bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of the Behaviors of an Open-Loop Heat-Removal System
Authors: Wang Xianmao , Shen Yonggang , Yang Jiang , Ouyang Yong , Rui Min , Qiu Suizheng 
Published: October 2018

In the third generation of nuclear reactors, passive systems have been widely used such as passive core cooling system and passive containment cooling system, which usually relay on natural circulation induced by buoyancy force to remove heat. Most of these passive cooling systems are closed-loop natural circulations. In recent years, some open-loop heat-removal systems have also been put forward. Open-loop heat-removal systems have its own advantages such as its simplification and low costs. However, the thermal-hydraulic behaviors of open-loop heat-removal systems are still not totally clear and need further study.
In this study, a simplified open-loop passive containment cooling system is studied. A calculation model is built based on RELAP SCDAPSIM code. The thermal-hydraulic behaviors of the system are studied. By changing some key parameters of the system, the influences of these parameters on the system are evaluated.
Experimental Research on the Flow Resistance and Heat Transfer Characteristics in Rod Bundle Channel
Authors: Zhu Zhiqiang , Tian Chunping , Yan Changqi , Wang Jianjun , Ren Tingting , Guo Zehua 
Published: October 2018

Single-phase natural circulation experiments were conducted to study the flow resistance and heat transfer characteristics in a 3 × 3 rod bundle channel with the ratio of rod pitch and rod outer diameter (P/D) 1.38. The range of inlet subcooling degree is 30∼90K and the heating power is 1∼20kW. The rods are heated with constant heat flux.
According to the experimental results, the flow regime under natural circulation condition is divided and the transition Reynolds number is considered as 800. The flow transition is recognized by the slope change of friction factor curve since the flow transition in the rod bundle channel is not as obvious as that in round pipe. Simultaneously, the flow transition in the rod bundle is much earlier and the upper critical Reynolds number is much larger compared to regular channel like round pipe and rectangular channel. Two correlations for laminar and transition regime are fitted to calculate the friction factor. As for the grid spacer local resistance coefficient, there is slight change at Reynolds number 800 and similarly two correlations are fitted to calculate the local resistance coefficient. The Nusselt number tendency changes at around Reynolds number 4000 but keep unchanged at transition point, which means the flow transition has no obvious effect to the heat transfer. The heat transfer results are compared with different single-phase convective heat transfer correlations. D-B and Gnielinski correlations are not suitable for the heat transfer prediction in rod bundle channel and the relative deviation is more than 20%. Weisman, Presser and Markoczy correlations predict relatively well in high Reynolds number region, and Markoczy correlation is the best of them. In low Reynolds number region, most experimental results are larger than the correlations. D-B correlation based methods may be unsuitable for the heat transfer prediction in rod bundle channel and a new correlation needs to be proposed.
SIRIO: An Experimental Facility for a New Heat Removal System Passively Controlled by Non-Condensable Gases
Authors: Marinari R. , Tarantino M. , Nitti F. S. , Alemberti A. , Caramello M. , Achilli A. , Ferri R. , Rizzo E. , Giannetti F. 
Published: October 2018

Heat removal systems are of major importance for both present and future nuclear power plants as they belong to the set of systems devoted to ensure the integrity of the reactor core and to avoid core damage. The past experience and lessons learned on this topic suggest to adopt passive safety systems which can perform the safety function independently from operators’ actions and external energy sources, ensuring long term reactor cooling. Application of these systems to innovative reactor concepts such as (heavy) liquid metal reactors poses a problem related to the characteristic properties of the coolant: as the final heat sink of passive safety systems is often the external environment, the liquid metal will eventually undergo a phase change and solidify at the end of a complex dynamic process. The solidification of the coolant may have important effects on the transient behavior if it happens at an early stage of an accident, as the main flow path of the heat exchanger can be blocked by the coolant freezing while the decay heat in the core is still sufficiently high and need to be efficiently removed.
An innovative passive safety system has been proposed for the decay heat removal system of ALFRED reactor (DEMO LFR, Gen.IV) where the issue of early coolant freezing is prevented. The innovation has been object of a patent and the system is potentially able to avoid solidification by reducing the amount of heat removed from the primary system by means of non-condensable gases passively injected into the water/steam mixture, which induce heat transfer degradation. Several numerical studies have been performed during the past years, but a complete validation of the operating principle requires an experimental assessment and characterization. To this aim the SIRIO experimental facility, scaled on the DHR of ALFRED, has been conceived. Several design activities have been performed so far for the development of the facility, such as scaling analysis on the basis of ALFRED DHR to determine the facility size, numerical simulations by means of RELAP5-3D to determine whether the facility is able to reproduce the expected physical phenomena and numerical simulations by means of Ansys CFX to investigate the performance of a heating system simulating the primary system of ALFRED based on a molten salt annulus. The present paper describes the design activities performed and provides insights on the methodologies adopted, as well as the current status of the design of the SIRIO facility.
Replacement of a Hot Cell Window at the Hot Fuel Examination Facility
Authors: Westphal Judith Carol , Johansen Ron , Kelly J. D. 
Published: October 2018

During the course of 42 years of irradiated operations in the Hot Fuel Examination Facility at the Idaho National Laboratory (INL), a hot cell window had never been replaced. Recently, slow deterioration of a window seal resulted in mineral oil leaking at a rate of over a liter per month from the window tank unit on through the protective A-slab seal and into the hot cell. A hot cell window consists of both a steel tank unit with five slabs of glass of varying thicknesses with the remaining free space filled with clear mineral oil, and a thinner protective interior A-slab of glass. The repair solution was to remove and replace the A-slab window followed by replacing the window tank unit in two distinct phases.
The facility original A-slab design was a leak tight barrier and a frame that was “L” shaped with a gasket between the glass and the window flange. Problems with the gasket adhering to the glass and the window flange resulted in pulling the glass from the frame during initial installation activities. Due to the adhesion problem, the gasket was changed to a dust seal during commissioning the facility. Over time, the window tank unit mineral oil leak flowed through this dust seal. Replacing the leaking tank unit necessitated the need for a new leak tight boundary as well as provide a method to drain the accumulated oil behind the A-slab until the tank unit could be replaced. These criteria led to a new A-slab design to be installed.
Initially, removal and replacement of the A-slab was performed in the main cell (hot side) to reestablish a leak tight barrier. Transfers of the windows and removal of the bolts/reinstallation of new bolts were all performed with specialized equipment designed for remote operations in a hazardous environment using remote manipulators and cranes. Removal and replacement of the window tank unit via the operating corridor (cold side) was scheduled during a facility outage to accommodate availability of contract service personnel who specialize in hot cell windows.
Due to the complexity of the replacement task, approximately 30% of the personnel on site were involved in the window replacement. Engineering, facility operations and radiation control personnel were primary contributors with electricians, carpenters and the analytical laboratory personnel contributing, as well. The multi-year installation program was safely concluded allowing the facility to resume full operations with the window properly sealed.
Computational Simulation of Hydrogen Permeation Experiment
Authors: Wu Xiao , Chan WaiLam , Shi Shanbin , Sun Xiaodong , Christensen Richard 
Published: October 2018

Tritium control and mitigation is one of the most significant issues in Fluoride Salt-cooled High-temperature Reactors (FHRs). Tritium is primarily generated from neutron activation of the primary coolant, FLiBe, a eutectic mixture of LiF and BeF2 and has the tendency of permeating into the surrounding environment especially under the high operating temperature of the reactor system. To address this issue, a cross-flow tritium removal facility has been proposed to collect and remove molecular tritium, T2, from the primary coolant. Previous simulations and calculations have shown the effectiveness of the cross-flow design. To validate the simulation results, a lab-scale experiment has been set up with a cross-flow tritium removal facility fabricated. For the validation experiment, instead of using a molten salt, a carrier gas is planned to be used and will be premixed with hydrogen before entering the cross-flow facility. A sweep gas will be flowing in the tubes and remove the permeated hydrogen. Samples will be collected from the gas inlets and outlets for component analysis using a gas chromatography. By obtaining the hydrogen concentration change with experiment time in the carrier and sweep gases, the efficiency of the cross-flow tritium removal facility can be derived.
Computational simulations have been carried out for the experiment setup using COMSOL to inform the experiment design. The COMSOL model is validated against a static hydrogen permeation experiment. The tritium removal rate under the planned experimental conditions is predicted. In the experiment, the operation temperature, initial tritium concentration, as well as the gas flow rates will be varied to study their effects on tritium removal. The simulation results will be compared to the experiment results once available.
CFD-Based Correlation for Forced Convection Heat Transfer in Circular Ducts of Internally Heated Molten Salts
Authors: Di Lecce Francesco , Dulla Sandra , Ravetto Piero , Cammi Antonio , Lorenzi Stefano , Fiorina Carlo 
Published: October 2018

Heat transfer phenomena involving internally heated fluid flows are of particular interest in several industrial applications, in chemical plants as in the nuclear field. This topic is relevant for the development of the Molten Salt Reactors (MSRs) since it involves the safety characteristics of the liquid molten salt fuel. In the literature, there is a lack of systematic studies on the heat transfer mechanism and correlations for flows in ducts featuring an internal heat source, apart from some analytical studies performed in Fiorina et al., “Thermal-hydraulics of internally heated molten salts and application to the MSFR”, Journal of physics, Conference series 501 (2014).
In this work, the Nusselt number is computed multiplying the traditional Nu for internal flows times a corrective factor to account for the internal heat source. As a main outcome of this work, it is possible to obtain a CFD-based improved estimate of the corrective factor correlation for turbulent flow regime with respect to the work by Fiorina. The numerical CFD analysis is performed with the open source code Open FOAM.
Despite its simplicity, the method is general and applicable for any geometrical and thermal situations.
Evaluation of IET Facility Applicability on Simulating SBLOCA in Large-Scale Passive PWR Plant
Authors: Kong Haozheng , Kuang Bo , Liu Pengfei , Lu Xia , Yao Yi , Liu Lifang , Dong Bo 
Published: October 2018

Focused on the overall experimental verification of important phenomena in small break loss of coolant accident (SBLOCA) of large-scale passive PWR plants, this paper put forward a top-down and bottom-up scaling analysis of SBLOCA process based on H2TS method, by which the scaling conditions of IET facility would be figured out to match with the conditions in real nuclear power plants. Meanwhile, parameter evaluation was conducted between IET facility and real power plants, and finally the results proved that the IET facility could, to a certain degree, represent the conditions in real plants in terms of scaling analysis, and the test data of facility could be applicable for the SBLOCA of real plants.
Further, in this paper, scenarios of SBLOCA were simulated and compared between IET facility and AP1000 nuclear power plant by the use of Relap5/MOD3 program. Then, after the conversion of flow area and time ratio, the comparison of results between those two systems was conducted in terms of pressure of reactor coolant system (RCS), injection flow rate of CMT and steam flow rate through ADS-1/2/3/4 valves, which also proved that the IET facility could simulate the SBLOCA of real plants well.
Association between glaucomatous optic disc and depressive symptoms independent of light exposure profiles: a cross-sectional study of the HEIJO-KYO cohort
Authors: Yoshikawa Tadanobu , Obayashi Kenji , Miyata Kimie , Ueda Tetsuo , Kurumatani Norio , Saeki Keigo , Ogata Nahoko 
Published: October 2018

BackgroundGlaucoma may cause physiological and behavioural circadian misalignment because of the loss of intrinsically photosensitive retinal ganglion cells, the primary receptors of environmental light. Although studies have suggested a high prevalence of depression in patients with glaucoma, it is unclear whether the association is independent of the light exposure profiles as an important confounding factor.MethodsIn this cross-sectional study of a community-based cohort of 770 elderly individuals (mean age, 70.9 years), glaucomatous optic discs were assessed using fundus photographs and depressive symptoms were assessed using the short version of the Geriatric Depression Scale (GDS). Daytime and night-time ambient light exposures were objectively measured for 2 days.ResultsDepressive symptoms (GDS score ≥6) were observed in 114 participants (prevalence, 14.8%) and glaucomatous optic discs were detected in 40 participants (prevalence, 5.2%). The prevalence of depressive symptoms was significantly higher in the group with glaucomatous optic disc than in the group without it (30.0% vs 14.0%, respectively; p=0.005). Multivariable logistic regression analysis adjusted for potential confounding factors, including daytime and night-time light exposures, revealed that the OR for depressive symptoms was significantly higher in the group with glaucomatous optic disc than in the group without it (OR 2.45, 95% CI 1.18 to 5.08; p=0.016).ConclusionsIn this general elderly population, glaucomatous optic disc was significantly associated with higher prevalence of depressive symptoms independent of a number of potential confounding factors, including daily light exposure profiles.
Metastases and death rates after primary enucleation of unilateral retinoblastoma in the USA 2007–2017
Authors: Lu Jonathan E , Francis Jasmine H , Dunkel Ira J , Shields Carol L , Yu Michael D , Berry Jesse L , Kogachi Kaitlin , Skalet Alison H , Miller Audra K , Santapuram Pranav R , Daniels Anthony B , Abramson David H 
Published: October 2018

Background/aimsEnucleation for retinoblastoma is performed less often in the past decade due to increasingly widespread alternative therapies, but enucleation remains an important option. There is a paucity of reports on the current incidence of metastases and metastatic deaths in unilateral retinoblastoma from US centres.MethodsRetrospective chart review at five tertiary retinoblastoma centres in the USA for unilateral retinoblastoma patients treated with primary enucleation, 2007–2017, with >1 year of follow-up or treatment failure.ResultsAmong 228 patients (228 eyes), there were nine metastases (3.9%) and four deaths (1.7%). The Kaplan-Meier estimate at 5 years for metastasis-free survival was 96% (95% CI, 94% to 99 %), and for overall survival was 98% (95% CI 96% to 100%). All metastases were evident within 12 months. Histopathology revealed higher risk pathology (postlaminar optic nerve and/or massive choroidal invasion) in 62 of 228 eyes (27%). Of these higher risk eyes, 39 received adjuvant chemotherapy. There were four subsequent metastases in this higher risk pathology with adjuvant chemotherapy group, with three deaths. Of the nine overall with metastases, seven (78%) showed higher risk pathology. All metastatic patients were classified as Reese-Ellsworth V and International Classification of Retinoblastoma Groups D or E. Initial metastases presented as orbital invasion in seven of nine cases.ConclusionsPrimary enucleation for unilateral retinoblastoma results in a low rate of metastatic death, but is still associated with a 3.9% chance of metastases within a year of enucleation. Most but not all patients who developed metastases had higher risk histopathological findings.
‘They care rudely!’: resourcing and relational health system factors that influence retention in care for people living with HIV in Zambia
Authors: Mwamba Chanda , Sharma Anjali , Mukamba Njekwa , Beres Laura , Geng Elvin , Holmes Charles B , Sikazwe Izukanji , Topp Stephanie M 
Published: October 2018

IntroductionDespite access to free antiretroviral therapy (ART), many HIV-positive Zambians disengage from HIV care. We sought to understand how Zambian health system ‘hardware’ (tangible components) and ‘software’ (work practices and behaviour) influenced decisions to disengage from care among ‘lost-to-follow-up’ patients traced by a larger study on their current health status.MethodsWe purposively selected 12 facilities, from 4 provinces. Indepth interviews were conducted with 69 patients across four categories: engaged in HIV care, disengaged from care, transferred to another facility and next of kin if deceased. We also conducted 24 focus group discussions with 158 lay and professional healthcare workers (HCWs). These data were triangulated against two consecutive days of observation conducted in each facility. We conducted iterative multilevel analysis using inductive and deductive reasoning.ResultsHealth system ‘hardware’ factors influencing patients’ disengagement included inadequate infrastructure to protect privacy; distance to health facilities which costs patients time and money; and chronic understaffing which increased wait times. Health system ‘software’ factors related to HCWs’ work practices and clinical decisions, including delayed opening times, file mismanagement, drug rationing and inflexibility in visit schedules, increased wait times, number of clinic visits, and frustrated access to care. While patients considered HCWs as ‘mentors’ and trusted sources of information, many also described them as rude, tardy, careless with details and confidentiality, and favouring relatives. Nonetheless, unlike previously reported, many patients preferred ART over alternative treatment (eg, traditional medicine) for its perceived efficacy, cost-free availability and accompanying clinical monitoring.ConclusionFindings demonstrate the dynamic effect of health system ‘hardware’ and ‘software’ factors on decisions to disengage. Our findings suggest a need for improved: physical resourcing and structuring of HIV services, preservice and inservice HCWs and management training and mentorship programmes to encourage HCWs to provide ‘patient-centered’ care and exercise ‘flexibility’ to meet patients’ varying needs and circumstances.
Depression, depressive symptoms and treatments in women who have recently given birth: UK cohort study
Authors: Petersen Irene , Peltola Tomi , Kaski Samuel , Walters Kate R , Hardoon Sarah 
Published: October 2018

ObjectivesTo investigate how depression is recognised in the year after child birth and treatment given in clinical practice.DesignCohort study based on UK primary care electronic health records.SettingPrimary care.ParticipantsWomen who have given live birth between 2000 and 2013.OutcomesPrevalence of postnatal depression, depression diagnoses, depressive symptoms, antidepressant and non-pharmacological treatment within a year after birth.ResultsOf 206 517 women, 23 623 (11%) had a record of depressive diagnosis or symptoms in the year after delivery and more than one in eight women received antidepressant treatment. Recording and treatment peaked 6–8 weeks after delivery. Initiation of selective serotonin reuptake inhibitors (SSRI) treatment has become earlier in the more recent years. Thus, the initiation rate of SSRI treatment per 100 pregnancies (95% CI) at 8 weeks were 2.6 (2.5 to 2.8) in 2000–2004, increasing to 3.0 (2.9 to 3.1) in 2005–2009 and 3.8 (3.6 to 3.9) in 2010–2013. The overall rate of initiation of SSRI within the year after delivery, however, has not changed noticeably. A third of the women had at least one record suggestive of depression at any time prior to delivery and of these one in four received SSRI treatment in the year after delivery.Younger women were most likely to have records of depression and depressive symptoms. (Relative risk for postnatal depression: age 15–19: 1.92 (1.76 to 2.10), age 20–24: 1.49 (1.39 to 1.59) versus age 30–34). The risk of depression, postnatal depression and depressive symptoms increased with increasing social deprivation.ConclusionsMore than 1 in 10 women had electronic health records indicating depression diagnoses or depressive symptoms within a year after delivery and more than one in eight women received antidepressant treatment in this period. Women aged below 30 and from the most deprived areas were at highest risk of depression and most likely to receive antidepressant treatment.