bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of registration quality of trials sponsored by China
Authors: Liu Xuemei , Li Youping , Yu Xinting , Feng Juan , Zhong Xunshu , Yang Xiaoyan , Li Jing
Published: March 2009

Objective To evaluate the quality of the registration information for trials sponsored by China registered in the WHO primary registries or other registries that meet the requirements of the International Committee of Medical Journal Editors (ICMJE).

Methods We assessed the registration information for trials registered in the 9 WHO primary registries and one other registry that met the requirements of ICJME as of 15 October 2008. We analyzed the trial registration data set in each registry and assessed the registration quality against the WHO Trial Registration Data Set (TRDS). We also evaluated the quality of the information in the Source(s) of Monetary or Material Support section, using a specially prepared scale.

Results The entries in four registries met the 20 items of the WHO TRDS. These were the Chinese Clinical Trial Registration Center (ChiCR), Australian New Zealand Clinical Trials Registry (NZCTR), Clinical Trials Registry – India (CTRI), and Sri Lanka Clinical Trials Registry (SLCTR). Registration quality varied among the different registries. For example, using the Scale of TRDS, the NZCTR scored a median of 19 points, ChiCTR (median = 18 points), ISRCTN.org (median = 17 points), and Clinical trials.org (median = 12 points). The data on monetary or material support for ChiCTR and ISRCTN.org were relatively complete and the score on our Scale for the Completeness of Funding Registration Quality ranged from ChiCTR (median = 7 points), ISRCTN.org (median = 6 points), NZCTR (median = 3 points) to clinicaltrials.gov (median = 2 points).

Conclusion Further improvements are needed in both the quantity and quality of trial registration. This could be achieved by full completion of the 20 items of the WHO TRDS. Future research should assess ways to ensure the quality and scope of research registration and the role of mandatory registration of funded research.
Improving the quality of reporting acupuncture interventions: describing the collaboration between STRICTA, CONSORT and the Chinese Cochrane Centre
Authors: MacPherson Hugh , Altman Douglas G
Published: March 2009

Background First published in 2001, STRICTA (STandards for Reporting Interventions in Controlled Trials of Acupuncture) was designed to expand on the reporting of one item within the CONSORT (Consolidated Standards of Reporting Trials) Statement checklist, the item relating to the intervention. Two recent reviews had found that STRICTA was highly regarded in the field and that there was a need for minor revisions.

Objective To revise STRICTA within the CONSORT family of reporting guidelines.

Design A collaborative effort involving the STRICTA Group, the CONSORT Group and the Chinese Cochrane Centre was agreed. A consultation process with 47 international experts provided detailed feedback on an initial draft of a revised checklist. These data, along with the two review studies, comprised the documentation for a consensus meeting in Freiburg, Germany in October 2008. A total of 21 participants attended the meeting, bringing their expertise as research methodologists, reporting guideline developers, acupuncturists, physicians and journal editors.

Results At the workshop, a revised draft checklist was agreed. There was general consensus that STRICTA should continue to function as a stand‐alone guideline as well as an extension to CONSORT. It was agreed that STRICTA should be sufficiently broad to cover all type of clinical studies, from case reports through uncontrolled studies to randomised controlled trials. It was also decided that explanations and examples, as with other CONSORT reporting guidelines, would provide a useful way of supporting the uptake to the new recommendations when published.

Discussion The checklist will be subjected to further revision processes in order to further its impact and support wider dissemination. Journals that regularly publish acupuncture trials will be encouraged to adopt the revised STRICTA, include it in their guidelines for authors, and promote the adoption of its recommendations for clinical studies of acupuncture.
From Mexico to Mali: four years in the history of clinical trial registration
Authors: Ghersi Davina , Pang Tikki
Published: March 2009

In the 4 years between the Ministerial Forums on research and health held in Mexico in 2004 and Mali in 2008, the landscape of clinical trial registration changed significantly. When the ICMJE announced that they would no longer consider publishing the findings of clinical trials unless the research had been prospectively registered, they were key to shifting the way the clinical trials community thinks about research transparency. The argument in favour of greater transparency had been building for more than 20 years. By 2004 there was consistent and convincing evidence of the existence of publication bias and the damage this does to people's ability to make well informed decisions about health care. There is now increasing acceptance that the registration of clinical trials in a publicly accessible registry is a scientific, ethical and moral responsibility. In 2004, less than 3000 clinical trials were registered on databases meeting ICMJE criteria. There are now more than 19000 and, in some countries, prospective registration in a publicly accessible registry is now a legal requirement. Further, since October 2008, prospective registration is required if researchers wish to comply with the Declaration of Helsinki. However, despite these advances and incentives, trial registration in many countries remains far from comprehensive and stronger enforcement mechanisms may be needed in those countries.
Prospective Registration of Clinical Trials in India: Strategies, Achievements & Challenges
Authors: Tharyan Prathap
Published: March 2009

Objective This paper traces the development of the Clinical Trial Registry‐India (CTRI) against the backdrop of the inequities in healthcare and the limitations in the design, conduct, regulation, oversight and reporting of clinical trials in India. It describes the scope and goals of the CTRI, the data elements it seeks and the process of registering clinical trials. It reports progress in trial registration in India and discusses the challenges in ensuring that healthcare decisions are informed by all the evidence.

Methods A descriptive survey of developments in clinical trial registration in India from publications in the Indian medical literature supplemented by firsthand knowledge of these developments and an evaluation of how well clinical trials registered in the CTRI up to 10 January, 2009 comply with the requirements of the CTRI and the World Health Organization's International Clinical Trial Registry (WHO ICTRP).

Results Considerable inequities exist within the Indian health system. Deficiencies in healthcare provision and uneven regulation of, and access to, affordable healthcare co‐exists with a large private health system of uneven quality. India is now a preferred destination for outsourced clinical trials but is plagued by poor ethical oversight of the many trial sites and scant information of their existence. The CTRI's vision of conforming to international requirements for transparency and accountability but also using trial registration as a means of improving trial design, conduct and reporting led to the selection of registry‐specific dataset items in addition to those endorsed by the WHO ICTRP. Compliance with these requirements is good for the trials currently registered but these trials represent only a fraction of the trials in progress in India.

Conclusion Prospective trial registration is a reality in India. The challenges facing the CTRI include better engagement with key stakeholders to ensure increased prospective registration of clinical trials and utilization of existing legislative opportunities to complement these efforts.
Induction of Escherichia coli O157:H7 into the viable but non‐culturable state by chloraminated water and river water, and subsequent resuscitation
Authors: Liu Yanming , Wang Chuan , Tyrrell Gregory , Hrudey Steve E. , Li Xing‐Fang
Published: March 2009

Induction of culturable Escherichia coli O157:H7 cells into a viable but non‐culturable (VBNC) state by chloraminated tap water was carefully investigated; as many as 90% of initial cells entered into a VBNC state within 15 min, compared with 14% in river water within 14 weeks. To understand what specific stresses may induce E. coli O157:H7 into a VBNC state, chloraminated tap water, autoclaved river water, and media with known ingredients (PBS buffer and deionized water) at 4°C or 25°C were used to examine induction efficiency. Chloramination alone, or the combination of starvation with either low temperature or osmotic pressure, induced E. coli O157:H7 into a VBNC state, while starvation alone did not induce the bacteria into a VBNC state within 1.5 years. The mRNA of the rfbE and fliC genes was detected in the 10‐month‐old VBNC cells induced by river water, confirming the viability of E. coli O157:H7 VBNC cells. The VBNC cells induced by chloraminated water and the 10‐month‐old VBNC cells induced by river water were first resuscitated using autoinducers produced by E. coli O157:H7 itself in a serum‐based medium; the VBNC cells of bovine isolates recovered more efficiently compared with those of clinical isolates. These results demonstrate a potential health risk of VBNC E. coli O157:H7 in environmental water and the utility of monitoring viable E. coli O157:H7 including VBNC cells based on the mRNA of the rfbE and fliC genes.
Microbial growth in Arctic tundra soil at −2°C
Authors: McMahon Shawna K. , Wallenstein Matthew D. , Schimel Joshua P.
Published: March 2009

There is some evidence that microbes inhabiting permanently frozen environments are capable of cell maintenance and growth under in situ conditions. In contrast, Arctic tundra surface soils that are only frozen during the winter have exhibited CO2 respiration under frozen conditions. This could result from maintenance metabolism fuelled by recycling cell material, but does necessarily indicate growth, which requires the synthesis of new cell material. We used 13C‐glucose to trace C into membrane lipids and 5‐bromo‐3‐deoxyuridine to monitor DNA synthesis in a laboratory microcosm study on Arctic tundra soils. Organisms were not equally active: fungi incorporated more C than any other group. Although some bacteria were growing, Gram(+) bacteria were almost completely inactive. Shrub tundra microbes were more active in early winter than tussock microbes, incorporating more C and synthesizing more DNA. In late winter, the C incorporation pattern reversed, although DNA production was similar. We demonstrated for the first time that microbes in frozen tundra soils synthesized new cell membranes and DNA, processes fundamentally associated with growth. That microbes can grow during Arctic winters may have important implications for C cycle modelling under a changing climate.
Dynamic Model, Haptic Solution, and Human-Inspired Motion Planning for Rolling-Based Manipulation
Authors: Goncharenko Igor , Svinin Mikhail , Hosoe Shigeyuki
Published: March 2009

A virtual reality haptic system for capturing skillful human movements in control of a hemisphere rolling on a plane without slipping is presented in this paper. A dynamic model of this nonholonomic rolling system with configuration-dependent inertia and gravity is derived, and a solver, required for the real-time haptic interaction, is implemented. The performance of the haptic system is verified under experiments with human subjects. Experimental data recorded by the haptic system are analyzed and some common features of human movements in the precession phase of the manipulation of the rolling system are observed. Finally, a simple actuation scheme, capturing these features, is proposed and verified under simulation.
Stability Boundary for Haptic Rendering: Influence of Damping and Delay
Authors: Gil Jorge Juan , Sánchez Emilio , Hulin Thomas , Preusche Carsten , Hirzinger Gerd
Published: March 2009

The influence of viscous damping and delay on the stability of haptic systems is studied in this paper. The stability boundaries have been found by means of different approaches. Although the shape of these stability boundaries is quite complex, a new linear condition, which summarizes the relation between virtual stiffness, viscous damping, and delay, is proposed under certain assumptions. These assumptions include a linear system, short delays, fast sampling frequency, and relatively low physical and virtual damping. The theoretical results presented in this paper are supported by simulations and experimental data using the DLR light-weight robot and the large haptic interface for aeronautic maintainability (LHIfAM).
A Component Taxonomy as a Framework for Computational Design Synthesis
Authors: Kurtoglu Tolga , Campbell Matthew I. , Arnold Cari Bryant , Stone Robert B. , Mcadams Daniel A.
Published: March 2009

In this paper, we present our findings on the development of a taxonomy for electromechanical components. In building this taxonomy, we have two main objectives: First, we strive to establish a framework for future computational tools that archive, search, or reuse component knowledge during the conceptual phase of design. Second, we aim to define a standard vocabulary that derives uniformity and consistency in the representation of electromechanical component space. Through both empirically dissecting existing products and defining categories based on functional analysis, we defined 135 generic component types. The use and necessity of the resulting taxonomy by a suite of computational design tools are illustrated in two applications of conceptual design.
Surface Reconstruction Using Dexel Data From Three Sets of Orthogonal Rays
Authors: Zhang Weihan , Leu Ming C.
Published: March 2009

Triple-dexel modeling is a geometric representation method, which depicts the intersection of a solid with rays cast in three orthogonal directions. Due to its fast Boolean operations, simple data structure, and easy implementation, triple-dexel modeling is highly suitable for real-time graphics-based simulation applications such as numerical control (NC) machining verification and virtual sculpting. This paper presents a novel surface reconstruction method from triple-dexel data by first converting the triple-dexel data into contours on three sets of orthogonal slices and then generating the solid’s boundary surface in triangular facets from these contours. The developed method is faster than the voxel-based method, and the reconstructed surface model is more accurate than the surface reconstructed from voxel representation using the marching cube algorithm. Examples are given to demonstrate the ability of surface reconstruction from the triple-dexel model in virtual sculpting.
Applicability of Operational Research Techniques in CANDU Nuclear Plant Maintenance
Authors: Doyle E. Kevin
Published: March 2009

As previously reported at ICONE 6 in New Orleans, 1996, and ICONE 9 in Niece, 2001, the use of various maintenance optimization techniques at Bruce has lead to cost effective preventive maintenance applications for complex systems. Innovative practices included greatly reducing Reliability Centered Maintenance (RCM) costs while maintaining the accuracy of the analysis. The optimization strategy has undergone further evolution and at the present an Integrated Maintenance Program (IMP) is being put in place. Further cost refinement of the station preventive maintenance strategy whereby decisions are based on statistical analysis of historical failure data is being evaluated. A wide range of Operational Research (OR) literature was reviewed for implementation issues and several encouraging areas were found that will assist in the current effort of evaluating maintenance optimization techniques for nuclear power production. The road ahead is expected to consist first of resolving 25 years of data issues and preserving the data via appropriate knowledge system techniques while post war demographics permit experts to input into the system. Subsequent analytical techniques will emphasize total simplicity to obtain the requisite buy in from Corporate Executives who possibly aren’t trained in Operational Research. Case studies of containment airlock seal failures are used to illustrate the direct applicability of stochastic processes. Airlocks and transfer chambers were chosen as they have long been known as high maintenance items. Also, the very significant financial consequences of this type of failure will help to focus the attention of Senior Management on the effort. Despite substantial investment in research, improvement in the design of the seal material or configuration has not been achieved beyond the designs completed in the 1980’s. Overall, the study showed excellent agreement of the relatively quick stochastic methods with the maintenance programs produced at great cost over years of trial and error. The pivotal role of expert opinion via experienced users/problem owners/maintenance engineers in all phases of the method and its application was noted and will be explored in subsequent efforts. The results are displayed via economic alternatives to more easily attract the attention of Maintenance Managers. Graphical overviews of the data demonstrated that substantial insight can be gained by simply organizing the data into statistically meaningful arrays such as histograms. The conclusions highlight several very positive avenues to evaluate at this particular juncture in time.
Direct Discrete Method for Neutronic Calculations
Authors: Vosoughi Naser , Shahriari Majid , Salehi Ali Akbar
Published: March 2009

The objective of this paper is to introduce a new direct method for neutronic calculations. This method which is named Direct Discrete Method, is simpler than the neutron Transport equation and also more compatible with physical meaning of problems. This method is based on physic of problem and with meshing of the desired geometry, writing the balance equation for each mesh intervals and with notice to the conjunction between these mesh intervals, produce the final discrete equations series without production of neutron transport differential equation and mandatory passing from differential equation bridge. We have produced neutron discrete equations for a cylindrical shape with two boundary conditions in one group energy. The correction of the results from this method are tested with MCNP-4B code execution.
Fuzzy Logic Controller Architecture for Water Level Control in Nuclear Power Plant Steam Generator (SG) Using ANFIS Training Method
Authors: Vosoughi Naser , Naseri Zahra
Published: March 2009

Since suitable control of water level can greatly enhance the operation of a power station, a Fuzzy logic controller architecture is applied to show desired control of the water level in a Nuclear steam generator. With regard to the physics of the system, it is shown that two inputs, a single output and the least number of rules ( 9 rules ) are considered for a controller, and the ANFIS training method is employed to model functions in a controlled system. By using ANFIS training method, initial member functions will be trained and appropriate functions are generated to control water level inside the steam generators while using the stated rules. The proposed architecture can construct an input – output mapping based on both human knowledge (in from of Fuzzy if – then rules) and stipulated input – output data. In this paper with a simple test it has been shown that the architecture fuzzy logic controller has a reasonable response to one step input at a constant power. Through computer simulation, it is found that Fuzzy logic controller is suitable, especially for the water level deviation and abrupt steam flow disturbances that are typical in the existing power plant. /3/, /6/
Linear Spatial Evolution Formulation of Two-Dimensional Waves on Liquid Films Under Evaporating/Isothermal/Condensing Conditions
Authors: Ye Xuemin , Li Chunxi , Yan Weiping
Published: March 2009

The linear spatial evolution formulation of the two-dimensional waves of the evaporating or isothermal or condensing liquid films falling down an inclined wall is established for the film thickness with the collocation method based on the boundary layer theory and complete boundary conditions. The evolution equation indicates that there are two different modes of waves in spatial evolution. And the flow stability is highly dependent on the evaporation or condensation, thermocapillarity, surface tension, inclination angle and Reynolds number.
Development of Enriched Borated Aluminum Alloy for Basket Material of Cask for Spent Nuclear Fuel
Authors: Kajihara Katsura , Aruga Yasuhiro , Shimojo Jun , Taniuchi Hiroaki , Takeda Tsutomu , Sasaki Masatosi
Published: March 2009

New enriched borated aluminum alloys manufactured by melting process are developed, which resulted in supplying structural basket materials for spent nuclear fuel packagings. In this process, the borated aluminum alloys were melted in a vacuum induction furnace at elevated temperature than that of ordinary aluminum melting processes. Boron dissolves into the matrix at the temperature of 1273K or more, and fine aluminum diboride is precipitated and uniformly dispersed upon cooling rapidity. It is confirmed that boron is homogeneously dispersed with the fine particles of approximate 5µm in average size in the product. Tensile strength and creep property at elevated temperature in 1mass-%B 6061-T651 plate and 1mass-%B 3004 extruded rectangular pipe as structural materials are examined. It is confirmed that the both of borated aluminum alloys have stable strength and creep properties that are similar to those of ordinary aluminum alloys.
Fatigue During Multi-Axial Random Loadings
Authors: Zarka Joseph , Karaouni Habib
Published: March 2009

During classical analysis, some special methods to extract and to count the cycles from the random stress path (very often, the Rainflow method) are used and it is needed to cumulate “damage” based on some S-N diagrams and the linear Miner-Palmgreen rule or some more elaborated non linear rules. The “damage” factor (scalar or tensor) is still the object of many researches; it is impossible to measure it during the whole loading path, even if, before failure, some slight changes on the elastic properties may be experimentally detected. Moreover, the representations of the loading and the counting methods are purely based on mathematical aspects and ignore the particular mechanical behavior of the present materials in the structure. Our objective in this paper is only limited to reach a real physical approach of the multiaxial random loadings which is very easy to perform. The main idea of the approach is to find an Equivalence rule between two complex loadings relative to “Damage” which may be used as a “Quantification” or norm of any loading relative to one particular material. This rule must have the physical meaning of “damage” and allows for the construction of simple and practical cyclic radial loadings and tools for fatigue analysis or accelerated fatigue tests.
New Rules to Be Included in Codes and Standards to Represent Multiaxial Variable Amplitudes Loadings on Structures
Authors: Zarka Joseph , Karaouni Habib
Published: March 2009

On a smooth tensile specimen, it is used to perform the fatigue characterizations: But there are still many open problems. These problems are even more obvious when we need to consider the structure and its loading. We propose special rules to describe the loading and to be taken as new standard. rules in the future. The main idea is to find an Equivalence rule between two loadings relative to «Damage» which may be used as a «Quantification» or norm of any loading relative to one particular structure made of particular materials. This rule needs to give a physical meaning of fatigue analysis during any loading and must allow for construction of simple and practical tools for fatigue analysis or accelerated fatigue tests. This representation has to be considered at the level of the materials and then at the level of the structure.
Hydrogen Recombiner: Theoretical Parametric Study
Authors: Avakian Gilles
Published: March 2009

There is not yet published data concerning a complete overview of the behaviour of a SIEMENS recombiner versus the thermal hydrualic conditions and the geometry of the catalytic plates. This paper reports on a numerical behaviour of the recombiner depending on several gas parameters as the total pressure, and the hydrogen concentration, as well as geometrical parameters of the catalytic elements as the height and the spacing. We use a theoretical model validated by using the KALI experiments. In this model (Avakian, 1999), the reaction rate is diffusion-controlled, i.e. the contribution of surface kinetics to the total rate of reaction is neglected. We demonstrate a quasi-linear behaviour of the recombination rate vs. the total pressure and the hydrogen concentration. We display the benefit in using smaller catalytic plates instead of taller plates and we give an idea of the influence of the spacing between the catalytic plates.
Direct Containment Heating: A Solved Risk Issue
Authors: Passalacqua Roberto
Published: March 2009

In case of a High Pressure Melt Ejection (HPME) heated gas and corium may be expelled from the bottom head of a reactor vessel reaching the containment atmosphere, leading to a Direct Containment Heating (DCH). In addition, released gases might burn (e.g. hydrogen) causing a high load of the reactor containment building. Corium dispersal phenomena also strongly affect consequences of Molten Core-Concrete Interaction (MCCI) since the corium mass, which remains within the cavity, may remarkably diminish. Several computer codes are able to simulate the response of nuclear plants during hypothetical severe accidents: MELCOR, MAAP, ESCADRE and ASTEC have the capability to describe corium slump into the reactor cavity, vessel gases blow-down and possible corium entrainment. In this paper the various steps of model development, validation, plant-specific applications, etc., are described in the attempt of establishing a risk-oriented methodology with the target of solving this particular risk-issue. ENEA mature expertise in level-2 PSA analyses shows that the DCH phenomenology can be considered a solved risk issue. The applied methodology gives also hints and/or guidelines for solving similar risk issues in current PSA (level 2) analysis.
Maintenance for the Millennium: Another Approach
Authors: Sculthorpe Barry R.
Published: March 2009

Nuclear units nationwide are struggling to increase plant reliability and availability while at the same time reduce their operating and maintenance costs. Some very costly investments have been made in programs such as Reliability Centered Maintenance [RCM]. Florida Power & Light’s approach at the St. Lucie Nuclear Plant has taken a slightly different approach. Building on our knowledge of the RCM process and an already existing “World Class” Predictive Maintenance Program, a “Condition-Based” Maintenance Program that takes advantage of the RCM philosophy and our toolbox full of advanced and highly successful predictive maintenance technologies. These tools currently consist of vibration analysis, lubricant analysis (both physical property & wear metals analysis, thermographic analysis, motor current signature analysis, tribology & process parameter trending. All employed with the intent to evaluate a machines health. This machine health check allows the forecasting of future preventative maintenance [PM’s] tasks and the revision of existing PM’s to maximize machine performance and eliminate “no-value-added” maintenance activities/costs. Within the last year, the Condition-Based Maintenance Program has produced a cost saving of approximately $1.5 million dollars. As the program matures, these cost savings will accumulate well into the millennium.
Systematic Source Term Analyses for Level 3 PSA of a BWR With Mark-II Type Containment With THALES-2 Code
Authors: Ishikawa Jun , Muramatsu Ken , Sakamoto Toru
Published: March 2009

The THALES-2 code is an integrated severe accident analysis code developed at the Japan Atomic Energy Research Institute in order to simulate the accident progression and transport of radioactive material for probabilistic safety assessment (PSA) of a nuclear power plant. As part of a level 3 PSA being performed at JAERI for a 1,100MWe BWR-5 with a Mark-II containment, a series of calculations were performed by THALES-2 to evaluate the source terms for extensive accident scenarios. For some of the containment failure modes not modeled in THALES-2, such as steam explosion, simple models were coupled with the analysis results of THALES-2 to estimate the source terms. This paper presents the methods and insights from the analyses. An insight from the analyses was that the source terms depend more strongly on the differences in the containment function failure scenarios, such as overpressure failure, controlled containment venting, and small leakage to the reactor building, than those core damage sequences.
The KORSAR Computer Code Modeling of Stratified Two-Phase Flow Hydrodynamics in Horizontal Pipes
Authors: Yudov Yu. V.
Published: March 2009

The KORSAR best estimate computer code has been developed at NITI since 1996. It is designed to numerically simulate transient and accident conditions in VVER-type reactors /1/. From 1999 and on, the code development activity has been coordinated by the Center for Computer Code Development under Russia’s Minatom.
Two Phase Flow Analysis for Secondary Side in Steam Generator
Authors: Yagi Y. , Murase M. , Nakamura A. , Fujii Y.
Published: March 2009

The steam generator (SG) in a pressurized water reactor (PWR) is an important component as boundary between the primary loop and the secondary loop. In this study, we performed two-phase flow analysis of SG reliability tests conducted by the Nuclear Power Engineering Corporation (NUPEC) using the two-fluid models of a thermal-hydraulic computer code PHOENICS. It was difficult to calculate the location of the boiling initiation accurately because the location was greatly affected by the friction coefficients (i.e. velocity distributions) and the heat transfer distributions. However, the friction coefficients and the heat transfer distributions did not greatly affect the void fractions in the upper region of the U-bent tubes and the calculated average void fractions agreed with the measured within 4%.
Local Interfacial Structure in Downward Two-Phase Bubbly Flow
Authors: Goda Hiroshi , Kim Seungjin , Paranjape Sidharth S. , Finch Joshua P. , Ishii Mamoru , Uhle Jennifer
Published: March 2009

The local interfacial structure for vertical air-water co-current downward two-phase flow was investigated under adiabatic conditions. A multi-sensor conductivity probe was utilized in order to acquire the local two-phase flow parameters. The present experimental loop consisted of 25.4 mm and 50.8 mm ID round tubes as test sections. The measurement was performed at three axial locations: L/D = 13, 68 and 133 for the 25.4 mm ID loop and L/D = 7, 34, 67 for the 50.8 mm ID loop, in order to study the axial development of the flow. A total of 7 and 10 local measurement points along the tube radius were chosen for the 25.4 mm ID loop and the 50.8 mm ID loop, respectively. The experimental flow conditions were determined within bubbly flow regime. The acquired local parameters included the void fraction, interfacial area concentration, bubble interface frequency, bubble Sauter mean diameter, and interfacial velocity.
Effect of Nitrogen Release From Accumulators on PWR LOCA Analysis
Authors: Yeung Woon-Shing , Sundaram Ramu K.
Published: March 2009

The accumulator in a Pressurized Water Reactor (PWR) is generally pressurized with inert nitrogen cover gas, and the accumulator water will be saturated with nitrogen. Nitrogen released due to system depressurization during a Loss-of-Coolant Accident (LOCA) transient, consists of the nitrogen that is in the gas phase as well as nitrogen coming out of the liquid from a dissolved state. The effect of nitrogen release from the accumulator on the accident sequence is generally not explicitly addressed in typical LOCA analyses. This paper presents an analytical nitrogen release model and its incorporation into the RELAP5/MOD3 computer code. The model predicts the amount of nitrogen release as a function of concentration difference between the actual and equilibrium conditions, and can track its subsequent transport through the downstream reactor coolant system in a LOCA transient. The model is compared to data from discharge tests with a refrigerant type fluid, pressurized with nitrogen. The results demonstrate that the model is able to calculate the release of the dissolved nitrogen as designed. The modified computer code has been applied to analyze the discharge from a typical PWR accumulator. The results are compared to those obtained without the nitrogen release model. The effect of nitrogen release on major system parameters, including accumulator level, accumulator flow rate, and accumulator pressure, is discussed.
Evaluation of Two 300 MWe Fourth Generation PbBi Reactor System Concepts
Authors: Miller Laurence F. , Khan M. Khurram , Williams Wesley , Mynatt F. R.
Published: March 2009

This paper describes the evaluation of two 300 MWe modular PbBi cooled reactor system concepts that can be field assembled from components shipped on standard rail cars or on trucks. Thus, the largest components must be smaller than 12’ × 12’ × 80’ (3.66 m × 3.66 m × 24.4m) and should weigh no more than 80 tons. One of these systems utilizes a cylindrical two-loop containment vessel for the core and the other is a slab design. The fuel for both designs consists of standard-sized metallic IFR fuel in 17×17 square array assemblies with a pitch-to-diameter ratio of 1.15. The coolant outlet temperature is limited by current material technology, which is estimated to be 550 C. The primary coolant inlet temperature is selected to be 350 C. This is well above the melting temperature of PbBi, and it is expected to be sufficiently high to limit transient-induced thermal stresses to acceptable values. Coolant flow rates through the core and external piping are below 1 m/s. The results from neutronics calculations include power distributions, reactivity coefficients, and fuel depletion, and results from heat transfer calculations include temperatures and flow rates at various locations in the primary and secondary systems. The neutronic design calculations are accomplished by using a discrete ordinate transport code and a cross section processing system developed at Oak Ridge National Laboratory. Two-dimensional flux distributions are obtained with the DOORS system, and ORIGEN-S, coupled with KENO, is used for time-dependent depletion calculations. The thermal-hydraulic design of the core consists of heat transfer and fluid flow calculation for an average channel. The inlet and outlet temperatures, along with the fuel centerline temperature, are determined in conjunction with core flow rates, pumping power, and total power output. This is accomplished by using a lumped parameter steady-state model with a spreadsheet and by using a one-dimensional time-dependent model. Results from the thermal-hydraulic calculation obtain a thermal efficiency of 41%, but an efficiency of about 45% could be obtained. The nominal power density and good thermal conductivity of Pb-Bi will permit decay heat to be handled more effectively than for sodium-cooled design or for light water reactors. The low vapor pressure of Pb-Bi permits the use of a thin walled pressure vessel on the order of centimeters as compared to the 30–40 cm thick PWR vessel, and the high boiling point of the lead bismuth assures that the core will remain covered in the event of a loss of coolant outside the primary vessel.
Reliability Analysis of Cooling Towers: Influence of Rebars Corrosion on Failure
Authors: Sudret Bruno , Pendola Maurice
Published: March 2009

Natural-draught cooling towers are used in nuclear power plants as heat exchangers. These structures are submitted to environmental loads such as wind and thermal gradients that are stochastic in nature. A probabilistic framework has been developed by EDF (Electricite´ de France) for assessing the durability of such structures. In this paper, the corrosion of the rebars due to concrete carbonation and the corresponding weakening of the reinforced concrete sections is considered. Due to the presence of time in the definition of the limit state function associated with the loss of serviceability of the cooling tower, time-variant reliability analysis has to be used. A novel approach is proposed to take into account the random “initiation time”, which corresponds to the time necessary for the carbonation to attain the rebars. Results are given in terms of the probability of failure of the structure over its life time.
Gross Gamma Dose Rate Measurements for TRIGA Spent Nuclear Fuel Burnup Validation
Authors: Winston P. L. , Sterbentz J. W.
Published: March 2009

Gross gamma-ray dose rates from six spent TRIGA fuel elements were measured and compared to calculated values as a means to validate the reported element burnups. A newly installed and functional gamma-ray detection subsystem of the In-Cell Examination System was used to perform the measurements and is described in some detail. The analytical methodology used to calculate the corresponding dose rates is presented along with the calculated values. Comparison of the measured and calculated dose rates for the TRIGA fuel elements indicates good agreement (less than a factor of 2 difference). The intent of the subsystem is to measure the gross gamma dose rate and correlate the measurement to a calculated dose rate based on the element s known burnup and other pertinent spent fuel information. Although validation of the TRIGA elements’ burnup is of primary concern in this paper, the measurement and calculational techniques can be used to either validate an element’s reported burnup or provide a burnup estimate for an element with an unknown burnup.
U.S. Operating Experience With Thermally Treated Alloy 600 Steam Generator Tubes
Authors: Smith April , Karwoski Kenneth J.
Published: March 2009

Steam generators placed in service in the 1960s and 1970s were primarily fabricated from mill-annealed Alloy 600. Over time, this material proved to be susceptible to stress corrosion cracking in the highly pure primary and secondary water chemistry environments of pressurized-water reactors. The corrosion ultimately led to the replacement of steam generators at numerous facilities, the first U.S. replacement occurring in 1980. Many of the steam generators placed into service in the 1980s used tubes fabricated from thermally treated Alloy 600. This tube material was thought to be less susceptible to corrosion. Because of the safety significance of steam generator tube integrity, this paper evaluates the operating experience of thermally treated Alloy 600 by looking at the extent to which it is used and recent results from steam generator tube examinations.
Experience in Modelling the Zaporozh’ye Nuclear Power Plant Using RELAP5
Authors: Sverdlov Vyacheslav V. , Sverdlov Alexey V.
Published: March 2009

Unit 5 of the Zaporozh’ye Nuclear Power Plant (ZNPP5), equipped with a VVER-1000/320 4-loop reactor, has been modelled in detail using the RELAP5/MOD3.2 thermal-hydraulic system code (Ref. 1). The 4-loop model affords a fidelity with ZNPP5 in terms of the system geometry such as the point of emergency core cooling (ECC) injection, for example. Both the reactor vessel and steam generators were nodalized in a quasi 3-dimensional (3-D) fashion thus allowing to capture asymmetric effects in the main reactor system components and realistic heat transfer distribution in the steam generators. Besides its use for accident analysis, the present model is intended to closely simulate operational events such as pre- and post calculations of anticipated transients and tests. At present, the model is used to support justification of the new — symptom-oriented — set of emergency operating instructions. ZNPP5 makes use of both digital and analog controls. They have been modelled in the RELAP5 model allowing to analyse in detail workings of various plant equipment. The present model was validated using three ZNPP5 transient events.
Flow Patterns of Gas-Liquid Two-Phase Flow in Round Tube With Sudden Expansion
Authors: Kondo Koichi , Yoshida Kenji , Matsumoto Tadayoshi , Okawa Tomio , Kataoka Isao
Published: March 2009

Experimental studies were made on the multi-dimensional behavior of upward gas-liquid two-phase flow through the vertical round tube with an axisymmetric sudden expansion, which is one of the typical multi-dimensional channel geometry. The aims of this study are to clarify the multi-dimensional behavior of bubbly or slug flow affected by sudden expansion channel geometry, and to accumulate the experimental data for two-phase flow analysis, which is applicable to predict with appropriate accuracy the multi-dimensional its behavior. The direct observation using high-speed video camera was performed and revealed the multi-dimensional dynamic flow behavior with bubbles and gas-slug affected by the sudden expansion part (20 mm-tube to 50 mm-tube). The characteristic phenomena were observed such as bubble break-up, deformation due to the strong shear of liquid flow, or liquid micro jet penetration through the gas-slug, and so on. From these results, the flow regime map and the flow patterns at the below and above of the sudden expansion part were classified in relation to the bubble diameter. Additionally, the measurement of the void fraction profiles in the tube cross sections of sudden expansion were conducted at the different axial positions. The void fraction was measured using a point-electrode resistivity probe. The void fraction measurements in this study showed in detail that how the two phase flow develops along the direction of the downstream of the sudden expansion. In just above the sudden expansion, the void fraction distribution appeared the wall peak or the core peak in void fraction in the upstream of the sudden expansion. In the downstream of the sudden expansion, the void fraction distribution changes from a saddle shape or power-low shape into finally the saddle shape as the bubbly flow develops along the downstream of the sudden expansion. These experimental data in the sudden expansion of a vertical upward bubbly flow would become benchmark with respect to the multi-dimensional behavior of the two-phase flow analysis.
Studies on Materials for Heavy-Liquid-Metal-Cooled Reactors in Japan
Authors: Takahashi Minoru , Igashira Masayuki , Obara Toru , Sekimoto Hiroshi , Kikuchi Kenji , Aoto Kazumi , Kitano Teruaki
Published: March 2009

Recent studies on materials for the development of lead-bismuth (Pb-Bi)-cooled fast reactors (FR) and accelerator-driven sub-critical systems (ADS) in Japan are reported. The measurement of the neutron cross section of Bi to produce 210Po, the removal experiment of Po contamination and steel corrosion test in Pb-Bi flow were performed in Tokyo Institute of Technology. A target material corrosion test was performed in the project of Transmutation Experimental Facility for ADS in Japan Atomic Energy Research Institute (JAERI). Steel corrosion test was started in Mitsui Engineering & Shipbuilding Co., LTD (MES). The feasibility study for FR cycle performed in Japan Nuclear Cycle Institute (JNC) are described.
Droplets Behavior of Hollow-Cone Spray in a Non-Condensable Environment
Authors: Takahashi Minoru , Qiu Suizheng , Kitagawa Shin-Ichi
Published: March 2009

The characteristics of droplets in a water hollow-cone spray from nozzles 1.1 mm and 3.6 mm in diameter in an air environment have been investigated experimentally. The dual phase Doppler anemometry (PDA) system was used to measure the size and two velocity components of individual spherical particles. The liquid spray geometry, including spray breakup length and spray angle were also obtained experimentally. The mechanism and the influence of these parameters on a hollow cone spray flow were described.
A Study of Cavitation Erosion
Authors: Isaka Hiromu , Tsutsumi Masatsugu , Kobayashi Hiroyuki , Shiraishi Tadashi
Published: March 2009

The authors performed experimental study for the purpose of the following two items from a viewpoint of cavitation erosion of a cylindrical orifice in view of a problem at the letdown orifice in PWR (Pressurized Water Reactor). 1. To get the critical cavitation parameter of the cylindrical orifice to establish the design criteria for prevention of cavitation erosion, and 2. to ascertain the erosion rate in such an eventuality that the cavitation erosion occurs with the orifice made of stainless steel with precipitation hardening (17-4-Cu hardening type stainless steel), so that we confirm the appropriateness of the design criteria. Regarding the 1st item, we carried out the cavitation tests to get the critical cavitation parameters inside and downstream of the orifice. The test results showed that the cavitation parameter at inception is independent of the length or the diameter of the orifice. Moreover, the design criteria of cavitation erosion of cylindrical orifices have been established. Regarding the 2nd item, we tested the erosion rate under high-pressure conditions. The cavitation erosion actually occurred in the cylindrical orifice at the tests that was strongly resemble to the erosion occurred at the plant. It will be seldom to reproduce resemble cavitation erosion in a cylindrical orifice with the hard material used at plants. We could establish the criteria for preventing the cavitation erosion from the test results.
A Contribution to Proof the Component Integrity Taking Into Account the Corrosion-Assisted Crack Growth
Authors: Roos Eberhard , Otremba Frank , Hu¨ttner Frank
Published: March 2009

The proof of the component integrity is fundamental for a safe and reliable operation of Nuclear Power Plants (NPP). The concept of the Material Testing Institute (MPA) for integrity assessment is based on fracture mechanic analysis which results in detailed regulations for nondestructive examination. This approach has to account for the main damage mechanisms as fatigue and corrosion. This paper focuses on the influence of corrosion-assisted crack growth which strongly depends on corrosion and environmental conditions (e.g. coolant purity). Up to stress intensity of approximately 60 MPa√m for ferritic low-alloy steels in high-purity water (acc. to specification) under constant load conditions the analysis can be based on a crack extension of max. 70 µm for each load cycle. Related to a test duration of 1000 hours this is equivalent to a formally calculated crack growth rate (CGR) of = 2 · 10−8 mm/s. For austenitic stainless steels more complex dependences on material, environmental and mechanical parameters exist. Particularly, for stabilized austenitic steels the crack growth rate data base is relatively weak. Under unfavourable environmental conditions in single cases crack growth rates up to 6 mm/a have been measured. Based on experimental results an arithmetic mean value of 0.95 mm/a and a median value of 0.6 mm/a have been determined. A further improvement of data base is desirable.