bluuebunny/crossref_metadata_2025 huggingface dataset:
Adjoint Sensitivity Analysis of a Cooling Tower
Authors: Di Rocco Federico , Cacuci Dan Gabriel
Published: October 2017

Every plant aimed for energy production on large scale mandatorily needs to include systems able to ensure a proper release of the residual heat into the external environment; in the case of nuclear power plants, cooling towers are the most popular answer to this compelling task. The development of a dedicated numerical model can be a powerful tool for the simulation of the tower performance, but for quantifying the amount of heat released into the atmosphere, experimentally measured data are needed, in order to properly characterize the external environment in terms of outlet air temperature, outlet water temperature and outlet air relative humidity. Material properties, correlations and boundary conditions are among the many model parameters which can influence the model’s responses; variations of the computed quantities of interest (or “model responses”) induced by variations in the values of the model parameters can be expressed in terms of the sensitivities (i.e., functional derivatives) of the model responses with respect to the model parameters. The methodology applied in this paper in order to compute these sensitivities is the general adjoint analysis methodology (ASAM) for nonlinear systems; with this procedure, the exact values of the sensitivities of the model responses to all of the 47 model parameters are calculated exactly and efficiently by means of a single adjoint computation. The sensitivities can then be used within the “predictive modeling for coupled multi-physics systems” (PM_CMPS) methodology, aimed at yielding best-estimate predicted nominal values and uncertainties for model parameters and responses.
Experiment and Numerical Analysis of Mixing Process of Two Component Gases in Vertical Fluid Layer
Authors: Takeda Tetsuaki
Published: October 2017

A depressurization accident is the one of the design-basis accidents of a Very-High-Temperature Reactor (VHTR). When a depressurization accident occurs, air is expected to enter into the reactor pressure vessel from the breach and oxidize in-core graphite structures. Therefore, it is important to understand the mixing processes of different kinds of gases in the stable and unstable stratified fluid layers. In particular, it is also important to examine the influence of localized natural convection and molecular diffusion on the mixing process from a safety viewpoint. Therefore, in order to predict or analyze the air ingress phenomena during a depressurization accident, it is important to develop a method for the prevention of air ingress during an accident. We carried out experiments and numerical analysis using three-dimensional (3D) CFD code to obtain the mixing process of two-component gases and the flow characteristics of localized natural convection. This study also investigated a control method for the natural circulation of air through the injection of helium gas.

The numerical model consists of a storage tank and a reverse U-shaped vertical rectangular passage. They are separated by a horizontal partition plate. One sidewall of the high-temperature side vertical passage is heated and the other sidewall is cooled. The low-temperature vertical passage is cooled by ambient air. The storage tank is filled with heavy gas and the reverse U-shaped vertical passage is filled with a light gas. In the vertical passage of the high-temperature side, localized natural convection is generated by the temperature difference between the vertical walls. The results obtained from the experiments were quantitatively simulated using 3D numerical analysis. The two component gases were mixed via molecular diffusion and natural convection. After some time elapsed, natural circulation occurred through the reverse U-shaped vertical passage. These flow characteristics are the same as those of phenomena generated in the passage between a permanent reflector and a pressure vessel wall of the VHTR.
Design Investigation on Flow Diffuser With Code_Saturne: CFD Simulation Analysis
Authors: Xu Tingting , Min Jiesheng , Bellet Serge , Howard Richard , Alvarez Dominique , Chen Guofei
Published: October 2017

The flow rate distribution at the entrance of the core plays a key role for reactor design since it has important implications for the performance, and efficient safety of a nuclear reactor. When the coolant passes from the downcomer to the core, it changes direction due to the inertia force and the curvature of the bottom vessel head. The internal components inside lower plenum work to homogenize the flow distribution. Their purpose is to prevent the formation of instabilities and the creation of vortices due to the flow reversal. In the frame of EDF’s new reactor design there is a desire to identify an optimal flow diffuser. The future intention is to study five different types of flow diffuser including EPR, VVER, Konvoï, APR+ and Westinghouse to look at the pros and cons of each design. The authors underline that the geometries of each Reactor Pressure Vessel (RPV) and associated diffuser device are quite different therefore a generic form needs to be used to make an equivalent comparison. The goal of the present work is to find the optimal mesh refinement and associated numerical parameters for the simulation of the lower plenum flow. This work is a preliminary step for a future study to compare existing diffuser concepts. Thus in the future work only the section containing the flow diffuser structure will be changed.

The PIRT methodology is applied to better define the physical phenomena and key parameters that will influence the flow distribution at the entrance of the core. In order to better understand the fluid distribution and the function of the diffuser component, 3D computational fluid dynamics (CFD) simulations are launched to improve our knowledge on the flow pattern inside the lower plenum.

Both the geometry and mesh are generated by Salomé1. Simulations are carried out using Code_Saturne2, an EDF in-house open-source CFD code. The generic test case is a 1/5 scale EDF “BORA” 4 loop mock-up with a flow rate of 0.1 m3/s injected into each cold leg. The unsteady flow algorithm with standard k-epsilon turbulence model has been used with a full explicit meshing except for the reactor core where a porous approach is adopted. The physical time for each calculation case is 5s for a converged simulation. Mesh sensitivity tests have been carried out ranging from 8 million cells to 28 million cells. A mesh of 22 million cells is found to provide the most appropriate balance between simulation quality and feasibility. Due to the size of the simulations, high performance computers are necessary to provide timely results. The results indicate that CFD can provide extra capacity to engineers for reactor design to evaluate the pros and cons of different existing diffuser concepts.
Reconstruction of Core Overheating Damage Fraction Based on Neural Network Method
Authors: Li Wenjing , Yang Xiaoming , Yu Xinlu
Published: October 2017

Core damage assessment is of great importance to the emergency response of nuclear power plants. In this paper, the neural network method is introduced into the core damage assessment process. The hydrogen concentration, together with the temperature and pressure in the containment, are taken as the input parameters of the model. With the simulated result of MAAP codes as the sample data, a neural network model is developed to reconstruct the core overheating damage fraction. According to the calculation of the neural network model, the deviations of the reconstructed results are quite small compared with the simulation results, and one of the typical errors is 1.76%. It can be concluded that the model based on neural network method satisfies the analysis accuracy requirements and can be used as a diverse analytical tool in the core damage assessment of nuclear power plant.
Study of the Impact of Stellite Material on PWR Co-60 Contamination
Authors: Zhang Liying , Wang Yaxiao , Wang Xiaoxia , Gao Bo , Mi Aijun , Mao Yawei
Published: October 2017

According with the requirements of HAF-102[1], the purpose of radiation protection optimization is to achieve occupational exposures as low as reasonably achievable (ALARA). More than 80% of the collective exposure doses are received during the outage for PWRs. Activated corrosion products, especially Co-60, deposited on the surface of reactor coolant system are the main causes of these doses. Co-60 is the principle contributor to out-of-core radiation fields in PWRs, which is a high energy gamma emitter with a 5.3 year half-life period. The contamination by Co-60 plates out in plant piping systems and produces long term high radiation areas in the plant. Stellite, a hard facing alloy trade, which has high Co-59 content (approximately 60%), is identified as one of the most important source of Co-60 in reactors, whereas the contribution of Stellite to cobalt are always not paid enough attention to. Cobalt is released through ware and corrosion of Stellite. When cobalt is released in systems with a flow path to the reactor, it can become activated by neutron to Co-60.

This paper analyzes the Stellite material release into the primary coolant. Based on the above considerations, the impact of Stellite replacement on plant contamination by Co-60 is calculated and analyzed with the use of activated corrosion product source term calculation program. The primary conclusions are as follows: (1) Reducing the quantity of Stellite material used during the design and building of PWRs can significantly reduce the Co-60 deposition on primary circuit. (2) The replacement of Stellite material has a positive impact on PWR contamination by Co-60, but the outcome is not so significant. Based on the above analysis, recommendations are made. Stellite material replacement project can be used for the operating reactors to reduce the Co-60 contamination. But for the design and building of new reactors, reduction of the use of Stellite material is the best choice.
Report on Feasibility Study for Radiation Alarming Data Collection From Containers at Laem Cha Bang International Sea Port, Thailand
Authors: Nilsuwankosit Sunchai
Published: October 2017

During the period of late-August 2015 to early-October 2015, a number of 105 data sets for the radiation alarming events from the containers passing through the “Laem Cha Bang” International Sea Port, Thailand, were collected. These radiation alarming events were for the containers which carried the goods that could be roughly identified as belonging to the following groups: (1) fertilizer, (2) chemicals, (3) plastics, (4) ceramics, (5) grain, feed, agriculture or dairy products (6) wood, rubber or furniture, (7) scrap, mineral or metal, (8) equipment, (9) parts or spare parts, (10) paper and (11) others. Most of the radiation measurements obtained were relatively low and showed no harm to the public and to the environment. Much of this radiation was from the radioactive materials found or occurred naturally and, thus, could be found anywhere. There were concern, however, regarding the possibility of the radioactive contamination or the smuggling of the harmful radioactive or nuclear materials. Further study was required to prepare against and to manage such situations.
Code Developing of Fragility Analysis Program for Seismic Safety Evaluation of Nuclear Power Plant
Authors: Wang Zhao , Yang Jianfeng , Wang Weijin , Feng Bingchen , Zhang Xiaoming
Published: October 2017

For seismic safety evaluation method of nuclear power plant, nuclear power plant seismic margin analysis (SMA) and nuclear power plant seismic probability safety assessment (SPSA) are the most widely used methods. SMA is a method base on deterministic theory. Seismic capacity is valued by high confidence and low failure probability (HCLPF). Through the seismic failure logic of structure, system and components (SSCs), the method can calculated the HCLPF of the whole nuclear power plant, and verify whether the plant can withstand a SSE earthquake test. The SPSA method is the most widely used seismic safety assessment method based on probability theory. Through the analysis and quantification of earthquake accident sequence, a SPSA project can fully identify the seismic risk of nuclear power plant and seismic weak points. Also SPSA can guide the nuclear power plant seismic safety improvement. No matter which method is used to analyze the seismic safety of nuclear power plant, it is necessary to analyze and calculate the seismic fragility of the SSCs. SMA method needs to use a large number of HCLPF data, and seismic fragility analysis and calculation results is one of the main sources of HCLPF data. The SPSA method needs to use seismic fragility data of SSCs which are list in the seismic equipment list (SEL) as input data, so that it can support the quantitative analysis of the risk assessment model. Because of the existence of uncertainty, the seismic fragilities cannot be put to directly logic operation. This brings great difficulty to the using of fragility data. In the paper, the logic operation method and the uncertainty analysis method of seismic fragility is studied, and the calculation program is compiled based on the Monte Carlo method. In this paper, a program is used to calculate the case. The performance of the program is verified and the uncertainty of the system fragility is analyzed. Due to the existence of uncertainty, the fragility cannot put into the numerical calculation directly. In this paper, the calculation method of the failure frequency of components is studied, and the corresponding program is developed by using Monte Carlo method. In this paper, a program is used to calculate the failure frequency of the components under different ground motion levels, and the uncertainty of the failure frequency is also studied.
The Investigation and Analysis of Public Acceptance in the Surrounding Region of Inland Nuclear Power Plant
Authors: Wang Aixing , Hong Jiabiao , Fan Ruichen , Yu Fei , Zhang Siying , Liu Yibao
Published: October 2017

Nuclear safety law and regulation related to the field of public acceptance and nuclear education of nuclear power (NP) is in blank, which seriously restricts the sustainable development of nuclear energy. In order to make up for nuclear safety legal system in the field of public acceptance of nulcear power plant (NPP) and education of NP and related fields, this paper provides data and gives some advice. The investigation used a random sample survey method to made a field survey of 301 people living near inland NPP. In this survey, 55.48% of people are concerned about NPPs development in their daily life, 73.09% of people support the development of NPPs, 63.79% of people are against NPPs built in the vicinity of their own, 30.90% of people think that NPPs is safe, 76.08% of people worry about the harmful impact on the surrounding residents, 81.06% of people know and learn the knowledge of NP by television and internet, 19.93% of people know the related knowledge of NP by government propaganda. In conclusion, most of people support and pay attention to the development of inland NPP, but they do not have a deep understanding of nuclear safety so they do not fully accept the inland NPP. It is suggested that we should increase information publicity of public network, promote popular science propaganda about NPP by government, improve nuclear safety laws and regulations, and strengthen the study on the psychological mechanism of public NP. If we can do all of this, it will help to improve the development of inland NPP Using the internet and television popularizes the NPP Invite officials from the site of the new NPP station and the relevant people in the surrounding regions to visit the NPP which has been built and participate in nuclear safety related knowledge training. Speeding up the process of “nuclear safety” law and perfecting the laws and regulations for protecting the safety and rights of public.
US Department of Energy’s CoDCon Project: An Aqueous Safeguards R&D Program
Authors: Bresee James C. , Paviet Patricia D. , Todd Terry A.
Published: October 2017

In 2015, Office of Nuclear Energy of the U.S. Department of Energy established a research and development project at Pacific Northwest National Laboratory to evaluate the process control capability to produce a specific uranium/plutonium product from used commercial nuclear fuel using an aqueous co-decontamination separations process. The process is controlled using on-line instrumentation supported by a dynamic process model. The new program is called the CoDCon project.

The result of the study will be a quantitative measure of the current capability to produce a specific U/Pu product, using U-IV to reduce plutonium to Pu-III and prepare a mixed product, the composition predicted by a dynamic model, measured with on-line instrumentation and controlled by the adjustment of process variables. This approach would be an alternative to the use of the PUREX aqueous separations process that produces separate plutonium and uranium products that are later blended to prepare the desired mixture. Since plutonium is always accompanied by uranium, the project will provide a safeguards-by-design tool for possible use in future commercial separations plant designs. The effectiveness of the design tool will be quantified using a methodology published by B. Cipiti, et al1.

The paper describes the process and the control system used by the project and provides details on the current status of the research and development program. Since this advanced process control system may have international applications, arrangements will be described for possible foreign participation in the project.
Development of Five-Equation Drift Flux Model for Thermal Non-Equilibrium Phenomena in LWRs
Authors: Shi Shanbin , Zhang Xiaoqin , Sun Xiaodong , Zhang Hongbin
Published: October 2017

The classic four-equation drift-flux model treats the two-phase flow as a mixture to formulate mass, momentum, and energy balance equations. The dispersed phase is modeled in the mass balance equation to describe the mass transfer between the two phases. However, this model implies an assumption of the thermal equilibrium in the mixture energy balance equation. Therefore, a five-equation drift-flux model and its constitutive equations have been developed to relax the thermal equilibrium assumption in the classic four-equation drift-flux model when it is applied to thermal non-equilibrium phenomena in Light Water Reactors (LWRs). The additional energy balance equation of the dispersed phase has been introduced to address thermal non-equilibrium phenomena in LWRs in the five-equation drift-flux model. In addition, the newly added energy equation for the dispersed phase does not change the basic kinematic parameters and uses the mixture velocity instead of the dispersed phase velocity.

The hyperbolicity of the drift-flux model system equations is investigated by examining if the partial differential equations have only real eigenvalues. The results show that the five-equation drift-flux model is a well-posed hyperbolic model, which can be solved by both advanced solvers using the finite element method, such as MOOSE Framework, and the traditional solvers using finite difference method, such as RELAP5 code.

In developing the thermal non-equilibrium five-equation drift-flux model, it is necessary to select, improve, or develop constitutive models as closure relations for variables used in the field equations. In our current study, a literature survey has been conducted to review appropriate constitutive models and correlations for the dispersed phase mass generation rate, interfacial energy transfer, distribution parameter, and drift velocity in the five-equation drift-flux model.
D&D and Waste Management: An AREVA Expertise From AREVA Sites Operations to Customers Projects
Authors: Bargues Stephane
Published: October 2017

AREVA is the only global player in this D&D and Waste Management domain which can propose its huge feedback in Europe and worldwide for all kind of nuclear facilities (from mining, chemical, fuel and recycling plants, Research Reactors to Nuclear Power Plants to legacy waste retrieval).

To be owner and operator of sites in dismantling phases with a lot of waste to retrieve, treat and package for final storage, gives AREVA a global view=on important key parameters of this kind of projects for more than 40 years.

Specificities of D&D and associated Waste projects are multiple:

• Complexity of operations to perform in buildings not designed for these tasks.

• Big components to decontaminate and to cut.

• Innovation, skills and Research and Development needs to solve and anticipate projects issues.

• Safety and security for workers and populations.

• Environmental issues to solve (contaminated soil to sort for example, or water to decontaminate).

• Risks management during all project life using lessons learnt.

• Costs optimization from the most important project phase: scenario and studies of the operations.

• Amount and type of waste (alpha with contamination, gamma with irradiation, high volume of very low level waste with or without free release opportunities).

• Interfaces with waste transports and storage facilities.

• ...
Severe Accident Analysis Using MAAP With Detailed Nodalization in Advanced Boiling Water Reactor
Authors: Chitose Hiromasa , Kamei Naoya , Kimura Ryusuke
Published: October 2017

In this study, severe accident analyses were conducted for the Advanced Boiling Water Reactor (ABWR) using a detailed nodalization and the impact of MAAP nodalization on the severe accident analysis was investigated. The results of the analysis obtained using a detailed nodalization shows that the PCV temperature is more challenging in comparison to the results of the original nodalization. However, it was found that the structural temperature of the PCV head flange can be maintained below the ultimate temperature of the head gasket when passive mitigation systems are successful, even if no reactor well injection is conducted.
Numerical Simulation of Flow Field Inside Reactor Upper Plenum for PWR With Code_Saturne
Authors: Liu Jiawei , Gao Puzhen , Xu Tingting , Min Jiesheng , Chen Guofei
Published: October 2017

Flow characteristic in upper plenum has a strong influence on reactor functional margin and rod cluster control assembly (RCCA) guide tube wear. Upper plenum flow governs loops flow rate measurement via hot leg temperature which has also an influence on the reactor protection system. For RCCA guide tube wear, it appears in operation with RCCA flow-induced vibration, leading to its replacement. It is important to know the flow condition in the upper plenum, and in particular the outlet.

Existing Generation III reactors have their own specialties on the design. Comparison between current technologies is a good way for better understanding on the key structure design for the upper plenum.

In this paper, simplified models based on upper plenum structure of Korean advanced pressurized water reactor (PWR) and Westinghouse design AP1000 are constructed and meshed with a volume around 6 million cells to obtain a 3-dimensional global and local flow distributions inside the upper plenum and to characterize the vital flow features for reactor safety. The Navier-Stokes equations are solved with standard k-ε turbulence model by using EDF in-house open source computational fluid dynamic (CFD) software: Code_Saturne. Through calculations, pressure and velocity distributions are obtained, axial and lateral variations have been analyzed. Compared with APR1400, it can be observed that for the design of AP1000, the rotational flow entrained in the edge of upper plenum and high velocity area due to the hot leg suction effect contribute to the relatively lower local pressure, and may have an impact on the drop velocity of control rod.
Pipeline Monitoring With Geotechnical Optical Fiber
Authors: Silva Christian , Ravet Fabien
Published: October 2017

The 408 km × 34" PERULNG pipeline (operated by Hunt LNG Operating Company) is monitored in its first 62 km by a geotechnical fiber optic cable, since these first 62 km are exposed to major geohazard threats such as landslides, large river crossings, high slopes, bofedales, etc.

The fiber optic cable geotechnical monitoring relies on the measurement of strain and temperature in the pipeline right-of-way.

Due to the continuous and real-time monitoring of the duct, it was possible to detect a tension cracking near KP 25 + 600 as an abnormal temperature change was captured by the temperature sensing cable; also near KP 27 + 900 and KP 34 + 750 unusual cable stresses were detected which announced landslides of the rotational type in both locations.

In these three cases, protection decisions could be taken to secure pipeline’s integrity.
OCENSA Oil Pipeline Damage due to the Construction of an Embankment for a Highway on Soft Soils: Case Study
Authors: Corrales Julian , García García Hugo Alberto , Marín Alejandro , Pereira Ordóñez Mauricio
Published: October 2017

The OCENSA pipeline crosses the Valley of the Magdalena river flood on its way to the Caribbean Sea, the area of the valley is commonly inundated during the rainy season on shallow waters that remain flooded swamps. These swamps soils are composed by extremely soft peat with thicknesses greater than 15 meters. In June 2016 started the construction of a highway with an embankment of 6 meters in height which was more than 30 meters away from the OCENSA 30” pipeline, Due to the high compressibility of peat, to construct the road the soil is subjected to a process of consolidation and the height of the embankment was corrected adding more material. In July 29 2016 occurs a failure by load capacity on the ground under the embankment and as a result of this fault a lateral displacement of the adjacent soil producing a horizontal displacement in the pipeline of more than 50 cm. This document shows results from the affectation to the pipe and the measures taken to correct the situation.
Proactive Approaches to Geohazard Management
Authors: Ruik Beyhaut S.
Published: October 2017

To control the threats from external forces, pipeline owners and operators require detailed information about their pipeline infrastructure and the environment surrounding that infrastructure. The contribution from geographic data is recognized as an increasingly important part of a complete integrity management program, particularly for the identification of geohazards. This is because geohazards are generally characterized by high spatial variability, are complex and difficult to quantify but may result in catastrophic failure of pipelines.

In recent years we have seen widespread technological development surrounding the processes to capture information in order to deliver quantitative inputs for pipeline engineers, risk & geotechnical experts. International codes & best practices (e.g. AS 2885.1-2012) state that “Environmental impact assessment is not simply a vehicle to obtain regulatory approval, it is a critical element of the planning for design, construction and operation of the pipeline.” Furthermore, geohazards frequently develop during the service life of pipelines. Consequently, regulators recommend that assessments are conducted on an ongoing basis to identify all potential threats and implement mitigation measures.

A process has been developed to create efficient and economical solutions for monitoring and assessing the significance of pipeline bending strain and whether actual movement has taken place. This process can make use of a variety of inputs including slope gradient, climate, groundwater conditions, slope instability, seismic intensity, and environmental impacts, and can provide important information in the determination of potential mitigations. This paper will review the benefits which can be gained from the implementation of integrated approaches to inform geohazard management.
Development of Risk-Based Inspection Methodology in River Crossings
Authors: de Paula Eduardo Lopes , Moratti Markus , Rodrigues Eduardo Henrique da Silva , Scherrer Elivelton Pinheiro
Published: October 2017

The transportation system for hydrocarbons consists of an important and complex network of pipelines used by oil and gas logistics companies, designed to quickly and efficiently transport oil and gas from its origin, to areas of some demand along territory where operates. Currently Brazil has 15,000 km of transportation pipelines within about 7,500 km of right-of-way pipelines. Along its territorial extension it faces several influences along its route, being the main ones influenced by the external hazards from nature and by third party actions. TRANSPETRO has about 450 water crossings in cataloged water bodies currently. These crossings are currently characterized only according to their geometric characteristics, not considering several aspects inherent to them. The inspections at these crossings are laborious and have a high cost due to necessity of divers and bathymetry in some cases.

To monitor the condition of all pipeline water crossings it is important to ensure the pipeline integrity. Depending on hydraulic phenomena, it is possible result in an exposure of the pipelines, free spans, changes in the original pipeline or excessive vibration. These changes can generate high mechanical stresses with both static and dynamic loads. The present study was characterized by the development of a methodology for assessing the susceptibility to the exposure of pipelines as a result of the hydrological hazards present at the crossings in which they are found. Moreover, this evaluation methodology offers a tool to define inspection extent and frequency, as well as the corresponding risk control actions. For this purpose, a pipeline management program has been set up, which consists in the definition of water crossings that constitute a potential hydrological hazard and where they can interact with the pipeline considering the probability of a specific hydrotechnical hazard leading the pipeline the exposure.

As a result of this research it was defined a methodology to characterize pipeline crossing areas as well as field survey, evaluation of the susceptibility of pipeline exposure at crossings and the programming of control actions were defined according to the susceptibility found. Finally, the study has also presented a cost analysis of crossings inspections comparing the traditional method to the new premises adopted in this project.
A Statistical Method for Benchmarking Nuclear Plant Models, Using ACAP
Authors: McCloskey John P. , Smith Richard J.
Published: October 2017

One of the requirements for validating nuclear reactor plant models is to benchmark the predicted results of selected transients against measured plant data or another qualified code. A major challenge with benchmarking is the criteria for validating a model are not always well defined and rely heavily on human judgment, thus introducing the possibility of human bias or inconsistent conclusions. The validation process can also be time consuming.

A new method is presented to aid in the validation of nuclear reactor plant models, using the Automated Code Assessment Program (ACAP), which is a tool developed at Pennsylvania State University under contract by the U. S. Nuclear Regulatory Commission (NRC). The proposed method was developed specifically for real-time best-estimate nuclear operator training simulator transients. However, the tool can be easily customized for most applications (e.g., design models, steady state data). Four distinct statistical metrics and weightings were chosen, as deemed appropriate for transient nuclear operator training simulator applications. The metrics account for errors in magnitude and trend, and incorporate an experimental uncertainty. The four metrics are then combined into a single Figure of Merit (i.e., a statistical level of agreement between the predicted and benchmarking data sets).

The use of ACAP for benchmarking is demonstrated by comparing experimental data from the Loss-of-Fluid-Test (LOFT) facility Large Break Loss-of-Coolant Experiment L2-5 with code predictions from a RELAP5-3D (Version 2.9.3+) model previously developed and published by Idaho National Laboratories. The proposed method is shown to have several advantages over conventional validation methods, in that it greatly reduces the possibility of human bias, generates reproducible results, can be easily automated to improve efficiency, and can be easily documented. After the initial validation, the tool can also be used to re-validate models after computer hardware changes, model changes, tool upgrades, and operating system upgrades.
Impact of preparation conditions on the properties of materials for replica stamps
Authors: Papenheim Marc , Eidemüller Wolfgang , Steinberg Christian , Mayer Andre , Scheer Hella-Christin
Published: October 2017

Replica stamps fabricated of cross-linked materials are commonly used for nanoimprint lithography. Their mechanical properties depend on the preparation conditions and on the configuration used for curing as well. Typically, curing of a thin layer goes hand in hand with a shrinkage in the vertical direction. In a curing situation where this shrinkage is hindered, the cross-link density is reduced, resulting in a lower modulus. With respect to this issue, three cross-linkable materials are investigated, sylgard-polydimethylsiloxane, ultraviolet-polydimethylsiloxane, and OrmoStamp. The modulus is determined from the deflection of two-layer samples under temperature loading. Curing is performed under varying processing conditions; moreover, the impact of hindered shrinkage is addressed by experiments holding the layer thickness fixed during curing, a situation typical with automated stamp replication. The hindered shrinkage results in a modulus reduced by about 20%. The results obtained are vital for reproducible and comparable stamp preparation, beyond a single laboratory. A thorough and complete specification of replica stamp preparation does not only require information on the conventional processing parameters; it requires information on the curing configuration as well.
Quantifying Young's moduli of protein fibrils and particles with bimodal force spectroscopy
Authors: Gilbert Jay , Charnley Mirren , Cheng Christopher , Reynolds Nicholas P. , Jones Owen G.
Published: October 2017

Force spectroscopy is a means of obtaining mechanical information of individual nanometer-scale structures in composite materials, such as protein assemblies for use in consumer films or gels. As a recently developed force spectroscopy technique, bimodal force spectroscopy relates frequency shifts in cantilevers simultaneously excited at multiple frequencies to the elastic properties of the contacted material, yet its utility for quantitative characterization of biopolymer assemblies has been limited. In this study, a linear correlation between experimental frequency shift and Young's modulus of polymer films was used to calibrate bimodal force spectroscopy and quantify Young's modulus of two protein nanostructures: β-lactoglobulin fibrils and zein nanoparticles. Cross-sectional Young's modulus of protein fibrils was determined to be 1.6 GPa while the modulus of zein nanoparticles was determined as 854 MPa. Parallel measurement of β-lactoglobulin fibril by a competing pulsed-force technique found a higher cross-sectional Young's modulus, highlighting the importance of comparative calibration against known standards in both pulsed and bimodal force spectroscopies. These findings demonstrate a successful procedure for measuring mechanical properties of individual protein assemblies with potential use in biological or packaging applications using bimodal force spectroscopy.
Identification of XBP1-u as a novel regulator of the MDM2/p53 axis using an shRNA library
Authors: Huang Can , Wu Shourong , Ji Hong , Yan Xuesong , Xie Yudan , Murai Saomi , Zhao Hezhao , Miyagishi Makoto , Kasim Vivi
Published: October 2017

The unspliced form of XBP1 stabilizes MDM2 protein by inhibiting its ubiquitination and regulates the MDM2/p53 axis.
Upscaling species richness and abundances in tropical forests
Authors: Tovo Anna , Suweis Samir , Formentin Marco , Favretti Marco , Volkov Igor , Banavar Jayanth R. , Azaele Sandro , Maritan Amos
Published: October 2017

We provide a framework to upscale biodiversity in tropical forests from local samples of species richness and abundances.
A spacetime tremor and a celestial light show
Authors: Cho Adrian
Published: October 2017

Unprecedented view of a neutron-star collision is a scientific gold mine.
Emails reveal pressures on NIH gun research
Authors: Wadman Meredith
Published: October 2017

Agency staff wanted program on firearms violence to continue.
Untangling spider biology
Authors: Pennisi Elizabeth
Published: October 2017

Genomics begins to unravel the roots of spider diversity and the recipes of their silk and venom.
Response to Comment on “Persistent effects of pre-Columbian plant domestication on Amazonian forest composition”
Authors: Junqueira André Braga , Levis Carolina , Bongers Frans , Peña-Claros Marielos , Clement Charles Roland , Costa Flávia , ter Steege Hans
Published: October 2017

McMichael
et al
. state that we overlooked the effects of post-Columbian human activities in shaping current floristic patterns in Amazonian forests. We formally show that post-Columbian human influences on Amazonian forests are indeed important, but they have played a smaller role when compared to the persistent effects of pre-Columbian human activities on current forest composition.
Breaking bad algorithms
Technically Wrong
Sara Wachter-Boettcher
Norton, 2017. 240 pp.
Authors: Hoffmann Anna Lauren
Published: October 2017

Biased tech design prompts a writer to call for resistance
In over our heads
The Water Will Come
Jeff Goodell
Little Brown, 2017. 349 pp.
Authors: Lamond Jessica
Published: October 2017

An urgent treatise on rising sea levels predicts a wild and watery future
Intestinal inflammation induced by oral bacteria
Authors: Cao Xuetao
Published: October 2017

Colonization of intestine by oral bacteria can induce inflammatory disorders
A biochemical sulfur delivery service
Authors: Rosenzweig Amy C.
Published: October 2017

A steady supply of iron-sulfur clusters sustains biosynthesis of the lipoyl cofactor
Using Treponemal Assay Signal Strength Cutoff Ratios To Predict Syphilis Infection
Authors: Bristow Claire C. , Klausner Jeffrey D.
Published: October 2017

Syphilis screening with the reverse algorithm, a treponemal test for screening followed by a nontreponemal test if reactive, is increasingly being used. That algorithm has several advantages, including use of an automated screening test, saving on laboratory time and costs, as well as detection of very early syphilis infection. However, under that algorithm, in situations where the treponemal result is positive and the nontreponemal result is nonreactive a second treponemal test must be performed, which may actually lead to inefficiencies in the laboratory. In this issue of the
Journal of Clinical Microbiology
, Y. F. Fakile et al. (J Clin Microbiol 56:e01165-17, 2017,
https://doi.org/10.1128/JCM.01165-17
) report the results of their study, which demonstrates the capability of signal strength ratio cutoffs for automated treponemal immunoassays to predict the outcome of repeat treponemal testing. Their findings suggest that anti-treponemal signal strength ratio values above a cutoff value can be used in lieu of repeat treponemal tests.
HIV-1 Infection of Primary CD4
+
T Cells Regulates the Expression of Specific Human Endogenous Retrovirus HERV-K (HML-2) Elements
Authors: Young George R. , Terry Sandra N. , Manganaro Lara , Cuesta-Dominguez Alvaro , Deikus Gintaras , Bernal-Rubio Dabeiba , Campisi Laura , Fernandez-Sesma Ana , Sebra Robert , Simon Viviana , Mulder Lubbertus C. F.
Published: October 2017

Endogenous retroviruses (ERVs) occupy extensive regions of the human genome. Although many of these retroviral elements have lost their ability to replicate, those whose insertion took place more recently, such as the HML-2 group of HERV-K elements, still retain intact open reading frames and the capacity to produce certain viral RNA and/or proteins. Transcription of these ERVs is, however, tightly regulated by dedicated epigenetic control mechanisms. Nonetheless, it has been reported that some pathological states, such as viral infections and certain cancers, coincide with ERV expression, suggesting that transcriptional reawakening is possible. HML-2 elements are reportedly induced during HIV-1 infection, but the conserved nature of these elements has, until recently, rendered their expression profiling problematic. Here, we provide comprehensive HERV-K HML-2 expression profiles specific for productively HIV-1-infected primary human CD4
+
T cells. We combined enrichment of HIV-1 infected cells using a reporter virus expressing a surface reporter for gentle and efficient purification with long-read single-molecule real-time sequencing. We show that three HML-2 proviruses—6q25.1, 8q24.3, and 19q13.42—are upregulated on average between 3- and 5-fold in HIV-1-infected CD4
+
T cells. One provirus, HML-2 12q24.33, in contrast, was repressed in the presence of active HIV replication. In conclusion, this report identifies the HERV-K HML-2 loci whose expression profiles differ upon HIV-1 infection in primary human CD4
+
T cells. These data will help pave the way for further studies on the influence of endogenous retroviruses on HIV-1 replication.

IMPORTANCE
Endogenous retroviruses inhabit big portions of our genome. Moreover, although they are mainly inert, some of the evolutionarily younger members maintain the ability to express both RNA and proteins. We have developed an approach using long-read single-molecule real-time (SMRT) sequencing that produces long reads that allow us to obtain detailed and accurate HERV-K HML-2 expression profiles. We applied this approach to study HERV-K expression in the presence or absence of productive HIV-1 infection of primary human CD4
+
T cells. In addition to using SMRT sequencing, our strategy also includes the magnetic selection of the infected cells so that levels of background expression due to uninfected cells are kept at a minimum. The results presented here provide a blueprint for in-depth studies of the interactions of the authentic upregulated HERV-K HML-2 elements and HIV-1.
Innate Sensing of Influenza A Virus Hemagglutinin Glycoproteins by the Host Endoplasmic Reticulum (ER) Stress Pathway Triggers a Potent Antiviral Response via ER-Associated Protein Degradation
Authors: Frabutt Dylan A. , Wang Bin , Riaz Sana , Schwartz Richard C. , Zheng Yong-Hui
Published: October 2017

Innate immunity provides an immediate defense against infection after host cells sense danger signals from microbes. Endoplasmic reticulum (ER) stress arises from accumulation of misfolded/unfolded proteins when protein load overwhelms the ER folding capacity, which activates the unfolded protein response (UPR) to restore ER homeostasis. Here, we show that a mechanism for antiviral innate immunity is triggered after the ER stress pathway senses viral glycoproteins. When hemagglutinin (HA) glycoproteins from influenza A virus (IAV) are expressed in cells, ER stress is induced, resulting in rapid HA degradation via proteasomes. The ER-associated protein degradation (ERAD) pathway, an important UPR function for destruction of aberrant proteins, mediates HA degradation. Three class I α-mannosidases were identified to play a critical role in the degradation process, including EDEM1, EDEM2, and ERManI. HA degradation requires either ERManI enzymatic activity or EDEM1/EDEM2 enzymatic activity when ERManI is not expressed, indicating that demannosylation is a critical step for HA degradation. Silencing of EDEM1, EDEM2, and ERManI strongly increases HA expression and promotes IAV replication. Thus, the ER stress pathway senses influenza HA as “nonself” or misfolded protein and sorts HA to ERAD for degradation, resulting in inhibition of IAV replication.

IMPORTANCE
Viral nucleic acids are recognized as important inducers of innate antiviral immune responses that are sensed by multiple classes of sensors, but other inducers and sensors of viral innate immunity need to be identified and characterized. Here, we used IAV to investigate how host innate immunity is activated. We found that IAV HA glycoproteins induce ER stress, resulting in HA degradation via ERAD and consequent inhibition of IAV replication. In addition, we have identified three class I α-mannosidases, EDEM1, EDEM2, and ERManI, which play a critical role in initiating HA degradation. Knockdown of these proteins substantially increases HA expression and IAV replication. The enzymatic activities and joint actions of these mannosidases are required for this antiviral activity. Our results suggest that viral glycoproteins induce a strong innate antiviral response through activating the ER stress pathway during viral infection.
Microbiota Diversification and Crash Induced by Dietary Oxalate in the Mammalian Herbivore
Neotoma albigula
Authors: Miller Aaron W. , Dale Colin , Dearing M. Denise
Published: October 2017

The bacteria associated with mammalian hosts exhibit extensive interactions with overall host physiology and contribute significantly to the health of the host. Bacteria are vital to the mitigation of the toxic effects of oxalate specifically as mammals do not possess the enzymes to degrade this compound, which is present in the majority of kidney stones. Contrary to the body of literature on a few oxalate-degrading specialists, our work illustrates that oxalate stimulates a broad but cohesive microbial network in a dose-dependent manner. The unique characteristics of the
N. albigula
microbiota make it an excellent source for the development of bacteriotherapies to inhibit kidney stone formation. Furthermore, this work successfully demonstrates methods to identify microbial networks responsive to specific toxins, their limits, and important elements such as microbial network cohesivity and architecture. These are necessary steps in the development of targeted bacteriotherapies.
Safety profile and efficacy of tacrolimus in the treatment of birdshot retinochoroiditis: a retrospective case series review
Authors: Islam Farrah , Westcott Mark , Rees Angela , Robson Anthony George , Kapoor Bharat , Holder Graham , Pavesio Carlos
Published: October 2017

Aim

Evaluation of the use of tacrolimus in the treatment of birdshot retinochoroiditis (BRC) at a tertiary referral centre with the aim to describe its safety and efficacy.

Methods

The medical records of 25 patients diagnosed with BRC at uveitis service, Moorfields Eye Hospital, and who had received tacrolimus treatment were retrospectively reviewed. The main outcome measures of the study were (1) safety of tacrolimus in terms of side effects and (2) efficacy, as measured both by control of inflammation and visual function assessed by Humphrey visual fields and electrophysiological testing over at least 6 months and then 1 year.

Results

Tacrolimus was commenced in 25 patients (mean age 50.4±10.8 years) and was well tolerated in 21 patients (84%). It was necessary to stop the tacrolimus in four patients. No patient showed major changes in renal function: 3/21 patients (14.28%) showed slightly abnormal (less than 30%) function at the end of the first month of treatment; 1/21 (4.76%) patients at 3 months, but at the end of a 6-month treatment period only 1/21 patients (4.76%) showed minor abnormality in renal function. The mean daily prednisolone dose was 19.7 mg at the beginning of the study, which had fallen to 6.9 mg at the end (t=5.071, p=0.001). Visual acuity mostly remained stable. Visual fields improved over time (mean improvement in Humphrey mean deviation, right eye=1.8±2.4 dB, t=3.821, p=0.004; left eye=1.9±2.7, dB, t=3.06, p=0.007). Electrophysiological function showed improvement in 10 patients, and in four patients an initial deterioration in function improved following tacrolimus dose adjustment.

Conclusion

Tacrolimus has a good safety profile for long-term use in patients with BRC as a second-line agent enabling steroid sparing and visual function stabilisation or improvement.