loop support system. Pressurizer supports consist of columns, lower lateral supports, upper lateral support and ring girder, and the steam generator supports consist of columns, lower lateral supports, upper lateral supports and intermediate lateral supports. Ring Girder of pressurizer consists of two semi-circular girders, vertical supports and splice connection of girder and the two half-ring girders are connected with splice connection using 11 bolts. The steam generator upper lateral support is mainly composed of bracket, snubber, pin and ubar and the ubar and the steam generator is connected via 16 bolts in the initial design. These bolts are to ensure the support junction can withstand the force and torque of various conditions of the reactor coolant system, which are important components of the main equipment support. There are large numbers of bolts in the splice connection of ring girder and ubar of upper lateral support of steam generator, and the bolts load was calculated using the uniform method in the general engineering design and analysis. During the design review it was found that the bolts load was uneven and in order to determine the non-uniformity of the bolts the finite element method was used to calculate the load on each bolt, and the resulting stress ratio was greater than 1 did not meet the requirements of the ASME Code. In this paper, the calculation method was studied and the design improvements for parts was made using the nonlinear analysis method to meet the requirements of ASME Code in the case of master supports of main equipment supports have been made good. At the same time the impact of bolts load because of gap was studied. It had very good economic benefits. The calculation and research of this paper show that the finite element method can calculate the force of bolts finely, and can get a more reasonable result than the empirical formula. It can be referred to when the multi-bolt connection structure needs to be refined, such as flange connection of important equipments and valves and flange and bolt design optimization.
Effect of Element Segregation on Thermal Aging Behavior of 17-4PH Martensitic Stainless Steel for Nuclear Power Plant
Authors: Bai Bing , Wang Hanxiao , Zhang Changyi , Tong Zhenfeng , Yang Wen
Published: December 2017

The valve stem used in the main steam system of nuclear power plant is usually 17-4PH martensitic stainless steel. When it served in 300 C° for a long time, the thermal aging embrittlement of valve stem will be significant, with the performance of the ductile brittle transition temperature (DBTT) and the hardness increased, the upper stage energy (USE) decreased. It will seriously affect the safety and economic operation of nuclear power plant (NPP). It is important to study the thermal aging effect of the 17-4PH steel for safe operation of nuclear power plant. In this work, Three-Dimensional Atom Probe (3DAP), Energy Dispersive X-Ray Spectroscopy (EDX), Scanning Electron Microscope (SEM) and Optical Microscope (OM) are used to analyze the element distribution in 17-4PH steel. The results show that lath martensite will grow significantly under high temperature for a long time. More δ-ferrite will be found between lath martensite, and some carbide aggregates at its interface. In addition, the number density of Cu clusters in the17-4PH steel is increased. It is found that Ni and Mn have obvious segregation with the Cu cluster.
Decoupling Method of Sloshing Water in PCCWST of Large-Scale Advanced Passive PWR Nuclear Power Plant
Authors: Han Boyu , Yuan Fang , Xia Zufeng , Ge Honghui , Liu Shenghua , Wang Xiaowen
Published: December 2017

Modeling water in passive containment cooling water storage tank (PCCWST) using fluid element will result in large amount of calculation when conducting seismic analysis of shield building or NI. Thus, it is necessary to simplify the modal of water so as to reduce the difficulty of seismic analysis under condition that the error is slight enough to be ignored. By formula deduction and analysis, on the one hand, this paper proofs that modeling “sloshing mass” as fixed mass on structure is unreasonable. On the other hand, this paper proposes that the reasonable simplified approach is to decouple “sloshing mass” totally from the structure system. Furthermore, conditions of utilizing decoupling method are illustrated.
Design and Analysis of Key Instruments of Supercritical Carbon Dioxide Brayton Cycle in Future Nuclear Power Field
Authors: Yuansheng Lin , Jun Wu , Can Ma , Chunhui Dai , Zhenxing Zhao , Mo Tao
Published: December 2017

The Brayton cycle with supercritical carbon (S-CO2) as working medium is one of the most promising new nuclear power systems. As the key device during the expansion and compression process in the Brayton power cycle, the turbine and compressor design and performance analysis is difficult for the strong nonlinear properties during the near critical region of S-CO2 medium. The design and analysis of the S-CO2 turbine and compressor is the key point for increasing the power device performance and operation security. As a result, this paper proposes a detail design and analysis method for turbine and compressor in the S-CO2 Brayton power cycle. The MW grade power cycle is used as the research project. The inlet and outlet parameters of the turbine and compressor are determined according to the power cycle scheme. Engineering thermodynamic principles combined with two-zone loss model are chosen to carry out the one-dimensional flow path design for the turbine and compressor respectively. Then the quasi-three dimension design of the flow path is accomplished by stream curvature method. The three dimensional geometry structure of the impeller is designed in detail. On this basis, numerical simulation models of the turbine and compressor are established to analysis the flow field and structural strength vibration in detail. Moreover, the simulation results show that the isentropic efficiency of the compressor impeller is 96.9%. The maximum total displacements of the compressor and turbine impeller are 0.12 mm and 0.106 mm respectively. The maximum von Mises equivalent stresses of the compressor and turbine impeller are 372 MPa and 320 MPa respectively. The impeller can meet the strength safty requiments for the maximum stress values are much less than the yield stress of the material.
Researched on the Character of Performance Test for a Type of Energy Absorbing Assembly and Mathematic Analysis Model
Authors: Zhu Ruirong , Liang Bingbing , Pan Keqi , Yuan Xinyu
Published: December 2017

It is the key point for the design and analysis of the energy absorbing assemblies in the whole R&D process of pipe whip restraint. An adequate and reasonable energy absorbing assembly design could guarantee the restraint function and control the reaction loads on the structure. Consequently, the performance character curve for the energy absorbing assembly is necessary and important. In this paper, researches are made to obtain the test and analysis method for the energy absorbing assembly. And the method is used to modify the design and release the load on structure to the extent of possible.
The Applicability Study on the Multi-Layer Shell Element Method in Steel Concrete Structure of Shield Building
Authors: Chao Wei
Published: December 2017

In order to withstand the malicious impact of large commercial aircraft, the structure of steel concrete is usually used for shield building’s exterior wall, but due to the form of steel concrete structure is special, it often bring difficulties to the computational analysis of finite element in the design and review. The multi-layer shell element is an equivalent method based on the actual physical layering of material, and has the corresponding function in large-scale finite element software (ANSYS, ABAQUS). The method basic idea is to build a shell element based on the mechanics of composite material. According to the requirement, the shell element can be divided into different thicknesses, material properties and appropriate number of integral points. In the finite element calculation, the stress and strain values can be calculated independently for each integration point. This paper aiming the steel concrete structure in the checking calculation of shield building, used the multi-layer shell element method to simulate and analysis. Based on the modal analysis and spectrum analysis calculations of shield building are performed by using the finite element methods, studying the applicable condition of the methods. The analysis showed that the multi-layer shell element method are able to effectively simulate the structure of steel concrete, and can view more detailed analysis of the stress distribution of steel inside the concrete steel and concrete between the layers, in order to better grasp the safety of the shielding plant.
Design and Implementation of Redundant Sensors in Active Magnetic Bearing
Authors: Shi Zhengang , Yang Jiaji , Mo Ni , Liu Xingnan , Zhou Yan
Published: December 2017

With the advantages of frictionless, no need of lubrication, no pollution, low consuming and long life, active magnetic bearing (AMB) is applied in the primary helium circulator of the High Temperature Gas-Cooled Reactor-Pebble bed Module (HTR-PM), which is under construction in Shidao Bay Nuclear Power Plant.

Active magnetic bearing is a typical mechatronic system with interconnection of mechanical and electronic components with the function of picking up signals, processing and producing. Displacement sensor is an important component to pick up signals for stability control, and also the most susceptible part to fail due to variation of air temperature and vibration of high rotation speed. However, rotating system can’t run normally if a single sensor fails in AMB without redundancy design. For security considerations, higher reliability is required in some special equipment, especially in primary helium circulator of HTR-PM. Design and implementation of redundant sensors is an effective method.

This paper reviewed the present research of fault diagnosis and redundant control of displacement sensors, simulation of coil’s short-circuit and open-circuit fault was made with MATLAB/SIMULINK. Parameters were optimized for fault diagnostic circuit by Multisim. Based on the high reliability demand, redundancy design was applied both on structure and control system in AMB. Schematic drawing and PCB board were finished by Altium Design, and experiments were carried out. The result showed that if the coils of sensor failed, AMB system could still work normally by switching to the redundant sensors automatically.
A Novel High-Power Magnetic Transmission System Based on Magnetic Conductivity Modulation Principle
Authors: Tao Mo , Wu Jun , Ke Zhiwu , Li Xianling , Li Yong
Published: December 2017

Due to the increasingly complexity of the nuclear power device system, the demands for its performance and security become rather high. There is a large number of rotating machinery working in the nuclear power plant.The static and dynamic misalignment between the rotating mechanical rotors may exist for various reasons like installation error, loading deformation, thermal expansion deformation and etc.Both of the radial vibration and the axial vibration can be generated by the misalignment. The security of nuclear power is severely threatened by these vibrations.

Compared with the mechanical gears, the merits of Field Modulated Magnetic Transmission System Based on Magnetic Conductivity Modulation Principle are remarkable.Since it has a high reliability, lower noise, smaller vibration and a capacity of protecting itself during overload. It also can reduce maintenances, moreover there is a physical isolation between input and output in the new system.Besides,the traditional magnetic transmission system has only a low torque transmitting density.But by the use of efficient permanent magnet, the new type magnetic field modulation gears’ high torque transmitting density is comparable to the mechanical ones, even better then them. The major work of this paper is extension.

Researching of the Field Modulated Magnetic Transmission System (FMMTS) based on Magnetic Conductivity Modulation Principle.

Considering about the particularity of the working principle and structure of the FMMTS.First the author studied and analyzed its working principle in details by using analytic method.Then deduced the mathematical relationship of the pole pairs of permanent magnet of inner rotor,the number of copper core in magnetic adjusting loop and the pole pairs of permanent magnet of outer rotor.After that, a mathematical model of torque and rotational speed over three factors: the inner rotor, the outer rotor and the magnetic adjusting loop, were modoled.

On the basis of principle analysis, the author verified the medol and did some further analysis by finite element simulating.Then we obtained the torque transmission characteristics of the Field Modulated Magnetic Transmission System, including the characteristics of Static torque and steady torque.

Based on the above researching, the author put forward the idea of the new type three-layer permanent magnet excitation High-power Field Modulated Magnetic Transmission System based on Halbach tech, that’s middle layer is also permanent magnet. By using the finite element method to analyze its magnetic flux distribution and torque characteristics.Compared with FMMTS under the same size, the new type system improved the power density dramatically.
Right heart dilatation in a fetus with an abnormal foramen ovale valve: an indicator of interatrial communication restriction
Authors: Lei Wenjia , Fan Miao , Wang Meilian , Wang Yu , Sun Wei , Sun Xue , Zhang Ying
Published: December 2017

Aims: Foramen ovale (FO) valve with a shape or motion abnormality is frequently detected during routine obstetric ultrasonic examinations. However, the hemodynamics mechanism of this entity remains unclear. The purpose of the study is to determine the relevance of interatrial communication restriction and resultant morphological modifications.Materials and methods: We reviewed the echocardiographic records of fetuses with isolated abnormal FO valve evaluated between January of 2010 and december of 2016. The size (DFO) of the FO orifice, opening angle (α) of the FO valve, and dimensions of cardiac chambers, FO channel outlet (DOUT) and inferior vena cava (DIVC) were measured. We evaluated their (DFO, DOUT, α) relationships to the diameters of RA and DIVC. Five hundred and seventy normal fetuses were selected to establish the normal range of the DOUT/DIVC ratio so as to provide a criterion for restriction.Results: An abnormal FO valve was identified in 89 fetuses without congenital heart disease, with restriction noted in 62 fetuses (45 fetuses with RA dilatation, 12 fetuses with RA and RV dilatation, and 5 fetuses with no RA dilatation). There were no significant correlations between RA/LA and DFO/DIVC, RA/ LA and α. RA/LA was negatively correlated with DOUT/DIVC (R2=0.97, p<0.01).Conclusions: For a fetus with an abnormal FO valve, right heart dilatation could be considered as an indicator of interatrial communication restriction, which could be assessed by evaluating the FO channel outlet. The degree of right atrium dilatation indicates the severity of the restriction.
Ultrasound and magnetic resonance imaging in the prenatal diagnosis of open spina bifida
Authors: Micu Romeo , Chicea Anca Lucia , Bratu Dan Georgian , Nita Paula , Nemeti Georgiana , Chicea Radu
Published: December 2017

Open spina bifida, also known as spina bifida aperta is a neural tube defect involving the lack of closure of vertebral arches and associated meninges and/or spinal cord abnormalities.Ultrasound examination is the gold standard for the diagnosis of spina bifida aperta. It represents the main imaging tool used to ascertain this diagnosis early in gestation. Three-dimensional ultrasound is necessary to detect the level and the size of the defect. Magnetic resonance imaging (MRI) represents a more sensitive tool, giving specific information of the defect and associated anomalies, playing an important role in ruling out differential diagnosis. Due to the advent of MRI use, it is possible today to achieve in utero treatment of fetuses with this pathology. The aim of the current review is to provide an update of literature regarding the role of ultrasound and MRI in the prenatal diagnosis of spina bifida aperta.
Tracking kidney stones in a homogeneous medium using a trilateration approach
Authors: Shoar Kya , Turney Benjamin W. , Cleveland Robin O.
Published: December 2017

Shock wave lithotripsy is a non-invasive procedure by which kidney stones are fragmented by thousands of shock waves. Currently, many shock waves are delivered to the body that do not impact the stone, but do result in tissue trauma. This motivates developing a monitoring system to locate kidney stones, with the goal of gating shock waves not aligned with the stone, and hence, reducing renal trauma during lithotripsy. The system consists of a circular array housing twenty-two 0.5 MHz transducers that can be mounted on a clinical lithotripter. It was deployed in a water tank and tested with two stone models made from gypsum cement and a stone model fragment. An algorithm consisting of threshold detection, automatic rejection of weak signals, and triangulation was developed to determine the location of stones. The results show that within ±15 mm of the focus of the lithotripter, the accuracy was better than 4 mm in the lateral directions and 2 mm in the axial direction. Using off-the-shelf hardware, the algorithm can calculate stone positions every 1 s allowing for real-time tracking during lithotripsy.
Influence of the neck shape for Helmholtz resonators
Authors: Mercier Jean-François , Marigo Jean-Jacques , Maurel Agnès
Published: December 2017

The resonance of a Helmholtz resonator is studied with a focus on the influence of the neck shape. This is done using a homogenization approach developed for an array of resonators, and the resonance of an array is discussed when compared to that of a single resonator. The homogenization makes a parameter B appear which determines unambiguously the resonance frequency of any neck. As expected, this parameter depends on the length and on the minimum opening of the neck, and it is shown to depend also on the surface of air inside the neck. Once these three geometrical parameters are known, B has an additional but weak dependence on the neck shape, with explicit bounds.
Vaccination of dogs in an African city interrupts rabies transmission and reduces human exposure
Authors: Zinsstag Jakob , Lechenne Monique , Laager Mirjam , Mindekem Rolande , Naïssengar Service , Oussiguéré Assandi , Bidjeh Kebkiba , Rives Germain , Tessier Julie , Madjaninan Seraphin , Ouagal Mahamat , Moto Daugla D. , Alfaroukh Idriss O. , Muthiani Yvonne , Traoré Abdallah , Hattendorf Jan , Lepelletier Anthony , Kergoat Lauriane , Bourhy Hervé , Dacheux Laurent , Stadler Tanja , Chitnis Nakul
Published: December 2017

A citywide dog vaccination effort in Chad reduced the local spread of rabies from dogs to humans.
Enhanced human hematopoietic stem and progenitor cell engraftment by blocking donor T cell–mediated TNFα signaling
Authors: Wang Weijia , Fujii Hisaki , Kim Hye Jin , Hermans Karin , Usenko Tatiana , Xie Stephanie , Luo Zhi-Juan , Ma Jennifer , Celso Cristina Lo , Dick John E. , Schroeder Timm , Krueger Joerg , Wall Donna , Egeler R. Maarten , Zandstra Peter W.
Published: December 2017

Blocking posttransplantation donor T cell–mediated inflammation enhances stem cell survival and accelerates blood cell reconstitution rates.
Hippocampal extracellular matrix alterations contribute to cognitive impairment associated with a chronic depressive-like state in rats
Authors: Riga Danai , Kramvis Ioannis , Koskinen Maija K. , van Bokhoven Pieter , van der Harst Johanneke E. , Heistek Tim S. , Jaap Timmerman A. , van Nierop Pim , van der Schors Roel C. , Pieneman Anton W. , de Weger Anouk , van Mourik Yvar , Schoffelmeer Anton N. M. , Mansvelder Huib D. , Meredith Rhiannon M. , Hoogendijk Witte J. G. , Smit August B. , Spijker Sabine
Published: December 2017

Alterations in the hippocampal extracellular matrix contribute to cognitive deficits in rats exhibiting a chronic depressive-like state after exposure to social defeat–induced persistent stress.