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

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.

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...

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.

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

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.

Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS)* at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dis semination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this jOint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volumes were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 40 (thesis year 1995) a total of 10,746 thesis titles from 19 Canadian and 144 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this impor tant annual reference work. While Volume 40 reports theses submitted in 1995, on occasion, certain uni versities do report theses submitted in previous years but not reported at the time.