bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation and optimization of a vibrotactile signal in an autonomous driving context
Authors: Duthoit Valérie , Sieffermann Jean‐Marc , Enrègle Éric , Michon Camille , Blumenthal David
Published: December 2017

An important issue in autonomous vehicle development is the transition phase between autonomous and manual driving. Here, we focused on a vibrotactile signal that warns the driver 1 min before they must take over. Our goal was to design a signal detectable by, and satisfactory for, all drivers. After listing parameters defining a vibrotactile signal, we performed a design‐of‐experiments study to select 16 signals for evaluation by 80 participants of different ages, body mass indexes, and genders. In a car on the road, autonomous driving conditions were simulated with the participant in the front passenger seat, who performed a task unrelated to driving. Whenever the participant detected a signal, they gave a satisfaction score. Modeling enabled us to evaluate the effects of the signal parameters and participant characteristics on satisfaction and detection. Moreover, we obtained specifications for the design of a tactile signal according to our two criteria.

Practical applications

To the best of our knowledge, this is the first study to focus on the sensory aspect of a tactile signal in a car environment. Both functional (i.e., signal detection) and hedonic aspects are important. We investigated the influence of gender, age, and body mass index of the participants on signal detection and satisfaction score, and optimized the satisfaction score under detection constraints. We use a 3‐point method to reach those two goals:

Constructing the design‐of‐experiments (DoE) based on signal parameters that influence the two criteria and can be tuned.

Sensory evaluation of the signals from the DoE.

Modeling to evaluate the influence of each parameter and determine optimal values.

Understanding the influence of the participant's characteristics, coupled with an optimization approach, will benefit the design of automated cars as well as other tactile interfaces, such as smartphones, connected wristbands, or touchscreens.
Parental perceptions of disease‐severity and health‐related quality of life in school‐age children with congenital heart disease
Authors: Ruggiero Kristine M. , Hickey Patricia A. , Leger Robin R. , Vessey Judith A. , Hayman Laura L.
Published: December 2017

Purpose

Understanding parents’ perceptions of their child's health status is important as parents are drivers of healthcare utilization in the pediatric setting. Understanding parent‐perceived disease‐severity and its effects on a child's health‐related quality of life (HRQOL) in children with congenital heart disease (CHD) is necessary to evaluate outcomes of care, improve care coordination, and inform policies focused on advancing family‐centered care for pediatric cardiac patients. The impact of CHDs and disease‐severity on the child's HRQOL has been investigated with inconsistent results. The overall aim of this study was to examine parents’ perceptions of HRQOL in their school‐age child with CHD, and to compare HRQOL among patients with CHD across severity categories.

Design

This was a descriptive correlational study design.

Methods

A total of 71 parents of school‐age children aged 5–12 years completed the Pediatric Quality of Life Inventory 4.0 Generic Core Scale (PedsQL) (including total, physical health, and psychosocial health summary scores) and cardiac‐specific HRQOL Scale (PedsQL 3.0). PedsQL scores among CHD severity categories were compared by analysis of variance.

Results

School‐age children with CHDs had an overall good HRQOL with significant differences among disease severity categories for all scores. Parents reported lower scores on their HRQOL of older children compared to younger children across severity groups (p < .01) and for those children with more severe disease (p < .01).

Practice implications

Based on the results of this study, interventions should focus on targeting psychosocial health in older children with CHD and physical health in younger children with CHD. This information is useful in providing practical recommendations in caring for children with CHDs while informing relevant policies.
In Streptomyces lividans, acetyl‐CoA synthetase activity is controlled by O‐serine and Nɛ‐lysine acetylation
Authors: VanDrisse Chelsey M. , Escalante‐Semerena Jorge C.
Published: December 2017

Protein acetylation is a rapid mechanism for control of protein function. Acetyl‐CoA synthetase (AMP‐forming, Acs) is the paradigm for the control of metabolic enzymes by lysine acetylation. In many bacteria, type I or II protein acetyltransferases acetylate Acs, however, in actinomycetes type III protein acetyltransferases control the activity of Acs. We measured changes in the activity of the Streptomyces lividans Acs (SlAcs) enzyme upon acetylation by PatB using in vitro and in vivo analyses. In addition to the acetylation of residue K610, residue S608 within the acetylation motif of SlAcs was also acetylated (PKTRSGK610). S608 acetylation rendered SlAcs inactive and non‐acetylatable by PatB. It is unclear whether acetylation of S608 is enzymatic, but it was clear that this modification occurred in vivo in Streptomyces. In S. lividans, an NAD+‐dependent sirtuin deacetylase from Streptomyces, SrtA (a homologue of the human SIRT4 protein) was needed to maintain SlAcs function in vivo. We have characterized a sirtuin‐dependent reversible lysine acetylation system in Streptomyces lividans that targets and controls the Acs enzyme of this bacterium. These studies raise questions about acetyltransferase specificity, and describe the first Acs enzyme in any organism whose activity is modulated by O‐Ser and Nɛ‐Lys acetylation.
Lexical Sophistication as a Multidimensional Phenomenon: Relations to Second Language Lexical Proficiency, Development, and Writing Quality
Authors: KIM MINKYUNG , CROSSLEY SCOTT A. , KYLE KRISTOPHER
Published: December 2017

This study conceptualizes lexical sophistication as a multidimensional phenomenon by reducing numerous lexical features of lexical sophistication into 12 aggregated components (i.e., dimensions) via a principal component analysis approach. These components were then used to predict second language (L2) writing proficiency levels, holistic lexical proficiency scores, and longitudinal lexical growth. The results from regression analyses indicated that 5 lexical components (i.e., bigram and trigram strength of directional association, content word properties, bigram mutual information, bigram and trigram proportions, and word specificity) explained 16.1% and 31.0% of the variance of L2 writing proficiency and lexical proficiency, respectively. Two additional components (i.e., word acquisition properties and content word frequency) explained an additional 8.5% of the variance of L2 writing proficiency. Six lexical components (i.e., bigram and trigram proportions, word acquisition properties, content word frequency, bigram frequency and range, content word properties, and function word frequency and range) showed significant developmental trends in L2 beginning learners over a year‐long period. These findings provide information about the multidimensional nature of lexical sophistication by expanding its scope beyond frequency and toward other primary dimensions that include various lexical and phrasal features such as concreteness, orthographic density, hypernymy, andn‐gram frequency and association strength.
Reproductive biology and pollination of the carnivorous Genlisea violacea (Lentibulariaceae)
Authors: Aranguren Y. , Płachno B. J. , Stpiczyńska M. , Miranda V. F. O.
Published: December 2017

Genlisea violacea is a Brazilian endemic carnivorous plant species distributed in the cerrado biome, mainly in humid environments, on sandy and oligotrophic soil or wet rocks. Studies on reproductive biology or pollination in the Lentibulariaceae are notably scarce; regarding the genus Genlisea, the current study is the first to show systematic and standardised research on reproductive biology from field studies to describe the foraging of visiting insects and determine the effective pollinators of Genlisea.

We studied two populations of G. violacea through the observation of flower visitors for 4 months of the rainy and dry seasons. Stigmatic receptivity, pollen viability, and breeding system were evaluated together with histochemistry and morphological analyses of flowers.

The flowers showed stigmatic receptivity of 100% in open buds and mature flowers, reducing to 80% for senescent flowers. Nearly 80% of pollen grains are viable, decreasing to 40–45% after 48 h. Nectar is produced by glandular trichomes inside the spur. Two bee species are effective pollinators: one of the genus Lasioglossum (subgenus Dialictus: Halictidae) and the other of the genus Ceratina (subgenus Ceratinula: family Apidae). Moreover, bee‐like flies of the Syrphidae family may also be additional pollinators.

Genlisea violacea is an allogamous and self‐compatible species. The differences in flower‐visiting fauna for both populations can be attributed to factors such as climate, anthropogenic effect, seasonal factors related to insects and plants, as well as the morphological variation of flowers in both populations.
Patients' and health care professionals' perceptions of blood transfusion: a systematic review
Authors: Abdul‐Aziz Brittannia , Lorencatto Fabiana , Stanworth Simon J. , Francis Jill J.
Published: December 2017

BACKGROUND

Blood transfusions are frequently prescribed for acute and chronic conditions; however, the extent to which patients' and health care professionals' (HCPs') perceptions of transfusion have been investigated is unclear. Patients' treatment perceptions influence how patients cope with illnesses or symptoms. HCPs' perceptions may influence treatment decision making.

STUDY DESIGN AND METHODS

This was a systematic review of studies post‐1984 reporting adult patients' and HCPs' perceptions of blood transfusion. Seven databases were searched using a three‐domain search strategy capturing synonyms relating to: 1) blood transfusion, 2) perceptions, and 3) participant group (patients or HCPs). Study and sample characteristics were extracted and narratively summarized. Reported perceptions were extracted and synthesized using inductive qualitative methods to identify key themes.

RESULTS

Thirty‐two studies were included: 14 investigated patients' perceptions and 18 HCPs' perceptions. Surgical patients were the highest represented patient group. HCPs were from a wide range of professions. Transfusions were perceived by patients and HCPs as being of low‐to‐moderate risk. Risk and negative emotions were perceived to influence preference for alternatives. Five themes emerged from the synthesis, classified as Safety/risk, Negative emotions, Alternatives (e.g., autologous, monitoring), Health benefits, and Decision making. “Safety/risk” and “Negative emotions” were most frequently investigated over time, yet periods of research inactivity are apparent.

CONCLUSIONS

The literature has identified themes on how transfusions are perceived by patients and HCPs, which overlap with recognized discussion points for transfusion specialists. These themes may help HCPs when educating patients about transfusion or consenting patients. Theory‐based qualitative methods may add an important dimension to this work.
Cryopreservation (−20 °C) of canine corneoscleral tissue: histological, microbiological, and ultrastructural study
Authors: Costa Daniel , Leiva Marta , Naranjo Carolina , Ríos José , Peña Maria T.
Published: December 2017

Objective

To evaluate microbiological, histological, and ultrastructural characteristics of short‐term cryopreserved (STC) canine corneoscleral tissue (<1 year) and to compare it with long‐term cryopreserved (LTC) tissue (>6 years).

Animals studied

Thirty‐six healthy canine globes.

Procedure

After a decontamination protocol, globes were enucleated and stored at −20 °C. Corneoscleral tissue was evaluated at different periods: <1 year (20 eyes) and >6 years (12 eyes). Four eyes were used as controls. Microbiologic study included direct (blood, McConkey and Sabouraud agars) and enrichment (brain‐heart infusion broth) cultures. Cryopreservation artifacts were evaluated by hematoxylin‐eosin. Corneoscleral collagen organization and number of normal and dead keratocytes were established by transmission electron microscopy (TEM). Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) was also used for keratocyte characterization.

Results

Corneal microbial growth was observed in 25% of the directSTCcultures, and in 47.4% and 16.7% of the enrichedSTCandLTCcultures, respectively. ScleralSTCdirect cultures were 30% positive, while enrichment cultures were positive in 66.7% and 16.7% of theSTCandLTC, respectively (P = 0.011). Cryopreservation artifacts were higher inLTCtissues (P < 0.001). Apoptotic keratocytes were predominant by TEM andTUNEL, in bothSTCandLTC. Minimal structural differences were detected in collagen organization betweenSTCandLTC.

Conclusions

Cryopreservation of canine corneoscleral tissue seems to reduce bacterial contamination over time. Apoptosis is the main way of death of cryopreserved canine keratocytes. Based on the lack of significant structural differences betweenSTCandLTCsamples, these cryopreserved tissues could potentially be used for tectonic support for at least 8 years without structural or microbiological impediment.
Modulation of sympathetic vasoconstriction is critical for the effects of sleep on arterial pressure in mice
Authors: Lo Martire Viviana , Silvani Alessandro , Alvente Sara , Bastianini Stefano , Berteotti Chiara , Valli Alice , Zoccoli Giovanna
Published: December 2017

Key points

While values of arterial pressure during sleep are predictive of cardiovascular risk, the autonomic mechanisms underlying the cardiovascular effects of sleep remain poorly understood.

Here, we assess the autonomic mechanisms of the cardiovascular effects of sleep in C57Bl/6J mice, taking advantage of a novel technique for continuous intraperitoneal infusion of autonomic blockers.

Our results indicate that non‐REM sleep decreases arterial pressure by decreasing sympathetic vasoconstriction, decreases heart rate by balancing parasympathetic activation and sympathetic withdrawal, and increases cardiac baroreflex sensitivity mainly by increasing fluctuations in parasympathetic activity.

Our results also indicate that REM sleep increases arterial pressure by increasing sympathetic activity to the heart and blood vessels, and increases heart rate, at least in part, by increasing cardiac sympathetic activity.

These results provide a framework for generating and testing hypotheses on cardiovascular derangements during sleep in mouse models and human patients.

The values of arterial pressure (AP) during sleep predict cardiovascular risk. Sleep exerts similar effects on cardiovascular control in human subjects and mice. We aimed to determine the underlying autonomic mechanisms in 12 C57Bl/6J mice with a novel technique of intraperitoneal infusion of autonomic blockers, while monitoring the electroencephalogram, electromyogram, AP and heart period (HP, i.e. 1/heart rate). In different sessions, we administered atropine methyl nitrate, atenolol and prazosin to block muscarinic cholinergic, β1‐adrenergic and α1‐adrenergic receptors, respectively, and compared each drug infusion with a matched vehicle infusion. The decrease in AP from wakefulness to non‐rapid‐eye‐movement sleep (N) was abolished by prazosin but was not significantly affected by atropine and atenolol, which, however, blunted the accompanying increase in HP to a similar extent. On passing from N to rapid‐eye‐movement sleep (R), the increase in AP was significantly blunted by prazosin and atenolol, whereas the accompanying decrease in HP was blunted by atropine and abolished by atenolol. Cardiac baroreflex sensitivity (cBRS, sequence technique) was dramatically decreased by atropine and slightly increased by prazosin. These data indicate that in C57Bl/6J mice, N decreases mean AP by decreasing sympathetic vasoconstriction, increases HP by balancing parasympathetic activation and sympathetic withdrawal, and increases cBRS mainly by increasing fluctuations in parasympathetic activity. R increases mean AP by increasing sympathetic vasoconstriction and cardiac sympathetic activity, which also explains, at least in part, the concomitant decrease in HP. These data represent the first comprehensive assessment of the autonomic mechanisms of cardiovascular control during sleep in mice.
Non-Metallic Sealing Material for Elevated Temperature Applications
Authors: Damdar Sherwin , Drago James , Evans Wayne
Published: December 2017

Higher and higher process temperatures in the power, hydrocarbon and chemical process industries are employed to quicken production and synthesize new materials. Ultra-high temperatures range from 850°F (454°C) to 1800°F (982°C). The choice of ultra-high temperature non-metallic sealing materials has been limited. Traditionally sealing materials for these extremes have been made with ceramics (e.g., aluminum silicate based) and mica. Recent developments utilized vermiculite and most recently talc. This paper will present the latest development of talc based material. Comparative physical properties and well as functional attributes of creep and sealing ability will be presented. Experience with the talc based material in solid oxide fuel cells, exhaust and gasification systems are highlighted.

Paper published with permission.
Experience in the Application of the Omega Creep Model in Creep Experiments and Component Analysis
Authors: Marriott Douglas L. , Sreeranganathan Arun , Carter Peter , Read Shannon
Published: December 2017

Since the publication of ASME FFS-1/API 579 in 2007, the Omega creep model has become a virtual de facto standard for reduction of creep data and for high temperature structural analysis. Experience in both experimental and analytical applications has revealed some important features of this model. This paper presents a number of case studies illustrating these features, and discussing the range and limitations of the scope of the model, and procedures built around it. The paper includes recommendation, based on this experience, on the place considered appropriate for this model in future FFS and RLA applications.

Paper published with permission.
Serviceability Assessment of Creep Strength Enhanced Ferritic Steels
Authors: Arnold John L.
Published: December 2017

The metallurgical advancements exhibited in creep strength enhanced ferritic steels have changed the dynamics of boiler design and operation by improving the fatigue life of thick-walled components and improving cycle efficiency by increasing operating temperatures. These advancements have a similar affect on the assessment of these materials. No longer can a serviceability evaluation be based on a general assumption of metallurgical properties. Instead, condition assessment protocols, examination methods, and flaw assessment approaches must reflect the metallurgical nuances of these high temperature alloy steels. This paper will provide guidance on new issues to be considered when developing a serviceability program.

Paper published with permission.
Constitutive Modeling of Haynes 230 for High Temperature Fatigue-Creep Interactions
Authors: Barrett Paul R. , Ahmed Raasheduddin , Hassan Tasnim
Published: December 2017

Non-linear stress analysis for high temperature cyclic viscoplasticity is increasingly becoming an important modeling framework for many industries. Simplified analyses are found to be insufficient in accurately predicting the life of components; such as a gas turbine engine of an airplane or the intermediate-heat exchanger of a nuclear power plant. As a result, advanced material models for simulating nonlinear responses at room to high temperature are developed and experimentally validated against a broad set of low-cycle fatigue responses; such as creep, fatigue, and their interactions under uniaxial stress states. . This study will evaluate a unified viscoplastic model based on nonlinear kinematic hardening (Chaboche type) with several added features of strain-range-dependence, rate-dependence, temperature-dependence, static recovery, and mean-stress-evolution for Haynes 230database. Simulation-based model development for isothermal creep-fatigue responses are all critically evaluated for the developed model. The robustness of the constitutive model is demonstrated and weaknesses of the model to accurately predict low-cycle fatigue responses are identified.

Paper published with permission.
Structural Materials and Code Development for Japanese Sodium-Cooled Fast Reactors
Authors: Asayama Tai , Nagae Yugi , Wakai Takashi , Tsukimori Kazuyuki , Morishita Masaki
Published: December 2017

This paper describes the latest status on the development of elevated temperature materials and structural codes for Japanese sodium-cooled fast reactors (SFRs). Based on the extensive research and development activities in the last decades in Japan, two materials, 316FR and Modified 9Cr-1Mo steels were recently incorporated into the 2012 Edition of Fast Reactor Design and Construction Code of the Japan Society of Mechanical Engineers (JSME). Structural design methodologies are continuously being improved towards the next major revision planed in 2016 Edition where methodologies for a 60-year design of Japanese demonstration fast reactor will be provided. Codes and guidelines for fitness-for-service, leak-before-break evaluation and reliability assessment are concurrently being developed utilizing the System Based Code concept aiming at establishing an integrated code system that encompasses a life cycle of SFRs.

Paper published with permission.
Comparison of the Requirements of the British R5, French RCC-MRx, Proposed New Rules in ASME Section VIII, and API 579 Codes in the Design of a Cylinder Subjected to Pressure With Thermal Gradient at Elevated Creep Temperatures
Authors: Anderson David , Chithranjan Nadarajah , Jawad Maan , Martin Antoine
Published: December 2017

The authors analyze two sample problems using four different international codes in the evaluation. The first is the British R5 code, the second is the French RCC-MRx code, third is the ASME Section VIII, Division 2, code using proposed new simplified rules taken from the ASME nuclear code section NH, and the fourth is the API 579 code. The requirements, assumptions, and limitations of each of the four codes as they pertain to the sample problems are presented.

The first sample problem is for creep-fatigue analysis of a cylindrical shell subjected to internal pressure with a linear thermal gradient through the wall. The second sample problem is evaluating the critical buckling strength of the cylindrical shell under external pressure in accordance with proposed new rules in ASME Section VIII, Division 2, API 579, and a finite element analysis.

Paper published with permission.
Design and Research of Spent Resin Conical Dryer Device
Authors: Zhou Yan , Zhang Haifeng
Published: December 2017

This paper introduced the design and research of spent resin conical dryer which was based on the analysis of the thermal decomposition characteristics of resins. The drying experiment of non-radioactive cation exchange resins and anion exchange resins was also carried out in this study. The result showed that the water content of resins reduced from about 55%(wt) to 8.5%(wt) and the volume reduction ration reached 2.17 with a drying end temperature of 90°C, which preliminarily verified the feasibility of the vacuum drying process and conical dryer device for treating radioactive spent resins.
Analytical and Experimental Study on CAP1000 Guide Tube Assembly
Authors: Xue Guohong , Zhang Ming , Zhang Zhai , Luan Jiaming
Published: December 2017

The guide tube (GT) representation in the reactor-internal system model has been crude and inaccurate in the past because the lack of experimental data on a) the rotary stiffness of the hold down bolt joint and b) the rotary stiffness of the support pins. In addition, the slotted enclosure and the complex interior in the continuous section further complicated the modeling accuracy. In this paper, the static and dynamic characteristic of the domestically manufactured CAP1000 guide tubes are studied both experimentally and analytically. Using the stiffness data obtained from the tests and combined with the enclosure stiffness calculated from the detailed 3D finite element models, i.e., one for the intermediate section and one for the continuous section, a simplified model of the GT was established. Using the simplified model, the dynamic characteristics (natural frequency and modal shapes) were compared to the dynamic test results in the aerial condition. It can be concluded that the simplified guide tube model is believed to be the most accurate one, by far, to be used in reactor-internal system analyses.
A Study on the Sealing Behaviors of the Laterally One Side Restrained C-Ring Under Internal Pressure by Numerical Simulation
Authors: Yuanyuan Dong , Ying Luo
Published: December 2017

C-ring, which is one of the main sealing elements of Reactor Pressure Vessels, is composed of a close-wound helical spring surrounded by two metal linings. C-ring has better resilience and sealing characteristics. Just because of the complex structure of C-ring, it was studied by experiments almost. There were also some numerical simulations on C-ring. With these methods, the compression-decompression process of C-ring under ideal condition can be simulated. But them cannot be used to study the sealing behavior of laterally one side restrained C-ring under internal pressure, which is fit for practical condition. This paper will establish a 3D numerical simulation method to study the C-ring which is mentioned as above. In this paper, it can be obtained that with internal pressure forcing and sealing groove squeezing, sealing performance of C-ring will reduce; when p>20MPa, the ratio of reducing becomes bigger; when p>140MPa, it will generate leakage; inner lining and outer lining will generate biggish plastic deformation, while the stress distribution in spring changes much.
Buried Steel Pipeline Beneath a Surface Impact Close to a Pipe-Structure Interface
Authors: Wang Shen
Published: December 2017

For nuclear power plant life extension projects, safety related buried steel pipelines need to be assessed for the effects of postulated accidental impact loads. Examples of such pipelines include emergency firewater lines and control room vent ducts. Published solutions concerning the buried pipeline beneath a surface impact, often aim at a generic problem dealing with a pipe within a half space. The interface between the buried pipes and the underground structure is often ignored. In the case that a buried steel pipe penetrates into nearby underground structure in short distance from a surface impact, shear and bending may originate from reactions at pipe-structure interface, in addition to ovaling and buckling of the pipe section. Neglecting such boundary effect may lead to underestimating potential damage of buried pipeline, and jeopardizing the safety of the nuclear power plant. Comprehensive analysis of such structure-pipe-soil system is often subjected to availability of state-of-art finite element tools, as well as costly and time consuming. This study presents a simplified approach using basic concepts, in order to evaluate the buried pipeline beneath a heavy surface impact considering nearby pipe-structure interface. Applied impulse loadings for postulated surface impact are first established, followed by the evaluation of consequential vertical pressure directly on the top of the pipeline. The pipe cross-section is checked for ovaling and buckling. The closed form solution is then proposed to evaluate effect of pipe-structure interface.
Investigation on Deposited Metal Properties of Homemade Nickel and Nickel-Free Electrodes and Fluxes for Submerged Arc Welding of SA-508 Gr.3 Cl.1
Authors: Mei Le , Zhang Junbao , Huang Yifeng , Yu Yan , Jiang Yong , Liu Qifan , Zhang Xiaoning , Gu Yu
Published: December 2017

Up to now, two kinds of filler metal with or without nickel element for submerged arc welding have been largely used in the reactor pressure vessel (RPV) manufacturing. In order to study the effect of nickel element on weld metal properties of SA-508 Gr.3 Cl.1, submerged arc welding material with nickel (AWS classification F8P4-EGN-F2N, F2 for short) and welding material without nickel (F8P4-EA3N-A3N, A3 for short) were used; and conventional mechanical properties, low-cycle fatigue test, and proton irradiation analysis of the two weld metals were studied. Results show that the mechanical properties of the two different weld metals are similar, except that the Charpy V-notch impact property of the weld metal with nickel is better than that without nickel; the micro-structures of F2 and A3 weld metals are both composed of ferrite base and granular bainite, but the columnar grain size of F2 weld metal is smaller relatively, which results in better impact property. In addition, the irradiated A3 weld metal has fewer dislocation loops than the irradiated F2 weld metal after the same proton irradiation dose; the irradiated weld metals both have higher micro-Vickers hardness than before.
Mechanical Characteristics of Nuclear Main Steam Line Penetration Fabricated by Electric Melting Additive Manufacturing
Authors: He Xiaoming , Zhang Xiaoning , Wang Yongdong , Wang Yiqing , Ning Dong
Published: December 2017

Additive Manufacturing (AM) can fabricate 3D near-net-shaped functional parts using unit materials, such as powder or wire. Additive manufacturing’s computer-aided design offers superior geometrical flexibility. The near-net shaping capability also reduces materials waste and increase manufacturing efficiency significantly. These benefits make AM desirable for critical industry applications, such as art, aerospace, ground transportation, and medical. Confident utilization of the technology requires thorough understanding of the AM materials, ensuring both structural integrity and performance requirements are met or exceeded. Safety and economics are essential to nuclear power plant. In this study, mechanical properties of a ferritic steel fabricated by electric melting additive manufacturing (EMAM) technique are studied and compared with ASME SA-336 Gr.F12, which applied to nuclear main steam line penetration, the results are systematically presented and discussed. Key technical issues of application of AM to manufacturing nuclear components are also discussed.
The Latest Progress of Containment Design in China
Authors: Shang Ziduan , Huang Xiao , Yang Yong , Chu Meng , Li Shaoping
Published: December 2017

Since first Nuclear Power Plant (NPP) in operation in early 1990s, China has built dozen of Light Water Reactor (LWR). Originated from Pressure Water Reactor (PWR) technology, almost all these plants, such as Qinshan, Dayawan, and Tianwan, were designed with a Pre-stressed Concrete Containment Vessel (PCCV). With the application of Third Generation (GEN III) reactor technology in recent years China is designing and building more Gen III NPPs. As the first kind of passive safety GEN III + technology, AP1000 uses double-layered containment structures comprising steel containment and shield building. GEN III EPR use similar double-layered containment structures, the outer layer is reinforced concrete shield structure, the inner layer is PCCV. In the traditional containment design, the design load and load combinations are determined based on different NPP operation conditions. This means the basic design principles of defense-in-depth and single failure criteria are incorporated into containment structure design through the consideration of all operation-related design basis loading conditions. However The Indian Ocean tsunami and the Fukushima earthquake and tsunami followed by the Fukushima Daiichi accident illustrated the hidden potential vulnerability in current NPP design when subjecting to Beyond Design Basis Event (BDBE) loading conditions. Containment, as the final physical shielding barrier to protect plant from potential radioactive releasing in accidental events, shall be designed to be not only functional during design basis accident conditions, but also be able to perform its containment and shielding functions, maintain the integrity of pressure boundary during BDBE and their loading conditions.

Aiming on containment and shield structure design for GEN III NPPs, this paper summarized preliminary research results on BDBE design. Considering the occurrence frequency and impact severity to containment structure, Beyond Design Basis Seismic (BDBS) is taken as the investigation focus in this paper. The summary is based on an investigation of the BDBS loadings and their impact to safety-related nuclear containment and shielding structures of the NPPs. The purpose of this investigation is to understand the failure pattern and modes under BDBS loads; and how such failure impact the safety features of the plant and the safety functions of the systems (e.g. the impact to passive safety functions). This paper also covers ways to reduce the impact and mitigate the consequences of BDBS impact by pre-incorporated measures in the structural design.
The Electro Magnetic Compatibility Tests for the AMB System on HTR-10GT
Authors: Yan Zhou , Xunshi Yan , Ni Mo , Guojun Yang , Zhengang Shi
Published: December 2017

With more and more widely used in the industrial field, Active Magnetic Bearings (AMB) have bigger challenge, such as the size and the load capacity are larger than before. In order to increase the reliability of the whole system, a lot of aspects have to be improved to adapt some special industrial requirements. Just like the 10MW high temperature gas-cooled test module reactor (HTR-10GT) with the core made of spherical fuel elements, which was designed and constructed by the Institute of Nuclear and New Energy Technology of Tsinghua University in China, take the AMB as the support bearings. HTR-10GT is the reactor with 3.5 meter long rotor, 230mm diameter, and 15000rpm Rated speed. Since there are some difficulties in HTR-10GT including the blade stages, small gap and so on, the high precision control on magnetic bearing is required very much. Once any part in the system is out of work, the rotor would happen to vibrate, which will lead to turbine blades scraping. The consequences could be disastrous especially when the system is in full power at the rated speed [1].

As you know, the electronic control system is the weakest point in AMB, both in operating site and the control room. Therefore, before engineering applications, the electronic control system must be tested for Electromagnetic Compatibility (EMC). Based on the experimental results, some design would be optimized, to improve anti-interference capability to meet the requirements of HTR-10GT. This paper describes the testing process and gives some solutions for EMC problems during the Electro Magnetic Susceptibility (EMS) test, such as the grounding, cable, wiring, filtering etc. These methods are the fundamental basis for reducing interference and improving the reliability of AMB in the HTR-10GT.
Theoretical Analysis of Step-Down of Hydraulic Cylinder Motion for Control Rod Hydraulic Drive System Based on Model II
Authors: Liu Qianfeng , Li Yuzheng , Qin Benke , Hanliang Bo
Published: December 2017

Hydraulic Control Rod Drive Technology (HCRDT) is a newly invented patent and Institute of Nuclear and New Energy Technology Tsinghua University own HCRDT’s independent intellectual property rights. The hydraulic cylinder is the key part of this technology, so the performance of the hydraulic cylinder directly affects the HCRDT. Firstly, the theoretical model of the cylinder hydraulic has been obtained and verified by the experiment. Second, the step-down process of the cylinder hydraulic is analyzed. The results are shown that the model can analyze the performance of the cylinder, including the motion time of the cylinder, the transient pressure of the cylinder arrival, the transient impact energy of the cylinder arrival. At last, the cylinder and the drive mechanism can be optimized based on the result.
Design of the Gas Sampling and Analyzing System of HTR-PM
Authors: Zhu Jiang , Xie Feng
Published: December 2017

The high temperature gas-cooled reactor pebbled-bed module (HTR-PM) which is a modular high temperature gas-cooled reactor demonstration power plant, is characterized by inherent safety features and high generating efficiency. It adopts numerous graphite for structural materials in the reactor core, helium as primary coolant, and tristructural isotropic (TRISO) coated particles embedded in the graphite matrix as fuel elements. However, at high temperature the impurities in the helium can react with the graphite to cause corrosion of structural materials. Therefore, it is very necessary to monitor and control the composition and content of gaseous impurities in the primary coolant. In HTR-PM, the gas sampling and analyzing system has been designed to sample the primary helium at different positions in the helium purification system which is used to reduce the quantity of chemical impurities and remove the radioactive dust and gaseous fission products in the primary loop, and monitor the gas composition and individual concentration online. In the current paper, the composition of the gaseous impurities which need to be monitored in the primary loop of HTR-PM is presented, the design of the gas sampling positions in the helium purification system is discussed, and the main gas analyzing instruments are introduced.
Effect of Structural State of Austenitic 15-15 Ti Steel on Initiation and Propagation of Solution-Based Corrosion Attack in Flowing Liquid Pb-Bi Eutectic at 400 and 500 °C
Authors: Tsisar Valentyn , Schroer Carsten , Wedemeyer Olaf , Skrypnik Aleksandr , Konys Jürgen
Published: December 2017

Investigations of corrosion behavior of austenitic 1.4970 (15–15 Ti) steel in Pb-Bi eutectic at 400–550 °C show an effect of structural state of material with identical composition on the depth of solution-based attack. Structural boundaries play a role of active paths along which the solution-based liquid-metal attack develops preferentially. In this view it is important to have quantitative and qualitative information about grain boundary type distribution in material and state of boundaries with respect to the accumulated strains. The EBSD analysis performed on 1.4970 steel in solution-annealed and cold-worked (40% reduction) states indicates that deformation increases substantially the total length of strained boundaries. The increase in fraction of active diffusion paths results in acceleration of corrosion attack on steel via solution.
Shaking Table Test for Base-Isolated Nuclear Island Structure Model
Authors: Jie Yang , ShaoPing Li , Fang Yuan , ZuFeng Xia , XiaoLin Huang
Published: December 2017

In this paper, the base-isolated design of Nuclear Island structure will be introduced, including the general requirement and the goal of the base-isolated design. Integrated assessment has been performed for the base-isolated design of Nuclear Island structure in the earthquake 0.6g. A series of nonlinear time-history analysis were performed to predict the maximum displacement and acceleration of the isolation layer, the maximum stress of the isolation units, and the floor response spectra of each story of the superstructure in the earthquake 0.6g, considering the realistic mechanical properties and the layout of the isolators.

In order to provide realistic data to validate the numerical method, a reduced-scale earthquake simulation of base-isolated nuclear structure on a shaking table was carried out. The study was primarily focused on the response of superstructure and the isolation unit. The dynamic characteristic was examined, together with the vibration acceleration and displacement under different levels of seismic wave. The test results of a reduced-scale nuclear island model previously tested on a shaking table were compared with three-dimensional finite element simulation results.

The results of this study provide the technical basis for the base-isolated design of Nuclear Island structure.
Study on Load Capacity of Main Steam Superpipe Nozzle Used in Nuclear Power Plant
Authors: Gengyu Zhou , Shuhua Liang , Lin Sun , Feng Lv
Published: December 2017

The main steam super pipe used in nuclear power plant is an important safety class2 component. There are several nozzles located on it and linked with main steam safety valves. In the past two decades, the hot extrusion forming technology has been widely used to manufacture the super pipe nozzles. Comparing with traditional insert weldolet, the wall thickness of the extruded nozzle is relative small, and the nozzle inner radius is hard to control precisely in the fabrication process. Due to high temperature working condition and complicated loading conditions, the load capacity of the super pipe extruded nozzle has become an issue of concern for manufacturers and users.

This paper presents a structural integrity assessment of a super pipe extruded nozzle. The nozzle stresses due to internal pressure and external loads for different operating conditions are obtained by the three-dimensional finite element analysis. The extruded nozzle is evaluated against the RCCM code Subsection C3200 Service Levels O, B and D stress limits for design, upset and faulted conditions. A parametric sensitivity analysis of the extruded nozzle inner radius size is also carried out. In addition, in order to reduce the calculation effort, an efficient calculation method is developed by using the commercial finite element program ANSYS.
Research, Design and Verification for the Performance Requirements of Safety Related Mini-Pleat HEPA Filters
Authors: Yang Kangjun , Ye Jianyun , Liu Shihao
Published: December 2017

The safety related mini-pleat HEPA Filter is an important part of nuclear power plant air cleaning system. It is used for eliminating radioactive particles generated during the operation of nuclear power plant. The rated flow of mini-pleat HEPA filters is much larger than that of other types HEPA filters, therefore the amount of solid radwaste can be reduced more effectively. Relevant domestic and foreign standards are studied and performance requirements are analyzed in this paper. And finally safety related mini-pleat HEPA Filters are designed and verified based on performance requirement tests.
Fluid-Structure Interaction Numerical Analysis of the Spent Fuel Pool and Storage Racks Under Earthquake
Authors: Yun Ling , Lei Li , Rongjun Xue , Hao Qian , Honghui Ge , Ziduan Shang
Published: December 2017

Spent fuel pool and storage racks are important nuclear security structures and components. In order to prevent it from structural failure, which includes the loss of the structural integrity of the spent fuel pool and stability of the spent fuel storage racks, also includes the possibility of fallen down of storage racks under seismic loading. Besides the necessary static analysis of structures, the influence of seismic loading on the interaction between water and structure should be fully considered, Especially concerned the analysis of the shaking effect of water sloshing on the storage racks, the displacement and the possibility of fallen down of the storage racks.

The present paper is concerned with the problem of modeling the fluid-structure interaction (FSI) in filled liquid and filled with spent fuel pool. The study focuses on the sloshing phenomena and on the coupling computational fluid dynamic (CFD) analysis with the finite element stress analysis (FEA) code LS-DYNA. By the results of the response of seismic, such as the displacement of the storage racks, pressure exerted on the plate of racks and the walls of the pool. This paper also evaluates the seismic performance of the structure and the safety margin.

Various numerical methods can be used for analysis of liquid storage pools, among these we mention explicit finite element, implicit Lagrangian-Eulerian, hybrid finite element, Smoothed Particle Hydrodynamics volume of fluid. In this article the coupled sloshing dynamics in a rectangle pool were studied using a model developed in LS-DYNA environment. The main solution methodology is based on explicit time integration. In order to demonstrate the FSI results of the FEA models of the spent fuel pool on seismic analysis, a 3D FEA models were developed. The Finite element model composed of the spent fuel pool (steel plate concrete), spent fuel storage racks, cushion block, water and air. Solid element modeling is used in concrete, cushion block, water and air. Steel plate and storage racks employ the shell element. The constitutive model of solid element is linear elastic. And the constitutive model of fluid element is described by the Gruneisen equation. Arbitrary Lagrangian-Eulerian (ALE) formulation is thought of as algorithms that perform automatic rezoning. It realized the advection of water and air in the ALE multi-material group.
Overview of the CAP1400 Reactor Hydraulic Simulation Tests
Authors: Shaoxuan Lin , Ming Zhang , Ying Fang , Zonghua Ding , Ping Yang , Sheng Wang , Wei Zhang , Yejia Liang
Published: December 2017

CAP1400 is the trademark of a newly designed, by Shanghai Nuclear Engineering Research and Design Institute, third generation passive PWR. To verify the hydraulic functions and to optimize the design of the CAP1400 reactor-internals, a series of simulation tests was conducted including the use a 1/6 scale replica of the CAP1400 reactor-internal model and several special-purpose models. This paper describes the design of the test models, the test setups, the results and the major conclusions from the various simulation tests.

There are four major simulation tests, namely, a) the reactor-internal hydraulic test and b) the mixing test c) the flow path visualization test and d) the bypass flow tests. From these tests, the various hydraulic parameters of the CAP1400 reactor-internal design were obtained — including the pressure drop across the various flow paths inside the pressure vessel, the comparison of core inlet flow distribution with different flow distribution devices, the mixing factor between the two primary loops, the flow paths inside the pressure vessel and the flow characteristics, such as the resistance, of the bypass channels.

The results of these tests were not only useful in understanding the hydraulic characteristics of the CAP1400 design and provided the bases for design optimization and future safety evaluations, but also the evidence that CAP1400 is a superior design.
Investigation of Thermal Fatigue Characteristics of Charging Line of RCV in PWR
Authors: Ahmad Naeem , Li XiangBin , Ahmad Iftikhar , Li Nan , Ahmed Shahroze , Abdul Gayoum AlFadl Ahmed Abdul Ghani
Published: December 2017

Nuclear Power Plant (NPP) components need to tolerate thermal constraints, internal pressure and thermal transients. These thermal transients being repeated again and again can lead to thermal fatigue of the component. It has significant effect on the degradation of the NPP components in long term. Studies of thermal fatigue on different NPP components such as mixing tees and valves have been carried out before but the charging line in the chemical and volume control system (RCV) of the NPP seems to have been ignored for thermal fatigue analysis.

Charging Line is the connection from RCV towards Reactor Coolant System (RCP). To enhance the safety of the charging line, thermal fatigue evaluation of piping system was performed using the Fluid Structure Interaction (FSI) analysis. Temperature distributions in the pipes were determined via thermal hydraulic analysis (CFX) and the results were applied to the structural model of the piping system to determine the thermal stress (Transient Structural).

Results revealed the location of fatigue cracks. Types of stress were identified that caused the fatigue damage. The CFD analysis enabled us to clarify the role of turbulence with respect to the thermal loading of the structure. The study will provide valuable information for establishing a permanent methodology to help minimize thermal fatigue damage in NPP components.