bluuebunny/crossref_metadata_2025 huggingface dataset:
Research-to-Resource: Self-Assessment and Reflection and Music Educators
Authors: Orzolek Douglas C.
Published: February 2018

Many researchers, authors, and thinkers submit that a teacher’s self-assessment and personal reflections are the best means to evaluate and improve teacher effectiveness. In addition, several researchers, authors, and organizations have taken the time to develop and consider tools to assist in the process of self-evaluation as well as considering the effectiveness of these measures. This research-to-resource article will summarize these ideas and tools as a means to help teachers determine the role that self-assessment and reflection might play in their professional development and teacher evaluation process.
mTOR masters monocyte development in bone marrow by decreasing the inhibition of STAT5 on IRF8
Authors: Zhao Yang , Shen Xiaofei , Na Ning , Chu Zhulang , Su Huiting , Chao Shanshan , Shi Lu , Xu Yanan , Zhang Lianfeng , Shi Bingyi , Zhao Yong
Published: February 2018

Key Points

mTOR intrinsically controls monocyte/macrophage development in the early stage. mTOR masters monocyte development via the STAT5-IRF8-CD115 pathway.
First-in-human phase 1 clinical study of the IL-15 superagonist complex ALT-803 to treat relapse after transplantation
Authors: Romee Rizwan , Cooley Sarah , Berrien-Elliott Melissa M. , Westervelt Peter , Verneris Michael R. , Wagner John E. , Weisdorf Daniel J. , Blazar Bruce R. , Ustun Celalettin , DeFor Todd E. , Vivek Sithara , Peck Lindsey , DiPersio John F. , Cashen Amanda F. , Kyllo Rachel , Musiek Amy , Schaffer András , Anadkat Milan J. , Rosman Ilana , Miller Daniel , Egan Jack O. , Jeng Emily K. , Rock Amy , Wong Hing C. , Fehniger Todd A. , Miller Jeffrey S.
Published: February 2018

Key Points

Single-agent IL-15/IL-15Rα-Fc (ALT-803) therapy was well tolerated and resulted in clinical responses in patients who relapsed post-HCT. First-in-human use of ALT-803 promoted NK and CD8+ T-cell expansion and activation in vivo without stimulating regulatory T cells.
Network modules uncover mechanisms of skeletal muscle dysfunction in COPD patients
Authors: Tényi Ákos , Cano Isaac , Marabita Francesco , Kiani Narsis , Kalko Susana G. , Barreiro Esther , de Atauri Pedro , Cascante Marta , Gomez-Cabrero David , Roca Josep
Published: February 2018

Background

Chronic obstructive pulmonary disease (COPD) patients often show skeletal muscle dysfunction that has a prominent negative impact on prognosis. The study aims to further explore underlying mechanisms of skeletal muscle dysfunction as a characteristic systemic effect of COPD, potentially modifiable with preventive interventions (i.e. muscle training). The research analyzes network module associated pathways and evaluates the findings using independent measurements.

Methods

We characterized the transcriptionally active network modules of interacting proteins in the vastus lateralis of COPD patients (n = 15, FEV146 ± 12% pred, age 68 ± 7 years) and healthy sedentary controls (n = 12, age 65 ± 9  years), at rest and after an 8-week endurance training program. Network modules were functionally evaluated using experimental data derived from the same study groups.

Results

At baseline, we identified four COPD specific network modules indicating abnormalities in creatinine metabolism, calcium homeostasis, oxidative stress and inflammatory responses, showing statistically significant associations with exercise capacity (VO2peak, Watts peak, BODE index and blood lactate levels) (P < 0.05 each), but not with lung function (FEV1). Training-induced network modules displayed marked differences between COPD and controls. Healthy subjects specific training adaptations were significantly associated with cell bioenergetics (P < 0.05) which, in turn, showed strong relationships with training-induced plasma metabolomic changes; whereas, effects of training in COPD were constrained to muscle remodeling.

Conclusion

In summary, altered muscle bioenergetics appears as the most striking finding, potentially driving other abnormal skeletal muscle responses.

Trial registrationThe study was based on a retrospectively registered trial (May 2017), ClinicalTrials.gov identifier:NCT03169270
Comparison of governance approaches for the control of antimicrobial resistance: Analysis of three European countries
Authors: Birgand Gabriel , Castro-Sánchez Enrique , Hansen Sonja , Gastmeier Petra , Lucet Jean-Christophe , Ferlie Ewan , Holmes Alison , Ahmad Raheelah
Published: February 2018

Policy makers and governments are calling for coordination to address the crisis emerging from the ineffectiveness of current antibiotics and stagnated pipe-line of new ones – antimicrobial resistance (AMR). Wider contextual drivers and mechanisms are contributing to shifts in governance strategies in health care, but are national health system approaches aligned with strategies required to tackle antimicrobial resistance? This article provides an analysis of governance approaches within healthcare systems including: priority setting, performance monitoring and accountability for AMR prevention in three European countries: England, France and Germany. Advantages and unresolved issues from these different experiences are reported, concluding that mechanisms are needed to support partnerships between healthcare professionals and patients with democratized decision-making and accountability via collaboration. But along with this multi-stakeholder approach to governance, a balance between regulation and persuasion is needed.
Multi-view large population gait dataset and its performance evaluation for cross-view gait recognition
Authors: Takemura Noriko , Makihara Yasushi , Muramatsu Daigo , Echigo Tomio , Yagi Yasushi
Published: February 2018

This paper describes the world’s largest gait database with wide view variation, the “OU-ISIR gait database, multi-view large population dataset (OU-MVLP)”, and its application to a statistically reliable performance evaluation of vision-based cross-view gait recognition. Specifically, we construct a gait dataset that includes 10,307 subjects (5114 males and 5193 females) from 14 view angles ranging 0° −90°, 180° −270°.

In addition, we evaluate various approaches to gait recognition which are robust against view angles. By using our dataset, we can fully exploit a state-of-the-art method requiring a large number of training samples, e.g., CNN-based cross-view gait recognition method, and we validate effectiveness of such a family of the methods.
Outpatient Management of Fever and Neutropenia in Adults Treated for Malignancy: American Society of Clinical Oncology and Infectious Diseases Society of America Clinical Practice Guideline Update
Authors: Taplitz Randy A. , Kennedy Erin B. , Bow Eric J. , Crews Jennie , Gleason Charise , Hawley Douglas K. , Langston Amelia A. , Nastoupil Loretta J. , Rajotte Michelle , Rolston Kenneth , Strasfeld Lynne , Flowers Christopher R.
Published: February 2018

Purpose

To provide an updated joint ASCO/Infectious Diseases Society of American (IDSA) guideline on outpatient management of fever and neutropenia in patients with cancer.

Methods

ASCO and IDSA convened an Update Expert Panel and conducted a systematic review of relevant studies. The guideline recommendations were based on the review of evidence by the Expert Panel.

Results

Six new or updated meta-analyses and six new primary studies were added to the updated systematic review.

Recommendation

Clinical judgment is recommended when determining which patients are candidates for outpatient management, using clinical criteria or a validated tool such as the Multinational Association of Support Care in Cancer risk index. In addition, psychosocial and logistic considerations are outlined within the guideline. The panel continued to endorse consensus recommendations from the previous version of this guideline that patients with febrile neutropenia receive initial doses of empirical antibacterial therapy within 1 hour of triage and be monitored for ≥ 4 hours before discharge. An oral fluoroquinolone plus amoxicillin/clavulanate (or clindamycin, if penicillin allergic) is recommended as empirical outpatient therapy, unless fluoroquinolone prophylaxis was used before fever developed. Patients who do not defervesce after 2 to 3 days of an initial, empirical, broad-spectrum antibiotic regimen should be re-evaluated and considered as candidates for inpatient treatment. Additional information is available at www.asco.org/supportive-care-guidelines and www.asco.org/guidelineswiki .
Allenedicarboxylate as a Stereochemically Labile Electrophile for Chiral Organic Base-catalyzed Stereoselective Michael Addition
Authors: Uraguchi Daisuke , Kawai Yasutaka , Sasaki Hitoshi , Yamada Kohei , Ooi Takashi
Published: February 2018

A highly stereoselective Michael addition of α-amino acid-derived 2-benzyloxythiazol-5(4H)-ones to dimethyl allenedicarboxylate was developed by employing P-spiro chiral triaminoiminophosphorane bearing (S)-sec-butyl groups as a catalyst. Theoretical investigation of the transition-state models for the reaction and control experiments suggested the intervention of a dynamic kinetic resolution of the axially chiral allene acceptor. The synthetic utility of this method was demonstrated through the transformation of the stereochemically homogeneous Michael adduct to an α-vinylic α-amino acid derivative.
ОСОБЕННОСТИ РАЗВИТИЯ ИССЛЕДОВАТЕЛЬСКОЙ КОМПЕТЕНЦИИ БУДУЩИХ ПЕДАГОГОВ В ПРОЦЕССЕ ПОДГОТОВКИ И ПРОХОЖДЕНИЯ ПРАКТИК
Authors: Rozlovan Valentina Valer'evna
Published: February 2018

Данная статья посвящена особенностям развития исследовательской компетенции будущих педагогов в процессе подготовки и прохождения практик. В качестве одного из условий эффективного развития исследовательской компетенции авторы предлагают рассмотреть подготовку и прохождение практик в рамках изучаемых дисциплин.Цель: рассмотрение особенностей развития исследовательской компетенции студентов – будущих педагогов.Метод или методология проведения работы: деятельностный и личностно-ориентированный подходы.Результаты: в статье рассматривается роль учебных и производственных практик в развитии исследовательской компетенции студентов. Проведен теоретический анализ Федеральных государственных образовательных стандартов, который позволяет определить приоритетные профессиональные задачи в рамках исследовательского вида деятельности. Акцентируется внимание на эффективности изучения дисциплин базовой части рабочего учебного плана при прохождении практик. Приведены примеры изучаемых дисциплин и возможные объекты для прохождения учебных и производственных практик города Сургута.Область применения результатов: подготовка студентов – будущих педагогов в вузе.
ОСОБЕННОСТИ РАЗРАБОТКИ УЧЕБНЫХ МАТЕРИАЛОВ ПРИ ПРИМЕНЕНИИ ТЕХНОЛОГИИ РЕВЕРСИВНОГО ОБУЧЕНИЯ
Authors: Tomashevskaya Irina Valerievna
Published: February 2018

Статья посвящена исследованию образовательной технологии реверсивного обучения и применению ее на практике. Актуальность заявленной темы связана с возрастающей популярностью использования современного Интернет пространства и мобильных устройств, предлагающих широкий выбор образовательных ресурсов. Целью, проведенного исследования, является выявление особенностей при разработке учебных материалов с применением технологии реверсивного обучения, а также разработка рекомендаций по применению технологии в рамках образовательного процесса. Автором статьи были проанализированы формы и методы организации учебных занятий. Определено содержание учебно-методических рекомендаций. Обоснована необходимость использования технологии реверсивного обучения на практике. Рассмотрены теоретические основы и предпосылки возникновения технологии. В результате анализа и обобщения теоретического материала, выявлены особенности при разработке учебных материалов с применением технологии, разработаны рекомендации по применению технологии в рамках образовательного процесса, а также доказано, что применение технологии реверсивного обучения является эффективным, так как технология способствует повышению успеваемости и интереса учащихся к учебному процессу.Цель. Статья посвящена исследованию образовательной технологии реверсивного обучения и применению ее на практике в рамках образовательного процесса. Предметом анализа выступают особенности разработки учебных материалов при применении технологии реверсивного обучения. Автор ставит целью выявить особенности при разработке учебных материалов с применением технологии и разработать рекомендации по применению технологии в рамках образовательного процесса.Метод и методология проведения работы. Основу исследования образуют метод анализа, метод синтеза и обобщения теоретического материала.Результаты. Результаты работы заключаются в том, что автор выявляет особенности при разработке учебных материалов при применении технологии реверсивного обучения, разрабатывает рекомендации по её использованию, при этом учитывая плюсы и минусы технологии, которые необходимо принимать во внимание при внедрении технологии в учебный процесс.Область применения результатов. Результаты исследования могут быть применены при изучении педагогики, теории и практики преподавания иностранных языков и культур, а также в качестве рекомендации по применению технологии в рамках образовательного процесса.
ПОЛИТИКО-ОБРАЗОВАТЕЛЬНАЯ ЛОГИСТИКА В СТРУКТУРНОЙ ОЦЕНКЕ РАЗЛИЧНЫХ ГОСУДАРСТВ
Authors: Zhitnov Evgeny Aleksandrovich
Published: February 2018

Целью данного исследования является: разработка теоретико-методологических основ политико-образовательной логистики с использованием квалиметрических моделей, характеризующих роль образовательной системы в структурной оценке государств.Метод или методология проведения работы. Основу исследования составляют образовательно-экономические теории и концепции. Данное исследование потребовало включить целый ряд междисциплинарных подходов с включением инструментария педагогики, политологии, экономики, экономической социологии и др.Результаты. Результаты работы заключаются в том, что автор сделал попытку создать интегральную модель оценки уровня развития государства, основанную на широком диапазоне различных информативных данных, включающих различные показатели.Область применения результатов. Результаты исследования могут быть использованы в педагогической, экономической, политической деятельностях, где требуется оценить уровень развития государства как в отдельном, так и интегральных аспектах.
Workload Management in Telemedical Physician Triage and Other Knowledge-Based Service Systems
Authors: Saghafian Soroush , Hopp Wallace J. , Iravani Seyed M. R. , Cheng Yao , Diermeier Daniel
Published: February 2018

Telemedical physician triage (TPT) is an example of a hierarchical knowledge-based service system (HKBSS) in which a second level of decision agent (telemedical physician) renders a decision on cases referred to him or her by the primary level agents (triage nurses). Managing the speed-versus-quality trade-off in such systems presents a unique challenge because of the interplay between agent knowledge and flow of work between the two levels. We develop a novel model of agent knowledge, based on the beta distribution, and deploy it in a partially observable Markov decision process model to describe the optimal policy for deciding which cases (patients) to refer to the second level for further evaluation. We show that this policy has a monotone control-limit structure that reduces the fraction of decisions made at the upper level as workload increases. Because the optimal policy is complex, we use structural insights from it to design two practical heuristics. These heuristics enable an HKBSS to adapt efficiently to workload shifts by adjusting the criteria for referring decisions to the upper level based on partial real-time queue length information. Finally, we conduct analytic and numerical analyses to derive insights into the management of a TPT system. We find that (1) the telemedical physician should evaluate more patients as congestion in the emergency room waiting area increases; (2) training that improves accuracy of the physician and/or nurses can be effective even if it only does so for a single patient type, but training that improves consistency must do so for all patient types to be effective; and (3) patient classification in triage should consider environmental and operational conditions in addition to the patient’s medical condition.

The online appendix is available at https://doi.org/10.1287/mnsc.2017.2905 .

This paper was accepted by Vishal Gaur, operations management.
Network Learning via Multiagent Inverse Transportation Problems
Authors: Xu Susan Jia , Nourinejad Mehdi , Lai Xuebo , Chow Joseph Y. J.
Published: February 2018

Despite the ubiquity of transportation data, methods to infer the state parameters of a network either ignore sensitivity of route decisions, require route enumeration for parameterizing descriptive models of route selection, or require complex bilevel models of route assignment behavior. These limitations prevent modelers from fully exploiting ubiquitous data in monitoring transportation networks. Inverse optimization methods that capture network route choice behavior can address this gap, but they are designed to take observations of the same model to learn the parameters of that model, which is statistically inefficient (e.g., requires estimating population route and link flows). New inverse optimization models and supporting algorithms are proposed to learn the parameters of heterogeneous travelers’ route behavior to infer shared network state parameters (e.g., link capacity dual prices). The inferred values are consistent with observations of each agent’s optimization behavior. We prove that the method can obtain unique dual prices for a network shared by these agents in polynomial time. Four experiments are conducted. The first one, conducted on a four-node network, verifies the methodology to obtain heterogeneous link cost parameters even when multinomial or mixed logit models would not be meaningfully estimated. The second is a parameter recovery test on the Nguyen–Dupuis network that shows that unique latent link capacity dual prices can be inferred using the proposed method. The third test on the same network demonstrates how a monitoring system in an online learning environment can be designed using this method. The last test demonstrates this learning on real data obtained from a freeway network in Queens, New York, using only real-time Google Maps queries.
Research roundup: February 2018
Authors: Seal Joanne , Willis Angela , Odd Dawn
Published: February 2018

In this section, a range of brief synopses of recently published articles that may be of interest to health visitors is presented. The aim of this roundup is to provide an overview, rather than a detailed summary, of the research papers selected. Should you wish to look at any of the papers in more detail, a full reference is provided.
Unwarranted variation in health visiting service provision
Authors: Peate Ian
Published: February 2018

As health and care services continue to face challenges, understanding where variations in care and outcomes occur—and what they mean—is needed more than ever before, says Ian Peate.
Obesity: A 21st-century dilemma
Authors: Nolan Yvonne
Published: February 2018

Obesity it is a challenging topic for the health visitor to address as its prevalence in the UK continues to rise unabated. Professional attitudes at all levels need further exploration and review, says Yvonne Nolan.
Elucidating the Burden of HIV in Tissues Using Multiplexed Immunofluorescence and In Situ Hybridization: Methods for the Single-Cell Phenotypic Characterization of Cells Harboring HIV In Situ
Authors: Vasquez Joshua J. , Hussien Rajaa , Aguilar-Rodriguez Brandon , Junger Henrik , Dobi Dejan , Henrich Timothy J. , Thanh Cassandra , Gibson Erica , Hogan Louise E. , McCune Joseph , Hunt Peter W. , Stoddart Cheryl A. , Laszik Zoltan G.
Published: February 2018

Persistent tissue reservoirs of HIV present a major barrier to cure. Defining subsets of infected cells in tissues is a major focus of HIV cure research. Herein, we describe a novel multiplexed in situ hybridization (ISH) (RNAscope) protocol to detect HIV-DNA (vDNA) and HIV-RNA (vRNA) in formalin-fixed paraffin-embedded (FFPE) human tissues in combination with immunofluorescence (IF) phenotyping of the infected cells. We show that multiplexed IF and ISH (mIFISH) is suitable for quantitative assessment of HIV vRNA and vDNA and that multiparameter IF phenotyping allows precise identification of the cellular source of the ISH signal. We also provide semi-quantitative data on the impact of various tissue fixatives on the detectability of vDNA and vRNA with RNAscope technology. Finally, we describe methods to quantitate the ISH signal on whole-slide digital images and validation of the quantitative ISH data with quantitative real-time PCR for vRNA. It is our hope that this approach will provide insight into the biology of HIV tissue reservoirs and to inform strategies aimed at curing HIV.
Numerical Modeling of Zirconium Alloys Hot Extrusion
Authors: Gaillac Alexis , Barberis Pierre
Published: February 2018

Hot extrusion is used within the forming route of cladding tubes to deform the billets into tube hollows, which are then cold-rolled to produce the final tubes with the suitable properties for in-reactor use. The hot extrusion goals are to give the appropriate geometry for cold pilgering (diameter and wall thickness suitable for cold-rolling mills, good concentricity) without surface defects and microstructural heterogeneities, which are detrimental for subsequent rolling. To ensure a good quality of the tube hollows, extrusion parameters (e.g., temperature of the billet, ram speed, extrusion ratio, lubrication) and extrusion tools have to be chosen as a function of the press capacity and mechanical and microstructural properties of the extruded alloy. For this purpose, finite-element and analytical models are used in addition to experimental tests. These models, particularly the former, can take into account the thermomechanical coupling that occurs in the tube and the tools during extrusion and provides a good prediction of the extrusion pressure and thermomechanical history of the extruded product. Together with a microstructural evolution model identified with small-scale extrusion tests, torsion tests, and heat treatments, this last result can also be used to calculate the fragmentation of the microstructure in the die and the meta-dynamic recrystallization after extrusion. Once validated against experimental data, numerical models were used to better understand and master the extrusion loads, the microstructure evolutions at the front end of the extruded tubes, and the temperature and stresses applied to the tools.
Investigation and Modeling of the Degradation of Zirconium-Based Fuel Cladding during Corrosion in Steam and Air-Steam Mixtures at High Temperatures
Authors: Haurais Florian , Beuzet Émilie , Steinbrück Martin , Simoni Éric , Ambard Antoine , Torkhani Mohamed
Published: February 2018

This paper presents the main results of a study conducted to quantify and to model the degradation state of zirconium-based fuel claddings submitted to severe-accident conditions in a nuclear reactor core: high temperatures and either pure steam or an air-steam mixture. Due to the progressive thickening of a dense and protective ZrO2 layer, the oxidation kinetics of zirconium-based claddings in steam at high temperatures typical of severe nuclear accidents are generally cubic or parabolic. However, for some temperature domains, this oxide layer may crack, becoming porous and no longer protective. In these “breakaway” conditions, the oxidation kinetics change from (sub)parabolic to linear or even accelerated. In addition, the temperature increase can lead core materials to melt and to relocate down to the vessel lower head, threatening its integrity. If it fails, and for specific conditions, air ingress may take place into the reactor. Hence, oxygen and nitrogen both react with zirconium-based claddings successively through the oxidation of zirconium (forming a ZrO2 layer), nitriding of zirconium (forming zirconium nitride particles), and the oxidation of zirconium nitride (forming ZrO2 and releasing nitrogen). These self-sustained chemical reactions enhance the deterioration of zirconium-based claddings and their ZrO2 layers, inducing an increase in their open porosity. To quantify this porosity, a series of two-step experiments was conducted. First, ZIRLO™ cladding samples were isothermally oxidized in pure steam or in a 50:50 mol% air-steam mixture at several different temperatures and durations. The main thermal effects on reaction kinetics and the high impact of air on the cladding degradation were all confirmed by experimental results. Second, pioneering porosimetry measurements by mercury intrusion were realized for the first time on such corroded cladding samples. In both atmospheres, it was pointed out that 1,200 and 1,250 K led to particularly porous oxide layers, especially due to strong breakaway effects. Moreover, we confirmed that the presence of air strongly enhances the oxide cracking: cladding samples were more porous when oxidized in the air-steam mixture than under pure steam. Finally, we observed that in all conditions, the open porous volume fraction of ZIRLO claddings continuously rose during their corrosion process. Hence, for each experimental condition, porosity correlations were determined through linear regressions, and porosity increase rates were deduced by derivation versus time and validated against porosimetry results of cladding samples corroded in transient (nonisothermal) conditions.
Long-Term Irradiation Growth in Zirconium Alloys
Authors: Rogerson Allan , Murgatroyd Robert A.
Published: February 2018

This paper reviews the experimental research program on irradiation growth in zirconium alloys performed by the United Kingdom Atomic Energy Authority between 1975 and 1988. The original technological objectives of the program, key aspects of rig and test specimen design, experiments aimed at improving fundamental understanding of the growth process, and key final results on long-term growth behavior are described. Our recollections of the program are given in relation to the understanding of irradiation growth mechanisms that prevailed at the beginning and end of the research program.
Transmission Electron Microscopy Examinations of Metal-Oxide Interface of Zirconium-Based Alloys Irradiated in Halden Reactor-IFA-638
Authors: Abolhassani Sousan , Proff Christian , Veleva Lyubomira , Karlsen Torill Marie , Bennett Peter , Oberländer Barbara , Espeland Marit , Jenssen Håkon , Hallstadius Lars , Garde Anand M.
Published: February 2018

This paper provides the results of investigations by transmission electron microscopy (TEM) on the selected materials from in-reactor oxidation tests in the Halden test reactor (Reference No. IFA-638) from 1998 to 2006. The objective of the IFA-638 test was to study the corrosion behavior of modern zirconium-based claddings to high burnup in pressurized water reactor water chemistry and thermal hydraulic conditions. The aim of this paper is to report on the microstructure of selected materials (ZIRLO®, E635, and Alloy A) after the irradiation to different burnup levels to determine the modifications induced by irradiation and to correlate results to their oxidation behavior. The TEM examinations revealed the nature of secondary phase particles (SPPs) and their modification under irradiation. Four types of SPPs were observed, namely β-niobium precipitates, Zr0.5Nb0.3Fe0.2 (mainly in the ZIRLO alloy), Zr(Fe,Nb)2 (in E635), and (Cr,Fe)2Zr,Nb with varying niobium content (present in Alloy A: Zr-0.58Sn-0.31Nb-0.36Fe-0.26Cr). TEM observations showed that all three materials contained still several precipitates after irradiation and in the case of the ZIRLO alloy even after high burnups. Furthermore, the analysis of the metal side of the interface and its comparison with the oxide side led to the conclusion that all types of precipitates dissolved to some extent under irradiation and that their alloying element content decreased. The dissolution was intensified in the oxide. However, a more detailed examination showed that the β-niobium precipitates dissolved at a slower rate, or knowing that their composition was much richer in niobium, the time needed for the precipitates to become fully depleted from niobium was longer. Regarding the amorphization under irradiation, the β-niobium- and chromium-containing precipitates did not amorphize in the metal part of the interface. This was not the case for the other types of precipitates. Furthermore, these two types of SPP both showed delayed oxidation and due to this behavior the typical crack above the SPP in the oxide was also observed. These results are discussed to gain an improved understanding of the oxidation behavior of materials studied as a function of irradiation and residence time.
Hydride Effects on Discharged Fuel Clad Related to Accident Conditions during Dry Storage and Handling
Authors: Kesterson Ron L. , Korinko Paul S. , Lam Poh-Sang , Sindelar Robert L.
Published: February 2018

Safe handling of nuclear reactor discharged fuel requires an understanding of how the fuel (cladding) will perform under the various encountered conditions, including off-normal events, such as drop events in handling the storage canister. Clad failures under two distinct loading modes are considered: a diametrical pinch mode and an axial-bend mode. The mechanical response to the pinch mode and the bend mode loading are evaluated with ring compression testing (RCT) and three-point bend (TPB) testing, respectively. ZIRLO® clad samples were hydrogen charged to levels from 100 ppm to 800 ppm and then subjected to a hydride reorientation treatment involving heating to 400°C and cooling while under hoop stresses ranging from 90 MPa to 170 MPa. Radial hydride reorientations were characterized and RCT and TPB tests were performed over a temperature range of ambient to 200°C. Ductile-to-brittle transition temperatures (DBTT) were determined.

Using finite element analysis (FEA), true stresses and strains are calculated and comparisons made between the RCT and TPB test modes. Because of the anisotropic properties of the clad and the relative orientation and generic effects of the hydrides, the DBTT was observed to be strongly dependent on the mode of strain application such that a DBTT associated with an RCT test is different from a DBTT obtained using an axial-bend test. Although the degree of radial hydriding strongly affected the pinch-mode RCT test, the same radial hydride impact was not observed for the axial-bend TPB test, which was affected strongly by the bulk hydride levels and not by the fraction of radial hydrides.
Effect of Irradiation on Terminal Solid Solubility of Hydrogen in Zr-2.5Nb
Authors: Nordin Heidi M. , Hilton Vicky , Buyers Andrew W. , Coleman Christopher E. , McRae Glenn A.
Published: February 2018

Knowledge of the temperature dependence of hydrogen solubility is used to define the conditions necessary for brittle hydrides to be present in reactor components during service. The terminal solid solubility (TSS) of hydrogen is affected by several factors, including irradiation, cold work, and decomposition of the β phase in Zr-2.5Nb. TSS temperatures for specimens irradiated in Osiris, Halden, and CANDU® reactors are reported. TSS was measured on Zr-2.5Nb specimens using differential scanning calorimetry (DSC) to complete four heat-up/cool-down cycles (heat to a peak temperature and cool to room temperature at a rate of 10°C/min) followed by a 1-h anneal at 500°C, and then four more heat-up/cool-down cycles. As with Zircaloy, irradiation slightly decreases the TSS temperatures, but subsequent annealing increases them. These changes are attributed to an initial effect of irradiation damage and reconstitution of the β phase and reversal of these effects by annealing, as indicated by X-ray diffraction data showing reduced dislocation density and higher β-phase volume fraction after the specimens were annealed.
Is Spent Nuclear Fuel Immune from Delayed Hydride Cracking during Dry Storage? An IAEA Coordinated Research Project
Authors: Coleman Christopher E. , Markelov Vladimir A. , Roth Maria , Makarevicius Vidas , He Zhang , Chakravartty Jayanta Kumar , Alvarez-Holston Anna-Maria , Ali Liaqat , Ramanathan Lalgudi , Inozemtsev Victor
Published: February 2018

Delayed hydride cracking (DHC) has been responsible for cracking in zirconium alloy pressure tubes and fuel cladding and is a concern for spent fuel storage. For cracking to start, sufficient hydrogen must be present for hydride to form at a flaw tip and the local tensile stress must be sufficiently large to crack the hydride (a crack will not extend if the threshold in the stress intensity factor, KIH, is not exceeded. A high-temperature limit exists when the yield stress of the cladding alloy becomes too low to crack the hydride. In this paper we describe measurements of KIH and the crack growth rate, V, in unirradiated Zircaloy-4 fuel cladding containing approximately 130 ppm hydrogen in the cold-worked stress–relieved condition representing pressurized water reactors (PWRs) and pressurized heavy-water (PHWR) reactors. Four methods are used to evaluate KIH. The test specimen and fixture used in these methods was the pin-loading tension configuration. The test temperature ranged from 227 to 315°C. The mean value of KIH below 280°C had little temperature dependence; it was about 5.5 MPa√m in the PWR cladding and slightly higher at 7 MPa√m in the PHWR material. At higher test temperatures, KIH increased dramatically to more than 12 MPa√m, whereas the crack growth rate declined toward zero. This behavior suggests that unirradiated Zircaloy-4 fuel cladding is immune from DHC above about 320°C; this temperature may be increased to 360°C by irradiation. The implications for spent fuel storage are that during early storage when the temperatures are high, any flaw will not extend by DHC, whereas at low temperatures, after many years of storage, flaws would have to be very large, approaching through wall, before being extended by DHC. To date, spent nuclear fuel is not known to have failed by DHC during storage, confirming the inference.
Mechanical Behavior at High Temperatures of Highly Oxygen- or Hydrogen-Enriched α and Prior-β Phases of Zirconium Alloys
Authors: Turque Isabelle , Chosson Raphaël , Saux Matthieu Le , Brachet Jean-Christophe , Vandenberghe Valérie , Crépin Jerome , Gourgues-Lorenzon Anne-Francoise
Published: February 2018

During a hypothetical loss-of-coolant accident, zirconium alloy fuel claddings can be loaded by internal pressure and exposed to steam at high temperatures (HTs) up to 1,200°C and then cooled and quenched in water. A significant fraction of the oxygen that reacts with the cladding during HT oxidation diffuses beneath the oxide through the metallic substrate. This induces a progressive transformation of the metallic βZr-phase layer into an intermediate layer of αZr(O) phase containing up to 7 weight % (wt.%) oxygen. Furthermore, in some specific conditions, the cladding may rapidly absorb a significant amount of hydrogen during steam exposition at HTs. As a βZr stabilizer, hydrogen would mainly diffuse and concentrate up to several thousands of parts per million by weight (wppm) into the inner βZr-phase layer. This study intends to provide new and more comprehensive data on the HT mechanical behavior of the αZr(O) and (prior-)βZr phases containing high contents of oxygen and hydrogen, respectively. Model samples produced from M5® and Zircaloy-4 cladding tubes homogeneously charged in oxygen (less than or equal to 6 wt.%) and hydrogen (less than or equal to 3,000 wppm), respectively, were prepared. Their mechanical behavior was determined under vacuum between 800 and 1,100°C for the oxygen-enriched αZr phase and in air between 700 and 20°C after cooling from the βZr temperature domain for the hydrogen-enriched (prior-)βZr phase. The αZr phase was substantially strengthened and embrittled by oxygen. The contribution of the αZr(O) layer to the HT creep behavior of an oxidized fuel cladding tube subjected to internal pressure is evaluated by finite element analysis. Mechanical strength and ductility of the model (prior-)βZr phase appear to be affected by hydrogen contents of 2000–3000 wppm in ways that depend on temperature.
Effects of Chemistry and Microstructure on Corrosion Performance of Zircaloy-2-Based BWR Cladding
Authors: Lin Yang-Pi , White David W. , Lutz Dan R.
Published: February 2018

In boiling water reactors (BWRs), Zircaloy-2 is typically the material of choice for fuel cladding. With increased focus on fuel performance and reliability, consistent cladding corrosion performance under varying BWR conditions has become an acknowledged requirement for modern BWR fuel. To support optimization of corrosion performance, modifications to alloy chemistry and manufacture conditions can be made, supported by ex-reactor corrosion testing and demonstrated through in-reactor operation. In this work, the combined effects of alloy chemistry and fabrication process were investigated. The effect of alloy chemistry is often complicated by variation within a production ingot. In this work, additional measurements were intentionally taken at the tube-shell stage (before cold pilgering) so that chemistry more representative of the final cladding could be obtained and the effect of iron, nickel, and tin could be examined more closely. Although chemistry range of Zircaloy-2 was the primary focus, the effect of iron above the ASTM limit in a new alloy was also explored. Three types of cladding fabrication processes were considered. Two types included a heat treatment applied after the first cold pilgering and annealing, and the treatment was limited to the outer portion of the cladding and differed in the temperature of the heat treatment; the third type had no special heat treatments after the first cold pilgering and annealing. The weight gain of the three types of cladding with varying compositions under two corrosion test conditions (400°C steam and 410/520°C two-stage steam) are discussed in terms of the initial second-phase particle sizes obtained from transmission electron microscopy examinations. Based on poolside inspections and hot-cell examinations, the in-reactor corrosion performance of the two cladding types up to typical discharge exposures are discussed in the terms of corrosion margin, microstructure evolution, and correlation with ex-reactor corrosion test data.
Understanding of Corrosion Mechanisms after Irradiation: Effect of Ion Irradiation of the Oxide Layers on the Corrosion Rate of M5
Authors: Tupin Marc , Verlet Romain , Wolski Krzysztof , Miro Sandrine , Baldacchino Gérard , Jublot Michael , Colas Kimberly , Bossis Philippe , Ambard Antoine , Kaczorowski Damien , Blat-Yrieix Martine , Idarraga Isabel
Published: February 2018

Irradiation damage in fuel cladding material is mainly caused by the neutron flux that results from fission reactions occurring in the fuel. To avoid the constraints inherent in handling radioactive material, the irradiation effects on the corrosion resistance of zirconium alloys can be studied by irradiating the materials with ions. We performed an original experiment using ion irradiation to more specifically study the influence of irradiation damage in the oxide on the corrosion rate of M5®. It has been established that irradiation with a 1.3-MeV helium ion at a fluence of 1017 cm−2 results in significant modifications of oxide properties, oxygen diffusion flux, and oxidation kinetics, as evidenced by Raman spectroscopy, secondary ion mass spectrometry (SIMS) analyses, and measurements of mass gains. A newly identified Raman vibration band at 712 cm−1 was linked to the presence of irradiation defects and allowed the evolution of their concentrations to be followed. The oxygen diffusion flux was significantly reduced after irradiation partly due to a surface concentration decrease of oxygen. The defects remained present in the oxide after 100 days of annealing in pressurized water reactor (PWR) conditions and were thus very stable in PWR conditions, which probably means that these defects would be stable in the reactor. According to the kinetics and in agreement with the results obtained by SIMS analyses, the oxidation rate was significantly reduced after ion irradiation, and this effect remained beyond 100 days in agreement with the high stability of irradiation defects in PWR conditions. An original model described quite well the oxidation kinetic results.
Post-Quench Ductility of Zirconium Alloy Cladding Materials
Authors: Mueller Andrew J. , Romero Javier E. , Partezana Jonna M. , Pan Guirong , Mitchell David B. , Garde Anand M. , Atwood Andrew R.
Published: February 2018

The ductility of zirconium-based alloys after steam oxidation at high temperatures, followed by quenching in water, is of significant interest for the nuclear industry. High-temperature steam oxidation and quenching of nuclear fuel cladding occurs during postulated loss-of-coolant accidents. The industry is currently establishing in-reactor operation limits for peak cladding temperature and time at temperature based on the measured ductile-to-brittle transition of different cladding materials, both in the as-fabricated condition and using hydrogen charging as a surrogate for in-reactor operation.

Aiming to study possible differences in post-quench ductility caused by differences in chemical composition, extensive testing on Zircaloy-4, ZIRLO®, and Optimized ZIRLO™ cladding materials as a function of hydrogen content, extent of oxidation, and peak cladding temperature was performed. The results showed similar ductile-to-brittle transition for the alloys studied despite differences in chemical composition, with a decrease in the extent of oxidation to reach the ductile to brittle transition with increasing hydrogen content. Microstructural characterization was performed to investigate the evolution of the oxygen-enriched layer that forms underneath the oxide, both during the time at high temperatures and during cooling. Significantly different morphologies of the oxygen-enriched layer were observed with different cooling rates, particularly for alloys containing niobium. Possible mechanisms for the development of the oxygen-enriched layer are discussed.
Equivalent Radiation Damage in Zirconium Irradiated in Various Reactors
Authors: Walters Lori , Douglas Stephen R. , Griffiths Malcolm
Published: February 2018

The physical properties and in-reactor performance of core components made from zirconium alloys are a function of the radiation-induced atomic displacements that occur during service. The vacancy and interstitial point defects and their clusters created by the atomic displacements modify the microstructure, and therefore physical properties such as strength and ductility, by forming dislocation loops. The rate of production of point defects also affects time-dependent properties such as creep and diffusion (mass transport). To simulate the effect of irradiation on core components, researchers have used materials test reactors for many years to irradiate and test materials. Such reactor tests can target an accumulated displacement damage dose to simulate the state of a material at a given stage in reactor life but at an accelerated rate. Each nuclear reactor has a specific neutron energy spectrum that also depends on the in-reactor location. Therefore, to use test reactor data to determine the effect of radiation damage on power reactor materials, one must convert the accumulated dose into a unit that is common in its effect on the material properties. For many property changes in nuclear reactor cores, this unit is displacements per atom. This paper compares the damage production for zirconium irradiated under differing neutron energy spectra in various power and test reactors. The damage rates as a function of different measures of neutron flux were used to relate atomic displacements in various materials test reactors to CANDU and light-water reactor conditions.
Microstructure Evolution in Ion-Irradiated Oxidized Zircaloy-4 Studied with Synchrotron Radiation Microdiffraction and Transmission Electron Microscopy
Authors: Colas Kimberly , Verlet Romain , Tupin Marc , Cai Zhonghou , Wolski Krzysztof , Jublot Michael , Bossis Philippe
Published: February 2018

The corrosion process (oxidation and hydriding) of zirconium alloy fuel cladding is one of the limiting factors on fuel rod lifetime, particularly for Zircaloy-4. The corrosion rate of this alloy shows indeed a great acceleration at high burnup in light water reactors (LWRs). Understanding the corrosion behavior under irradiation for this alloy is an important technological issue for the safety and efficiency of LWRs. In particular, understanding the effect of irradiation on the metal and oxide layers is a key parameter in the study of corrosion behavior of zirconium alloys. In this study, Zircaloy-4 samples underwent helium and proton ion irradiation up to 0.3 dpa, forming a uniform defect distribution up to 1 μm deep. Both as-received and precorroded samples were irradiated to compare the effect of metal irradiation to that of oxide layer irradiation. After irradiation, samples were corroded to study the impact of irradiation defects in the metal and in preexisting oxide layers on the formation of new oxide layers. Synchrotron X-ray microdiffraction and microfluorescence were used to follow the evolution of oxide crystallographic phases, texture, and stoichiometry both in the metal and in the oxide. In particular, the tetragonal oxide phase fraction, which has been known to play an important role in corrosion behavior, was mapped in both unirradiated and irradiated metals at the submicron scale and appeared to be significantly affected by irradiation. These observations, complemented with electron microscopy analyses on samples in carefully chosen areas of interest, were combined to fully characterize changes caused by irradiation in metal and oxide phases of both alloys.
Effects of Irradiation Fluence and Creep on Fracture Toughness of Type 347/348 Stainless Steel
Authors: Haggag Fahmy M. , Server William L. , Reuter Walter G. , Beeston Joseph M.
Published: February 2018

The postirradiation fracture toughness of Type 347/348 stainless steel was investigated using 5.08-mm thick three-point bend specimens tested at 427°C. The JIc values were determined using the single-specimen unloading compliance technique in accordance with ASTM Test Method for JIc, A Measure of Fracture Toughness (E 813-81). Equivalent values of plane strain fracture toughness, KIc, were computed from experimentally determined values for several fluence levels ranging from 2.3 to 4.8 × 1022 neutrons (n)/cm2 (E >1.0 MeV) and for irradiation creep of 0.0, 0.6, 1.1, and 1.85%. The test matrix involved four variables: fluence, creep, helium content, and heat-to-heat variation. Hence, separation of the individual effects of these variables on the KIc values was not possible due to limited irradiated material. However, the results show that an interpolated trend exists, that is, KIc decreases with increasing combinations of fluence, creep, and helium content. These results also suggest that irradiation creep has less effect on reducing KIc than has been suggested previously.
Fatigue Behavior at 650°C of 20% Cold-Worked Type 316 Stainless Steel Irradiated at 550°C in the High-Flux Isotope Reactor (HFIR)
Authors: Grossbeck M. L. , Liu K. C.
Published: February 2018

Type 316 stainless steel in the 20% cold-worked condition was irradiated in the High Flux Isotope Reactor (HFIR) and subsequently tested in fatigue. The specimens were irradiated at 550°C to damage levels of 8 to 12 displacements per atom (dpa) and transmutation helium levels of 300 to 500 atomic parts per million (appm). Fatigue testing at 650°C revealed that cyclic life was not significantly affected by the irradiation. However, unlike the results of tests of the same material at 550°C, no endurance limit was observed. The absence of an endurance limit is interpreted in terms of thermal creep.