bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Characterization of Airflow Within a Clean HEPA Filter Used for the Containment of Radioactive Contamination in Nuclear Facilities
Authors: Youssef Alilou , Soleiman Bourrous , Dominique Thomas , Nathalie Bardin-Monnier , Philippe Nérisson , Thomas Gélain
Published: October 2016

In hazardous industrial activities such as in nuclear facilities, High Efficiency Particulate Air filters (HEPA filters) are essential to ensure the containment of airborne contamination. Most of the filters used in ventilation networks are pleated, in order to offer a larger surface of filtration. For industrial risks likely to lead to an important release of particles (e.g. fire), predicting the evolution of the pressure drop of pleated filters is very important, in order to anticipate any dysfunction, failure or breaking of these devices. Pressure drop variations are linked to airflow rate variations and to clogging process of the medium by airborne particles.

Thus, the airflow pattern in a pleat channel is essential for optimizing the filter design and enhancing its lifetime. Particles are transported by the airflow and deposited at the filter surface; hence, the geometry of the dust cake (shape and location) is partially determined knowing the velocity streamlines.

The present paper focuses on the characterization of airflows in a clean HEPA filter. The difficulty to perform fine measurement on a real scale filter led us to develop an experimental device, consisting in the reproduction of a single pleat, identical to a real pleat constituting industrial filters. The small dimension of the pleat makes the velocity measurement difficult to establish. That is why μ-PIV method has been adapted to measure the velocity field inside the filter for different filtration velocities at the first moments of the experiment, in order to avoid the impact of clogging by particles used to seed the flow. These particles are DEHS droplets 0.01 < St < 0.05. In the future, these well-characterized airflows will be the basis for CFD computation of particle transport and deposition inside the pleats. Ultimately, the aim is to develop or upgrade physical models predicting the pressure drop evolution of pleated filters, during clogging process in accidental situations.
Severe Accident Context Evaluation for BWR NPPS Based on Long-Term Station Blackout
Authors: Petkov Gueorgui I. , Vela-Garcia Monica
Published: October 2016

The realistic study of dynamic accident context is an invaluable tool to address the uncertainties and their impact on safety assessment and management. The capacities of the Performance Evaluation of Teamwork procedure for dynamic context quantification and determination of alternatives, coordination and monitoring of human performance and decision-making are discussed in this paper. The procedure is based on a thorough description of symptoms during the accident scenario progressions (timelines) with the use of thermo-hydraulic model and severe accident codes (MELCOR and MAAP). The opportunities of PET procedure for context quantification are exemplified for the long-term station blackout (LT SBO) accident scenario at Fukushima Daiichi #1 and an hypothetic unmitigated LT SBO at Peach Bottom #1 Boiling Water Reactor Nuclear Power Plants. The context quantification of these LT SBO scenarios is based on the IAEA Fukushima Daiichi accident report, “State-of-the-Art Reactor Consequence Analysis” and thermo-hydraulic calculations made by using MAAP code at the EC Joint Research Centre, Institute for Energy and Transport, Nuclear Reactor Safety Assessment Unit.
Examining the Effect of Gamma Radiation Exposure in Early Stage of Concrete Curing on its Strength and Long-Term Durability
Authors: Burnham Steven , Huang Long , Jevremovic Tatjana
Published: October 2016

Hydration is a main process following mixing of cement with water, producing a chemical reaction between cement particles and water molecules known as Calcium-Silica-Hydroxide (C-S-H). The C-S-H acts as a binder between coarse and fine mix aggregates. During mixing, capillary voids are formed where water can easily become trapped. The van der Waals force being the principal source of strength between such compounds, voids become detrimental to long-term strength of concrete because they decrease the amount of surface area aggregate and cement particles have to come into contact with each other. An overall decrease in both pores size and their distribution in concrete increase density, therefore increasing the van der Waals force between these particles. In order to reduce capillary pores size and their distribution, in this paper we present a result from preliminary investigation on how gamma ray exposure during the early stages of the curing process affect the concrete mixture strength values. The gamma ray enhanced curing is expected to break the water molecules trapped in capillary pores into H+ and OH−, allowing these ions to escape and therefore result in densifying the concrete mixture.

Concrete cubes of 5cm3 in volumes are exposed to isotropic 137Cs gamma emitting source. The absorbed dose in cubes is measured as well as calculated using MCNP6. Each concrete cube is exposed to a 630 MBq 137Cs source for seven continuous days. The absorbed dose is experimentally measured using a Landauer nanoDot system. The average measured dose is 1.12 Gy at the front and 0.33 at the back of a concrete, totaling 0.79 Gy. The average measured dose is 0.98 Gy at the front and 0.29 Gy at the back, totaling 0.69 Gy of absorbed dose, thus showing a good agreement between the numerical predictions and experimental measurements.

Compressive strength of concrete mixes exposed to gamma rays during the curing time and those cured without exposure to gamma radiation are tested. Preliminary data shows that the average compressive strength for gamma ray enhanced curing of concrete mixes is in order of 9,000 psi while the average com-pressive strength for the cubes cured in dry air is on average about 5,000 psi. A number of new experiments is planed until the time of the Conference in providing more exact answer to the question: does gamma ray enhanced curing of concrete increase its strength and reduces the curing time?
Numerical Investigation of Flow Diffuser Optimization for a PWR Reactor With Code_Saturne: Analysis on EPR Type Reactor
Authors: Xu Tingting , Min Jiesheng , Chen Guofei , Delepine Samuel , Bellet Serge , Ge Jian , Tian Wenxi
Published: October 2016

In order to provide scientific basis for new reactor design in terms of optimal Flow Diffuser, a study was launched on the analysis and investigation on flow distribution of existing flow diffuser design of five different reactors including EPR, VVER, Konvoi, APR+ and Westinghouse. The strategy is to change each time only the flow diffuser within the 1/5 scale BORA mock-up1. The authors consider that the optimal design needs to reach a homogeneous inlet core flow rate, which is defined as figures of merit. This study combines PIRT (Phenomena Identification and Ranking Table) methodology and Computational Fluid Dynamics (CFD) calculations to identify the optimal flow diffuser design.

This paper introduces main physical phenomena analysis with PIRT methodology to list the most important phenomena and parameters from cold legs to lower core plate which have a high level of influence on the flow distribution at reactor core inlet for EPR reactor type. CFD calculations are performed under the injection condition of 0.1 m3/s per cold leg at 1/5 scale BORA mock-up for EPR flow diffuser configuration. EDF in-house open-source codes are applied to perform CFD calculations including Salomé2 for pre-processing and postprocessing and Code_Saturne3 for solver.
Strategies to Ensure Safety Measures for ABWRs in Kashiwazaki-Kariwa Nuclear Power Station
Authors: Mizuno Satoshi , Matsuo Toshihiro , Kawamura Shinichi
Published: October 2016

This paper describes strategies to ensure safety measures for ABWRs in Kashiwazaki-Kariwa Nuclear Power Station reflecting the lessons learned from the Fukushima Daiichi accident. The accident and response actions were analysed to extract lessons. Based on the lessons policies to enhance safety and containment integrity were derived. Firstly with considerations of multiple failures of the Fukushima Daiichi accident, defense in depth (DID) was enhanced by applying more diverse safety measures. For this purpose, in addition to refurbishing safety measures for beyond design base events, safety measures for each DID layer was enhanced not only by strengthen robustness to single failure but also by strengthen diversity and by physical separation. Especially capacities for ensuring containment integrity have been drastically improved by installing diverse safety measures for the third layer and the fourth layer of DID including the alternative coolant circulation system. Secondly phased approach was introduced in choosing mitigation measures considering timing of the response actions and required reliabilities. The basic concept of phased approach is that we have to select safety measures based on the assumption that possible and available measures and their required reliability are different depending on time to spare. Lastly performance requirements was clarified for containment vessel and its auxiliary systems after core damage. The basic policy was to define clearly twice design pressure of PCV as its upper limit pressure and to define 200 degree C as PCV upper limit temperature, and then to define function requirements for other auxiliary systems in order to contain fission products in the PCV and to make them decay as long as possible not only by enhancing PCV capacity but by utilizing auxiliary systems to ensure PCV integrity after core damage. Various safety measures were implemented based on these policies and applied at ABWRs in Kashiwazaki-Kariwa Nuclear Power Station.
Evaluation of Retardation Effect of Cesium Ions Through Groundwater Unsaturated Zone
Authors: Ozutsumi Takenori , Niibori Yuichi , Chida Taiji
Published: October 2016

Around near-surface underground, an unsaturated zone is formed in such porous layer composed of mainly silicate and silica sand. In the unsaturated zone in which pores are not completely filled with groundwater but also air, the migration of RNs is influenced by the presence of air phase. So far, though many studies have been reported about the unsaturated zone, little studies on the relation of the unsaturated zone and the migration of RNs have been carried out. In this study, the change of the migration of tracer ions in the unsaturated zone was examined by using a bed column, and analyzed by applying advection dispersion equation to the experimental results. As tracer ions, cesium (Cs) and strontium (Sr) were chosen in this study. These elements are the most important elements for the decontamination of Eastern Japan area caused by Fukushima the Daiichi Nuclear Power Plant accident. The experimental results showed the facilitation of the migration of tracer ions in the unsaturated zone. This causes the decrease in the sorption of tracer ions due to the inhibition of air phase. That is, the increase in the retardation effect by the clogging with air phase in flow paths was not remarkable. In the assessment of RNs migration under the unsaturated condition, these competing effects should be reflected adequately.
Electric Power Supply of German NPPs: Defence in Depth, Protection Against External Hazards and Retrofitting as a Consequence of the Fukushima Accident
Authors: Meiss Sebastian A.
Published: October 2016

The history of building and operating nuclear power plants (NPPs) in Germany dates back to the late 1950s and will come to an end in 2022. By then all NPPs still in operation will have to shut down in a defined sequence, according to the revisions made to the German Atomic Energy Act as a consequence of the accident at the Fukushima Dai-Ichi NPP. Nine out of 17 NPPs have already been shut down permanently as a consequence.

Due to the progress in science and technology, the design of the electrical power supply of German NPPs got more complex and hardened against various scenarios with time. The latest generation of NPPs built in Germany in the late 1980’s — the pressurized water reactor of type Konvoi — was designed with Defence in Depth in mind. They are connected to several voltage levels of the power grid and feature two layers of AC emergency power systems, each of which fulfills the n+2 redundancy criteria. The second of those layers is especially hardened against the influence of certain internal and external events and is part of an emergency control system which can keep the plant in a safe state autonomously for 10 hours under certain conditions.

With this being the state of science and technology at that time in Germany, most of the older NPPs in operation had been retrofitted by 2011 with systems that were designed to partially compensate for these plants’ weaker original design.

Various events such as the accident at the Chernobyl 4 NPP in 1986 and also the accident at the Fukushima Dai-Ichi NPP in 2011 led to changes in the German regulatory framework and recommendations to the NPPs for further retrofitting activities. In the regime of electrical power supply, the latest changes in requirements and corresponding retrofitting of the NPPs in operation include mobile diesel generators with corresponding, redundant feeding points, an enhanced coping capability for station blackouts with only DC-power left and measures to ensure bringing back AC-power within the available time.

In this presentation the author gives an overview over the historic development of the electric design in German NPPs and discuss details of the most recently added requirements on retrofitting — e.g. in the new regulatory framework — to enhance the robustness of the electrical power supply of those NPPs. An update on the progress on the actual retrofitting process of the German NPPs with respect to these new requirements is given.
Experimental Study on Critical Heat Flux in Three Pin Bundle With Wire Spacer for Boiling Water Reactor
Authors: Tanabe Sho , Le Dan Tri , Kondo Masatoshi , Takahashi Minoru
Published: October 2016

Related to the high conversion type BWR, the experimental study on the CHF were performed with a forced convection type water flow loop. In the test section of the loop, three heater pins as a rod bundle are installed, and water flows around the heater pins in the triangular flow channel at atomospheric pressure. The ratio of distance between two heater pins and the diameter of the heater pin (i.e., P/D) was the constant as 1.18 in all the experiments. This experiment conducted at the constant mass flux of 435 kg/m2s. The wire spacers, which were made of stainless steel wire coated by Teflon tube, were wound on the heater pins. The pitches of the wire spacer wound on the surface of the heater pins were 50 mm and 100mm. The water temperature at the inlet of the test section was controlled in the range between 60 and 90 °C by the pre-heater. The parameters in the current work were the pitch of the wire spacer and the quality at the location of the burnout (i.e., local quality). The results indicated that the CHF obtained in the test section with the wire spacer was larger than that without the wire spacer. The wire spacer must promote the CHF value. The smaller pitch of the wire spacer resulted to the smaller CHF value.
Design of the Process and Effluent Radiation Monitoring System of HTR-PM
Authors: Xie Feng , Li Wenqian , Li Zhihui , Cao Jianzhu , Li Hong , Tong Jiejuan , Wang Haitao
Published: October 2016

The process and effluent radiation monitoring system can provide information about kinds of the radionuclide and activity concentrations, which is indispensable, important, and peculiar for a nuclear power station compared to a regular thermal power station. On the basis of knowledge about pressurized water reactors (PWRs) and high temperature gas-cooled reactors (HTGRs), the process and effluent radiation monitoring system of HTR-PM has been designed. It mainly contains several monitoring channels for concerned process systems, certain important areas, and gaseous and liquid effluents. For the coolant is helium and spherical fuel elements containing tristructural isotropic (TRISO) coated particles are adopted in HTR-PM, the source terms are different from those of PWRs. Not only fission or activation products in the gaseous or liquid form are monitored, but also the radioactive dust in the primary loop is sampled for analysis. The tritium (H-3) and carbon-14 (C-14) are taken a key consideration, which will be sampled in the primary loop, in certain important areas, in the secondary loop, and in the gaseous effluent in the stack. Design features of the process and effluent radiation monitoring system of HTR-PM are introduced and discussed compared to those of PWRs.
Fast Neutron Multiplicity Simulation of Nuclear Material Based on Geant4
Authors: Li Sufen , Qiu Suizheng , Zhang Quanhu , Huo Yonggang , Liu Limin
Published: October 2016

Fast neutron multiplicity counting (FNMC) analysis method is a new nondestructive method for nuclear materials, which defines sample plutonium quality by the fast neutron detection array with multiplicity counting technique. Referring to the most advanced FNMC experimental device, fast neutron multiplicity counter model was constructed in this paper. A series of typical plutonium material sample models were designed, which includes the plutonium metal with different isotopic abundance and different quality and the plutonium oxide. The correctness of the equations and the necessity to amend the original equation were verified by computer simulated measurement through C++ language programming with the help of Geant4 simulation toolbox, fission software library function by Lawrence Livermore National Laboratory, and the IAEA provided neutron reaction data in Geant4 format. The simulation results showed the advantage of the new equation calculations than original equation calculations and the error of the new equations is less than half of that of the original equations.
Assessment of RANS Based CFD Methodology Using JAEA Fuel Assembly Experiment
Authors: Jeong Jae-Ho
Published: October 2016

This paper presents an assessment results for the developed RANS (Reynolds Averaged Navier-Stokes simulation) based CFD (Computational Fluid Dynamics) methodology applicable to real scale 217-pin wire wrapped fuel assembly of the KAERI (Korea Atomic Energy Research Institute) PGSFR (Prototype Gen-IV Sodium-cooled Fast Reactor).

Complicated and vortical flow phenomena in the wire-wrapped fuel bundles were captured by a shear stress transport (SST) turbulence model, and by a vortex structure identification technique based on the critical point theory. The CFD results show good agreement with the JAEA experiment with the 127-pin wire-wrapped fuel assembly. The JAEA experiment study was implemented using water for validating pressure drop formulas in ASFRE code. The edge vortex structures are longitudinally developed, and have a higher axial velocity than corner vortex structures and wakes nearby pins and wires. The wire spacers locally induce a tangential flow by up to about 16 % of the axial velocity. The tangential flow in the corner and edge sub-channels is much stronger than that in the interior subchannels. The large-scale edge vortex structures have higher turbulence intensity and lower vorticity than the small-scale wakes. The corner vortex structures have lower turbulence intensity and vorticity than the small-scale wakes. The driving forces in the X-, Y-, and Z-directions are not only dependent on the axial velocity, but also significantly dependent on the angular position between the wire-spacer and rod, and the relative position between the wire-spacer and duct wall.
A Fuel Cycle and Core Design Analysis Method for New Cladding Acceptance Criteria Using PHISICS, RAVEN and RELAP5-3D
Authors: Alfonsi Andrea , Mesina George L. , Zoino Angelo , Rabiti Cristian
Published: October 2016

The Nuclear Regulatory Commission (NRC) has considered revising the 10 CFR 50.46C rule [1] for analyzing reactor accident scenarios to take the effects of burn-up rate into account. Both maximum temperature and oxidation of the cladding must be cast as functions of fuel exposure in order to find limiting conditions, making safety margins dynamic limits that evolve with the operation and reloading of the reactor. In order to perform such new analysis in a reasonable computational time with good accuracy, INL (Idaho National Laboratory) has developed new multi-physics tools by combining existing codes and adding new capabilities. The PHISICS (Parallel Highly Innovative Simulation INL Code System) toolkit [2,3] for neutronic and reactor physics is coupled with RELAP5-3D [4] (Reactor Excursion and Leak Analysis Program) for the LOCA (Loss of Coolant Accident) analysis and RAVEN [5] for the PRA (Probabilistic Risk Assessment) and margin characterization analysis.

In order to perform this analysis, the sequence of RELAP5-3D input models had to get executed in a sequence of multiple input decks, each of them had to restart and slightly modify the previous model (in this case, on the neutronic side only) This new RELAP5-3D multi-deck processing capability has application to parameter studies and uncertainty quantification. The combined RAVEN/PHISICS/RELAP5-3D tool is used to analyze a typical PWR (Pressurized Water Reactor).
Overview of Revised Level 2 PRA Standard in Japan
Authors: Nakamura Koichi , Narumiya Yoshiyuki , Abe Yutaka
Published: October 2016

In this paper, we introduce the overview of the standard for Procedure of Level 2 Probabilistic Risk Assessment (PRA) for nuclear power plants established and issued by the Atomic Energy Society of Japan (AESJ). The first edition of the standard was published in 2008 through the discussions at the Level 2 Subcommittee under the Risk Technical Committee of the Standards Committee. As an enforcement standard based on the PRA procedure, the standard specifies the requirements which should have the PRA dealing with incidents resulting from internal events at nuclear power plants during power operation, and the concrete methods of meeting it. This new version standard is regular revision. In revising the 2008 version standard, we updated various requirements to reflect advancements in Level 2 PRA techniques based on new technological findings after the publication of the previous standard and to improve the quality and transparency of this standard. In particular, the lessons learned and new findings from the severe accidents of Fukushima Dai-ichi nuclear power plants, which occurred on March 11 of 2011, were significant. The reason was that three cores were melted down and large amounts of FP were released in the accidents. We investigated the latest documents relevant to severe accident research, and the measure against a severe accident established after the severe accidents of Fukushima Dai-ichi nuclear power plants. Furthermore, we extracted the matter, which should be reflected by comparison with international standard for PRA, ASME/ANS standard and IAEA SSG-4. Here, we introduce the outline and the feature of the AESJ standard for level 2 PRA. We also introduce the future renewal plan of the standard including the extension of the scope for external event, such as an earthquake and tsunami.
Results of the CSNI Task Group on the Robustness of Electrical Systems (ROBELSYS)
Authors: Regnier Pascal , Choi Young Joon , Koganeya Toshiyuki
Published: October 2016

In this paper we present the results of the CSNI task group on the Robustness of Electrical systems in the light of the Fukushima Daiichi accident (ROBELSYS). Based on the conclusion of a workshop organized in April 2014 and on further work, this task group has identified the three following main areas for international cooperation: Enhancement of the robustness of electrical systems, development and improvement in the analysis and simulation of the behavior of NPP’s electrical systems and safety challenges related to the use of power and software based electronics in electrical power systems. The paper concludes on the recently approved CSNI framework that will address these issues.
Fukushima Unit 2 Accident Simulation With MELCOR 2.1
Authors: Bocanegra Rafael , Di Marcello Valentino , Sanchez Victor , Jiménez Gonzalo
Published: October 2016

A Fukushima Daiichi Unit 3 MELCOR model from Technical Research Centre of Finland (VTT) was modified to simulate the Fukushima Daiichi Unit 2 accident. Several simulations were performed using three different modeling approaches. The base model (1F2 v1) includes only the basic modifications to reproduce the accident. The intermediate model (1F2 v2) includes an improved model of the Wet Well. In the advanced model (1F2 v3), the reactor core isolation cooling system logic was modified to avoid the use of tabular functions for the mass flow inlet and outlet. As a result of this analysis it is concluded that there is a strong dependency on parameters which still have many uncertainties, such as the reactor core isolation cooling system two-phase flow operation, the alternative water injection, the suppression pool behavior, the rupture disk behavior and the containment failure modes which affect the final state of the reactor core.
A Study of Axial Compression in the ASME B&PV Code for Pipe Supports and Restraints
Authors: Wiseman Phillip E. , Hoch Zara Z.
Published: October 2016

Axial compression allowable stress for pipe supports and restraints based on linear elastic analysis is detailed in the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section III, Division 1, Subsection NF. The axial compression design by analysis equations within NF-3300 are replicated from the American Institute of Steel Construction (AISC) using the Allowable Stress Design (ASD) Method which were first published in the ASME Code in 1973. Although the ASME Boiler and Pressure Vessel Code is an international code, these equations are not familiar to many users outside the American Industry. For those unfamiliar with the allowable stress equations, the equations do not simply address the elastic buckling of a support or restraint which may occur when the slenderness ratio of the pipe support or restraint is relatively large, however, the allowable stress equations address each aspect of stability which encompasses the phenomena of elastic buckling and yielding of a pipe support or restraint. As a result, discussion of the axial compression allowable stresses provides much insight of how the equations have evolved over the last forty years and how they could be refined.
Uncertainty Assessment of Component Degradation Model Based on Support Vector Regression
Authors: Yang Chunzhen , Liu Jingquan , Zeng Yuyun , Saeed Muhammad
Published: October 2016

Degradation modeling and condition assessment of critical components are important issues in the maintenance of nuclear power plant, but modeling uncertainties must be taken into account seriously by considering the stochastic nature of degradation and observation process. Based on support vector regression algorithm, this article proposes a wall thinning model for carbon steel pipes in a nuclear power plant using in-service inspections data and further performs the uncertainty quantitive assessment for the proposed model. In the beginning, Latin hypercube sampling method is used to create new sample sets from the original observation with certain distribution of the mean values which are assumed from the observed data. Furthermore, part of the reconstructed sample sets are chosen as training sets to develop a wall thinning model and the remaining samples are used as test sets to verify the model. By comparing model predicted wall thickness values of the test sets and the observed values, a quantitative assessment of the degradation model uncertainty is obtained. The obtained results demonstrate that the deviations between observed thickness values and average model predicted values fluctuate around 1%, while model predicting variances are much smaller than the observed variances. This report concludes that the proposed support vector regression model for component degradation can provide accurate condition assessments with rather small variance.
Environmentally Assisted Cracking Susceptibility Assessment of AP1000® RCP Flywheel Retainer Ring A 289 18Cr-18Mn Steel Material Through Slow Strain Rate Testing Under Simulated Primary Water Environment
Authors: Rao Gutti V.
Published: October 2016

The AP 1000 reactor coolant pump design included the selection and scrutiny of a Flywheel Retainer Ring Material to ensure its performance during its service life. This paper summarizes the results of an autoclave slow strain rate test (SSRT) program undertaken to establish the Environmentally Assisted Cracking (EAC) susceptibility of AP 1000 RCP Flywheel Retainer Ring (A 289 18Cr-18Mn Steel) material under simulated RCS environment. The tests program represented “beyond design basis” condition of leakage in the Alloy 625 hermetically sealed flywheel can. There is very little service experience or test data available in the literature on the performance of A289 material under exposure to primary water environment. The current program is undertaken to support the ACRS request. The testing was done under two phases. The first phase consisted of preliminary screening testing at 1×10−6/sec. The second phase represented slower strain rate at 2×10−7/sec. Both phases accompanied control sample tests under nitrogen. The primary coolant environment was maintained close to 1000 ppm boron as boric acid and 2 ppm lithium as lithium hydroxide which corresponded to a 300?C pH value of 7.0. The concentration of hydrogen was maintained at 25 cc/kg and the test temperature was maintained at 260 to 280?F. A number of SSRT parameters were employed in assessing the material susceptibility to EAC. The fracture morphologies were correlated by Scanning Electron Microscopy. Overall, the 18Cr-18Mn material SSR tests demonstrated sufficiently adequate resistance to SCC in primary water. Details of test parameters and test results will be presented.
On Experimental Simulation of Passive Evaporation-and-Condensation Systems of Reactor Thermal Shielding
Authors: Gershuni Alexander N. , Nishchik Alexander P. , Pis’mennyi Evgeviy N. , Razumovskiy Victor G. , Pioro Igor L.
Published: October 2016

Object of the study relates to passive safety systems of cooling, heat removal and thermal protection that operate as independent evaporation-condensation (EC) systems and could maintain required thermal conditions of the technological systems of nuclear power cycle. Reliability of the passive systems is provided by absence of moving parts and by their operation based on physical laws of nature, i.e., without any intervention of staff, power supply, and control signals.

One of the main features of these systems is their ultimate heat transferring ability. There are hydrodynamic limitations of heat transferring ability connected with provision of coolant circulation in vapor-condensate lines of transportation zone that could be combined into two groups: 1) the crises depending upon quantity and distribution of liquid phase; and 2) the crises affected by hydrodynamic interaction of liquid and vapor phases. The authors undertook investigation of various thermophysical factors limiting this ability, determined and analyzed its regularities, which depend upon thermodynamical conditions, transport ability of capillary structures (if any), and the interaction of vapor and liquid flows of HP coolant.

Heat transferring ability of a model of EC system of passive surface cooling and thermal shielding under the conditions of heat supply from radiating surface of reactor simulator to heat pipes as the elements of two-row screen was investigated.

The analysis and calculations made by the authors proved the possibility to create an efficient passive evaporation EC system of surface cooling and thermal shielding of reactor unit. Such a system has a number of advantages as compared with known active safety systems (e.g., autonomy, higher reliability, and operational safety), does not require emergency water resources, compressed air systems, numerous valves, etc.).

The tests were performed at vertical orientation of HP evaporation zone (condensation zone was above evaporation zone) as a part of the double-row screen. The heat pipe was tested at its location in each of two rows and at two options of condensation zone: vertical and inclined in transportation zone at 20° to horizon.

It was found that only insignificant circumferential nonisothermality of heat-pipe surface under steady one-side heat supply in evaporation zone took place. Quite satisfactory agreement of the experimental and predicted values of heat flux transmitted by heat pipes of two-row screen was obtained.

The investigation proved efficiency and reliability of EC system of surface cooling and thermal shielding of the reactor equipment.
Deposition and etching characteristic of magnetite thin film for absorptive wire grid polarizer with 45 nm line and space pattern
Authors: Cho Young Tae , Jeong Jiyun , Kim Ji Hoon , Kim Yun Jae , Jeong Yeon Ho , Jung Yoon Gyo , Kwon Sin
Published: October 2016

Magnetite, Fe3O4, is a mineral and one of three commonly naturally occurring oxides of iron. Small grains of magnetite exist in almost all igneous and metamorphic rocks. Most advance studies on magnetite films have focused on the characteristics of films by the growth of crystals such as nanowires. In this study, several processes of the magnetite film and patterning recipes are proposed. The authors deposited the Fe3O4 about 100 nm on the glass wafer using an e-beam evaporator. The 45 nm line/space pattern using nanoimprint process was made, and the residual layer could be reduced up to about 20 nm thickness. In addition, several possible etching gases and optimal conditions are suggested with proper etch selectivity.
Design and fabrication of bio-hybrid materials using inkjet printing
Authors: Maddaus Alec , Curley Patrick , Griswold Matthew A. , Costa Bianca Daniela , Hou Shujie , Jeong Kyung Jae , Song Edward , Deravi Leila F.
Published: October 2016

The integration of biomolecules such as proteins, carbohydrates, or enzymes into functional materials, whether through physical or chemical coupling, remains a critical processing step in the fabrication of engineered biosensors or tissue scaffolds, where anisotropy and composition can directly impact material function and host integration. A means to achieve these features is through the selective patterning of biomolecules, which is used to recruit and direct cell growth in vitro. The authors describe the design of protein-based materials using inkjet printing and discuss how fluid physical properties of the formulated inks influence pattern formation and material performance. When interfaced with carbon nanotubes, the biohybrid films retain their chemical signature but with enhanced structural stability and electrical conductivity over time. These structures also support the adhesion and proliferation of human dermal fibroblasts. Together, these properties demonstrate the utility of printed biohybrid films as materials that can conceivably be used to recapitulate or enhance biological function for tissue engineering applications.
Relative acoustic frequency response of induced methane, carbon dioxide and air gas bubble plumes, observed laterally
Authors: Kubilius Rokas , Pedersen Geir
Published: October 2016

There is an increased need to detect, identify, and monitor natural and manmade seabed gas leaks. Fisheries echosounders are well suited to monitor large volumes of water and acoustic frequency response [normalized acoustic backscatter, when a measure at one selected frequency is used as a denominator, r(f)] is commonly used to identify echoes from fish and zooplankton species. Information on gas plume r(f) would be valuable for automatic detection of subsea leaks and for separating bubble plumes from natural targets such as swimbladder-bearing fish. Controlled leaks were produced with a specially designed instrument frame suspended in mid-water in a sheltered fjord. The frame was equipped with echosounders, stereo-camera, and gas-release nozzles. The r(f) of laterally observed methane, carbon dioxide, and air plumes (0.040–29 l/min) were measured at 70, 120, 200, and 333 kHz, with bubble sizes determined optically. The observed bubble size range (1–25 mm) was comparable to that reported in the literature for natural cold seeps of methane. A negative r(f) with increasing frequency was observed, namely, r(f) of about 0.7, 0.6, and 0.5 at 120, 200, and 333 kHz when normalized to 70 kHz. Measured plume r(f) is also compared to resolved, single bubble target strength-based, and modeled r(f).
Measurements and time-domain simulations of multiphonics in the trombone
Authors: Velut Lionel , Vergez Christophe , Gilbert Joël
Published: October 2016

Multiphonic sounds of brass instruments are studied in this article. They are produced by playing a note on a brass instrument while simultaneously singing another note in the mouthpiece. This results in a peculiar sound, heard as a chord or a cluster of more than two notes in most cases. This effect is used in different artistic contexts. Measurements of the mouth pressure, the pressure inside the mouthpiece, and the radiated sound are recorded while a trombone player performs a multiphonic, first by playing an F3 and singing a C4, then playing an F3 and singing a note with a decreasing pitch. Results highlight the quasi-periodic nature of the multiphonic sound and the appearance of combination tones due to intermodulation between the played and the sung sounds. To assess the ability of a given brass instrument physical model to reproduce the measured phenomenon, time-domain simulations of multiphonics are carried out. A trombone model consisting in an exciter and a resonator nonlinearly coupled is forced while self-oscillating to reproduce simultaneous singing and playing. Comparison between simulated and measured signals is discussed. Spectral content of the simulated pressure match very well with the measured one, at the cost of a high forcing pressure.
Loss of epithelial G
q
and G
11
signaling inhibits TGFβ production but promotes IL-33–mediated macrophage polarization and emphysema
Authors: John Alison E. , Wilson Michael R. , Habgood Anthony , Porte Joanne , Tatler Amanda L. , Stavrou Anastasios , Miele Gino , Jolly Lisa , Knox Alan J. , Takata Masao , Offermanns Stefan , Jenkins R. Gisli
Published: October 2016

Signaling by G
q/11
is required for optimal TGFβ activation in the lung to prevent inflammation.
A glucocorticoid- and diet-responsive pathway toggles adipocyte precursor cell activity in vivo
Authors: Wong Janica C. , Krueger Katherine C. , Costa Maria José , Aggarwal Abhishek , Du Hongqing , McLaughlin Tracey L. , Feldman Brian J.
Published: October 2016

Fat tissue produces the secreted protease ADAMTS1, which activates a pathway that inhibits diet- or glucocorticoid-stimulated expansion of adipose tissue.
Pathogen exploits Wnt receptors
Authors: VanHook Annalisa M.
Published: October 2016

Clostridium difficile
toxin B blocks Wnt signaling and damages colonic epithelial cells by binding to Frizzled.
Papers of note in
Science Translational Medicine
Authors: Ferrarelli Leslie K.
Published: October 2016

This week’s articles describe ways to potentially prevent metastasis and the development of autoimmune disease.
In Vitro
Activities of Novel Azole Compounds ATTAF-1 and ATTAF-2 against Fluconazole-Susceptible and -Resistant Isolates of Candida Species
Authors: Fakhim Hamed , Emami Saeed , Vaezi Afsane , Hashemi Seyedeh Mahdieh , Faeli Leila , Diba Kambiz , Dannaoui Eric , Badali Hamid
Published: October 2016

The
in vitro
activities of two novel azole compounds (aryl-1,2,4-triazol-3-ylthio analogues of fluconazole [ATTAFs]) and five comparator antifungal agents against 52 clinical
Candida
isolates from 5 different species were determined. The novel azole compounds had the lowest geometric mean MICs, followed by fluconazole. Moreover, combinations of these compounds with fluconazole exhibited synergistic effects against fluconazole-susceptible (22 of 23 isolates), fluconazole-susceptible dose-dependent (10 of 13 isolates), and fluconazole-resistant (1 of 16 isolates)
Candida
isolates.
Pharmacodynamics of Aerosolized Fosfomycin and Amikacin against Resistant Clinical Isolates of Pseudomonas aeruginosa and Klebsiella pneumoniae in a Hollow-Fiber Infection Model: Experimental Basis for Combination Therapy
Authors: Sime Fekade Bruck , Johnson Adam , Whalley Sarah , Santoyo-Castelazo Anahi , Montgomery A. Bruce , Walters Kathie Ann , Lipman Jeffrey , Hope William W. , Roberts Jason A.
Published: October 2016

There has been a resurgence of interest in aerosolization of antibiotics for treatment of patients with severe pneumonia caused by multidrug-resistant pathogens. A combination formulation of amikacin-fosfomycin is currently undergoing clinical testing although the exposure-response relationships of these drugs have not been fully characterized. The aim of this study was to describe the individual and combined antibacterial effects of simulated epithelial lining fluid exposures of aerosolized amikacin and fosfomycin against resistant clinical isolates of
Pseudomonas aeruginosa
(MICs of 16 mg/liter and 64 mg/liter) and
Klebsiella pneumoniae
(MICs of 2 mg/liter and 64 mg/liter) using a dynamic hollow-fiber infection model over 7 days. Targeted peak concentrations of 300 mg/liter amikacin and/or 1,200 mg/liter fosfomycin as a 12-hourly dosing regimens were used. Quantitative cultures were performed to describe changes in concentrations of the total and resistant bacterial populations. The targeted starting inoculum was 10
8
CFU/ml for both strains. We observed that neither amikacin nor fosfomycin monotherapy was bactericidal against
P. aeruginosa
while both were associated with rapid amplification of resistant
P. aeruginosa
strains (about 10
8
to 10
9
CFU/ml within 24 to 48 h). For
K. pneumoniae
, amikacin but not fosfomycin was bactericidal. When both drugs were combined, a rapid killing was observed for
P. aeruginosa
and
K. pneumoniae
(6-log kill within 24 h). Furthermore, the combination of amikacin and fosfomycin effectively suppressed growth of resistant strains of
P. aeruginosa
and
K. pneumoniae
. In conclusion, the combination of amikacin and fosfomycin was effective at maximizing bacterial killing and suppressing emergence of resistance against these clinical isolates.
Screening the Pathogen Box for Identification of Candida albicans Biofilm Inhibitors
Authors: Vila Taissa , Lopez-Ribot Jose L.
Published: October 2016

Candida albicans
remains the main causative agent of candidiasis, one of the most frequent nosocomial infections, with unacceptably high mortality rates. Biofilm formation is a major risk factor for invasive candidiasis, as
Candida
biofilms display high-level resistance to most antifungal agents. In this work we have screened the Pathogen Box chemical library (Medicines for Malaria Venture [MMV], Switzerland) in search for inhibitors of
C. albicans
biofilm formation. Our initial screen identified seven hits, and additional dose-response assays confirmed the biofilm-inhibitory activity of six of these small molecules. Three compounds, MMV688768, MMV687273, and MMV687807, were also able to reduce the metabolic activity of cells within preformed biofilms. Interestingly, the most potent of these, compound MMV688768, displayed increased antibiofilm activity compared to its activity against planktonic cultures, indicating that it may affect processes with a predominant role during the biofilm mode of growth. This compound demonstrated a high selectivity index when its antibiofilm activity was compared with its toxicity in liver hepatocellular cells.
In vitro
combination assays showed a synergistic interaction between compound MMV688768 and fluconazole against preformed biofilms. Overall, our results indicate that this compound may constitute a potential candidate for further clinical development.
Plasmodium falciparum Genetic Diversity in Continental Equatorial Guinea before and after Introduction of Artemisinin-Based Combination Therapy
Authors: Guerra Mónica , Neres Rita , Salgueiro Patrícia , Mendes Cristina , Ndong-Mabale Nicolas , Berzosa Pedro , de Sousa Bruno , Arez Ana Paula
Published: October 2016

Efforts to control malaria may affect malaria parasite genetic variability and drug resistance, the latter of which is associated with genetic events that promote mechanisms to escape drug action. The worldwide spread of drug resistance has been a major obstacle to controlling
Plasmodium falciparum
malaria, and thus the study of the origin and spread of associated mutations may provide some insights into the prevention of its emergence. This study reports an analysis of
P. falciparum
genetic diversity, focusing on antimalarial resistance-associated molecular markers in two socioeconomically different villages in mainland Equatorial Guinea. The present study took place 8 years after a previous one, allowing the analysis of results before and after the introduction of an artemisinin-based combination therapy (ACT), i.e., artesunate plus amodiaquine. Genetic diversity was assessed by analysis of the
Pfmsp2
gene and neutral microsatellite loci.
Pfdhps
and
Pfdhfr
alleles associated with sulfadoxine-pyrimethamine (SP) resistance and flanking microsatellite loci were investigated, and the prevalences of drug resistance-associated point mutations of the
Pfcrt
,
Pfmdr1
,
Pfdhfr
, and
Pfdhps
genes were estimated. Further, to monitor the use of ACT, we provide the baseline prevalences of K13 propeller mutations and
Pfmdr1
copy numbers. After 8 years, noticeable differences occurred in the distribution of genotypes conferring resistance to chloroquine and SP, and the spread of mutated genotypes differed according to the setting. Regarding artemisinin resistance, although mutations reported as being linked to artemisinin resistance were not present at the time, several single nucleotide polymorphisms (SNPs) were observed in the K13 gene, suggesting that closer monitoring should be maintained to prevent the possible spread of artemisinin resistance in Africa.
Arginase Is Essential for Survival of Leishmania donovani Promastigotes but Not Intracellular Amastigotes
Authors: Boitz Jan M. , Gilroy Caslin A. , Olenyik Tamara D. , Paradis Dustin , Perdeh Jasmine , Dearman Kristie , Davis Madison J. , Yates Phillip A. , Li Yuexin , Riscoe Michael K. , Ullman Buddy , Roberts Sigrid C.
Published: October 2016

Studies ofLeishmania donovanihave shown that both ornithine decarboxylase and spermidine synthase, two enzymes of the polyamine biosynthetic pathway, are critical for promastigote proliferation and required for maximum infection in mice. However, the importance of arginase (ARG), the first enzyme of the polyamine pathway inLeishmania, has not been analyzed inL. donovani. To test ARG function in intact parasites, we generated Δargnull mutants inL. donovaniand evaluated their ability to proliferatein vitroand trigger infections in mice. The Δargknockout was incapable of growth in the absence of polyamine supplementation, but the auxotrophic phenotype could be bypassed by addition of either millimolar concentrations of ornithine or micromolar concentrations of putrescine or by complementation with either glycosomal or cytosolic versions of ARG. Spermidine supplementation of the medium did not circumvent the polyamine auxotrophy of the Δargline. Although ARG was found to be essential for ornithine and polyamine synthesis, ornithine decarboxylase appeared to be the rate-limiting enzyme for polyamine production. Mouse infectivity studies revealed that the Δarglesion reduced parasite burdens in livers by an order of magnitude but had little impact on the numbers of parasites recovered from spleens. Thus, ARG is essential for proliferation of promastigotes but not intracellular amastigotes. Coupled with previous studies, these data support a model in whichL. donovaniamastigotes readily salvage ornithine and have some access to host spermidine pools, while host putrescine appears to be unavailable for salvage by the parasite.