bluuebunny/crossref_metadata_2025_split huggingface dataset:
Risk-Informed and Defense-in-Depth Oriented Plant Design Approach
Authors: Morota Hidetsugu , Suzuki Hiroshi , Sakihama Takashi , Nasif Hesham R. , Sano Hiroshi 
Published: October 2013

Defense-in-Depth is the basis of safety design of nuclear plants, and refined and strengthened year by year. Nowadays, the importance of it has been further highlighted triggered by the accident at Fukushima Daiichi Nuclear Power Station.
Accidents described previously have been shown it could not care enough to uncertainty related to design, construction, maintenance and operation has exposed. It’s the lessons learned of that is to say to reduce uncertainty of design is the use of risk informed is essential. Therefore, the establishment of the design approach that uses risk informed consideration of the Defense-in-Depth is an important theme.
Defense-in-Depth is a measure which prevents the increase of the event frequency and core damage in consideration of the degree of safety margins, redundancy, diversity and consideration of radiation safety due to core damage and security.
The plant designers and utilities have made efforts to ensure safety utilized conventional design technique, which means deterministic, and risk information, in order to incorporate Defense-in-Depth concepts.
To consider Defense-in-Depth in the design phase, various requirements should be taken into consideration. It has been coming to be able to perform more rational and quantitative judgment by utilization of risk information.
In that case, while the designers of various fields will work in cooperation to ensure safety, if there are common utilization schemes for risk information among designers, more efficient and rational design works can be advanced in consideration of Defense-in-Depth. However, conventionally, it is hard to say that such schemes have functioned in order that designers may advance design works in collaboration.
This research intends to generate the schemes which advance design works in sharing the same risk information databases, which mean various risk indications etc), in other words, the schemes which will become lingua franca for utilizing risk information, in case of nuclear plants designs.
Teaching of Nuclear Power Plant Safety at the National Technical University of Ukraine Within the New Course in Safety Culture
Authors: Begun Vasilij V. , Begun Sergij V. , Kilina Olena O. 
Published: October 2013

The necessity of safety analysis methods and probable scenarios of accidents teaching in the education of experts for nuclear industry in Ukraine has been realised only after the Chernobyl accident. We developed the content of the first educational course in probabilistic safety analysis in 1995 based on the experience of the countries having developed nuclear power, the USA first of all, and on the training course of the Idaho National Laboratory. After this in 1996 the new course in probabilistic safety analysis of nuclear power plant (NPP) was adopted at our university.
The new educational course in safety for students was developed and adopted in 2009 educational year - “Safety culture at nuclear installations of Ukraine”. Education and training in safety culture in higher educational institutions and in the nuclear power plants is a part of the general modern process of maintenance of safety, it is recommended by IAEA standards. The principles of safety culture are taken as a basis of the modern concept of safety of nuclear power plants.
This work has received a positive appreciation from the management of departments of safety and training of the personnel of operating organization National Nuclear Energy Generating Company Energoatom (NNEGC Energoatom) and from other leaders of nuclear industry. The content of this educational course was discussed at the international scientific conferences on safety culture in 2008 and 2010, and was preliminary printed in the professional journal «Nuclear and radiation safety». The purposes of education have been defined as a survey, generalizing course on safety of the NPP with an allocation of safety issues on the foreground. Practical questions of the equipment and NPP systems work, their interaction in emergencies and the role of the human-operator are studied. The procedure of failure analysis at NPP is studied. Students analyze equipment work, root and direct causes of incidents. Methods of estimation of safety conditions based on observable operational indicators are studied. Parameters, variables and indicators of safety culture are studied.
As a result of gained experience we have come to the conclusion about high advisability of educational courses in safety for students. Specially formed knowledge and education in the field of safety from a student’s bench are the basis of safety culture of the future nuclear industry expert.
Module Fabrication Strategy for Today’s Nuclear Industry
Authors: Smith Clayton T. , Hammeran John H. , Lockwood Carl 
Published: October 2013

First generation nuclear power plants were built onsite with large construction forces over a number of years using a design that was being revised during construction. Vendor supplied equipment skids were the closest thing to modular building techniques at that time. Modularization techniques are available today as a tool for performing parallel construction activities such as fabrication and assembly of components offsite to support the construction cost and schedule goals of a project. Accordingly, extensive planning and coordination is required by engineering, procurement, fabricators, and construction to support modularization.
The importance of developing a strategy for the utilization of modularization to the Nuclear Industry, Owners, and Engineering Procurement and Construction (EPC) entities, cannot be over emphasized, ensuring the development of a Corporate Modularization Fabrication Strategy, which incorporates and addresses the following, various elements:
• Project Modularization Plan
• Definitions and terms for module, modularization, and on-off-site fabrication
• Module types • Modularization boundaries
• Work processes for interface between Engineering, Procurement, Fabricator, and Quality to allow good communication between entities
• Constructability reviews • Modularization schedule linked to integrated project schedule
• Compliance with approved procedures and Quality Program requirements
• Commitment from management
This paper and presentation will discuss and highlight the following for a typical Advanced Boiling Water Reactor (ABWR) application:
• Typical Corporate Modularization Fabrication Strategy;
• Typical Modularization Concepts;
• Modularization: Friend or Foe.
Operating Condition of Steam Injector as a Passive Cooling System at Severe Accident of Nuclear Power Plant
Authors: Abe Yutaka , Shibayama Shunsuke , Kaneko Akiko , Iwaki Chikako , Narabayashi Tadashi , Mori Michitsugu 
Published: October 2013

Steam injector (SI) is a passive jet pump which is driven by high-performance steam condensation onto water jet and it is expected to be active at severe accident of nuclear power plant with no electricity. SI is mainly consists of convergent-divergent nozzle. Supersonic steam flow condenses onto water jet in the mixing nozzle and mass, momentum, and energy of steam is transferred to water in the mixing nozzle. Condensed water jet is accelerated at the throat and kinetic energy is converted into pressure in the diffuser, which produces higher pressure than inlet steam pressure. It is easy to apply the SI to nuclear power plant since SI has quite simple and compact structures.
The objectives of the present study are to clarify the mechanism of heat and momentum transfer in the mixing nozzle and to determine operating range of SI for practical use.
A transparent test section is adopted to conduct visualization of the flow structure with a high-speed video camera as well as measurement of pressure distribution in mixing nozzle, throat, and diffuser with changing back pressure. Fundamental parameters change between operative and inoperative state of the injector were evaluated by measuring pressure and temperature distribution along axial direction of the test section. Discharge pressure as one of operating characteristics of the injector was also measured in changing back pressure by decreasing the opening ratio of the back pressure valve attached downstream of the test section.
It was confirmed that discharge pressure increased and the injector became inoperative unsteadily with decreasing opening ratio of the back pressure valve just after it produced the maximum discharge pressure. In the present investigation, this maximum discharge pressure is evaluated as the operation limit of the injector. Furthermore, discharge pressure from diffuser, which is one of the indicators of operating performance as well as operating limit is predicted from inlet condition adopting one-dimensional analysis model proposed previously. By comparing analytical result with experimental data, as well as visualization of flow structure in throat and diffuser, physics model including two-phase flow structure with shock wave which was observed at throat and diffuser are discussed in order to predict injector’s operation with high accuracy.
Effect of CRGT Cooling on Modes of Global Vessel Failure of a BWR Lower Head
Authors: Villanueva Walter , Tran Chi-Thanh , Kudinov Pavel 
Published: October 2013

An in-vessel stage of a severe core melt accident in a Nordic type Boiling Water Reactor (BWR) is considered wherein a decay-heated pool of corium melt inflicts thermal and mechanical loads on the lower-head vessel wall. This process induces creep leading to a mechanical failure of the reactor vessel wall. The focus of this study is to investigate the effect of Control Rod Guide Tube (CRGT) and top cooling on the modes of global vessel failure of the lower head.
A coupled thermo-mechanical creep analysis of the lower head is performed and cases with and without CRGT and top cooling are compared. The debris bed heat-up, re-melting, melt pool formation, and heat transfer are calculated using the Phase-change Effective Convectivity Model and transient heat transfer characteristics are provided for thermo-mechanical strength calculations. The creep analysis is performed with the modified time hardening creep model and both thermal and integral mechanical loads on the reactor vessel wall are taken into account. Known material properties of the reactor vessel as a function of temperature, including the creep curves, are used as an input data for the creep analysis.
It is found that a global vessel failure is imminent regardless of activation of CRGT and top cooling. However, if CRGT and top cooling is activated, the mode and timing of failure is different compared to the case with no CRGT and top cooling. More specifically, with CRGT and top cooling, there are two modes of global vessel failure depending on the size of the melt pool: (a) ‘ballooning’ of the vessel bottom for smaller pools, and (b) ‘localized creep’ concentrated within the vicinity of the top surface of the melt pool for larger pools. Without CRGT and top cooling, only a ballooning mode of global vessel failure is observed. Furthermore, a considerable delay (about 1.4 h) on the global vessel failure is observed for the roughly 30-ton debris case if CRGT and top cooling is implemented. For a much larger pool (roughly 200-ton debris), no significant delay on the global vessel failure is observed when CRGT and top cooling is implemented, however, the liquid melt fraction and melt superheat are considerably higher in non-cooling case.
Observations of Irradiation-Induced Defect Formation on Si (111) Surface by a Linked Facility Between an Ion Accelerator and STM
Authors: Sato Motohiro , Kikuchi Tairo , Murakami Kenta , Miyashiro Satoshi , Okita Taira 
Published: October 2013

A linked facility between an ion accelerator and STM enabled to elucidate cascade damage process experimentally with an atomistic scale.
By adjusting experimental conditions, we have successfully attained very clear images of Si (111) surface irradiated by very low-flux and stable ion beams. We can obtain the information of displacement damage produced by one injected ion. Much higher density of defects is observed than the number of injected ions throughout the area of the image, indicating that there are processes for defect formation other than direct collision with injected particles.
How Vertical Project Team Integration Between End User, End User’s Engineer, Nuclear QA, and Equipment Vendor Provided for Minimized Cost and Installation Expense
Authors: Tyman Jordan , Bruno Joe , Holzman Perry 
Published: October 2013

In today’s economic environment, larger capital investments by power plants, especially nuclear plants, are tending towards shorter project lead times; and at the same time with an emphasis on improved performance and future reliability. These ideas are generally not synonymous with cost effectiveness. Often it is very beneficial that the engineering phase for this equipment be flexible such that the needs of the end user, engineer, and equipment vendor are met in a cooperative fashion.
The recent power uprate scope of supply at NextEra Energies Point Beach Nuclear Power Plant was modified about 36 weeks before the outage start date to include large replacement condensate coolers for each unit with the Unit 2 exchanger delivery being critical. This left a small window in which to generate a specification, purchase, and produce the first of two 14,500 ft2 heat exchangers. The project had many design challenges that needed to be addressed including the installation, size limitations, nozzle locations, nuclear plant quality requirements and consideration of lake/sea grass (string from algae) fouling, zebra/quagga mussel fouling, and alewife (small fish) pluggage concerns in order to bring the project to a successful conclusion. These issues needed the combined strengths of the Engineer, End User, and Fabricator working quickly and making timely decisions to bring the total project to the most cost effective and successful conclusion.
Experimental Investigation on Heat Transfer for Two-Phase Flow Under Natural Convection
Authors: Amižić Milan , Guyez Estelle , Seiler Jean-Marie 
Published: October 2013

In the frame of severe accident research for the second and the third generation of nuclear power plants, some aspects of the concrete cavity ablation during the molten corium–concrete interaction are still remaining issues. The determination of heat transfer along the interfacial region between the molten corium pool and the ablating basemat concrete is crucial for the assessment of concrete ablation progression and eventually the basemat melt-through.
For the purpose of experimental investigation of thermal-hydraulics inside a liquid pool agitated by gas bubbles, the CLARA project has been launched jointly by CEA, EDF, IRSN, GDF-Suez and SARNET. The CLARA experiments are performed using simulant materials and they reveal the influence of superficial gas velocity, liquid viscosity and pool geometry on the heat transfer coefficient between the internally heated liquid pool and vertical and horizontal pool walls maintained at uniform temperature. The first test campaign has been conducted with the smallest pool configuration (50 cm × 25 cm × 25 cm). The tests have been performed with liquids covering a wide range of dynamic viscosity from approximately 1 mPa s to 10000 mPa s. This paper presents some preliminary conclusions deduced from the experiments which involve a liquid pool with the gas injection only from the bottom plate. A comparison with existing models for the assessment of heat transfer has also been carried out.
The ABC-Type Efflux Pump MacAB Protects Salmonella enterica serovar Typhimurium from Oxidative Stress
Authors: Bogomolnaya Lydia M. , Andrews Katharine D. , Talamantes Marissa , Maple Aimee , Ragoza Yury , Vazquez-Torres Andres , Andrews-Polymenis Helene 
Published: October 2013

ABSTRACT

Multidrug efflux pumps are integral membrane proteins known to actively excrete antibiotics. The macrolide-specific pump MacAB, the only ABC-type drug efflux pump in
Salmonella
, has previously been linked to virulence in mice. The molecular mechanism of this link between
macAB
and infection is unclear. We demonstrate that
macAB
plays a role in the detoxification of reactive oxygen species (ROS), compounds that salmonellae are exposed to at various stages of infection.
macAB
is induced upon exposure to H
2
O
2
and is critical for survival of
Salmonella enterica
serovar Typhimurium in the presence of peroxide. Furthermore, we determined that
macAB
is required for intracellular replication inside J774.A1 murine macrophages but is not required for survival in ROS-deficient J774.D9 macrophages.
macAB
mutants also had reduced survival in the intestine in the mouse colitis model, a model characterized by a strong neutrophilic intestinal infiltrate where bacteria may experience the cytotoxic actions of ROS. Using an Amplex red-coupled assay,
macAB
mutants appear to be unable to induce protection against exogenous H
2
O
2
in vitro
, in contrast to the isogenic wild type. In mixed cultures, the presence of the wild-type organism, or media preconditioned by the growth of the wild-type organism, was sufficient to rescue the
macAB
mutant from peroxide-mediated killing. Our data indicate that the MacAB drug efflux pump has functions beyond resistance to antibiotics and plays a role in the protection of
Salmonella
against oxidative stress. Intriguingly, our data also suggest the presence of a soluble anti-H
2
O
2
compound secreted by
Salmonella
cells through a MacAB-dependent mechanism.

IMPORTANCE
The ABC-type multidrug efflux pump MacAB is known to be required for
Salmonella enterica
serovar Typhimurium virulence after oral infection in mice, yet the function of this pump during infection is unknown. We show that this pump is necessary for colonization of niches in infected mice where salmonellae encounter oxidative stress during infection. MacAB is required for growth in cultured macrophages that produce reactive oxygen species (ROS) but is not needed in macrophages that do not generate ROS. In addition, we show that MacAB is required to resist peroxide-mediated killing
in vitro
and for the inactivation of peroxide in the media. Finally, wild-type organisms, or supernatant from wild-type organisms grown in the presence of peroxide, rescue the growth defect of
macAB
mutants in H
2
O
2
. MacAB appears to participate in the excretion of a compound that induces protection against ROS-mediated killing, revealing a new role for this multidrug efflux pump.
A Critical Role for the Putative NCS2 Nucleobase Permease YjcD in the Sensitivity of Escherichia coli to Cytotoxic and Mutagenic Purine Analogs
Authors: Kozmin Stanislav G. , Stepchenkova Elena I. , Chow Stephen C. , Schaaper Roel M. 
Published: October 2013

ABSTRACT

The base analogs 6-
N
-hydroxylaminopurine (HAP) and 2-amino-HAP (AHAP) are potent mutagens in bacteria and eukaryotic organisms. Previously, we demonstrated that a defect in the
Escherichia coli ycbX
gene, encoding a molybdenum cofactor-dependent oxidoreductase, dramatically enhances sensitivity to the toxic and mutagenic action of these agents. In the present study, we describe the discovery and properties of a novel suppressor locus,
yjcD
, that strongly reduces the HAP sensitivity of the
ycbX
strain. Suppressor effects are also observed for other purine analogs, like AHAP, 6-mercaptopurine, 6-thioguanine, and 2-aminopurine. In contrast, the
yjcD
defect did not affect the sensitivity to the pyrimidine analog 5-fluorouracil. Homology searches have predicted that
yjcD
encodes a putative permease of the NCS2 family of nucleobase transporters. We further investigated the effects of inactivation of all other members of the NCS2 family, XanQ, XanP, PurP, UacT, UraA, RutG, YgfQ, YicO, and YbbY, and of the NCS1 family nucleobase permeases CodB and YbbW. None of these other defects significantly affected sensitivity to either HAP or AHAP. The combined data strongly suggest that YjcD is the primary importer for modified purine bases. We also present data showing that this protein may, in fact, also be a principal permease involved in transport of the normal purines guanine, hypoxanthine, and/or xanthine.

IMPORTANCE
Nucleotide metabolism is a critical aspect of the overall metabolism of the cell, as it is central to the core processes of RNA and DNA synthesis. At the same time, nucleotide metabolism can be subverted by analogs of the normal DNA or RNA bases, leading to highly toxic and mutagenic effects. Thus, understanding how cells process both normal and modified bases is of fundamental importance. This work describes a novel suppressor of the toxicity of certain modified purine bases in the bacterium
Escherichia coli
. This suppressor encodes a putative high-affinity nucleobase transporter that mediates the import of the modified purine bases. It is also a likely candidate for the long-sought high-affinity importer for the normal purines, like guanine and hypoxanthine.
Altered Dynamics of Candida albicans Phagocytosis by Macrophages and PMNs When Both Phagocyte Subsets Are Present
Authors: Rudkin Fiona M. , Bain Judith M. , Walls Catriona , Lewis Leanne E. , Gow Neil A. R. , Erwig Lars P. 
Published: October 2013

ABSTRACTAn important first line of defense againstCandida albicansinfections is the killing of fungal cells by professional phagocytes of the innate immune system, such as polymorphonuclear cells (PMNs) and macrophages. In this study, we employed live-cell video microscopy coupled with dynamic image analysis tools to provide insights into the complexity ofC. albicansphagocytosis when macrophages and PMNs were incubated withC. albicansalone and when both phagocyte subsets were present. WhenC. albicanscells were incubated with only one phagocyte subtype, PMNs had a lower overall phagocytic capacity than macrophages, despite engulfing fungal cells at a higher rate once fungal cells were bound to the phagocyte surface. PMNs were more susceptible toC. albicans-mediated killing than macrophages, irrespective of the number ofC. albicanscells ingested. In contrast, when both phagocyte subsets were studied in coculture, the two cell types phagocytosed and clearedC. albicansat equal rates and were equally susceptible to killing by the fungus. The increase in macrophage susceptibility toC. albicans-mediated killing was a consequence of macrophages taking up a higher proportion of hyphal cells under these conditions. In the presence of both PMNs and macrophages,C. albicansyeast cells were predominantly cleared by PMNs, which migrated at a greater speed toward fungal cells and engulfed bound cells more rapidly. These observations demonstrate that the phagocytosis of fungal pathogens depends on, and is modified by, the specific phagocyte subsets present at the site of infection.IMPORTANCEExtensive work investigating fungal cell phagocytosis by macrophages and PMNs of the innate immune system has been carried out. These studies have been informative but have examined this phenomenon only when one phagocyte subset is present. The current study employed live-cell video microscopy to break downC. albicansphagocytosis into its component parts and examine the effect of a single phagocyte subset, versus a mixed phagocyte population, on these individual stages. Through this approach, we identified that the rate of fungal cell engulfment and rate of phagocyte killing altered significantly when both macrophages and PMNs were incubated in coculture withC. albicanscompared to the rate of either phagocyte subset incubated alone with the fungus. This research highlights the significance of studying pathogen-host cell interactions with a combination of phagocytes in order to gain a greater understanding of the interactions that occur between cells of the host immune system in response to fungal invasion.