bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Limit Load Analysis Methods Applied to High Temperature Design: Part 2 — Analysis and Results
Authors: Dewees Dave , Jain Rahul
Published: December 2017

Limit Load Analysis (LLA) is a powerful tool for design at temperatures below the creep range, and there is desire to extend the method to the elevated temperature (creep) regime. However, there is no direct relationship between LLA and elevated temperature allowable stresses and failure modes, such that the basic LLA methods or results must be manipulated in some way to be generally meaningful for elevated temperature design. The most direct way to judge simplified methods is against a rigorous solution; this requires an inelastic material model consistent with allowable stresses. Such a creep model was described in Part 1 of this work (the Omega model), and subsequently applied in a rational way to the problem of primary load carrying capacity and design using a simple sample problem. In this paper, extension is made to the case of a typical steam header, and existing simplified (LLA) methods are compared against further detailed transient inelastic finite element analysis. Recommendations are then made for the application of LLA to evolving ASME high temperature design rules.

Paper published with permission.
Research on the Application of FEN for EAF Evaluation of the Austenitic SS Pipe Under Combined Transient Loads
Authors: Liang Bingbing , Zhang Xu , Yin Haifeng , Dai Yang
Published: December 2017

Accumulative test data indicates that the effects of the light water reactor (LWR) environment could cause the fatigue resistance of materials used in the reactor coolant pressure boundary components to significantly reduce. EAF is used as the abbreviation of the environmentally assisted fatigue in the nuclear field. In 2007, NRC issued RG. 1.207. It was updated in 2014. And it requires that the effects of the light-water environment on the fatigue life reduction of metal components should be considered for new plants. And it suggests to use environmental correction factor (Fen) to account for EAF. Fen = Nair/Nwater (N is occurrences). NUREG/CR-6909 [1] presents the detail Fen calculation formula which includes the complicated influence of combined multi-parameters. Fen is a function of temperature, strain amplitude & rate, dissolved oxygen level in water, and sulfur content of the steel. Accordingly, Fen calculation will present a comparatively conservative result. Depends on the experience of the primary pressure boundary piping transient operation, Fen vary during each transient. More uncertainty and confusion are raised during the application of the Fen method. In the research work involved in this article, first, the typical character of piping thermal transient is derived based on the existing experience. Second, small specimen EAF tests are conducted depend on the above derived combined loading characters. Then effort is taken to improve the application of the Fen method for the combined multi-transient loading conditions. And the result is compared with that of the lowest instantaneous Fen method and equalization of the weighted Fen method. Finally, a designed test matrix is needed to prove its practicability furthermore.
Predictive Study of CAP1400 Core Barrel Vibration: Part 2 — Structural Responses
Authors: Yuan Li , Wei Zhang , Ming Zhang , Qing Yu
Published: December 2017

As described in Part 1 of this paper, [1], CAP1400 is a 1400 MWe pressurized water reactor developed by SNERDI to be the next series of nuclear power plants in China. As a part of the feasibility study, a 1/6 scale model test, conducted in Chengdo, China, of the CAP1400 pressure vessel and its internals was carried out to study the flow induced vibration (FIV) characteristics.

This paper describes the predictive study on the structural responses of the core barrel vibration with particular emphasis on using the “Fourier node” method in modeling the hydrodynamic mass effect. It is noted that this is the second part of a two-part series and is focusing on the structural response calculation using the forcing functions described in Part 1, [1], and the comparison with the measured data.
The Application of Risk Informed Method in Pressure Calibration Cycle Extending of RHR Systems SEBIM Valve
Authors: Shuixiang Ye , Kaibao Sun , Qiongzhe Li
Published: December 2017

The stability of the SEBIM valve setting value can be validated based on the pressure calibration test during each refueling cycle. Depending on the feedback of other similar types of nuclear power plants, this test has been revised to two refueling cycles to execute for its excellent performance of SEBIM valves and has got satisfactory performance for several successive refueling cycles. Therefore, this paper will analyze and evaluate the feasibility of extending SEBIM valve setting value test period by employing risk-informed method. The results show that the performance of RHR system’s SEBIM valve is satisfactory; the increment risk is small and meets the quantitative risk acceptance criterion. Thus, the pressure calibration test of the RHR system’s SEBIM valve can be revised to execute for two refueling cycles.
Thermal Fatigue Test on Dissimilar Welded Joint Between Gr.91 and 304SS
Authors: Wakai Takashi , Kobayashi Sumio , Kato Shoichi , Ando Masanori , Takasho Hideki
Published: December 2017

This paper describes a thermal fatigue test on a structural model with a dissimilar welded joint. In the present design of Japan sodium cooled fast reactor (JSFR), there may be dissimilar welded joints between ferritic and austenitic steels especially in intermediate heat exchangers (IHX) and steam generators (SG). Creep-fatigue is one of the most important failure modes in JSFR components. However, the creep-fatigue damage evaluation method has not been established for dissimilar welded joint. To investigate the evaluation method, structural test will be needed for verification. Therefore, a thermal fatigue test on a thick-wall cylinder with a circumferential dissimilar welded joint between Mod.9Cr-1Mo steel and type 304 austenitic stainless steel (304SS) was performed. Since the coefficients of thermal expansion of these steels were significantly different, buttering layer of Ni base alloy was installed between them. After the completion of the test, deep cracks were observed at the heat affected zone (HAZ) in 304SS, as well as at HAZ in Mod.9Cr-1Mo steel. There were many tiny surface cracks in base metal (BM) of 304SS. According to the fatigue damage evaluation based on the finite element analysis results, the largest fatigue damage was calculated at HAZ in 304SS. Large fatigue damage was also estimated at BM of 304SS. Fatigue cracks were observed at HAZ and BM of 304SS in the test, so that analytical results are in a good agreement with the observations. However, though relatively small fatigue damage was estimated at HAZ in Mod.9Cr-1Mo steel, deep fatigue cracks were observed in the test. To identify the cause of such a discrepancy between the test and calculations, we performed a series of finite element analyses. Some metallurgical investigations were also performed.
The Necessity of Reexamine Key Component Material With Spectrometry Analysis in the Nuclear Island
Authors: Chongzhi Wu , Jindong Zhang , Zongkui Wang , Zengkui Zhang , Shenqing Fu
Published: December 2017

In order to avoid the misuse of metal material in nuclear projects, typical cases happened in AP1000 nuclear power projects in China are analyzed. The analysis finding indicates that some cases were caused by defective procedures or undemanding processes performance, and every case is relevant with human error.

It is considered that procedural management cannot completely avoid the misuse of metal material when it is caused by human error, and spectrometry analysis is suggested to reexamine the material of key components.
A Study for Evaluating Local Damage to Reinforced Concrete Panels Subjected to Oblique Impact: Part 2 — Simulation Analysis of the Experimental Results of Local Damage Caused by Impact of Deformable Projectiles
Authors: Nishida Akemi , Ohta Yoshimi , Tsubota Haruji , Li Yinsheng
Published: December 2017

Many empirical formulae have been proposed for evaluating the local damage to reinforced concrete structures caused by rigid projectile impact. Most of these formulae are based on impact tests perpendicular to the target structures. To date, few impact tests oblique to the target structures have been conducted. In this study, we aim to obtain a new formula for evaluating the local damage caused by oblique impacts based on previous experimental and simulation results. We analyze and simulate the local damage owing to impact by deformable projectiles. The experimental and simulation results were in good agreement and confirmed the validity of the proposed analytical method. Furthermore, the internal energy of the deformable projectile absorbed upon impact was approximately 60% of the total energy. In comparison to a rigid projectile, it is possible to reduce the impact load and consequently the damage to the target.
Determination of Design Ground Motion for Potential GEN III and Plus Plants in China: A Regulatory Level Review
Authors: Shang Ziduan , Sun Yugang , Gou Hongliang , Zhang Lutong , Chu Meng , Ge Honghui
Published: December 2017

The determination of Design Ground Motion time history (or response spectra) is the primary and critical step to derive correct Seismic Design Inputs for a Nuclear Power Plant (NPP) design. Historically Design Ground Motion (design SSE input) for a NPP was determined by early version procedure provided in RG 1.60. It was based on a theory of deterministic approach; the resulting ground motion is given in acceleration response spectra located at free surface of a site. As a transition point, 1997 was the year where new procedure was developed and recommended in RG 1.165 based on the new theory of SSE ground motion probabilistic approach. RG 1.165 was authorized for application on all new NPPs’ design after 1997. With the advancing of PSHA approach, RG 1.165 was withdrawn and replaced with new RG 1.208 in 2008. RG 1.208 established an effective way through the similar probabilistic approach used in RG 1.165 by improving PSHA method. Both RG1.165 results and RG 1.208 results are focused on addressing site-specific design, its Ground Motion Response Spectra (GMRS) and Ground Motion Time History (converted from GMRS) are used as design inputs to specific Nuclear Island (NI) seismic design. To accomplish a Standard Design Certification, the RG 1.60 DRS is used to develop the Certified Seismic Design Response Spectra (CSDRS) by modifying control points on original RG 1.60 curves to broaden the spectra in higher frequency range. In reality, CSDRS serves as a good approach to define DRS and Design Ground Motion Time History for standard design of new NPPs in current timeframe, hence envelop the site-specific GMRS given in RG 1.208. In this paper, through the comparison of above US NRC regulatory requirements and Chinese regulatory requirements, gives recommendations on the determination of Design Ground Motion Response Spectra (or Time History), which serves as the basis for deriving seismic design inputs at required specific location (e.g. the bottom of NI foundation level) for potential “GEN III & Plus” plants in China.
Qualification Requirements Design for Neutron Absorber Plate for Spent Fuel Racks in Domestic Nuclear Power Plants
Authors: Shi You , Ning Dong , Yang Yi-zhong
Published: December 2017

Boron Carbide (B4C) particle-reinforced aluminum matrix composite is the key material for use as neutron absorber plate in spent fuel storage racks as well as new fuel and in-containment fuel storage racks for GENIII advanced passive nuclear power plants in China. This material has once depended upon importing with high expense and restricted delivery schedule by foreign supplier. Therefore it has meaningful practical significance to realize the localized manufacturing for this material in China. More importantly, since it’s the first time for this material to be used in domestic plant, particular care should be taken to assure the formal supplied neutron absorber material products exhibit high stabilized and reliable service in domestic nuclear engineering. This paper initiates and proposes a principle design framework from technical view in qualification requirements for this neutron absorber material so as to guide the practical engineering application.

Aiming at neutron absorber materials supplied under practical manufacturing condition in engineering delivery, the qualification requirements define B4C content, matrix chemistry, 10B isotope, bulk density, 10B areal density, mechanical property and microstructure as key criteria for material performance. The uniformity assessment as to different locations of this material is also required from at least three lots of material. Only qualified material meeting all of the qualification requirements should proceed to be verified by lifetime testing such as irradiation, corrosion and thermal aging testing.

Systematic and comprehensive performance assessments and verification for process stabilization could be achieved through the above qualification. The long-term service for this neutron absorber material in reliable and safe way could be convincingly expected in spent fuel storage application in China.
RPV Structure Integrity Assessment With Surface Cracks Under PTS
Authors: Lu Wei , He Zheng
Published: December 2017

As one of the most critical barrier of pressurized-water reactor, Reactor Pressurized Vessel (RPV) is exposed to high temperature, high pressure and irradiation. During the lifetime of RPV, the core belt material will become brittle under the influence of neutron irradiation. The ductile-brittle transition temperature will increase and upper shelf energy will decrease. Thus the structure integrity evaluation of RPV concerning brittle fracture is one of the most important tasks of RPV lifetime management. The non-LOCA accident of Rancho Seco nuclear power plant in 1978 indicates that the emergent cooling transients the sudden cooling down may accompany with the re-pressurize of main loop. The combination of pressure loads and thermal loads may induce a large tensile stress in RPV internal surface, which is the so called pressurized thermal shock (PTS). Due to the existence of welding cladding on the inner surface of RPV, the discontinuity of stress distribution on the cladding-base interface of RPV wall will make calculation of stress-intensity-factor (SIF) difficult. In present research, a two dimensional axial-symmetrical model is built and Finite Element Method (FEM) is adopted to calculate the transient thermal distribution and stress distribution. The influence function method is adopted to calculate crack SIF. Stress distributions in the base and cladding are decomposed respectively and SIFs are calculated respectively to obtain the crack SIF. ASME method is used to calculate the fracture toughness. Present PTS program is validated by the comparative benchmark calculation (the International Comparative Assessment Study of Pressurized Thermal-Shock in Reactor Pressure Vessels). The calculated SIF from present program lies in the reasonable region of the comparing group results. A LOCA transient is investigated with a semi-elliptical surface crack on the RPV beltline region. The temperature and stress distribution along the vessel wall during the transient are given. The stress intensity factors at the deepest and interface point are given respectively. The integrity of RPV under PTS transient is evaluated by comparing stress intensity factor with fracture toughness. Results indicate that the stress intensity factor will not exceed the fracture toughness of the RPV material. The difference between the stress intensity factor and fracture toughness reach a minimum value at the crack tip temperature 20°C. Present research gives a reliable and efficient program to perform RPV structure integrity assessment with surface crack under PTS, which is suitable for further parameter analysis and probabilistic analysis.
Verification of Probabilistic Fracture Mechanics Analysis Code PASCAL
Authors: Li Yinsheng , Katsumata Genshichiro , Masaki Koichi , Hayashi Shotaro , Itabashi Yu , Nagai Masaki , Suzuki Masahide , Kanto Yasuhiro
Published: December 2017

Probabilistic fracture mechanics (PFM) has been recognized as a promising methodology in structural integrity assessments of aged pressure boundary components of nuclear power plants because it can rationally represent the influencing parameters in their inherent probabilistic distributions without over conservativeness. In Japan, a PFM analysis code PASCAL (PFM Analysis of Structural Components in Aging LWR) has been developed by the Japan Atomic Energy Agency (JAEA) to evaluate the through-wall cracking frequencies of Japanese reactor pressure vessels (RPVs) considering neutron irradiation embrittlement and pressurized thermal shock (PTS) transients. In addition, efforts have been made to strengthen the applicability of PASCAL to structural integrity assessments of domestic RPVs against non-ductile fracture.

On the other hand, unlike deterministic analysis codes, the verification of PFM analysis codes is not easy. A series of activities has been performed to verify the applicability of PASCAL. In this study, as a part of the verification activities, a working group was established in Japan, with seven organizations from industry, universities and institutes voluntarily participating as members. Through one year activities, the applicability of PASCAL for structural integrity assessments of domestic RPVs was confirmed with great confidence. This paper presents the details of the verification activities of the working group including the verification plan, approaches and results.
A Method to Select Weights in Online Dynamic Balance Technology Based on Rotor-Active Magnetic Bearing System
Authors: Xunshi Yan , Jingjing Zhao , Zhe Sun , Zhengang Shi
Published: December 2017

Online dynamic balance technology is the key to rotor-active magnetic bearing system, which helps the rotating speed of the system surpass the critical speed. Usually, balance weight and angle are calculated by influence coefficient method. However, how to decompose the weight and angle into sub-weights fixed in the balance holes is troublesome, and determined manually by trial and error, which is always time-consuming. In this paper, a new hierarchical and automatic method is proposed to find the optimized solution to select proper sub-weights in a short time, which limits to a pre-defined error. The algorithm focuses on reducing the move of sub-weights and addition of new sub-weights. Experiments show our algorithm perform effective and efficient.
Microstructure Analysis of Stainless Steel Cladding on Low Alloy Steel Weld in a PWR Safe End Nozzle and Corrosion in High Temperature Water
Authors: Xiong Qi , Lu Zhanpeng , Chen Junjie , Ru Xiangkun , Li Hongjuan , Peng Hao , Ma Jiarong
Published: December 2017

The complex microstructures of stainless steel (SS) cladding on low alloy steel (LAS) joint and the corrosion behavior in high temperature water environments were examined. Scanning electron microscopy, focused ion beam, transmission electron microscope and Raman spectroscopy were used. The heat-affected zone (HAZ) in the low alloy steel was mainly comprised of pearlite and ferrite, while the HAZ in the stainless steel was mainly comprised of austenite and ferrite. The HAZ in the low alloy steel was divided into overheated crystal region, complete recrystallization region and incompletely recrystallization region. A decarburization zone in the low alloy steel side and a carbon-enriched zone in the stainless steel side were identified. M23C6 and M7C3 precipitation were observed mainly in carbon-enriched zone. The surfaces of the weld after corrosion in simulated PWR primary water environment at 290 °C were significantly affected by dissolved oxygen. In aerated solution, the oxide film on A508III steel was mainly γ-Fe2O3, which becomes spinel oxide on the 309L/308L cladding. In deaerated solution, the oxide film was mainly Fe3O4 on A508III steel, which was spinel oxide on the 309L/308L cladding.
Theoretical Research About the Dynamics of a Rotor With a Decreasing Length Suspended by Active Magnetic Bearing
Authors: Xingnan Liu , Zhengang Shi , Guojun Yang , Xunshi Yan
Published: December 2017

The Active Magnetic Bearing (AMB) will be used in the High Temperature Reactor being constructed in Shandong Province, China. The calculation of rotor dynamics is very important for design of the AMB, and is difficult when the AMB is used in the Plasma Rotation Electrode Process (PREP). In this process, the length of the rotor, which is a rotating titanium stick, is decreasing gradually. In a PREP project, a new device supported by the AMBs was used to replace an old device supported by rolling bearings to fit higher working speed. Based on this project, the rotor dynamics of a “length-decreasing” rotor suspended by the AMBs was analyzed. Firstly, the critical speed and the unbalance response of the titanium stick were calculated for the two devices respectively. It’s found that, for the new device, the third order critical speed at the beginning of the process should be larger than the working speed, and the second order critical speed at the end of the process should be smaller than the working speed. Secondly, the influencing factors of the critical speed were studied. It’s found that, with the increasing of the brush’s diameter and length, all critical speeds decrease, especially for higher order critical speed. And with the increasing of the stick’s length, all critical speeds decrease, especially for higher order critical speed. At last, a design for the replacement of the device was present.
Effects of Charged Hydrogen on Oxidation Behavior of Alloy 690 in High Temperature Water Environments
Authors: Peng Hao , Lu Zhanpeng , Ru Xiangkun , Chen Junjie , Ma Jiarong , Xiong Qi , Xiao Qian , Li Hongjuan
Published: December 2017

The oxide films formed on non-charged and hydrogen-charged Alloy 690 specimens exposed to 290 °C pure water environment with different dissolved oxygen concentrations were characterized. It was found that the oxide film formed on the hydrogen-charged specimen was thicker than that on the noncharged specimen. Local protruding oxides were observed on the hydrogen-charged Alloy 690 but not on the non-charged specimen. The Ni and Fe contents of local protrusion on the hydrogen-charged specimen were higher than those on the noncharged specimen.
Seismic Analysis for an Explosion-Proof Valve Used in Nuclear Power Plant
Authors: Luo Juan , Luo Jiacheng , Sun Lei
Published: December 2017

Nuclear class equipment should be assessed for seismic safety before they are used in nuclear power plant. According to nuclear safety codes and regulations, all seismic category I equipments shall be designed enduring safety shutdown earthquake (SSE). That is, the stress evaluation needs to be accomplished for those structures. For some components, the deformation evaluation needs to be performed as well to assure the function integrity of the equipment. In this paper, the seismic analysis for an explosion-proof valve used in nuclear power plant, which exactly belongs to seismic category I equipment, has been conducted based on finite element method. The natural frequency, vibration mode and seismic response of the structure have been obtained through calculation, and the stress and deformation under the combined loadings of gravity, internal pressure, blast and seismic load have been evaluated according to ASME AG-1. The bolts of the structure have been qualified according to ASME III-NF as well. The results show that the design of the explosion-proof valve is in compliance with the requirement of corresponding nuclear safety standards.
Fire and Explosion Analysis of Steel-Plate Composite Concrete Shield Building Under Large Commercial Aircraft Impact
Authors: Li Shuaixi , Cheng Shujian , Ge Honghui , Yuan Fang , Huang Xiaolin , Xia Zufeng , Wang Xiaowen , Sun Yugang
Published: December 2017

The fire and explosion assessment is necessary for NPP to evaluate the effect caused by malicious large commercial aircraft impact. This report focuses on the fire and explosion effect on shield building structure of nuclear island according to the impact screening. With the investigation and analysis for the fire and explosion of aircraft impact, a simple and effective method was established. With this method the pool fire and fire explosion are analyzed and their effects on shield building structure are assessed based on the temperature and pressure distribution obtained from the FEA model.
Thermal Stratification Analysis and Fatigue Evaluation for Pressurizer Surge Line in Nuclear Power Plant
Authors: Xu Xiao , Liu Pan , Zhang Guihe , Wang Dasheng , Jin Ting
Published: December 2017

Thermal stratification of pressurizer surge line in nuclear power plant induced by the stratification of fluid results in additional stresses (system-dependent and system-independent stresses). These additional stresses are related to the thermal stratification distribution, such as temperature difference, stratification location, stratification length and boundary layer slope and thickness. This thermal stratification distribution is effected by several parameters such as turbulent penetration length and surge line slope. These influence factors are studied with numerical method. For the additional stresses, this study theoretically establishes the solution of the system-dependent stresses according to the thermal stratification distribution assumption. With the system-dependent and system-independent stresses, a complex three-dimension problem is simplified into a one-dimension. Using this effective one-dimension method, fatigue evaluation can be fast processed and accurate improved in engineering analyses.
The Research of Integration of Design and Analysis Based on 3D Design Platform of NPP
Authors: Yu Xiao
Published: December 2017

This paper studies the development method of integration between design and analysis. Development is based on the current design platform of nuclear power plant of SNERDI - PDS. Because of complexity and iterations, the calculation and analysis work often takes a lot of manpower and drags down the entire design progress. To improve efficient and accuracy, the integration between design and analysis became the trend of technology development. Some design systems, such as Ansys Workbanch, ProE, Catia and so on, can be integrated modeling and analysis in a unified platform. However, these systems can be only applied to product design, but not in nuclear power design. At present, CAP series NPP mainly uses PDS as the layout design platform of all disciplines. This paper describes the bidirectional data sharing between design and analysis, effectively expand the scope of data utilization, and enhance the efficiency of the analysis.
A Study on Hydrogen Emission of Zirconium Hydride
Authors: Xiaogang Fu , Bo Qin , Haoran Ma , Jinquan Zhang , Bin Long
Published: December 2017

The hydrogen emission of zirconium hydride at high temperature is a challenging issue for many researchers. The hydrogen emission content of zirconium hydride pins should be evaluated to confirm the application feasibility. The comparison of theory analysis and experiment data indicated Richardson’s Law could offer a conservative result for calculating the hydrogen emission content of zirconium hydride pins at high temperature. Furthermore, the methods of preventing hydrogen loss should be developed for the purpose of extending the work temperature or time. The results showed a ZrO2 layer prepared for zirconium hydride could not prevent hydrogen loss after exposure at 923K in an inert environment and ZrO2 transformed into Zr3O gradually due to the opposite movement of hydrogen and oxygen. Finally, a further improvement to prevent hydrogen loss was developed. The zirconium hydride with a ZrO2 layer in the cladding of He+CO2 exhibited no significant reduction of hydrogen content. It is helpful to prevent the hydrogen loss by increasing the oxygen potential on the outside of ZrO2 layer.
Case Study Analyses of Flaw Growth and Tolerance of Stainless Steel Canisters in Marine Environment
Authors: Heui-Yung Chang
Published: December 2017

The majority of dry cask storage systems used in the world confine nuclear fuel within austenitic stainless steel canisters. Past experience indicates that stainless steel may become susceptible to stress corrosion cracking (SCC) in the presence of stress and chloride salts. Recently, a cracking growth rate (CGR) model was developed and applied to evaluate the flaw depth of stainless steel canisters over the timeframe of the storage at independent spent fuel storage installations. This paper presents the results of case study analyses on stainless steel canisters of dry storage systems in the 1st and 2nd nuclear power plants in Taiwan. In detail, the flaw depth was first evaluated using the CGR model, site climate data, and surface temperature at the location of interest on the canister. The critical flaw sizes and depth were then determined from the structural tolerance assessment of canister shells to flaws of varying sizes. It was found that the difference in thermal-hydraulic behaviors of drystorage canisters can cause a great variation in the SCC initiation time. But that may not cause a significant difference in the surface temperature at initial salt deliquesce (ranging from 55 to 60 °C). The CGR at the SCC initiation is greater, and the flaw growth takes a great part. The surface temperature and activation energy get low as the time increases. The total flaw depth therefore may not vary greatly with the SCC initiation time. Overall, the drystorage canisters have shown relatively high structural tolerance to flaw sizes and depths.
Research on Corrosion Behavior of Copper in Reactor Thermal Hydraulic Test
Authors: Xu Haiyan , Lu Donghua , Wu Xiaohang , Su Qianhua
Published: December 2017

Safety instrument test facility (FITY) is one of the high temperature and high pressure test facilities in CGN. It is designed to conduct tests on thermal-hydraulic of safety system and instruments under the similar condition of reactor severe accident. FITY uses lot of copper components to realize sealing and insulation of vessel. Varies of hot state tests revealed that copper components worked well during the test, however, electrochemical corrosion was found as well, making water quality get worse. This article introduces chemical composition, physical properties and electrochemical corrosion behavior of copper component used in FITY, then analyzes the cause of corrosion and summarizes the notice for electronic component design under high temperature and high pressure conditions.
Small-Scaled Experimental Research on the Buckling of Steel Containment Under Axial Compression
Authors: Li Pengfei , Hu Fuquan , Wang Xuwei , He Zheng , Gang Zhi
Published: December 2017

Focusing on the general and localized elastoplastic buckling of the cylindrical section of steel containment under axial pressure, nonlinear finite element method (FEM) and small-scaled experiments are applied to analysis. First, FEM analysis is conducted considering nonlinear items caused by geometric shape imperfection and elastoplastic constitutive model by the arc-length method RIKS procedure. Parameter sensitivity of the buckling is revealed. Then, small-scaled experiments are carried out. Buckles status is observed, and key geometrical parameters’ influence are found. The results show that cylindrical buckling under axial pressure is sensitive to geometrical parameters and imperfection. It is necessary to employ more realistic parameters to the FEM analysis via accurate geometrical measurement. This research has reference value for the design and fabrication of AP series steel containment vessel.
Steam Generator Modal Analysis of Nuclear Power Plant
Authors: Yan Lu , Qibao Chu , Qing Wang , Yonggang Fang
Published: December 2017

A method for forming a simplified model of steam generator which will be used in reactor coolant loop analysis has been shown here, as well as the modal analysis to this simplified SG model. This modal analysis results and the results of the SG provided by NPP designer are compared together in order to prove the design correctness. The comparison shows that the two are basically consistent.
Effect of Reactor Coolant Environment on Fatigue Property of Austenitic Stainless Steel in PWR
Authors: Yonggang Fang , Jiashuo Zhan , Qibao Chu , Qing Wang , Yu Xu
Published: December 2017

It is required that the fatigue analysis be done for nuclear reactor components consisting of the reactor pressure boundary. Currently, it is certified that the fatigue design curves currently used in the analysis weren’t conservative enough for not considering reactor coolant environment. The article gives some general information related with the regulatory requirements and research work conducted abroad. It introduces coolant environment assisted fatigue experiment based on the domestic austenitic stainless steels and provides the data comparison with the code design fatigue curves. It concludes and recommends the methodology for the nuclear component fatigue design.
Enhanced Heat Transfer Structure Design for Ion Dump of EAST-NBI System Based on Hypervapotron
Authors: Tao Ling , Hu Chundong , Xie Yuanlai
Published: December 2017

Ion dump is an important functional component of the Neutral Beam Injection (NBI) system of Experimental Advanced Superconducting Tokamak (EAST) for absorbing un-neutralized particles deflected by deflection magnets during neutralization, and by means of the corresponding measurement and analyzing method on it, the total energy deposition value and instantaneous energy deposition distribution of the deflected ion beam can be obtained. According to the operation mechanism of the NBI system, ion dump is directly subjected to high-energy particle bombardment for long time, the corresponding heat-loaded on its plates is high, so the temperature rise control is demanding. In order to realize the running power of 2–4MW and running pulse length of more than 100s or even 1000s in the future NBI system, the structure of the ion dump must be designed in accordance with the quasi-steady state operation requirements to provide the guarantee for the steady state operation of EAST system. The Hypervapotron structure based on the subcooled boiling principle is used as an alternative structure to enhance the heat transfer of this high-heat-flux component. According to the operating requirements, space requirements, measurement requirements and beam power distribution characteristics, the engineering design and implementation of ion dump based on the enhanced heat transfer structure is realized for the future long pulse quasi-steady NBI system. The computational results of the heat-fluid-solid coupling simulation based on the two-phase heat transfer are also confirmed the feasibility of the proposed ion dump structure under quasi-steady-state operating conditions. This study is of great significance to explore the optimal heat transfer structure for quasi-steady ion dump to realize the high current, quasi-steady state and high power operation of EAST-NBI system.
Benefit of Shear-wave Elastography in the differential diagnosis of breast lesion: a diagnostic meta-analysis
Authors: Luo Jie , Cao Yong , Nian Weiqi , Zeng Xiaohua , Zhang Hui , Yue Yeli , Yu Feng
Published: December 2017

Aims: The purpose of this diagnostic meta-analysis was to explore the benefit of shear wave elastography (SWE) combinedly used with conventional ultrasound (US) in the diagnosis of the benign and malignant breast lesion.Material and methods: After a literature search on MEDLINE, Cochrane library, and Embase we included 14 studies with a total 1951 patients and 2060 breast lesions for further analyses. Summary descriptive statistics such as pooled sensitivity, specificity, and summary receiver operating characteristics curve were generated via a bivariate random effect model. Summary indicators such as area under curve (AUC) and confident region were used to compare the performance of conventional US and combination of conventional US and shear wave imaging (SWI) or two-dimensional and three-dimensional SWI.Results: As indicated by the results, the pooled sensitivity, specificity, and diagnostic odds ratio for combined usage of SWE and the conventional US were 0.877 (95%CI: 0.855-0.896) and 0.849 (95%CI: 0.826-0.869) and 40.164 (95%CI:31.135- 51.811). The AUC for combined use and the conventional US only were 0.928 and 0.899, suggesting a promise of integrating SWE in the routine of breast lesion examination. Also, the summary AUC for 2D and 3D SWE were 0.917 and 0.952 respectively. No significant difference was found between 2D and 3D SWE. No obvious publication bias was identified after employing Deeks’ regression test for asymmetry.Conclusion: Our analysis concluded that SWE improved the differential diagnosis of the breast lesion.
The role of 4D US in evaluation of fetal movements and facial expressions and their relationship with fetal neurobehaviour
Authors: Grigore Mihaela , Gafitanu Dumitru , Socolov Demetra , Grigore AnaMaria , Nemeti Georgiana , Micu Romeo
Published: December 2017

The introduction of four-dimensional (4D) ultrasonography (US) allows the study of fetal movements and facial expressions in real time. The possibility of evaluating fetal movements has led to the study of fetal neurobehaviour, which has been for a long period of time a mystery for physicians. The study of fetal activity in utero could differentiate between normal and abnormal behavioural patterns, thus making possible the early recognition of fetal brain impairment. Facial expressions observed with 4D US represent a marker for neurobehaviour and at the same time could enhance fetal-maternal bonding. The present review represents an update of the literature on fetal movements, facial expressions, and their relationship with fetal neurobehaviour.
Human ESC–derived retinal epithelial cell sheets potentiate rescue of photoreceptor cell loss in rats with retinal degeneration
Authors: Ben M’Barek Karim , Habeler Walter , Plancheron Alexandra , Jarraya Mohamed , Regent Florian , Terray Angélique , Yang Ying , Chatrousse Laure , Domingues Sophie , Masson Yolande , Sahel José-Alain , Peschanski Marc , Goureau Olivier , Monville Christelle
Published: December 2017

Human ESC–derived retinal pigment epithelial cell sheets are more effective than cell suspensions at rescuing photoreceptor cell loss in rats with retinal dystrophy.
Stress signal ACTs to hinder sleep in PTSD
Authors: Michopoulos Vasiliki
Published: December 2017

Adrenocorticotropic hormone (ACTH) modulation is associated with sleep disturbances in individuals with posttraumatic stress disorder.
Personalized medicine finds the MAPK for breast cancer
Authors: Venere Monica
Published: December 2017

Whole-exome sequencing and RNA-seq on a mouse model of triple-negative breast cancer reveal actionable therapeutic targets for precision medicine guided treatment.
Intersubject Synchronisation Analysis of Brain Activity Associated with the Instant Effects of Acupuncture: An Fmri Study
Authors: Jin Lingmin , Sun Jinbo , Xu Ziliang , Yang Xuejuan , Liu Peng , Qin Wei
Published: December 2017

Objective

To use a promising analytical method, namely intersubject synchronisation (ISS), to evaluate the brain activity associated with the instant effects of acupuncture and compare the findings with traditional general linear model (GLM) methods.

Methods

30 healthy volunteers were recruited for this study. Block-designed manual acupuncture stimuli were delivered at SP6, and de qi sensations were measured after acupuncture stimulation. All subjects underwent functional MRI (fMRI) scanning during the acupuncture stimuli. The fMRI data were separately analysed by ISS and traditional GLM methods.

Results

All subjects experienced de qi sensations. ISS analysis showed that the regions activated during acupuncture stimulation at SP6 were mainly divided into five clusters based on the time courses. The time courses of clusters 1 and 2 were in line with the acupuncture stimulation pattern, and the active regions were mainly involved in the sensorimotor system and salience network. Clusters 3, 4 and 5 displayed an almost contrary time course relative to the stimulation pattern. The brain regions activated included the default mode network, descending pain modulation pathway and visual cortices. GLM analysis indicated that the brain responses associated with the instant effects of acupuncture were largely implicated in sensory and motor processing and sensory integration.

Conclusion

The ISS analysis considered the sustained effect of acupuncture and uncovered additional information not shown by GLM analysis. We suggest that ISS may be a suitable approach to investigate the brain responses associated with the instant effects of acupuncture.
Antiplatelet pretreatment and outcomes following mechanical thrombectomy for emergent large vessel occlusion strokes
Authors: Pandhi Abhi , Tsivgoulis Georgios , Krishnan Rashi , Ishfaq Muhammad F , Singh Savdeep , Hoit Daniel , Arthur Adam S , Nickele Christopher , Alexandrov Andrei , Elijovich Lucas , Goyal Nitin
Published: December 2017

Background

Few data are available regarding the safety and efficacy of antiplatelet (APT) pretreatment in acute ischemic stroke (AIS) patients with emergent large vessel occlusions (ELVO) treated with mechanical thrombectomy (MT). We sought to evaluate the association of APT pretreatment with safety and efficacy outcomes following MT for ELVO.

Methods

Consecutive ELVO patients treated with MT during a 4-year period in a tertiary stroke center were evaluated. The following outcomes were documented using standard definitions: symptomatic intracranial hemorrhage (sICH), successful recanalization (SR; modified TICI score 2b/3), mortality, and functional independence (modified Rankin Scale scores of 0–2).

Results

The study population included 217 patients with ELVO (mean age 62±14 years, 50% men, median NIH Stroke Scale score 16). APT pretreatment was documented in 71 cases (33%). Patients with APT pretreatment had higher SR rates (77% vs 61%; P=0.013). The two groups did not differ in terms of sICH (6% vs 7%), 3-month mortality (25% vs 26%), and 3-month functional independence (50% vs 48%). Pretreatment with APT was independently associated with increased likelihood of SR (OR 2.18, 95% CI1.01 to 4.73; P=0.048) on multivariable logistic regression models adjusting for potential confounders. A significant interaction (P=0.014) of intravenous thrombolysis (IVT) pretreatment on the association of pre-hospital antiplatelet use with SR was detected. APT pretreatment was associated with SR (OR 2.74, 95% CI 1.15 to 6.54; P=0.024) in patients treated with combination therapy (IVT and MT) but not in those treated with direct MT (OR 1.78, 95% CI 0.63 to 5.03; P=0.276).

Conclusion

APT pretreatment does not increase the risk of sICH and may independently improve the odds of SR in patients with ELVO treated with MT. The former association appears to be modified by IVT.
Genome-wide divergence patterns support fine-scaled genetic structuring associated with migration tendency in brown trout
Authors: Lemopoulos Alexandre , Uusi-Heikkilä Silva , Vasemägi Anti , Huusko Ari , Kokko Harri , Vainikka Anssi
Published: December 2017

Brown trout (Salmo trutta) exhibit highly diverse life histories varying from resident, slow-growing, and early maturing to migratory, fast-growing, and late maturing, even within single watersheds. We sampled 11 locations within the transboundary Finnish–Russian River Koutajoki watershed to evaluate genomic differences among mainstem and headwater sites, of which some are isolated by migration barriers. Restriction site associated sequencing (RADSeq) revealed that the most headwater localities supported unique, isolated populations with generally lower heterozygosity compared with the mainstem populations. The sampled migratory adults in the three main stems showed signals of admixture despite small but statistically significant genetic divergence, while the headwater populations, except for two, showed a high level of divergence and a lack of admixture. These results suggest that most of the headwater populations consist of resident brown trout and that the population genetic structuring is often maintained even in the absence of migration barriers. Our results have clear implications for fisheries management and conservation; each brown trout subpopulation represents an evolutionarily important unit with unique genetic makeup and life history variation.
de Sitter geodesics
Authors: Cotăescu Ion I.
Published: December 2017

The geodesics on the (1 + 3)-dimensional de Sitter (dS) spacetime are considered studying how their parameters are determined by the conserved quantities in the conformal Euclidean, Friedmann–Lemaître–Robertson–Walker, de Sitter–Painlevé and static local charts with Cartesian space coordinates. Moreover, it is shown that there exists a special static chart in which the geodesics are genuine hyperbolas whose asymptotes are given by the conserved momentum and the associated dual momentum.
A modified Friedmann equation
Authors: Ambjørn J. , Watabiki Y.
Published: December 2017

We recently formulated a model of the universe based on an underlying W3-symmetry. It allows the creation of the universe from nothing and the creation of baby universes and wormholes for spacetimes of dimension 2, 3, 4, 6 and 10. Here we show that the classical large time and large space limit of these universes is one of exponential fast expansion without the need of a cosmological constant. Under a number of simplifying assumptions, our model predicts that w = −1.2 in the case of four-dimensional spacetime. The possibility of obtaining a w-value less than −1 is linked to the ability of our model to create baby universes and wormholes.
Topological insights in many-flavor QCD on the lattice
Authors: Aoki Yasumichi , Aoyama Tatsumi , Bennett Ed , Kurachi Masafumi , Maskawa Toshihide , Miura Kohtaroh , Nagai Kei-ichi , Ohki Hiroshi , Rinaldi Enrico , Shibata Akihiro , Yamawaki Koichi , Yamazaki Takeshi , LatKMI Collaboration
Published: December 2017

LatKMI Collaboration discusses the topological insights in many-flavor QCD on the lattice. We explore walking/conformal/confining phase in [Formula: see text] and 12 (in particular [Formula: see text]) lattice QCD via the topological charge and susceptibility, eigenvalues and anomalous dimension.
Recent results on renormalization-group evolution of theories with gauge, fermion, and scalar fields
Authors: Shrock R.
Published: December 2017

We discuss recent results on renormalization-group evolution of several types of theories. First, we consider asymptotically free vectorial gauge theories with various fermion contents and discuss higher-loop calculations of the UV to IR evolution in these theories, including an IR zero of the beta function and the value of the anomalous dimension [Formula: see text] at this point, together with comparisons with lattice measurements. Effects of scheme transformations are discussed. We then present a novel way to determine the value of [Formula: see text] in an [Formula: see text] technicolor model from a particular embedding in an extended technicolor theory. Finally, we analyze the renormalization-group behavior of several non-asymptotically free theories, including a U(1) gauge theory, a non-Abelian gauge theory with many fermions, an [Formula: see text] [Formula: see text] scalar theory, and Yukawa theories.