bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two Stage Data Driven V&V for an Agile Thermohydraulic Analysis Method
Authors: Bennett Christopher , Adams Scott , Alexander Nick 
Published: October 2018

Rolls-Royce has embarked on a Small Modular Reactor (SMR) design programme, which is developing a safe, deployable and affordable Nuclear Power Plant. An element of the work undertaken is the determination of the performance of nuclear reactor plants through the application of thermal hydraulic analysis methods. These methods are used throughout the product lifecycle; beginning with exploring the performance potential of design options and ultimately providing analysis to support the safety justification.
To provide performance analysis at the earliest stages of design it is imperative to have a flexible analysis method that evolves alongside the design process while being able to inform the system architects at each phase. To achieve this goal an analysis method has been developed that allows for varying plant configurations with adjustable plant component geometries. The process of updating each of the plant component subsystem models has been automated and linked with an overarching database that allows system designers to directly update geometrical parameters.
This approach to early concept design has led to the practice of two-stage verification and validation. The first stage is the traditional understanding of V&V, the verification of the models and supporting scripts through the use of a predefined rigorous test suite which encompasses unit tests through to full system integration tests.
The second stage is data verification and validation, as the method has the ability to constantly update based on data input the verification of this input data is paramount. The design data is hierarchical, which in addition to a mean and an uncertainty distribution, requires knowledge of a transfer function.
Each item of data is owned by the department that is the expert in that field, for example the steam generator dimensions are owned by the components team. It is the responsibility of each of the data owners to verify their data and ensure that any transfer functions are implemented correctly.
As data is used in a cross discipline setting it requires a central storage location, this is the Master Parameter List (MPL). This repository defines the data, its format, its owner, and the last time it was updated among other things. This repository is the single point of truth for every data item used in analysis.
The aim of this paper is to demonstrate the way in which a flexible analysis method is created along with the framework that provides confidence in the analysis results through a two phase data driven V&V approach.
The Effect of a Low Constraint Geometry on Measured T0 Values for a Nuclear Reactor Pressure Vessel Ferritic Steel
Authors: Rait Geena K. , Davies Catrin M. , Garwood Stephen J. 
Published: October 2018

Current requirements for assessing the fracture toughness of reactor pressure vessel (RPV) ferritic steels are potentially overly conservative due to the employment of high constraint geometries such as compact tension (C(T)) or single edge notch bend, SEN(B), specimens for material testing. These high constraint conditions are not representative of the actual conditions experienced by the RPV in service. If this conservatism could be reduced, more appropriate predictions for RPV lifetime extension could become a possibility. In this study, a known low constraint geometry, single edge notch tension, SEN(T), has been tested alongside the higher constraint SEN(B) specimen in order to compare measured T0 and fracture toughness values for both cases. Finite element analyses have also been conducted for both geometries in order to measure T-stress and calculate Q values thereby allowing quantification of the level of constraint for both geometries. Eight SEN(B) and eight SEN(T) specimens were tested with dimensions 24 × 254 × 96 mm and 20 × 20 × 200 mm, respectively.
Testing was conducted at sub-zero temperatures, as close to the T0 as possible, in accordance with the guidelines presented in ASTM E1921-17a. Contrary to expected behaviour the SEN(T) specimen indicated a higher (less negative) T0 then the SEN(B) specimen. The reason for these results are explored in this paper.
A Quantitative Assessment of Microstructural Evolution for Grade 91
Authors: Che Chang , Qian Gong , Yang Xisheng 
Published: October 2018

China has the most supercritical boilers in the world. Grade 91 steels are widely used for high temperature components of supercritical boiler. During high temperature service, microstructural evolution of Grade 91 steel may affect the mechanical properties, including creep strength. However, there are very few studies on quantitative assessment of microstructural evolution for Grade 91 steel, especially on precipitates content.
In this article, microstructural evolution of Grade 91 was studied. A quantitative assessment of microstructure evolution was given during long-term creep, focusing on the precipitated phase content in Grade 91 steel. The results show, the precipitates content of Grade 91 steel has a corresponding relationship with creep damage.
Environmental Assisted Fatigue and EDF 900 MWe PWRs Fleet: Towards an Exemption of Environmental Effects Consideration for Secondary Circuit Components
Authors: Cuvilliez Sam , Léopold Gaëlle , Métais Thomas 
Published: October 2018

Environmentally Assisted Fatigue (EAF) is receiving nowadays an increased level of attention for existing Nuclear Power Plants (NPPs) as utilities are now working to extend their life. In the wake of numerous experimental fatigue tests carried out in air and also in a PWR environment, the French RCC-M code [1] has recently been amended (in its 2016 edition) with two Rules in Probatory Phase (RPP), equivalent to ASME code-cases, “RPP-2” and “RPP-3” [2] [3]. RPP-2 consists of an update of the design fatigue curve in air for stainless steels (SSs) and nickel-based alloys, and is also associated with RPP-3 which provides guidelines for incorporating the environmental penalty “Fen” factor in fatigue usage factor calculations.
Alongside this codification effort, an EAF screening has recently been carried out within EDF DT [4] on various areas of the primary circuit of the 900 MWe plants of the EDF fleet. This screening led to the identification of a list of 35 “sentinel locations” which are defined as areas most prone to EAF degradation process. These locations will be subjected to detailed EAF analysis in the stress report calculations (according to the above-mentioned RCC-M code cases) for the fourth decennial inspection of the 900 MWe (VD4 900 MWe) power plants.
The potential impact of EAF on the secondary circuit components is another question to address in anticipation of the VD4 900 MWe, as they may be considered as class 1 or class 2 equipment for RCC-M application according to the equipment specification. This paper presents the approach proposed by EDF towards an exemption of environmental effects consideration for secondary circuit components. The argument is first based on a review of experimental campaigns led in Japan and France (respectively on fatigue test specimens and at the component scale) which indicate a Dissolved Oxygen (DO) content threshold below which environmental effects are almost inexistent. The (conservative) value of 40 ppb has been selected consistently with NUREG/CR-6909 revision 0 [5]. The second part of the argument is built, on the one hand, on the analysis of the EDF Technical Specifications for Operation (STE) which narrows the scope of the study only to unit outages, and, on the other hand, on the analysis of 5 years of operations of all 900 MWe plants of the EDF fleet (equivalent to 170 reactor-years). It has been shown that the DO content rarely exceeded the 40 ppb threshold in the secondary coolant, and that in this case, the considered locations were not submitted to any fatigue loading.
Evaluation of the Compatibility of High-Strength Aluminum Alloy 7075-T6 to High-Pressure Gaseous Hydrogen Environments
Authors: Ogawa Yuhei , Kim Dain , Matsunaga Hisao , Matsuoka Saburo 
Published: October 2018

To develop safer and more cost-effective high-pressure hydrogen tanks used in fuel cell vehicles (FCVs), the metallic materials with the following three key properties, i.e. lightweight, high strength and excellent resistance to hydrogen embrittlement should be explored. In this study, the compatibility of high-strength, precipitation-hardened aluminum alloy 7075-T6 was evaluated according to the four types of mechanical testing including slow-strain rate tensile (SSRT), fatigue life, fatigue crack growth (FCG) and fracture toughness tests in high-pressure gaseous hydrogen environments (95 ∼ 115 MPa) at room temperature. Even though numerous publications have previously reported significant degradation of the mechanical properties of 7075-T6 in some hydrogenating environments, such as moist atmosphere, the understanding with regards to the performance of this alloy in high-pressure gaseous hydrogen environments is still lacking.
In SSRT tests, the alloy showed no degradation of tensile strength and ductility. Furthermore, fatigue life, fatigue crack growth and fracture toughness properties were also not degraded in hydrogen gas. Namely, it was first demonstrated that the material has big potential to be used for hydrogen storage tanks for FCVs, according to its excellent resistance to high-pressure gaseous hydrogen.
ASME Section XI Appendix L Flaw Tolerance Evaluation of Pressurized Water Reactor Piping Systems to Support Second License Renewal (80-Years Operation)
Authors: Udyawar Anees , Tomes Charles , Carolan Alexandria , Marlette Steve , Meikle Thomas , Bamford Warren 
Published: October 2018

One of the goals of ASME Section XI is to ensure that systems and components remain in safe operation throughout the service life, which can include plant license extensions and renewals. This goal is maintained through requirements on periodic inspections and operating plant criteria as contained in Section XI IWB-2500 and IWB-3700, respectively. Operating plant fatigue concerns can be caused from operating conditions or specific transients not considered in the original design transients. ASME Section XI IWB-3740, Operating Plant Fatigue Assessments, provides guidance on analytical evaluation procedures that can be used when the calculated fatigue usage exceeds the fatigue usage limit defined in the original Construction Code. One of the options provided in Section XI Appendix L is through the use of a flaw tolerance analysis.
The flaw tolerance evaluation involves postulation of a flaw and predicting its future growth, and thereby establishing the period of service for which it would remain acceptable to the structural integrity requirements of Section XI. The flaw tolerance approach has the advantage of not requiring knowledge of the cyclic service history, tracking future cycles, or installing systems to monitor transients and cycles. Furthermore, the flaw tolerance can also justify an inservice inspection period of 10 years, which would match a plant’s typical Section XI in-service inspection interval. The goal of this paper is to demonstrate a flaw tolerance evaluation based on ASME Section XI Appendix L for several auxiliary piping systems for a typical PWR (Pressurized Water Reactor) nuclear power plant. The flaw tolerance evaluation considers the applicable piping geometry, materials, loadings, crack growth mechanism, such as fatigue crack growth, and the inspection detection capabilities. The purpose of the Section XI Appendix L evaluation is to demonstrate that a reactor coolant piping system continues to maintain its structural integrity and ensures safe operation of the plant.
Investigations of Very High Cycle Fatigue Behavior of Metastable Austenitic Steels Using Servohydraulic and Ultrasonic Testing Systems
Authors: Daniel Tobias , Boemke Annika , Smaga Marek , Beck Tilmann 
Published: October 2018

To investigate the fatigue behavior of metastable austenite steels in the VHCF-regime, high loading frequencies are essential to realize acceptable testing times. Hence, two high-frequency testing systems were used at the authors’ institute: an ultrasonic testing system with a test frequency of 20 000 Hz and also, a servohydraulic system with a test frequency of 980 Hz. In the present study, two different batches of the metastable austenitic stainless steel AISI 347 were investigated.
Fatigue tests on metastable austenitic steel AISI 347 batch A were carried out at an ultrasonic test system at a test frequency of 20 000 Hz, at ambient temperature. Because the test rig acts as a mechanical resonant circuit excited by a piezoelectric transducer the specimen must be designed for oscillation in its vibration Eigenmode at the test frequency to assure maximum displacement at the end and maximum stress in the gauge length center, respectively. For analyzing the deformation behavior during the tests, the change in temperature was measured. Additionally, Feritscope™ measurements at the specimen surface were performed ex-situ after defined load cycles. First results showed a pronounced development of phase transformation from paramagnetic face-centered cubic γ-austenite to ferromagnetic body-centered cubic α‘-martensite. Because formation of α‘-martensite influences the transient behavior and high frequency loadings leads to pronounced self-heating of the material, ultrasonic fatigue tests on metastable austenites represent a challenge in controlling of displacement amplitude and limiting the specimen temperature.
First investigations on metastable austenitc steel AISI 347 batch B using a servohydraulic test system at a frequency of 980 Hz and a temperature of T = 300 °C resulted in no fatigue failure beyond N = 107 cycles in the VHCF-regime. However, only specimens with a low content of cyclic deformation-induced α‘-martensite achieved the ultimate number of cycles (Nu = 5·108).
Sensitivity Study on the Effects of Nondestructive Examinations on Failure Probabilities of Reactor Pressure Vessels
Authors: Arai Kensaku , Katsuyama Jinya , Li Yinsheng 
Published: October 2018

Reactor pressure vessels (RPVs) in nuclear power plants are important components that prevent non-ductile fracture considering neutron irradiation embrittlement as aging degradation and several types of transients. An analysis code called PASCAL for assessing failure frequencies of RPVs based on probabilistic fracture mechanics has been developed by the Japan Atomic Energy Agency. In failure frequency analyses, flaw size distribution in RPVs is one of the most important parameters, and it is determined by considering possible flaws generated during fabrication and the flaw-detection capabilities of nondestructive examinations (NDEs). Flaw-detection capabilities of NDEs are represented as probability of detection (POD) curves related to flaw sizes.
In this study, the effects of NDEs on failure frequencies of RPVs are evaluated using PASCAL considering simplified POD curves in terms of minimum detectable flaw size, the smallest probability of non-detection (PND), and flaw size where POD value reaches the smallest PND.
Diagnostic value of a combination of next-generation sequencing, chorioretinal imaging and metabolic analysis: lessons from a consanguineous Chinese family with gyrate atrophy of the choroid and retina stemming from a novel OAT variant
Authors: Huang Junting , Fu Jiewen , Fu Shangyi , Yang Lisha , Nie Kailai , Duan Chengxia , Cheng Jingliang , Li Yumei , Lv Hongbin , Chen Rui , Liu Longqian , Fu Junjiang 
Published: October 2018

Background/Aim
Gyrate atrophy of the choroid and retina (GACR) is an extremely rare autosomal recessive inherited disorder characterised by progressive vision loss. To identify the disease-causing gene in a consanguineous Chinese pedigree with GACR, we aimed to accurately diagnose patients with GACR through a combination of next-generation sequencing (NGS) genetic diagnosis, clinical imaging and amino acid metabolic analysis.

Methods
A consanguineous Chinese pedigree with GACR, including two patients, was recruited and a comprehensive ophthalmological evaluation was performed. DNA was extracted from a proband and her family members, and the sample from the proband was analysed using targeted NGS. Variants ‎detected by NGS were confirmed by Sanger sequencing and subjected to segregation analysis. Tandem mass spectrometry (MS/MS) was subsequently performed for metabolic assessment.

Results

We identified a ‎novel, deleterious, homologous ornithine aminotransferase (
OAT
) variant, c.G248A: p.S83N, which contributes to ‎the progression of GACR in patients. Our results showed that the p.S83N autosomal recessive ‎variant of OAT is most likely ‎pathogenic, with changes in protein stability drastically decreasing functionality. MS/MS verified that ornithine levels in patients were significantly elevated.

Conclusions

Recruitment of a third-degree first cousin consanguineous marriage family with GACR allowed us to identify a novel pathogenic
OAT
variant in the Chinese population, broadening the mutation spectrum. Our findings reported the diagnostic value of a combination of NGS, retinal imaging and metabolic analysis of consanguineous marriage pedigrees in low-income/middle-income and low-incidence countries, including China, and may help to guide accurate diagnosis and ‎treatment of this disease.
Systematic review of interventions targeting sickness absence among pregnant women in healthcare settings and workplaces
Authors: Pedersen Pernille , Labriola Merete , Nielsen Claus Vinther , Maimburg Rikke Damkjær , Nohr Ellen Aagaard , Momsen Anne-Mette 
Published: October 2018

ObjectivesThe high rate of sickness absence from work during pregnancy is recognised as a problem, and may be higher than necessary from a health perspective. The aim was to evaluate the effectiveness of interventions in healthcare settings and workplaces targeting sickness absence among pregnant women.MethodsStudies were eligible if they included pregnant women participating in any intervention in healthcare settings or workplaces. The outcome was length of sickness absence in days or number of episodes. Study design had to be either randomised controlled trials (RCTs) or quasi-experimental studies.The search for studies was conducted in PubMed, Scopus, CINAHL, PsycINFO, ClinicalTrials.gov and WHO trial registry. Risk of bias was assessed by the Joanna Briggs Institute standardised quality assessment instrument.ResultsA total of nine studies were quality assessed and of these, four were excluded due to insufficient methodological quality. Five RCTs conducted in healthcare settings in Sweden and Norway were included. Due to heterogeneity, meta-analysis was not performed.Two RCTs examined complementary and alternative medicine and three RCTs the effect of physical exercise. In general, the frequency of women on sickness absence was lower in the intervention groups than the control groups, however, only among pregnant women who participated in a 12-week exercise programme, the frequency was significantly lower (22% vs 30%, p=0.04).ConclusionThe evidence of interventions targeting sickness absence among pregnant women in healthcare settings is sparse, and no studies were conducted at workplaces.Future interventions including physical activity provided in collaboration with healthcare settings and workplaces are requested. Studies should measure sickness absence based on valid methods, measure compliance to the intervention and provide transparency of statistical methods.PROSPERO registration numberCRD42018084802.
Loss of horizontal macular ganglion cell complex asymmetry: an optical coherence tomography indicator of chiasmal compression
Authors: Jørstad Øystein Kalsnes , Wigers Andreas Reidar , Marthinsen Pål Bache , Moe Morten Carstens , Evang Johan Arild 
Published: October 2018

ObjectiveTo estimate the macular ganglion cell complex (GCC) asymmetry in patients with suprasellar tumours, to compare its diagnostic performance to the nasal GCC thickness and visual field (VF) and to investigate how the parameters correlate with magnetic resonance imaging (MRI) findings.Methods and analysisCross-sectional study of patients with suprasellar tumours affecting the optic chiasm. Macular optical coherence tomography (OCT) scans were evaluated for nasal GCC sector thinning and loss of normal GCC asymmetry between corresponding nasal-temporal sectors. Equivalently, VFs were analysed for defects compatible with chiasm dysfunction. The relationship between optic chiasm and tumour was measured on MRI.ResultsThirty-three eyes of 33 patients were included. There were OCT findings in 14 eyes. Nasal GCC thinning was found in 9 eyes and loss of GCC asymmetry in 12 eyes; the two parameters were not significantly different with respect to number of positive findings (p=0.45). Loss of GCC asymmetry, however, occurred in 5 eyes among 24 without GCC thinning (proportion 0.21; 95% confidence interval 0.071 to 0.42). In 8 eyes, VF indicated pathology; of these, 7 had concurring OCT findings. The prevalence of OCT and VF findings increased significantly with suprasellar tumour extension on MRI.ConclusionThe diagnostic capabilities of nasal GCC thinning and loss of GCC asymmetry were comparable, whilst their complementary performances increased the proportion of eyes in which OCT suggested compression. The prevalence of both OCT and VF findings grew with suprasellar tumour extension. In several cases, however, structural findings on OCT preceded detectable VF deficits.
Effect of data validation audit on hospital mortality ranking and pay for performance
Authors: Haviari Skerdi , Chollet François , Polazzi Stéphanie , Payet Cecile , Beauveil Adrien , Colin Cyrille , Duclos Antoine 
Published: October 2018

BackgroundQuality improvement and epidemiology studies often rely on database codes to measure performance or impact of adjusted risk factors, but how validity issues can bias those estimates is seldom quantified.ObjectivesTo evaluate whether and how much interhospital administrative coding variations influence a typical performance measure (adjusted mortality) and potential incentives based on it.DesignNational cross-sectional study comparing hospital mortality ranking and simulated pay-for-performance incentives before/after recoding discharge abstracts using medical records.SettingTwenty-four public and private hospitals located in FranceParticipantsAll inpatient stays from the 78 deadliest diagnosis-related groups over 1 year.InterventionsElixhauser and Charlson comorbidities were derived, and mortality ratios were computed for each hospital. Thirty random stays per hospital were then recoded by two central reviewers and used in a Bayesian hierarchical model to estimate hospital-specific and comorbidity-specific predictive values. Simulations then estimated shifts in adjusted mortality and proportion of incentives that would be unfairly distributed by a typical pay-for-performance programme in this situation.Main outcome measuresPositive and negative predictive values of routine coding of comorbidities in hospital databases, variations in hospitals’ mortality league table and proportion of unfair incentives.ResultsA total of 70 402 hospital discharge abstracts were analysed, of which 715 were recoded from full medical records. Hospital comorbidity-level positive predictive values ranged from 64.4% to 96.4% and negative ones from 88.0% to 99.9%. Using Elixhauser comorbidities for adjustment, 70.3% of hospitals changed position in the mortality league table after correction, which added up to a mean 6.5% (SD 3.6) of a total pay-for-performance budget being allocated to the wrong hospitals. Using Charlson, 61.5% of hospitals changed position, with 7.3% (SD 4.0) budget misallocation.ConclusionsVariations in administrative data coding can bias mortality comparisons and budget allocation across hospitals. Such heterogeneity in data validity may be corrected using a centralised coding strategy from a random sample of observations.