Download or read book An Experimental and Modelling Study of Natural circulation Boiling Water Reactor Dynamics written by Róbert Zboray and published by IOS Press. This book was released on 2002 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contents of this Doctoral Dissertation include: Understanding the linear stability characteristics of BWRs, Experiments on the stability of the Desire facility, Applications of the reducer-order model, Numerical analysis of the nonlinear dynamics of BWRs, Experiments on the nonlinear dynamics of natural-circulation two-phase flows, Experiments on the neutronic-thermalhydraulic stability, Conclusions and Discussion

Download or read book Experimental and Analytical Modeling of Natural Circulation and Forced Circulation BWRs written by Masahiro Furuya and published by IOS Press. This book was released on 2006 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: 20% of the Nuclear Power Plants are known as Boiling Water Reactors (BWRs). These BWRs have pumps that cool their reactor. In the design of new BWRs, ways to cool the core by a natural circulation flow, without pumps, also called natural circulation BWRs, are being considered. In these new systems, a chimney is installed on top of the core to increase natural circulation flow. A possible disadvantage of natural circulation BWRs might be their susceptibility to instabilities, which could then lead to both flow and power oscillations. The stability features of both natural circulation and forced circulation BWRs have been investigated thoroughly, using dedicated experimental setups, analytical models and numerical codes. We distinguish between pure thermal-hydraulic stability - where the fission power is assumed to be constant - and coupled thermalhydraulic-neutronic stability - where the two-phase mixture in the core influences the fission chain reaction...

Download or read book Experimental and Numerical Stability Investigations on Natural Circulation Boiling Water Reactors written by Christian Pablo Marcel and published by IOS Press. This book was released on 2007 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the design of novel nuclear reactors active systems are replaced by passive ones in order to reduce the risk of failure. For that reason natural circulation is being considered as the primary cooling mechanism in next generation nuclear reactor designs such as the natural circulation boiling water reactor (BWR). In such a reactor, however, the flow is not a controlled parameter but is dependent on the power. As a result, the dynamical behavior significantly differs from that in conventional forced circulation BWRs. For that reason, predicting the stability characteristics of these reactors has to be carefully studied. In this work, a number of open issues are investigated regarding the stability of natural circulation BWRs (e.g. margins to instabilities at rated conditions, interaction between the thermal-hydraulics and the neutronics, and the occurrence of flashing induced instabilities) with a strong emphasis on experimental evidence.

Download or read book Analyses of Experimental Power reactivity Feedback Transfer Functions for a Natural Circulation Boiling Water Reactor written by J. A. DeShong and published by . This book was released on 1958 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of the simplified model for parameter studies is demonstrated by a series of calculations to evaluate the effect of heat transfer time constant on stability.

Download or read book Computational Fluid Dynamics Analysis of Natural Circulation Flows in a Pressurized Water Reactor Loop Under Severe Accident Conditions written by U.s. Nuclear Regulation Comion and published by CreateSpace. This book was released on 2014-06-30 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational fluid dynamics is used to predict the natural circulation flows between a simplified reactor vessel and the steam generator of a pressurized-water reactor (PWR) during a severe accident scenario. The results extend earlier predictions of steam generator inlet plenum mixing with the inclusion of the entire natural circulation loop between the reactor vessel upper plenum and the steam generator. Tube leakage and mass flow into the pressurizer surge line are also considered. The predictions are utilized as a numerical experiment to improve the basis for simplified models applied in one-dimensional system codes that are used during the prediction of severe accident natural circulation flows. An updated inlet plenum mixing model is proposed that accounts for mixing in the hot leg too. The new model is consistent with the predicted behavior and accounts for flow into a side mounted surge line if present. A density- based Froude number correlation is utilized to provide a method for determining the flow rate from the vessel to the hot leg directly from the conditions at the ends of the hot leg pipe. This provides a physically based approach for establishing the hot leg flows. The mixing parameters and correlations are proposed as a best-estimate approach for estimating the flow rates and mixing in one-dimensional system codes applied to severe accident natural circulation conditions. Sensitivity studies demonstrate the applicability of the approach over a range of conditions. The predictions are most sensitive to changes in the steam generator secondary side temperatures or heat transfer rates to the steam generator. Grid independence is demonstrated through comparisons with previous models and by increasing the number of cells in the model. A further modeling improvement is suggested regarding the application of thermal entrance effects in the hot leg and surge line. This work supports the U.S. Nuclear Regulatory Commission studies of steam generator tube integrity under severe accident conditions.

Download or read book Dynamic Analysis of Natural Circulation Boiling Water Power Reactors written by Eric S. Beckjord and published by . This book was released on 1958 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Linear Feedback Control Theory is used to analyze the small-signal dynamic behavior of direct cycle, natural circulation boiling water reactor systems.

Download or read book Dynamic Analysis of Coolant Circulation in Boiling Water Nuclear Reactors written by Chathilingath K. Sanathanan and published by . This book was released on 1964 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamics of two-phase flow through the coolant channels of a natural-circulation boiling water nuclear reactor is studied analytically. One-dimensional conservation equations describing the flow through each channel are written in a linearized perturbed form, and Laplace transformation in time is performed. A systematic procedure is developed to approximate the solution. The solution may be oscillatory both in time and space, and the stability depends largely upon the steady-state profile of velocity and void fraction along the channel, as well as the channel length. The simplifying assumption made by earlier investigators that the slip ratio is constant along the channel length is shown to yield results close to the true solution.

Download or read book An Analytical and Experimental Investigation of Natural Circulation Transients in a Model Pressurized Water Reactor written by and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Natural Circulation phenomena in a simulated PWR was investigated experimentally and analytically. The experimental investigation included determination of system characteristics as well as system response to the imposed transient under symmetric and asymmetric operations. System characteristics were used to obtain correlation for heat transfer coefficient in heat exchangers, system flow resistance, and system buoyancy heat. Asymmetric transients were imposed to study flow oscillation and possible instability. The analytical investigation encompassed development of mathematical model for single-phase, steady-state and transient natural circulation as well as modification of existing model for two-phase flow analysis of phenomena such as small break LOCA, high pressure coolant injection and pump coast down. The developed mathematical model for single-phase analysis was computer coded to simulate the imposed transients. The computer program, entitled ''Symmetric and Asymmetric Analysis of Single-Phase Flow (SAS), '' were employed to simulate the imposed transients. It closely emulated the system behavior throughout the transient and subsequent steady-state. Modifications for two-phase flow analysis included addition of models for once-through steam generator and electric heater rods. Both programs are faster than real time. Off-line, they can be used for prediction and training applications while on-line they serve for simulation and signal validation. The programs can also be used to determine the sensitivity of natural circulation behavior to variation of inputs such as secondary distribution and power transients.

Download or read book A Study of Boiling Water Reactor BWR Dynamics written by Luv Sharma and published by . This book was released on 2007 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: A study of a Boiling Water Reactor (BWR) dynamics is presented with the objective of determining the attractors, domains of attraction and change in system stability with fluctuations in the system parameters. A reduced order model of the system was used for the investigations. The cell to cell mapping technique (CCMT) is used to determine the attractors and the domains of attraction for the system. The CCMT is a numerical technique for the global analysis of non-linear dynamics of systems and models system evolution as a Markov chain in time. The probabilistic modeling of the system dynamics and no differentiability requirements on the governing equations makes CCMT naturally suited for analysis of systems with stochastic parameters. This method, however, runs into performance problems with increasing number of state variables (degrees of freedom) of the system under investigation. Two methods are proposed to improve the performance of the CCMT for higher order systems. One of them is based on choosing different mapping time steps for different initial conditions for the system. The second method restricts the source cell region and gives a conditional probability of the system location. MATLAB v7.0 was used to set up the system and the simulations were run using the Ohio Supercomputing Center's distributed computing facilities. It is shown that these proposed methods lead to significant reduction in computational time compared to conventional CCMT. The results obtained are also generally better compared to the conventional approach. Using these proposed techniques it is determined that the BWR system has only one attractor and the only way to keep the reactor stable is to control the values of the system parameters. The parametric analysis was conducted using Taguchi methods, which are based on design of experiment techniques and the application of the signal-to-noise ratios. The experiment design was done using MINITAB v14. The experiments were used to determine the effects of parameter variation on the stability of the system as well as the interactions amongst the parameters. The parametric studies reveal that the heat transfer coefficient (k), the heat generation coefficient (Q), the Doppler's coefficient of reactivity ([gamma]1), delayed neutron precursor concentration ([beta]) and fitting parameters a1 and a2 have a notably larger effect on the response. Out of these parameters k, a, Q and [gamma]1 tend to destabilize the system at higher values while [beta], a1 and a2 have a stabilizing effect at higher values. Further, cross effects between a, k and Q were also found to be negligible compared to the main effects of the control factors.

Download or read book Natural Circulation Phenomena and Modelling for Advanced Water Cooled Reactors written by International Atomic Energy Agency and published by . This book was released on 2012 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: Based on an IAEA coordinated research project focused on the use of passive safety systems and natural circulation to help meet the safety and economic goals of advanced nuclear power plants, this publication includes the identification and definition of the thermo-hydraulic phenomena that affect the reliability of passive safety systems, characterization of each phenomenon, integral tests to examine the passive systems and natural circulation, and a methodology for examining passive system reliability.

Download or read book Experimental and analytical study of stability characteristics of natural circulation boiling water reactors during startup transient thesis written by Kyoungsuk Woo and published by . This book was released on 2008 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Space independent Model of Two phase Flow and Its Application to Experiment written by Louis M. Shotkin and published by . This book was released on 1966 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Performance Light Water Reactor written by Thomas Schulenberg and published by KIT Scientific Publishing. This book was released on 2014-07-28 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results of the project "High Performance Light Water Reactor--Phase 2," carried out September 2006-February 2010 as part of the 6th European Framework Program.

Download or read book Single phase Two phase and Supercritical Natural Circulation Systems written by Pallippattu Krishnan Vijayan and published by Woodhead Publishing. This book was released on 2019-06-19 with total page 650 pages. Available in PDF, EPUB and Kindle. Book excerpt: Single-Phase, Two-Phase and Supercritical Natural Circulation Systems provides readers with a deep understanding of natural circulation systems. This book equips the reader with an understanding on how to detect unstable loops to ensure plant safety and reliability, calculate heat transport capabilities, and design effective natural circulation loops, stability maps and parallel channel systems. Each chapter begins with an introduction to the circulation system before discussing each element in detail and analyzing its effect on the performance of the system. The book also presents thermosyphon heat transport devices in nuclear and other industrial plants, a common information need for students and researchers alike. This book is invaluable for engineers, designers, operators and consultants in nuclear, mechanical, electrical and chemical disciplines. Presents single-phase, two-phase and supercritical natural circulation systems together in one resource to fill an existing knowledge gap Guides the reader through relevant processes, such as designing, analyzing and generating stability maps and natural circulation loops, calculating heat transport capabilities, and maintaining natural circulation system operations Includes global case studies and examples to increase understanding, along with important IAEA standards and procedures

Download or read book An Analytical and Experimental Investigation of Natural Circulation Transients in a Model Pressurized Water Reactor written by Mahmoud Massoud and published by . This book was released on 1987 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Statics and Dynamics of a Natural Circulation Cooled Boiling Water Reactor written by Armand Jean Christiaan Stekelenburg and published by . This book was released on 1994 with total page 165 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Self sustained Hydrodynamic Oscillations in a Natural Circulation Two phase Flow Boiling Loop written by Kamal C. Jain and published by . This book was released on 1965 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of geometry, subcooling, and pressure on the inception and development of oscillatory behavior in a natural-circulation boiling-water loop were studied. A range of parameters were covered by the experimental study.