bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigations on RELAP5-3D to RELAP5-3D Coupling Methodology by PVMEXEC
Authors: Parrinello Valeria , Lanfredini Marco , Petruzzi Alessandro , Cherubini Marco 
Published: October 2016

In the framework of a BEPU (Best Estimate Plus Uncertainty) approach within the licensing process of a nuclear power plant, the need to extend the resources of nuclear system thermal-hydraulics codes, such as RELAP5-3D, arises to allow more detailed simulations of the complex 3D reality of Nuclear Power Plants (NPPs), either under normal steady-state or during various accident scenarios.
Currently, it is not possible to achieve the same degree of detail for a whole nuclear system when it is simulated with RELAP5-3D and this is due to the inherent limitations in the number of components and volumes to be used for the analysis. For this reason, it is of extreme interest the use of tools for codes coupling that enable the use of different codes for the simulation of different portions of a system in a unified analysis.
In this paper the attention will be focused on the decomposition of the thermal-hydraulic domain of a system into subsystems to be simulated by different instances of the same code (e.g. RELAP5-3D) coupled together by means of PVMEXEC program and parallel virtual machine (PVM) technology. Explicit and semi-implicit solution algorithms were used for the analyses.
Among the analyzed cases, the following will be discussed in detail with the aim to provide additional guidelines for the use of the PVMEXEC tool: (i) the Edward’s pipe blowdown test, (ii) a simplified countercurrent heat exchanger, (iii) different hydraulics and heat structure coupling schemes for a shell-tube heat exchanger and (iv) a three-task coupled model of a simplified BWR model.
Use of FEA Software in Evaluating Pump Vibration and Potential Remedial Actions to Abate Resonance in Industrial Vertical Pump/Motor Combinations
Authors: Tompkins Michael , Stakenborghs Robert , Kramer Gregory 
Published: October 2016

Reactor recirculation motor generator lube oil twin screw pumps are commonly found in nuclear power plants and throughout industry. In a vertical mounting configuration in which the electric motor is bolted atop the twin screw pump in an unsupported manner the natural frequency of the pump/motor structure can be quite low, resulting in damaging vibration. When a structure’s natural frequency coincides at or near the operating speed, or multiple thereof, a phenomena known as resonance can occur. Resonance can occur when a driving force, in this case minor imbalances in either the motor or pump, begins to vibrate and excite the structure resulting in greatly amplified levels of vibration.
In this paper, finite element analysis software is utilized to first calculate the natural frequency of the pump/motor structure, and then potential modifications are modeled to determine their impact on eliminating harmful resonance.
Development of Hydrogen Treatment System in Severe Accident: Part 2 — Study on Reaction Characteristic of a Hydrogen Processing Unit
Authors: Iwaki Chikako , Kittaka Daigo , Yoshii Toshihiro , Yagyu Motoshige , Okamura Masato , Tanabe Masashi , Ishibashi Fumihiko 
Published: October 2016

In the course of a severe accident, a large amount of hydrogen gas is generated by a metal-water reaction in a PCV (Primary Containment Vessel) of Light Water Reactors. Although the filter vent of gas mixture, which includes hydrogen and steam, is an effective method for the accident management of BWR that prevents the PCV overpressure, the filter vent at the early stage of severe accident may cause releasing radioactive material to environment. We have been developing the hydrogen treatment system to prevent excessive pressure without PCV vent and releasing radioactive material to environment.
We focus on the oxidation-reduction reaction of metal oxides with high reaction rates, for the hydrogen treatment system. Metal oxide material would be an effective device under low-oxygen conditions like PCV of BWR. The hydrogen treatment system mainly consists of a hydrogen processing unit, a blower and pipes. The hydrogen treatment unit has a lot of reaction pipes in which metal oxides are filled. Some fundamental chemical experiments which we have done have revealed that copper oxides (CuO) rapidly react with hydrogen to form cupper (Cu). Their results show that metal oxides are effective as hydrogen treatment elements. On the other hand, there are few evaluations for the characteristics of hydrogen treatment unit. The dependency of hydrogen treatment performance on gas temperature, hydrogen concentration and pressure is investigated in the present study.
We conducted experiments using a test section with one reaction pipe, which simulated a hydrogen processing unit. The processing materials granulated CuO, MnO2 and Co3O4 with 2mm diameter were used. Gradual increase of processing material temperature in the test section was observed along the gas streams caused by oxidation-reduction reaction after the mixing gases were supplied. Consequently, the hydrogen concentration at the outlet of the test section decreased with time. The increase of the hydrogen reaction rate was also observed with increase of gas temperature, hydrogen concentration and pressure. We have developed the thermal-chemical model of hydrogen processing unit from these experiment results, and confirmed that the model could predict the characteristics of a hydrogen processing unit qualitatively.
The Development of RELAP5 for Reactor System Analysis and Simulation Use of Visualized Modularization Software (RELAP-MV)
Authors: Yousif Eltayeb , Zhang Zhijian , Tian Zhaofei , Ju Haoran 
Published: October 2016

The RELAP5 code, designed to predict the behavior of reactor systems during accident conditions, is used widespread over the world. This work aims to show and describe the RELAP-MV graphical software developed using computer language (XML) and Visualized Modularization software technology to recognized best estimated transient simulation program of Light water reactor, in combination with new options for improved modeling methods, advanced programming, computational simulation techniques and integrated graphics displays. RELAP5 code is complex and inconvenient for utilizing method of data cards and close logic relationship of data in input file. The main purpose of developing RELAP5-MV is to simplify progress and increase simulation efficiency.
Traditional modeling method and modular modeling method are supported with RELAP5-MV to achieve aims of device and system simulation. For traditional modeling method, all kinds of components are developed such as single volume, single junction, pipe, branch, time dependent volume, etc. For modular modeling method, the module library is established in the software. The library packages include the main system equipments of primary and secondary loops such as reactor core, U tube steam generator, once through steam generator, pump, pressurizer, steam turbine, condenser, heat exchanger, deaerator, etc. in a pressurized water reactor, which can be analyzed and modeled in details. From the library the capabilities are easy to select icons interface from the library packages. The analysis results show that the software can effectively simulate nuclear power system by RELAP5.
Plot and data binding function is supported for post-processing of calculation result. Personal computer interface of RELAP5-MV makes it more convenient, fast and visualized in simulation system establishing process. Performance Relap5 related analysis activities, such as creating and modifying input file, viewing component division figures and generating output files can be realized by RELAP5-MV. The interactive simulation interface feature allows the users to simulate specific reactor transients and accidents — such as LOCA, LOFA, scram, etc. Accuracy and reliability of RELAP5-MV have already been confirmed by simulating main coolant system of Pressurize Water Reactor (PWR) and modeling efficiency increases significantly by using RELAP5-MV.
Visualization modeling, analysis and computational simulation for thermal hydraulic analysis of nuclear reactor can not only lower the RELAP5 threshold but also improve the efficiency of nuclear science research greatly, and also promoting the development of related research in RELAP5 safety analysis.
RELAP5-MV can give an approach to build, verify and assess simulation design of reactor power system.
Thermal-Hydraulic Investigations to the Flow of Model Gases at a PWR Fuel Assembly Dummy and Overflow of Air Above the Top of the Dummy
Authors: Chahi H. , Kästner W. , Alt S. 
Published: October 2016

The burnt fuel assemblies, which are unloaded from the reactor core, are storage in a water-cooled storage pool until radioactivity and heat decays to the authorized transportation value of dry storage containers.
With the incident in a storage pool fatal consequences can occur that depend on the initiating event (station blackout, loss of coolant, etc.). The integrity of the cladding tubes of the fuel assemblies is an important aspect in the nuclear safety.
Thermal-hydraulic phenomena were investigated, which occur during evaporation of the storage pool and overheating of the steam followed by an upwards flow in the fuel assembly boxes. According the principle of similarity, physical parameters of the steam upwards flow were simulated by not heated model gases.
The overflow of air above the fuel assembly storage boxes was experimentally investigated in a horizontal overflow channel. The conditions of the air overflow were vary by air conditioning (temperature, humidity). The interactions of density driven flow or diffusion (air / gas model) and the interaction (air / steam) with the overflow simulated the thermal-hydraulic phenomena during these processes.
The paper includes the presentation of the experimental facility and some results of the experiments.
This research project supported by the German Federal Ministry of Education and Research named SINABEL (Safety of spent fuel pools: Experimental analysis, modeling and validation of system and CFD codes) delivers with a combination of experiments and simulations, knowledge’s of the heat transfer processes for the case of a partially or completely evaporated spent fuel storage pool in light water reactor nuclear power plants both within the fuel rod bundle of a fuel assembly (FA) and in the spaces between the FA in order to be able to predict via the modeling and simulation the development of the axial and radial temperature profiles of rods by different accident scenarios.
SINABEL is a joint research project which three research institutions (TU-Dresden, HZDR and HSZG) work together.
Influencing Factors of the HTR-10 Core Dynamics in Reactivity Insertion ATWS Tests
Authors: Gou Feng , Chen Fubing , Dong Yujie 
Published: October 2016

After the full power operation of the 10 MW High Temperature Gas-cooled Reactor-Test Module (HTR-10), several safety demonstration tests, representing the anticipated transient without scram (ATWS) conditions, were successfully performed on this reactor. Among these tests, two reactivity insertion ATWS tests were conducted by withdrawing a single control rod without reactor scram at 30% rated power.
In the Institute of Nuclear and New Energy Technology (INET) of Tsinghua University, these two tests have been reanalyzed using the THERMIX code, and the code itself was strictly checked through the test data. According to the previous code benchmark activities utilizing the HTR-10 tests, the temperature coefficient of reactivity (TCR), the residual heat level (RHL) and the xenon poisoning effect (XPE) could be considered the most important influencing factors of the THERMIX simulation accuracy for the core dynamics. In this study, sensitivity analyses are performed on the basis of the assumed variations of TCR, RHL and XPE. The impacts of these concerned parameters on the reactor power transient are qualitatively identified.
Biochemical and Genetic Bases of Indole-3-Acetic Acid (Auxin Phytohormone) Degradation by the Plant-Growth-Promoting Rhizobacterium Paraburkholderia phytofirmans PsJN
Authors: Donoso Raúl , Leiva-Novoa Pablo , Zúñiga Ana , Timmermann Tania , Recabarren-Gajardo Gonzalo , González Bernardo 
Published: October 2016

ABSTRACT

Several bacteria use the plant hormone indole-3-acetic acid (IAA) as a sole carbon and energy source. A cluster of genes (named
iac
) encoding IAA degradation has been reported in
Pseudomonas putida
1290, but the functions of these genes are not completely understood. The plant-growth-promoting rhizobacterium
Paraburkholderia phytofirmans
PsJN harbors
iac
gene homologues in its genome, but with a different gene organization and context than those of
P. putida
1290. The
iac
gene functions enable
P. phytofirmans
to use IAA as a sole carbon and energy source. Employing a heterologous expression system approach,
P. phytofirmans
iac
genes with previously undescribed functions were associated with specific biochemical steps. In addition, two uncharacterized genes, previously unreported in
P. putida
and found to be related to major facilitator and tautomerase superfamilies, are involved in removal of an IAA metabolite called dioxindole-3-acetate. Similar to the case in strain 1290, IAA degradation proceeds through catechol as intermediate, which is subsequently degraded by
ortho
-ring cleavage. A putative two-component regulatory system and a LysR-type regulator, which apparently respond to IAA and dioxindole-3-acetate, respectively, are involved in
iac
gene regulation in
P. phytofirmans
. These results provide new insights about unknown gene functions and complex regulatory mechanisms in IAA bacterial catabolism.

IMPORTANCE
This study describes indole-3-acetic acid (auxin phytohormone) degradation in the well-known betaproteobacterium
P. phytofirmans
PsJN and comprises a complete description of genes, some of them with previously unreported functions, and the general basis of their gene regulation. This work contributes to the understanding of how beneficial bacteria interact with plants, helping them to grow and/or to resist environmental stresses, through a complex set of molecular signals, in this case through degradation of a highly relevant plant hormone.
Metabolic Engineering of Raoultella ornithinolytica BF60 for Production of 2,5-Furandicarboxylic Acid from 5-Hydroxymethylfurfural
Authors: Hossain Gazi Sakir , Yuan Haibo , Li Jianghua , Shin Hyun-dong , Wang Miao , Du Guocheng , Chen Jian , Liu Long 
Published: October 2016

ABSTRACT

2,5-Furandicarboxylic acid (FDCA) is an important renewable biotechnological building block because it serves as an environmentally friendly substitute for terephthalic acid in the production of polyesters. Currently, FDCA is produced mainly via chemical oxidation, which can cause severe environmental pollution. In this study, we developed an environmentally friendly process for the production of FDCA from 5-hydroxymethyl furfural (5-HMF) using a newly isolated strain,
Raoultella ornithinolytica
BF60. First,
R. ornithinolytica
BF60 was identified by screening and was isolated. Its maximal FDCA titer was 7.9 g/liter, and the maximal molar conversion ratio of 5-HMF to FDCA was 51.0% (mol/mol) under optimal conditions (100 mM 5-HMF, 45 g/liter whole-cell biocatalyst, 30°C, and 50 mM phosphate buffer [pH 8.0]). Next,
dcaD
, encoding dicarboxylic acid decarboxylase, was mutated to block FDCA degradation to furoic acid, thus increasing FDCA production to 9.2 g/liter. Subsequently,
aldR
, encoding aldehyde reductase, was mutated to prevent the catabolism of 5-HMF to HMF alcohol, further increasing the FDCA titer, to 11.3 g/liter. Finally, the gene encoding aldehyde dehydrogenase 1 was overexpressed. The FDCA titer increased to 13.9 g/liter, 1.7 times that of the wild-type strain, and the molar conversion ratio increased to 89.0%.

IMPORTANCE
In this work, we developed an ecofriendly bioprocess for green production of FDCA in engineered
R. ornithinolytica
. This report provides a starting point for further metabolic engineering aimed at a process for industrial production of FDCA using
R. ornithinolytica
.
Extended-Spectrum-Beta-Lactamase- and Plasmid-Encoded Cephamycinase-Producing Enterobacteria in the Broiler Hatchery as a Potential Mode of Pseudo-Vertical Transmission
Authors: Projahn Michaela , Daehre Katrin , Roesler Uwe , Friese Anika 
Published: October 2016

ABSTRACT

Antimicrobial resistance through extended-spectrum beta-lactamases (ESBLs) and transferable (plasmid-encoded) cephamycinases (pAmpCs) represents an increasing problem in human and veterinary medicine. The presence of ESBL-/pAmpC-producing commensal enterobacteria in farm animals, such as broiler chickens, is considered one possible source of food contamination and could therefore also be relevant for human colonization. Studies on transmission routes along the broiler production chain showed that 1-day-old hatchlings are already affected. In this study, ESBL-/pAmpC-positive broiler parent flocks and their corresponding eggs, as well as various environmental and air samples from the hatchery, were analyzed. The eggs were investigated concerning ESBL-/pAmpC-producing enterobacteria on the outer eggshell surface (before/after disinfection), the inner eggshell surface, and the egg content. Isolates were analyzed concerning their species, their phylogroup in the case of
Escherichia coli
strains, the respective resistance genes, and the phenotypical antibiotic resistance. Of the tested eggs, 0.9% (
n
= 560) were contaminated on their outer shell surface. Further analyses using pulsed-field gel electrophoresis showed a relationship of these strains to those isolated from the corresponding parent flocks, which demonstrates a pseudo-vertical transfer of ESBL-/pAmpC-producing enterobacteria into the hatchery. Resistant enterobacteria were also found in environmental samples from the hatchery, such as dust or surfaces which could pose as a possible contamination source for the hatchlings. All 1-day-old chicks tested negative directly after hatching. The results show a possible entry of ESBL-/pAmpC-producing enterobacteria from the parent flocks into the hatchery; however, the impact of the hatchery on colonization of the hatchlings seems to be low.

IMPORTANCE
ESBL-/pAmpC-producing enterobacteria occur frequently in broiler-fattening farms. Recent studies investigated the prevalence and possible transmission route of these bacteria in the broiler production chain. It seemed very likely that the hatcheries play an important role in transmission and/or contamination events. There are only few data on transmission investigations from a grandparent or parent flock to their offspring. However, reliable data on direct or indirect vertical transmission events in the hatchery are not available. Therefore, we conducted our study and intensively investigated the broiler hatching eggs from ESBL-/pAmpC-positive broiler parent flocks as well as the hatchlings and the environment of the hatchery.
Allelochemicals Produced by Brown Macroalgae of the Lobophora Genus Are Active against Coral Larvae and Associated Bacteria, Supporting Pathogenic Shifts to Vibrio Dominance
Authors: Morrow Kathleen M. , Bromhall Katrina , Motti Cherie A. , Munn Colin B. , Bourne David G. 
Published: October 2016

ABSTRACT

Pervasive environmental stressors on coral reefs are attributed with shifting the competitive balance in favor of alternative dominants, such as macroalgae. Previous studies have demonstrated that macroalgae compete with corals via a number of mechanisms, including the production of potent primary and secondary metabolites that can influence coral-associated microbial communities. The present study investigates the effects of the Pacific brown macroalga
Lobophora
sp. (due to the shifting nature of the
Lobophora
species complex, it will be referred to here as
Lobophora
sp.) on coral bacterial isolates, coral larvae, and the microbiome associated with the coral
Porites cylindrica.
Crude aqueous and organic macroalgal extracts were found to inhibit the growth of coral-associated bacteria. Extracts and fractions were also shown to inhibit coral larval settlement and cause mortality at concentrations lower (<0.3 mg · ml
−1
) than calculated natural concentrations (4.4 mg · ml
−1
). Microbial communities associated with coral tissues exposed to aqueous (e.g., hydrophilic) crude extracts demonstrated a significant shift to
Vibrio
dominance and a loss of sequences related to the putative coral bacterial symbiont,
Endozoicomonas
sp., based on 16S rRNA amplicon sequencing. This study contributes to growing evidence that macroalgal allelochemicals, dissolved organic material, and native macroalgal microbial assemblages all play a role in shifting the microbial equilibrium of the coral holobiont away from a beneficial state, contributing to a decline in coral fitness and a shift in ecosystem structure.

IMPORTANCE
Diverse microbial communities associate with coral tissues and mucus, providing important protective and nutritional services, but once disturbed, the microbial equilibrium may shift from a beneficial state to one that is detrimental or pathogenic. Macroalgae (e.g., seaweeds) can physically and chemically interact with corals, causing abrasion, bleaching, and overall stress. This study contributes to a growing body of evidence suggesting that macroalgae play a critical role in shifting the coral holobiont equilibrium, which may promote the invasion of opportunistic pathogens and cause coral mortality, facilitating additional macroalgal growth and invasion in the reef. Thus, macroalgae not only contribute to a decline in coral fitness but also influence coral reef ecosystem structure.