bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Study on the Interaction of Molten Sn With Water
Authors: He Longkun , Liu Pengfei , Zhang Xisi , Hu Wenjun , Kuang Bo , Wei Liangzhang
Published: October 2018

In nuclear power plants, fuel-coolant interaction (FCI) often accompanied with core melt accidents, which may escalate to steam explosion destroying the integrity of structural components and even the containment under certain conditions. In the present study, a new facility for intermediate-scaled experiments named ‘Test for Interaction of MELt with Coolant’ (TIMELCO) has been set up to study FCI phenomena and thermal-hydraulic influence factors in metal or metallic oxide/water mixtures with melt at maximum 2750°C. The first series of tests was performed using 3kg of Sn which was heated to 800°Cand jetted into a column of 1m water depth (300mm in diameter) under 0.1MPa ambient pressure. The main changing parameter was water temperature, at 60 °C and 72 °C respectively. From the high-speed video camera, violent explosion phenomenon occurred at water temperature of 60°C, while no evident explosion observed at 72°C. The size of melt debris at 60°C is smaller than this at 72°C.On the contrary, the dynamic pressure at 60°C is larger. The results indicate that water temperature has an important effect on FCI and decreasing the temperature of the coolant is advantageous to the explosion.
CFD Validation With a PIV Provided Experimental Data for the Coolant Velocity Measurement in Reactor Vessel Down-Comer
Authors: Eltayeb Abdelgadir , Tan Sichao , A. Ala Ayodeji , Qi Zhang , M. Ahmed Nisrene
Published: October 2018

The description of the fluid flow and the coolant velocity field within a Pressurized Water Reactor (PWR), for the safety analysis is always desirable. In this work, a validation of CFD code ANSYS Fluent performed in the frame of experimental investigations to study the velocity field of coolant flow in a single phase at a reactor vessel down-comer. Under steady-state conditions. Several Experiments using Particle Image Velocimetry, have done at small hemispherical vessel, which designed by the College of Nuclear science and Technology at Harbin Engineering University (HEU) to obtain experimental data for velocity field. The measurements of the fluid flow velocities at two different locations as investigation area in the down-comer under the inlet part, for two different inlets velocities have experimentally calculated and comprehensively simulated using FLUENT. A 3D model of hemispherical cylinder, created by commercial package SolidWorks 2016 and star –CCM code has used as tool for geometry meshing and the simulations process performed with ANSYS-FLUENT code. RANS was first calculated with boundary conditions such as the velocity used at the inlet and the outlet. Two different locations were been selected as in the experimental model and the velocity has measured. The results of CFD analyses demonstrated very good agreement with the experimental data. The results that obtained by the experiment and Fluent help to understand the velocity distribution in the down-comer.
The Cross-Flow Mixing Analysis of Quasi-Static Pebble Flow in Pebble Bed Reactor
Authors: Xiang Fang , Xingtuan Yang , Shengyao Jiang
Published: October 2018

In the pebble bed reactor, large number of fuel pebbles’ movement law and moving state can affect the reactor’s design, operation and safety directly. Therefore the pebble flow, which is based on the theory of particle streaming, is one of the most important research subjects of the pebble bed reactor engineering. The in-core pebble flow is a very slow particle flow (or called quasi-static particle flow), which is very different from the usual particle motion. How to accurately describe the characteristics of in-core pebble flow is a central issue for this subject. Due to the presence of random flow, the cross-mixing phenomenon will occur inevitably. In the present paper, the mixing phenomenon of pebble flow is generalized on the basis of experiment results. The pebble flow cross-mixing probability serves as the parameter which describes both the regularity and the randomness of pebble flow. The results are provided in the form of diagrammatic presentation.
CANDU 6 Accident Analysis Using RELAP/SCDAPSIM With the Integrated Uncertainty Package
Authors: Nistor-Vlad Roxana-Mihaela , Dupleac Daniel , Prisecaru Ilie , Allison Chris , Perez-Ferragut M. , Hohorst Judith
Published: October 2018

RELAP/SCDAPSIM is a best-estimate nuclear tool designed to analyze the behaviour of reactor systems during normal and accident conditions. Three main versions of RELAP/SCDAPSIM are currently used by program members and licensed users to support a variety of activities. RELAP/SCDAPSIM/MOD3.4 is the version of the code used by licensed users and program members for critical applications such as research reactors and nuclear power plant applications. Even though the code was initially designed for LWRs (Light Water Reactors), Politehnica University of Bucharest demonstrated the applicability of the RELAP/SCDAPSIM code for CANDU (CANada Deuterium Uranium) reactors analyses, by simulating some of the most important postulated accident transients (i.e. large break LOCA, main steam line break, the natural circulation in the heat transport system). Current trends refer to the BEPU (Best Estimate Plus Uncertainty) approach in the safety analysis of nuclear reactors. BEPU is a modern and technically consistent approach has been built upon best estimate methods including an evaluation of the uncertainty in the calculated results. ISS and UPC started the development of an uncertainty evaluation package to RELAP/SCDAPSIM/MOD4.0 code version which is currently implemented in MOD3.4 version of the code also. The uncertainty evaluation capability is implemented as an alternative run mode, the “uncertainty” mode, which allows the automatic execution of an uncertainty analysis based on the probabilistic approach. A complete uncertainty analysis using RELAP/SCDAPSIM/MOD3.4 code requires the execution of three related phases, namely the “setup” phase, the “simulation” phase consisting of several executions, and the “postprocessing” phase. The uncertainty data has to be supplied for the two types of parameters, the “input treatable” and the “source correlation” quantities. The required information is the probability distribution function and its characteristic parameters. This paper is mainly focused on the application of the uncertainty package in CANDU reactors accident analysis and it describes the steps to perform the uncertainty analysis, the uncertainty selected parameters (input treatable and source correlation parameters), the calculation results with RELAP/SCDAPSIM and some conclusions.
Sensitivity Analysis of the SBLOCA Induced Severe Accident for a Natural Circulation Small Modular Reactors
Authors: Li Longze , Wang Jue , Zhang Yapei , Su G. H.
Published: October 2018

The natural circulation small modular reactor (NCSMR) is a 330 MW reactor which has no reactor coolant pumps (RCP) and no active safety injection systems at all. The reactor is mainly comprised of the reactor pressure vessel (RPV) with integral pressurize r and steam generator. RPV is enclosed by a vacuumed pressure containment vessel (PCV) and the PCV is submerged in the underground containment pool. A MELCOR model and corresponding input deck are developed for the RPV, PCV, and containment pool. The containment pool takes the role of ultimate heat sink (UHS) in accident situations. The containment pool may crack and leak in some critical accidents as the earthquake, leading to the severe accident of the reactor. A TMI-2 like SBLOCA in the RPV (stuck open RVVs) along with the containment pool crack (loss of ultimate heat sink) is simulated in the work. So me key parameters as the RRVs stuck open fraction, the PCV-SRVs open or not, the containment pool crack position would have large influence on the severe accident sequence. The sensitivity of these parameters to the accident sequence is analyzed in the work. According to the simulation results, the RPV pressure decreased with the RRVs stuck open. The depressurization of RPV accelerated with the RPV-SRV open fraction increase. The PCV pressure increased after that. Two cases as the PCV-SRV open after PCV pressure increase to 5 MPa, and PCV break while the RV d id not open, are analysis. The coolant discharge mass flo wrate in RPV and PCV were different in two cases, leading to the different degradation situation of the core. Since the containment pool is so important for the accident mitigation, sensitivity analysis is done for the containment pool crack position in the pool. The work will be meaningful in gaining an insight into the detailed process involved. One of the final goals of this work would be to identify appropriate accident management strategies and countermeasures for the potential extreme natural hazard induced severe accidents during the design process of NCSMR.
Dynamic Control Analysis of the AFR-100 SMR SFR With a Supercritical CO2 Cycle and Dry Air Cooling: Part I — Plant Control Optimization
Authors: Moisseytsev Anton , Sienicki James J.
Published: October 2018

Supercritical carbon dioxide Brayton cycle power converters can benefit advanced nuclear reactors, as well as small modular reactors, by reducing the plant cost and increasing plant electrical output. The sCO2 cycles can also be designed for operation under direct dry air cooling. This paper presents the results of the coupled control analysis of a sCO2 cycle for a 100 MWe sodium-cooled fast reactor. The plant control mechanisms were investigated and optimized for load following operation.
Dynamic Control Analysis of the AFR-100 SMR SFR With a Supercritical CO2 Cycle and Dry Air Cooling: Part II — Plant Control Under Varying Ambient Conditions
Authors: Moisseytsev Anton , Sienicki James J.
Published: October 2018

Supercritical carbon dioxide Brayton cycle power converters can benefit advanced nuclear reactors, as well as small modular reactors, by reducing the plant cost and increasing plant electrical output. The sCO2 cycles can also be designed for operation under direct dry air cooling. The paper presents the results of the coupled control analysis of a sCO2 cycle for a 100 MWe sodium-cooled fast reactor under changing ambient air temperatures. The optimum plant operation modes are identified.
A Brief Review of Computational Intelligence Techniques for Critical Heat Flux Prediction
Authors: Jiang B. T. , Liu Y. N.
Published: October 2018

Critical heat flux (CHF) is one of the important design criteria of water cooled nuclear reactors and plays a key role for the safety and economics of nuclear power plants (NPPs). One of the goals of nuclear reactor design is to receive maximum efficiency under full power and its efficiency would be improved when the core exit temperature increases. From this perspective, the design of a nuclear reactor needs to take into account the appropriate thermal margin to ensure that the fuel design limits are within acceptable limits for any normal operating conditions. However, in general, CHF limits the heat flux from the fuel rods and the power capacity of the nuclear reactor. CHF refers to the transition from nucleate boiling to film boiling and causes an abrupt rise of the fuel rod surface temperature. Therefore, prediction of CHF is vital to the design and safety analysis of water cooled nuclear reactors. During the last five decades, large efforts have been carried out on the CHF prediction by many researchers. Generally, CHF prediction can be achieved in three main ways: empirical correlations, look-up tables and phenomenological models. Due to the complex nature of CHF, there is no deterministic theory for the prediction of CHF. Even the look-up tables and the empirical correlations have their own application ranges and limitations. To overcome these limitations, some computational intelligence (CI) techniques have been developed for the prediction of CHF by many researchers in the last two decades. This paper provides a brief overview of CI techniques for prediction of CHF. In this paper, the reviewed CI techniques mainly include artificial neural networks (ANNs), genetic algorithms (GAs), support vector machines (SVMs), and their hybrid models. This review also compares the strengths and weaknesses of several CI techniques and provides basic technical support for future selection of appropriate methods by those involved in the field.
A Computational Study of Strongly Heated Internal Hydrogen Flow Under Non-Uniform Heat Flux
Authors: Ji Yu , Sun Jun , Shi Lei
Published: October 2018

Nuclear thermal propulsion (NTP) systems is regarded as a promising technology for human space exploration in the near future due to its large thrust and high specific impulse. Hydrogen serves as both the system coolant and engine propellant here. Convective heat transfer to hydrogen flow is a complicated process accompanying large properties variation of hydrogen due to high heat flux. In this paper, the strongly heated internal hydrogen flow is investigated numerically. According to the previous work, it has been found that the standard k-ε model with the assistance of enhanced wall treatment shows the excellent agreement with the experimental data. Based on this validated approach, the effects of heat flux profile on flow and heat transfer characteristics are evaluated. Results show high dependency of the thermal hydraulics characteristics such as wall temperature distribution and heat transfer coefficient on the heat flux profile imposed at the tube wall. Besides, the results suggest that the flow acceleration to a flat velocity profile contributes to the heat transfer deterioration, while the distorted velocity to “M-shape” is considered to be more often related to the recovery of turbulence production and subsequent heat transfer.
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.
Virtual Prototyping and Simulation of Robotic Devices and Maintenance Procedures for Remote Handling Activities in the Access Cell of DONES
Authors: Papa Stefano , di Gironimo Giuseppe , Casoria Federica , Micciché Gioacchino
Published: October 2018

The paper describes the activities of conceptual design of tools and procedures and the virtual simulation of the Remote Handling (RH) tasks provided in the maintenance of the systems present in the Access Cell (AC) of DONES (DEMO Oriented Neutron Source) facility. In particular, the RH maintenance of the Target Assembly (TA) is critical because of its position in the most severe region of neutron irradiation, the Test Cell (TC), where the material specimen are tested to understand the degradation of the materials properties throughout the reactor operational life. The main RH maintenance activity includes the replacement of the entire TA and the cleaning of the surfaces of connection in the TC. The cleaning operation is fundamental because it allows the removal of any lithium solid deposition from the surfaces: any further deposition on the surfaces could compromise the sealing of the TA. The RH is based on the idea of a reconfigurable modular chain of devices connected to the Access Cell Mast Crane (ACMC) located in the AC. To increase the modularity and to reduce the costs of the Remote Handling System (RHS), a telescopic boom is used equipped with a Gripper Change System (GCS) that allows the use of different end effectors. To perform the tasks, a Parallel Kinematic Manipulator (PKM) and a Robotic Arm (RA) are proposed, allowing the tools to move with more degree of freedom in the AC space. The modeling of the devices and the 3D kinematic simulations maintenance operations tasks were simulated and tested in virtual reality environment, aimed at developing and validating the implemented maintenance procedures, in collaboration with the IDEAinVR Laboratory of CREATE/University of Naples Federico II, and the research center at ENEA Brasimone, Italy.
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.
A Universal Adjoint-Weighted Algorithm for Geometric Sensitivity Analysis of K-Eigenvalue Based on Continuous-Energy Monte Carlo Method
Authors: Li Hao , Yu Ganglin , Huang Shanfang , Wang Kan
Published: October 2018

There exists a typical problem in Monte Carlo neutron transport: the effective multiplication factor sensitivity to geometric parameter. In several methods attempting to solve it, Monte Carlo adjoint-weighted theory has been proven to be quite effective. The major obstacle of adjoint-weighted theory is calculating derivative of cross section with respect to geometric parameter. In order to fix this problem, Heaviside step function and Dirac delta function are introduced to describe cross section and its derivative. This technique is crucial, and it establishes the foundation of further research. Based on above work, adjoint-weighted method is developed to solve geometric sensitivity. However, this method is limited to surfaces which are uniformly expanded or contracted with respect to its origin, such as vertical movement of plane or expansion of sphere. Rotation and translation are not allowed, while these two transformation types are more common and more important in engineering projects. In this paper, a more universal method, Cell Constraint Condition Perturbation (CCCP) method, is developed and validated. Different from traditional method, CCCP method for the first time explicitly articulates that the perturbed quantity is the parameter of spatial analytic geometry equations that used to describe surface. Thus, the CCCP can treat arbitrary one-parameter geometric perturbation of arbitrary surface as long as this surface can be described by spatial analytic geometry equation. Furthermore, CCCP can treat the perturbation of the whole cell, such as translation, rotation, expansion and constriction. Several examples are calculated to confirm the validity of CCCP method.
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.
iB1350: Part 2 — Level1 PRA Considering Optimization of Safety Systems for the iB1350
Authors: Go Tanaka , Takashi Sato , Yuji Komori , Keiji Matsumoto
Published: October 2018

iB1350 stands for an innovative, intelligent and inexpensive BWR 1350. It is the first Generation III.7 reactor after the Fukushima Daiichi accident, and has incorporated both the lessons learned from the Fukushima Daiichi accident and the WENRA safety objectives. It has a double cylinder RCCV (Mark W containment) and an in-depth hybrid safety system (IDHS). The IDHS currently consists of 4 division active safety systems for a DBA, and 2 division active safety systems as well as built-in passive safety systems (BiPSS) consisting of an isolation condenser (IC) and an innovative passive containment cooling system (iPCCS) for a Severe Accident (SA), which brings the total to 6 division active safety systems. Taking into account of excellent feature of the BiPSS, the IDHS has potential to optimize its 6 division active safety systems. The iPCCS that composes the BiPSS has been enhanced and has greater capability to remove decay heat than the conventional PCCS. While the conventional PCCS never can cool the S/P, the iPCCS can automatically cool the S/P directly with benefits from the structure of the Mark W containment. That makes it possible for the iB1350 to cool the core using only core inject systems and the iPCCS without RHR system: conventional active decay heat removal system. To make the most of this excellent feature of the iPCCS, it is under consideration to take credit for the iPCCS as safety systems for a DBA to optimize configuration of the IDHS. Currently, there are several proposed configurations of the IDHS that are expected to achieve cost reduction and enhance its reliability resulting from passive feature of the iPCCS. To compare those configurations of the IDHS, Level 1 Internal Events Probabilistic Risk Assessment (PRA) and sensitivity analyses considering external hazards have been performed for each configuration to provide measure of plant safety.
Structural Dynamic Transient Analysis of Fire Protection System at a Nuclear Power Plant
Authors: Dong Milton , Tom Eugene
Published: October 2018

NRC Information Notice 98-31[1] describes a water hammer event that occurred at Columbia Generating Station. In this event, actuation of a Fire Protection System (FPS) led to voiding in a tall dead-ended riser with subsequent water hammer in the riser when the main fire pumps were activated. Due to the severity of the event, NRC requires that FPS with similar configurations at other nuclear power plants be analyzed for similar events. This paper describes an evaluation of two selected riser piping systems performed to quantify the susceptibility of the potential water hammer events in the FPS at a nuclear power plant. The FPS was modeled in a proprietary computer program, USLAM (Hydraulic Analysis Code), and selected operational scenarios (analysis cases) were analyzed to quantify the potential waterhammer loads (fluid forces). A tall riser piping system in the Reactor Building was chosen as a sample system for structural dynamic analysis. Based on the results of the sample system, it was concluded that the fire protection piping systems could experience piping stress far exceed the faulted allowable loads as allowed by the ASME/ANSI piping code. A cost-effective mitigation scheme was then proposed plan in paper ICONE65-82622[2] as Part 1 of this study with consideration only hydraulic loading where 11 vacuum breakers are to be installed at various locations of the FPS. The structural analyses discussed only piping stress in this paper and demonstrate for the effectiveness of the proposed mitigation scheme from the revised hydrodynamic loads. As the continuation of Ref. 2, the results from this study validate the acceptance of these two piping systems.
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.
Sharp GaN nanowires used as field emitter on active cantilevers for scanning probe lithography
Authors: Lenk Claudia , Hofmann Martin , Ivanov Tzvetan , Ahmad Ahmad , Lenk Steve , Rangelow Ivo W. , Reum Alexander , Reuter Christoph , Holz Mathias , Behzadirad Mahmoud , Rishinaramangalam Ashwin K. , Feezell Daniel , Busani Tito
Published: October 2018

Field emission scanning probe lithography (FE-SPL), which offers sub-10 nm resolution under ambient conditions, strongly relies on the quality and shape of the applied scanning probe tip. The technological development of AFM systems is also strongly connected to the performance of the cantilever. Thereby, the probes evolved from a simple passive deflection element to a complex MEMS through integration of functional groups, such as piezoresistive detection sensors and bimaterial based actuators. Here, the authors show actual trends and developments of miniaturization efforts for fabrication of active cantilevers with mounted sharp GaN and diamond nanowires. Both materials exhibit a higher mechanical stability than the typically applied silicon, which is supposed to increase tip lifetime and reproducibility of the lithography process. Furthermore, diamond offers a high chemical stability, whereas electrical and optical properties of GaN are tunable. They present preliminary results on the applicability of GaN nanowires and diamond tips, mounted on active scanning probes, as field emitter for FE-SPL. Therefore, field emission measurements, stability of field emission current, and exemplary high resolution features generated with the tested tips are shown.
Differential orientation and conformation of surface-bound keratinocyte growth factor on (hydroxyethyl)methacrylate, (hydroxyethyl)methacrylate/methyl methacrylate, and (hydroxyethyl)methacrylate/methacrylic acid hydrogel copolymers
Authors: Sen-Britain Shohini , Hicks Wesley L. , Hard Robert , Gardella Joseph A.
Published: October 2018

The development of hydrogels for protein delivery requires protein–hydrogel interactions that cause minimal disruption of the protein’s biological activity. Biological activity can be influenced by factors such as orientational accessibility for receptor binding and conformational changes, and these factors can be influenced by the hydrogel surface chemistry. (Hydroxyethyl)methacrylate (HEMA) hydrogels are of interest as drug delivery vehicles for keratinocyte growth factor (KGF) which is known to promote re-epithelialization in wound healing. The authors report here the surface characterization of three different HEMA hydrogel copolymers and their effects on the orientation and conformation of surface-bound KGF. In this work, they characterize two copolymers in addition to HEMA alone and report how protein orientation and conformation is affected. The first copolymer incorporates methyl methacrylate (MMA), which is known to promote the adsorption of protein to its surface due to its hydrophobicity. The second copolymer incorporates methacrylic acid (MAA), which is known to promote the diffusion of protein into its surface due to its hydrophilicity. They find that KGF at the surface of the HEMA/MMA copolymer appears to be more orientationally accessible and conformationally active than KGF at the surface of the HEMA/MAA copolymer. They also report that KGF at the surface of the HEMA/MAA copolymer becomes conformationally unfolded, likely due to hydrogen bonding. KGF at the surface of these copolymers can be differentiated by Fourier-transform infrared-attenuated total reflectance spectroscopy and time-of-flight secondary ion mass spectrometry in conjunction with principal component analysis. The differences in KGF orientation and conformation between these copolymers may result in different biological responses in future cell-based experiments.
Inclusive Spaces and Locker Rooms for Transgender Athletes
Authors: Cunningham George B. , Buzuvis Erin , Mosier Chris
Published: October 2018

The purpose of this article is to articulate the need for a strong commitment to transgender inclusion in sport and physical activity, including in locker rooms and team spaces. The authors begin by defining key constructs and offering a theoretical overview of stigma toward transgender individuals. The focus then shifts to the changing opportunities for transgender athletes at all participation levels, case law and rulings germane to the topic, and the psychological, physical, and social outcomes associated with inclusion and exclusion. Next, the authors present frequently voiced concerns about transgender inclusion, with an emphasis on safety and privacy. Given the review, the authors present the case for inclusive locker rooms, which permit access by transgender athletes to facilities that correspond to their gender identity. The authors conclude with the official AKA position statement—“The American Kinesiology Association endorses inclusive locker rooms, by which we mean sex-segregated facilities that are open to transgender athletes on the basis of their gender identity”—and implications for sport and physical activity.
Viscous control of cellular respiration by membrane lipid composition
Authors: Budin Itay , de Rond Tristan , Chen Yan , Chan Leanne Jade G. , Petzold Christopher J. , Keasling Jay D.
Published: October 2018

How membrane viscosity affects respiration

In bacteria, energy production by the electron transport chain occurs at cell membranes and can be influenced by the lipid composition of the membrane. Budin
et al.
used genetic engineering to influence the concentration of unsaturated branched-chain fatty acids and thus control membrane viscosity (see the Perspective by Schon). Experimental measurements and mathematical modeling indicated that rates of respiratory metabolism and rates of cell growth were dependent on membrane viscosity and its effects on diffusion. Experiments on yeast mitochondria also showed similar effects. Maintaining efficient respiration may thus place evolutionary constraints on cellular lipid composition.

Science
, this issue p.
1186
; see also p.
1114
An electron transfer path connects subunits of a mycobacterial respiratory supercomplex
Authors: Gong Hongri , Li Jun , Xu Ao , Tang Yanting , Ji Wenxin , Gao Ruogu , Wang Shuhui , Yu Lu , Tian Changlin , Li Jingwen , Yen Hsin-Yung , Man Lam Sin , Shui Guanghou , Yang Xiuna , Sun Yuna , Li Xuemei , Jia Minze , Yang Cheng , Jiang Biao , Lou Zhiyong , Robinson Carol V. , Wong Luet-Lok , Guddat Luke W. , Sun Fei , Wang Quan , Rao Zihe
Published: October 2018

An electron bridge in place of a ferry

Respiratory complexes are massive, membrane-embedded scaffolds that position redox cofactors so as to permit electron transfer coupled to the movement of protons across a membrane. Gong
et al.
used cryo–electron microscopy to determine a structure of a stable assembly of mycobacterial complex III–IV, in which a complex III dimer is sandwiched between two complex IV monomers. A potential direct electron transfer path stretches from the quinone oxidizing centers in complex III to the oxygen reduction centers in complex IV. A loosely associated superoxide dismutase may play a role in detoxifying superoxide produced from uncoupled oxygen reduction.

Science
, this issue p.
eaat8923
Encapsidation of Viral RNA in
Picornavirales
: Studies on Cowpea Mosaic Virus Demonstrate Dependence on Viral Replication
Authors: Kruse Inga , Peyret Hadrien , Saxena Pooja , Lomonossoff George P.
Published: October 2018

The mechanism whereby members of the order
Picornavirales
specifically package their genomic RNAs is poorly understood. Research with monopartite members of the order, such as poliovirus, indicated that packaging is linked to replication, although the presence of “packaging signals” along the length of the viral RNA has also been suggested. Thanks to the bipartite nature of the CPMV genome, which allows the manipulation of RNA-1 without modifying RNA-2, we show here that this specificity is due to a functional link between the two processes of viral replication and encapsidation. This has important implications for our understanding of the fundamental molecular biology of
Picornavirales
and opens the door to novel research and therapeutic applications in the field of custom RNA packaging and delivery technologies.
N
-Glycosylation of Seasonal Influenza Vaccine Hemagglutinins: Implication for Potency Testing and Immune Processing
Authors: An Yanming , Parsons Lisa M. , Jankowska Ewa , Melnyk Darya , Joshi Manju , Cipollo John F.
Published: October 2018

In the present study, the glycosylation patterns of the 2014-2015 influenza vaccine season standard antigens A/California/07/2009 H1N1, A/Texas/50/2012 H3N2, and B/Massachusetts/02/2012 were revealed, and the sensitivity of the single radial immunodiffusion (SRID) potency test to glycosylation was tested. Differences in hemagglutinin glycosylation site composition and heterogeneity seen in antigens produced in different cell substrates suggest differences in processing and downstream immune responses. The SRID potency test used for vaccine release is not sensitive to differences in glycosylation under standard use conditions. This work reveals important differences in vaccine antigens and may point out areas where improvements may be made concerning vaccine antigen preparation, immune processing, and testing.
Retinoblastoma presenting as haemorrhagic choroidal detachment in a 10-year-old girl
Authors: Sosuan George Michael Ngo , Eleazar-Verde Jazel T , Mercado Gary John V , Arroyo Milagros H
Published: October 2018

To report a case of retinoblastoma presenting as haemorrhagic choroidal detachment in a 10-year-old girl. The patient, apparently well, presented with sudden blurring of vision in the setting of blunt trauma. On examination and ocular ultrasound, haemorrhagic choroidal detachment was suspected. She underwent external drainage via sclerostomies. The haemorrhage resolved ultrasonographically, but the vision did not improve. Five months postoperatively, she presented with sudden eye pain, lid swelling and proptosis. The ancillary workups were consistent with panophthalmitis and was treated as such. Six months postoperatively, the pain and lid swelling persisted; hence, the painful near absolute eye was enucleated. The histopathology revealed small round blue cells with necrosis consistent with retinoblastoma. Immunohistochemistry was positive for synaptophysin and negative for S100 confirming retinoblastoma. Retinoblastoma is the most common intraocular malignancy in children. The importance of increased awareness of its various presentations is of utmost importance to prevent life-threatening and vision-impairing complications.
Trans-Frontal Five-Fluorouracil (TraFFF): a novel technique for the application of adjuvant topical chemotherapeutic agents in sinonasal adenocarcinoma
Authors: Singh Narinder , Wong Eugene , Huang Johnson , Riffat Faruque
Published: October 2018

Sinonasal adenocarcinoma has traditionally been treated with surgery (craniofacial or endoscopic) and adjuvant radiotherapy. Two large series have demonstrated favourable 5-year survival using surgery with adjuvant topical chemotherapy applied repeatedly over several weeks. The authors describe a novel, transnasal application of topical 5-fluorouracil. However, complete coverage of the frontal region of the anterior skull base can be difficult to achieve with a purely transnasal approach in an outpatient setting. We present a novel adjunct method of delivering chemotherapeutic agents into this key area used in a 37-year-old man with T2N0M0 ethmoid adenocarcinoma. The procedure was well tolerated in an outpatient setting and remains disease free at 3 years postoperatively. We suggest that frontal trephination is a useful adjunct to aid accurate placement of adjuvant topical chemotherapeutic agents in the treatment of sinonasal adenocarcinoma.
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

Background

Glaucoma 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.

Methods

In 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.

Results

Depressive 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).

Conclusions

In 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/aims

Enucleation 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.

Methods

Retrospective 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.

Results

Among 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.

Conclusions

Primary 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.