bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sealing Structure Design for Normal Residual Heat Removal Exchanger
Authors: Li Xilin , Jiao Ming 
Published: December 2017

Normal residual heat removal exchanger (RNS HX) is used to remove reactor residual heat during the second stage of reactor shutdown. A hypothetical over-pressurized accident, during which RNS HX would suffer the normal operating pressure and operating temperature of RCS should be considered during the design of RNS HX.
This paper introduces Bolt-Flange-Gasket seal structures for RNS HX, considering the leakage-proof during over pressurized situation and some other operating-related aspects. At tube side, Metal-to-metal contact (MMC), with which a mass energy could be stored in metals during bolt preloading and could release when inner pressure increases, is used, so that the energy stored in metals could resist high pressure to prevent the joint disjoin. Another feather of tube side joint is that a slight angle is designed at the periphery of tubesheet.
At shell side, a segmental gasket, which is divided into two or more pieces rather than a whole circle, is used to seal the joint. As the gasket pieces are installed from the side of tube bundle, the shell does not need to be removed away completely from the bundle in order to install a circle gasket, which could facilitate gasket changing process and save the operating space.
Research on the Structure Integrity Analysis of Flywheel of Reactor Coolant Pump in Nuclear Power Plant
Authors: Zhang Jian , Zuo Yongde , Chen Xingjiang , Zhang Qinghong 
Published: December 2017

The flywheels on reactor coolant pump motors provide inertia to ensure a slow decrease in coolant flow in order to prevent fuel damage as a result of a loss of power to the pump motors. During operation at normal speed, a flywheel has sufficient kinetic energy to produce high-energy missiles and excessive vibration of the reactor coolant pump assembly if the flywheel failed. Overspeed of the pump rotor assembly during a transient increases both the potential for failure and the kinetic energy of the flywheel. The safety consequences could be significant because of possible damage to the reactor coolant system, the containment, or other equipment or systems important to safety.
Usually, the design of connection between flywheel and pump rotor has two types, one is keyway, and the other is rotor shrink fitting. This paper has done the research on the analysis of the integrity of flywheel in design rules and guidelines, such as NUREG, RG and NB, which have given the allowable stress limits but not given the potential for failures types and the stress verification type. So the stress verification of the flywheel is different in different technicals and structures. Some papers also have different analysis methods in China.
This paper considers the failures mode of flywheel, using the analytical method in THEORY OF ELASTICITY and Tresca criteria to give the method of the stress analysis of flywheel. Next, this paper pays attention on the analysis of the flywheel integrity about two connection types, and gives the other requirements of integrity. Such as stress analysis, fatigue analysis, ductile failure analysis, non-ductile failure analysis, crack propagation analysis etc.
The Demonstrated Function of PLR Pump Mechanical Seal Under SBO Conditions
Authors: Yoshioka Toshiyuki , Motani Takashi , Fujimaru Atsushi , Yamada Koji , Hasegawa Kunihiro , Shimizu Takeshi , Torigoe Hiroyuki 
Published: December 2017

Generic Safety Issue 23 (GSI-23) by the U.S. Nuclear Regulatory Commission (NRC) was identified in 1980 as a result of staff concerns about reactor coolant pump (RCP) seal failure during Station Blackout (SBO), that is, seal degradation leading to a significant loss of reactor coolant in pressurized-water reactor (PWR) plants. Resolutions of GSI-23 have been considered at PWR plants. In 2000, NRC decided to close GSI-23 and issue Regulatory Issue Summary00–002 (RIS 00–002)[1], based on considerations such as; for example, the improvement of RCP seal performance[2], and the reduction of the risk of RCP seal failure in certain plants by the addition of alternate power sources. After the closure of GSI-23, some licensees were planning to make other associated improvements under their individual plant program. In Japan, the RCP seal was showed that leakage rate was low under SBO testing conditions[3] in licensing safety reviews conducted according to new nuclear regulatory standards after the nuclear accident at the Fukushima Daiichi Nuclear Power Plant.
On the other hand, a boiling-water reactor (BWR) is not included in GSI-23 because operating experience indicates that seal failures in BWRs result in smaller leak rates than seal failures in PWRs and, BWRs have the reactor coolant injection capability under SBO conditions, such as the reactor core isolation cooling (RCIC) and the high-pressure coolant injection (HPCI) system. In addition, for the particular BWR-2 type plants that do not have emergency makeup systems, the pump mechanical seal was tested under SBO conditions and successfully showed minimal leakage[4]. However, for the BWR-5 type plants which have the reactor coolant injection capability, such as the RCIC and HPCI systems, the pump seal had not been tested. In Japan, after the nuclear accident at the Fukushima Daiichi Nuclear Power Plant, licensing safety reviews of BWRs and PWRs are being conducted according to new nuclear regulatory standards. We took this opportunity to test the leak rate from Primary Loop Recirculation (PLR) pump mechanical seals under SBO condition.
The peak of leak rate was approximately 0.6ton/h (2.6gpm) during the 24 hours of SBO testing condition. Despite damage of O-rings in the mechanical seal by heated water which were ovserbed at post-inspection test, a very low leak rate was realized because the leakage path after passing through the damaged parts of the O-rings was limited by the other restricting pathway in the mechanical seal. This seal leakage was very low, compared with the reactor coolant makeup capability of the RCIC system and the reactor coolant release capability from main steam safety relief valve (SRV). Therefore, we reconfirmed that the result of this leak rate does not affect the safety evaluation for the reactor. It is shown in this paper that the leak rate from PLR pump mechanical seals is low under SBO condition by our demonstration test.
Numerical Research of CAP1700 IHP Cooling by Natural Convection
Authors: Zhang Xingliang , Yu Hao , Zhang Wei , He Yinbiao 
Published: December 2017

The feasibility of using natural convection, in substitution of the cooling fans inside the integrated head package (IHP), to cool the control rod drive mechanism (CRDM) assemblies of the proposed CAP1700 design is studied in this paper.
The flow and the temperature fields of the CRDMs and their surrounding areas, including the IHP, all cooled by natural air convection, were simulated using CFD. The results showed that the average temperature of the CRDM wall surface will stay equal to or below 300°C, which is the pre-requisite of using the newly developed high temperature coils. Therefore, cooling by the natural convection is judged to be feasible for the CAP1700 no-fan design.
Study on Spent Fuel Pool and Storage Racks of the Advanced Nuclear Power Plant
Authors: Yun Ling , Chao Zhang , Lei Li , Hao Qian , Honghui Ge , Zufeng Xia 
Published: December 2017

The present paper is concerned with the problem of modeling dynamic test. The study focuses on the fluid-structure interaction (FSI) in spent fuel pool, which is filled with liquid and spent fuel components. Through the comparison of the results of numerical analysis (Based on LS-DYNA) and modeling test, such as the sloshing wave amplitude; the displacement & inclination angle of the storage racks; pressure exerted on the plate of racks and the walls of the pool were obtained, This paper evaluates the seismic performance and the safety margin of the structure, and also provides the surface pressure input for the design of storage racks.
The phenomena of liquid sloshing in spent fuel pool presents a great interest for civil and nuclear engineering, the dynamic effects of sloshing in spent fuel pool could affect the plates of storage racks and the wall of spent fuel pool during strong earthquakes. Study of sloshing in spent fuel pool is proved challenging due to the presence of strong flow interactions with storage racks in the pool. The movement effect caused by the sloshing load of liquid is the primary reason for the problem to become more complicated.
In this study, two models were created, one is scaled model for shacking table test, another is a numerical model utilize finite element analysis code LS-DYNA. LS-DYNA command *CONSTRAINED_LAGRANGE_IN_SOLID was used to simulate the interaction between solid material and fluid material (fluid-solid coupling effect). Considering the fluid-solid coupling effect between solid and fluid, ALE (Arbitrary Lagrange Euler) element and Lagrange element were used to simulate fluid material and solid material respectively based on their different characters in the numerical model. Using the three spatial components of artificial time histories generated from the design response spectra. The following parameters should be paid attention to in both the scaled model shacking table test and the numerical simulation of time history analysis: The relative displacement between the structure of the spent fuel pool and storage racks; inclination angle of the storage racks; pressure exerted on the plate of storage racks and the wall of pool and the sloshing wave amplitude.
In this paper, the integrated pressure represented by the impulsive hydrodynamic pressure on the plate of storage racks between the shacking table test model and the numerical model were calculated and compared. The analytical parameters of numerical model were corrected to make the numerical model result consistent with modeling test result. In this way, a more reasonable numerical model is obtained.
Research on Rolling-Sliding Integrated Auxiliary Bearing and its Application in High Temperature Reactor
Authors: Jianqiang Chen , Zhe Sun , Guojun Yang , Xingnan Liu , Zhengang Shi 
Published: December 2017

The active magnetic bearings (AMB), with the advantages of no friction, no abrasion, no lubrication and active control, is used in the primary helium circulator for high-temperature gas-cooled reactor (HTR). But the magnetic bearing is a complex system, which contains sensor, controller, power amplifier circuit and actuators. Any part of failure is likely to make high-speed rotor off balanced position and fell in the inner ring of the bearing, causing huge impact and fiction heat that may damage the magnetic bearing. Therefore, it is necessary to bring the auxiliary bearing in the magnetic bearing to protect and temporarily support the high-speed rotor. The auxiliary bearings are mainly divided into two categories: rolling bearings and plain bearings. Generally speaking, for rolling bearings, the force of friction is smaller and the heat caused by it is lower during the touchdown. However, it needs to be detected online to ensure that it can work well in emergencies, and the rolling bearings has a smaller load capacity because of the point contact between the ball and the ring. Compared with the rolling bearings, the structure of plain bearings is simple and durable. With a larger load capacity and the advantage of non-contact detection, the plain bearing is gradually becoming a research hot-spot in the field of the auxiliary bearing. But the great friction and inevitable heat are also cannot be ignored.
In High temperature gas-cooled reactor demonstration power station (HTR_PM), the work load of helium main fan is very large, once the support of electromagnetic bearing is out of work, the auxiliary bearing need to suffer from a very large drop impact load, which is accompanied by a huge friction fever. Therefore, it is important to develop a rolling-sliding integrated bearing which can bear heavy load and have little friction, combined with the advantages of plain bearings and rolling bearings. And that is an important direction of the development for the main helium pan in high temperature gas-cooled reactor nuclear power plant.
This paper establish a simulation model for a horizontal rotor and rolling-sliding integrated auxiliary bearing system. In the case of synchronous rotation of the inner ring with the rotor, the speed of the outer race of the bearing is determined. and based on the main helium fan in HTR-PM, using the finite element analysis software LS-Dyna, the rolling-sliding integrated auxiliary bearing is proposed and the impact force and the MISES stress nephogram when the peak inflation occurred during the first impact and the axial axes displacement curve during rotor drop in the auxiliary bearing are preliminarily simulated in this paper., then certain theoretical reference is provided for the design and engineering application of the rolling-sliding integrated auxiliary bearing.
Seism Analysis of Large-Type Radioactive Liquid Tank
Authors: Shoutong Dai 
Published: December 2017

There are many large standing liquid tanks for collecting radioactive waste liquid in nuclear engineering, the tanks must keep structural integrity and the structural break shouldn’t happen in order to avoid the radioactive leaking accident, so the accuracy of the seism analysis is most important. The liquid sloshing is very sharp in the large standing liquid tank because the weight of waste liquid in the tank always exceeds ten tons.
In order to think over the sloshing effect accurately in seism analysis the 3D mass-spring finite element model is applied instead of the conventional method such as the fixing mass method because the latter is too conservative for Large Radioactive Liquid Tank.
In this paper the software ANSYS is used to simulate the seism response, the waste liquid in the large tank is divided into two portion, one is the static portion and the other is the sloshing portion comparing to the tank on the condition of the seism, the spectrum method is adopted to research the response of the structure model under the seism.
The results show that the mass-spring model referenced to 3-D model is effective for the seism analysis of the large standing liquid tanks. The results of the mass-spring model are more accurate than that of the conventional method.
The Impact of Physical Activity on Serum Inflammatory Markers in Overweight Pubertal Boys: 24-Month Follow-Up Study
Authors: Remmel Liina , Tillmann Vallo , Mengel Eva , Kool Pille , Purge Priit , Lätt Evelin , Jürimäe Jaak 
Published: December 2017

Purpose: To investigate the differences in the pattern of changes in serum inflammatory cytokines measured annually over a 24-month period, between less active and more active overweight boys. Participants/Methods: In total, 25 pubertal overweight boys were divided by their moderate to vigorous physical activity (MVPA) levels into 2 groups: less active group (LAG; n = 10; MVPA < 60 min/d) and more active group (MAG; n = 15; MVPA > 60 min/d). Physical activity was measured by 7-day accelerometry. Serum concentration of 13 inflammatory cytokines [interleukin (IL)-2, IL-4, IL-6, IL-8, IL-10, IL-1α, IL-1β, vascular endothelial growth factor, interferon-γ, tumor necrosis factor-α, monocyte chemotactic protein-1, epidermal growth factor, and C-reactive protein] was measured at baseline (T0), after 12 months (T1), and after 24 months (T2) from fasting blood samples. Results: Serum IL-6 level was significantly higher [LAG: 1.27 (0.86, 1.98) pg/mL; MAG: 0.80 (0.52, 0.84) pg/mL] at T0 and IL-8 level [LAG: 10.26 (8.80, 11.64) pg/mL; MAG: 7.42 (6.10, 9.54) pg/mL] at T2 in LAG compared with MAG. The changes over the study period varied between different inflammatory markers. None of the slopes of any measured markers were statistically different between the LAG and MAG, although the slopes of interferon-γ and IL-10 tended to be different between the groups. Conclusions: The pattern of changes over the study period varied between different inflammatory markers, but these changes were not different between the MVPA groups. More longitudinal studies are needed to investigate whether IL-6, IL-8, IL-10, and interferon-γ would be the choice of inflammatory markers to study the associations between obesity and physical activity in future.
Defining Accelerometer Nonwear Time to Maximize Detection of Sedentary Time in Youth
Authors: Cain Kelli L. , Bonilla Edith , Conway Terry L. , Schipperijn Jasper , Geremia Carrie M. , Mignano Alexandra , Kerr Jacqueline , Sallis James F. 
Published: December 2017

Purpose: The present study examined various accelerometer nonwear definitions and their impact on detection of sedentary time using different ActiGraph models, filters, and axes. Methods: In total, 61 youth (34 children and 27 adolescents; aged 5–17 y) wore a 7164 and GT3X+ ActiGraph on a hip-worn belt during a 90-minute structured sedentary activity. Data from GT3X+ were downloaded using the Normal filter (N) and low-frequency extension (LFE), and vertical axis (V) and vector magnitude (VM) counts were examined. Nine nonwear definitions were applied to the 7164 model (V), GT3X+LFE (V and VM), and GT3X+N (V and VM), and sedentary estimates were computed. Results: The GT3X+LFE-VM was most sensitive to movement and could accurately detect observed sedentary time with the shortest nonwear definition of 20 minutes of consecutive “0” counts for children and 40 minutes for adolescents. The GT3X+N-V was least sensitive to movement and required longer definitions to detect observed sedentary time (40 min for children and 90 min for adolescents). VM definitions were 10 minutes shorter than V definitions. LFE definitions were 40 minutes shorter than N definitions in adolescents. Conclusion: Different nonwear definitions are needed for children and adolescents and for different model-filter-axis types. Authors need to consider nonwear definitions when comparing prevalence rates of sedentary behavior across studies.
Assessing Differences in Cardiorespiratory Fitness With Respect to Maturity Status in Highly Trained Youth Soccer Players
Authors: Doncaster Greg , Iga John , Unnithan Viswanath 
Published: December 2017

Purpose: The purpose of the study was to examine differences in measures of cardiorespiratory fitness and determinants of running economy with respect to maturity status in a group of highly trained youth soccer players. Methods: A total of 21 highly trained youth soccer players participated in this study. On separate visits, players’ peak oxygen uptake (VO2peak), running economy at 3 different speeds [8 km·h−1, 80% gaseous exchange threshold (GET), and 95% GET], and pulmonary oxygen uptake (VO2) kinetics were determined. Players also performed a Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1). Players were categorized as either “pre-PHV” (peak height velocity) or “mid-PHV” group using the measure of maturity offset. Independent t tests and Cohen’s d effect sizes were then used to assess differences between groups. Results: The mid-PHV group was significantly taller, heavier, and advanced in maturity status. Absolute measures of VO2peak were greater in the mid-PHV group; however, when expressed relative to body mass, fat-free mass, and theoretically derived exponents, VO2peak values were similar between groups. Pre-PHV group presented a significantly reduced VO2 response, during relative submaximal running speeds, when theoretically derived exponents were used, or expressed as %VO2peak. VO2 kinetics (tau) were faster during a low (standing) to moderate (95% GET) transition in the pre-PHV group. Yo-Yo IR1 performance was similar between groups. Conclusion: Although measures of VO2peak and Yo-Yo IR1 performance are shown to be similar between groups, those categorized as pre-PHV group display a superior running economy at relative submaximal running speeds and faster taus during a low to moderate exercise transition than their more mature counterparts.
Newborn in cardiogenic shock
Authors: Wagner Franziska , Gebauer Roman A , Paech Christian 
Published: December 2017

Clinical introductionA 2-month-old baby boy was referred to our centre due to tachycardia and acute heart failure. The ECG showed a narrow complex tachycardia with a heart rate of 300 beats per minute (Figure 1). Echocardiographically, a patent foramen ovale and a parachute mitral valve with mild regurgitation were diagnosed; cardiac function was highly impaired.Figure 1ECG (50 mm/s) showing the small complex tachycardia.QuestionWhich of the following is the most likely diagnosis?Ectopic atrial tachycardiaAtrial flutterChaotic atrial tachycardiaFocal micro re-entrant tachycardiaAtrial fibrillation
Dynamical origin of the electroweak scale and a 125 GeV boson
Authors: Tuominen K. 
Published: December 2017

A fully dynamical origin for the masses of weak gauge bosons and heavy quarks of the Standard Model is considered. Electroweak symmetry breaking and the gauge boson masses arise from new strong dynamics, which leads to the appearance of a composite scalar in the spectrum of excitations. In order to generate mass for the Standard Model fermions, we consider extended gauge dynamics, effectively represented by four fermion interactions at presently accessible energies. By systematically treating these interactions, we show that they lead to a large reduction of the mass of the scalar resonance. Therefore, interpreting the scalar as the recently observed 125 GeV state, implies that the mass originating solely from new strong dynamics can be much heavier, of the order of 1 TeV. The couplings of the scalar resonance with the Standard Model gauge bosons and fermions are evaluated, and found to be compatible with the current LHC results.
Top-Mode pseudo-Nambu–Goldstone Boson Higgs model
Authors: Fukano Hidenori S. 
Published: December 2017

We discuss the Top-Mode pseudo-Nambu–Goldstone Boson Higgs (TMpNGBH) model which has recently been proposed as a variant of the top quark condensate model in light of the 125 GeV Higgs boson discovered at the LHC. In this talk, we focus on the vacuum alignment and the phenomenologies of characteristic particles of the TMpNGBH model.