Results 1 - 10 of 7587
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[en] As the number of large reservoirs has grown rapidly, drawdown of water level has become a major factor in inducing landslides. A new simulator was developed to simulate the in-flight drawdown in a centrifuge model test. A series of centrifuge model tests was conducted on slopes with different gradients under drawdown conditions. The failure mechanism was obtained via an integrated analysis of deformation and failure processes according to the displacement histories of the slopes measured by the image capture and displacement measurement system. The slip surface, with slippage failure, was developed from the top downwards due to the drawdown. The displacement histories of the sliding body could be divided into three stages with the increase rate changing from small to large and finally becoming negligible. The deformation of the slope only appeared within a limited zone with a nearly invariable boundary surface during the drawdown. The boundary surface moved closer to the slope surface with the deceasing slope gradient. The drawdown caused a significant coupling process of local failure and deformation localization, which developed from the upper part to the lower part. The upper part of the sliding body behaved as a rigid body, and the lower parts exhibited significant deformation after the slip surface formed, which should be reasonably captured in a stability analysis of a slope under drawdown conditions.
[en] In order to optimize future dismantling operations of nuclear installations virtual reality allows the validation of predefined scenarios and their adequacy with the environment. CEA uses an immersion and interactive room to validate maintenance and dismantling operations. The equipment of this room is composed of a video wall that gives a 3-dimensional view of the virtual environment, and of a system for motion capture. For the simulation of handling operations a haptic interface has been designed, it allows the user to receive a tactic and effort-feeling feed back. The immersion is completed by a phonic ambience that creates sounds for virtual operations. The use of the immersion room for optimizing the dismantling of a spent fuel dissolver (MAR 200) used in hot cell is presented. (A.C.)
[en] Use of adaptive simulation is intended to improve the fidelity and robustness of important core attribute predictions such as core power distribution, thermal margins, and core reactivity. Adaptive simulation utilizes a selected set of past and current reactor measurements of reactor observables, i.e., in-core instrumentation readings, to adapt the simulation in a meaningful way. The companion paper, ''Adaptive Core Simulation Employing Discrete Inverse Theory - Part I: Theory,'' describes in detail the theoretical background of the proposed adaptive techniques. This paper, Part II, demonstrates several computational experiments conducted to assess the fidelity and robustness of the proposed techniques. The intent is to check the ability of the adapted core simulator model to predict future core observables that are not included in the adaption or core observables that are recorded at core conditions that differ from those at which adaption is completed. Also, this paper demonstrates successful utilization of an efficient sensitivity analysis approach to calculate the sensitivity information required to perform the adaption for millions of input core parameters. Finally, this paper illustrates a useful application for adaptive simulation - reducing the inconsistencies between two different core simulator code systems, where the multitudes of input data to one code are adjusted to enhance the agreement between both codes for important core attributes, i.e., core reactivity and power distribution. Also demonstrated is the robustness of such an application
[en] The Fuel Cycle Simulator (FCS) project was initiated late in FY-10 as the activity to develop a next generation fuel cycle dynamic analysis tool for achieving the Systems Analysis Campaign 'Grand Challenge.' This challenge, as documented in the Campaign Implementation Plan, is to: 'Develop a fuel cycle simulator as part of a suite of tools to support decision-making, communication, and education, that synthesizes and visually explains the multiple attributes of potential fuel cycles.'
[en] We show how a single, harmonically trapped atom in a tailored magnetic field can be used for simulating the effects of a broad class of non-Abelian gauge potentials. We demonstrate how to implement Rashba or linear-Dresselhaus couplings, or observe Zitterbewegung of a Dirac particle.
[en] We report the orbital distribution of the trans-Neptunian comets discovered during the first discovery year of the Canada-France Ecliptic Plane Survey (CFEPS). CFEPS is a Kuiper Belt object survey based on observations acquired by the Very Wide component of the Canada-France-Hawaii Telescope Legacy Survey (LS-VW). The first year's detections consist of 73 Kuiper Belt objects, 55 of which have now been tracked for three years or more, providing precise orbits. Although this sample size is small compared to the world-wide inventory, because we have an absolutely calibrated and extremely well-characterized survey (with known pointing history) we are able to de-bias our observed population and make unbiased statements about the intrinsic orbital distribution of the Kuiper Belt. By applying the (publically available) CFEPS Survey Simulator to models of the true orbital distribution and comparing the resulting simulated detections to the actual detections made by the survey, we are able to rule out several hypothesized Kuiper Belt object orbit distributions. We find that the main classical belt's so-called 'cold' component is confined in semimajor axis (a) and eccentricity (e) compared to the more extended 'hot' component; the cold component is confined to lower e and does not stretch all the way out to the 2:1 resonance but rather depletes quickly beyond a = 45 AU. For the cold main classical belt population we find a robust population estimate of N(Hg < 10) = 50 ± 5 x 103 and find that the hot component of the main classical belt represents ∼60% of the total population. The inner classical belt (sunward of the 3:2 mean-motion resonance) has a population of roughly 2000 trans-Neptunian objects with absolute magnitudes Hg < 10, and may not share the inclination distribution of the main classical belt. We also find that the plutino population lacks a cold low-inclination component, and so, the population is somewhat larger than recent estimates; our analysis shows a plutino population of N(Hg < 10)∼ 25+25-12 x 103compared to our estimate of the size of main classical Kuiper Belt population of N(Hg < 10) ∼ (126+50-46) x 103.
[en] The paper describes the way and results of human reliability data analysis collected as a part of the Bohunice Simulator Data Collection Project (BSDCP), which was performed by VUJE Trnava, Inc. with funding support from the U.S. DOE, National Nuclear Security Administration. The goal of the project was to create a methodology for simulator data collection and analysis to support activities in probabilistic safety assessment (PSA) and human reliability assessment for Jaslovske Bohunice nuclear power plant consisting of two sets of twin units: two VVER 440/V-230 (V1) and two VVER 440/V-213 (V2) reactors. During the project, training of V-2 control room crews was performed at VUJE Trnava simulator. The simulator training and the data collection were done in parallel. The main goal of BSDCP was to collect suitable data of human errors under simulated conditions requiring the use of symptom-based emergency operating procedures (SBEOPs). The subjects of the data collection were scenario progress time data, operator errors, and real-time technological parameters. The paper contains three main parts. The first part presents preparatory work and semi-automatic computer-based methods used to collect data and to check technological parameters in order to find hidden errors of operators, to be able to retrace the course of each scenario for purposes of further analysis, and to document the whole training process. The first part gives also an overview of collected data scope, human error taxonomy, and state classifications for SBEOP instructions coding. The second part describes analytical work undertaken to describe time distribution necessary for execution of various kinds of instructions performed by operators according to the classification for coding of SBEOP instructions. It also presents the methods used for determination of probability distribution for various operator errors. Results from the data evaluation are presented in the last part of the paper. An overview of observed human error probabilities (HEP) according to the developed taxonomy is given. HEP observed during training process were used as reference input data for HRA (Human Reliability Assessment) within existing PSAs performed by VUJE. Observing two different training seasons offered an opportunity to compare a progress achieved through the training process. This paper shows us how it is possible to make this kind of comparison in order to establish an objective measure of training quality and to determine training weaknesses. Results gained during the project evoked interest of different NPPs (Nuclear Power Plant) in Slovak Republic to collect and process simulator data for further improvement of human factor safety, operational procedures, training process, etc. (author)
[en] Highlights: • Examined the backflow characteristics of neutral particles in a detached plasma. • TPD-Sheet IV with a Super-X-divertor-like target was used. • The effect caused by the divergent magnetic field to a generation of the detached plasma is small. • A backflow-suppressing “plasma plugging” effect was confirmed. • It is suggested that there is an optimal value of magnetic-field divergence for preventing backflow of neutral particles. - Abstract: We confirm the neutral-particle backflow characteristics of detached plasma with a Super-X divertor-like target using a linear divertor simulator TPD-Sheet IV. The effect of a divergent magnetic field upon the generation of the detached plasma is found to be weak. Under a divergent magnetic field, the heat load on the target plate with a Super-X divertor-like target is suggested to be reduced by 3–5 times compared with a case in which a conventional diverter (CD) is used. In addition, it is suggested that there is an optimal magnetic-field divergence that prevents backflow of neutral particles.