DOCSLIB.ORG

Granular Dynamics in Pebble Bed Reactor Cores

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Granular Dynamics in Pebble Bed Reactor Cores Granular Dynamics in Pebble Bed Reactor Cores by Michael Robert Laufer A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Engineering – Nuclear Engineering in the Graduate Division of the University of California, Berkeley Committee in Charge: Professor Per Peterson, Chair Professor Brian Wirth Professor Tarek Zohdi Dr. Robert Budnitz Spring 2013 Granular Dynamics in Pebble Bed Reactor Cores Copyright 2013 by Michael Robert Laufer Abstract Granular Dynamics in Pebble Bed Reactor Cores by Michael Robert Laufer Doctor of Philosophy in Engineering – Nuclear Engineering University of California, Berkeley Professor Per F. Peterson, Chair This study focused on developing a better understanding of granular dynamics in pebble bed reactor cores through experimental work and computer simulations. The work completed includes analysis of pebble motion data from three scaled experiments based on the annular core of the Pebble Bed Fluoride Salt-Cooled High- Temperature Reactor (PB-FHR). The experiments are accompanied by the development of a new discrete element simulation code, GRECO, which is designed to offer a simple user interface and simplified two-dimensional system that can be used for iterative purposes in the preliminary phases of core design. The results of this study are focused on the PB-FHR, but can easily be extended for gas-cooled reactor designs. Experimental results are presented for three Pebble Recirculation Experiments (PREX). PREX 2 and 3.0 are conventional gravity-dominated granular systems based on the annular PB-FHR core design for a 900 MWth commercial prototype plant and a 16 MWth test reactor, respectively. Detailed results are presented for the pebble velocity field, mixing at the radial zone interfaces, and pebble residence times. A new Monte Carlo algorithm was developed to study the residence time distributions of pebbles in different radial zones. These dry experiments demonstrated the basic viability of radial pebble zoning in cores with diverging geometry before pebbles reach the active core. Results are also presented from PREX 3.1, a scaled facility that uses simulant materials to evaluate the impact of coupled fluid drag forces on the granular dynamics in the PB-FHR core. PREX 3.1 was used to collect first of a kind pebble motion data in a multidimensional porous media flow field. Pebble motion data were collected for a range of axial and cross fluid flow configurations where the drag forces range from half the buoyancy force up to ten times greater than the buoyancy force. Detailed analysis is presented for the pebble velocity field, mixing behavior, and residence time distributions for each fluid flow configuration. 1 The axial flow configurations in PREX 3.1 showed small changes in pebble motion compared to a reference case with no fluid flow and showed similar overall behavior to PREX 3.0. This suggests that dry experiments can be used for core designs with uniform one-dimensional coolant flow early in the design process at greatly reduced cost. Significant differences in pebble residence times were observed in the cross fluid flow configurations, but these were not accompanied by an overall horizontal diffusion bias. Radial zones showed only a small shift in position due to mixing in the diverging region and remained stable in the active core. The results from this study support the overall viability of the annular PB-FHR core by demonstrating consistent granular flow behavior in the presence of complex reflector geometries and multidimensional fluid flow fields. GRECO simulations were performed for each of the experiments in this study in order to develop a preliminary validation basis and to understand for which applications the code can provide useful analysis. Overall, the GRECO simulation results showed excellent agreement with the gravity-dominated PREX experiments. Local velocity errors were found to be generally within 10-15% of the experimental data. Average radial zone interface positions were predicted within two pebble diameters. GRECO simulations over predicted the amount of mixing around the average radial zone interface position and therefore can be treated as a conservative upper bound when used in neutronics analysis. Residence time distributions from the GRECO velocity data based on the Monte Carlo algorithm closely matched those derived from the experiment velocity statistics. GRECO simulation results for PREX 3.1 with coupled drag forces showed larger errors compared to the experimental data, particularly in the cases with cross fluid flow. The large discrepancies suggest that GRECO results in systems with coupled fluid drag forces cannot be used with high confidence at this point and future development work on coupled pebble and fluid dynamics with multidimensional fluid flow fields is required. 2 To my wife, Carolyn. You are the most caring and dedicated person that I know. Your support and encouragement made this possible. I love you with all of my heart. To my parents, Henry and Marsha. You inspire me to take on the big problems in the world. i Acknowledgements I am deeply grateful to many people who have helped to make this dissertation possible both in my time at U.C. Berkeley and before. I am sure that I will forget to acknowledge some of them here and I must apologize in advance for any oversight. First, I would like to express many thanks to my advisor, Per Peterson, who has been a constant source of support and interesting insights throughout this project. It is not an exaggeration to say that the origins of this project came from Per asking a supposedly simple question based on the results of the 2009 NE 270 Senior Design Project. I offered to investigate and four years later this dissertation is the answer. He also has been helpful in providing the critical pressure at the end of this process that has prevented me from spending too much time working on the many other interesting projects in our laboratory. I must also thank each of the other members of my dissertation committee. Brian Wirth was a reliable source of encouragement and provided important feedback early in this process on what scope of work I should pursue. Tarek Zohdi provided useful resources on particle simulations with coupled physics even more complicated than that covered in this thesis. Finally, Bob Budnitz from Lawrence Berkeley Laboratory provided a valuable outside perspective and an eye for detail that has improved this dissertation. He was also a source of great enthusiasm. Jeff Bickel has been invaluable throughout this process and the experimental components of this project would not have been possible without his help. Jeff built PREX 3.0 as part of his master’s project in 2010 and it was the first experiment that I used to produce data on the motion of pebbles at the visible surface. As a research engineer in our laboratory, Jeff is responsible for most of the detailed design and fabrication of PREX 3.1. A number of graduate students at U.C. Berkeley made valuable contributions to this project and have been a source of support through this process. I owe a great deal of gratitude to Ed Blandford, who provided me with great advice throughout my graduate studies and who I view as an important mentor. Jeff Powers, Raluca (Scarlat) Merric de Bellefon, and Tommy Cisneros all started with me in the same year and we have each studied different aspects of pebble fuel. Jeff and I had regular coffee outings that were a staple of my graduate school experience. I must also thank David Krumwiede for his help in keeping our exciting new granular flow projects in the Thermal-Hydraulics laboratory moving forward while I have been working hard to wrap up this thesis. Lisa Zemelman, the Graduate Student Affairs Officer for the ii Nuclear Engineering Department at U.C. Berkeley, has also been extremely helpful throughout my graduate program in navigating the university bureaucracy. The experimental results in this thesis were collected with the help of many U.C. Berkeley undergraduate students. I am thankful to all of the students who helped to build and run the PREX experiments, in addition to many hours of pebble sorting. The 2009 NE 170 Senior Design Class (Rada Hong, Steve Huber, Kenneth Lee, Patrick Purcell, Sahak Margossian, and John-David Seelig) built PREX 2 and I must acknowledge their role in helping me find this interesting topic. Kyle Chestnut, Sebastian Dionisio, and John Doojphibupol helped to collect data for this project from PREX 2 and 3.1. Andrew Serpa and Grant Buster did a meticulous job in their residence time studies with PREX 3.0. Alex Dixon also helped with the pebble projects in the lab, including the amazing task of figuring out how to get metal pins through the plastic pebbles for our future work in the X-PREX facility. My family has also been a great source of support and encouragement throughout my life. My parents provide constant inspiration to take on big challenges in life and are always cheering me on. I also owe a great deal of thanks to Jerry Cahill and Kathy King, who have welcomed me into their family and made me feel at home here in the Bay Area. I am also thankful for the love and support of my brothers and their families. I am incredibly grateful to my wife, Carolyn, who provided constant emotional support through both my undergraduate and graduate studies. I am in constant amazement of her tireless work ethic and she has helped to keep me on track throughout this process. She has also made sure that I take care of myself when I get absorbed in my work. I am looking forward to all of our future adventures in life together.
Load more

Recommended publications
  • KERNFORSCHUNGSANLA JULICH Gmbh
    KERNFORSCHUNGSANLA JULICH GmbH Proceedings of the Workshop on Structural Design Criteria for HTR Jiilich, 31. January - 1. February 1989 Editors: G. Breitbach F. Schubert H. Nickel Jiil-Conf-71 April 1989 ISSN 0344-5798 Als Manuskript gedruckt Berichte der Kernforschungsanlage Jülich - Jül-Conf-71 Zu beziehen durch: ZENTRALBIBLIOTHEK der Kernforschungsanlage Jülich GmbH Postfach 1913 • D-5170 Jülich (Bundesrepublik Deutschland) Telefon: 02461/610 • Telex: 833556-0 kf d Proceedings of the Workshop on Structural Design Criteria for HTR Jiilich, 31. January - 1. February 1989 Editors: G. Breitbach F. Schubert H. Nickel Workshop on Structural Design Criteria for HTR Introductural remarks Most of the presentations given in this workshop are based on the German research and development project "HTR Design Criteria" carried out under the sponsorship of the Federal Ministry of Research and Technology. The main emphasis of this work was to acquire the fundamental principles and basic data for the establishment of German KTA-rules (KTA: Nuclear Safety Standards Commission) for the design of HTR-structural components. The project began in 1984 and the research work divided among several working groups and task forces, with participation from several institutions and companies. The role of coordination has been carried out by the Institute for Reactor Materials, Nuclear Research Centre Julien, headed by Prof. Dr. H. Nickel. The work has been organized into four working groups: a) Technical safety boundary conditions; b) Metallic structural components; c) Prestressed concrete pressure vessel; d) Graphitic structural components. The required work in each group was divided between a number of task forces. The membership of each group and task force is given in the appendix.
    [Show full text]
  • Nuclear and Energy Independence
    Meetings ANS WINTER MEETING Nuclear and energy independence HILE ORGANIZATIONS HAVE canceled or altered conferences in W the wake of the events of Sep- Major themes of the plenary: tember 11, the American Nuclear Society at- tracted more than 1100 attendants to its Win- N ter Meeting in November in Reno, Nev. “In H2 power can be an application light of recent events, that is a remarkable ac- complishment,” ANS President Gail Marcus of nuclear commented during the opening plenary. The large gathering was due perhaps to the upbeat mood of the industry in general, thanks N 50 years since first electricity with EBR-I in part to the Bush administration’s support of the continued use and further deployment of N nuclear power, and because any hope for re- A proposal for a continental supergrid ducing greenhouse gas emissions likely would include nuclear power in a national energy policy. oring the EBR-I and the nuclear pioneers who was associate project director of the EBR-I During the plenary Marcus paraphrased developed it. The proclamation recognized the and project manager for another reactor, the Charles Dickens by saying, “It is the best of environmental benefits of nuclear power and EBR-II. He later became director of the Re- times, it is the worst of times,” in reference feted those who worked to provide the world actor Engineering Division at Argonne Na- to the terrorist attacks on the United States with “clean, sustainable energy for the bene- tional Laboratory before moving on to Illinois and the opportunity for nuclear power to fit of humankind for centuries by making use Power Company.
    [Show full text]
  • HTGR Dust Safety Issues and Needs for Research and Development
    INL/EXT-11-21097 HTGR Dust Safety Issues and Needs for Research and Development P. W. Humrickhouse June 2011 DISCLAIMER This information was prepared as an account of work sponsored by an agency of the U.S. Government. Neither the U.S. Government nor any agency thereof, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness, of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. References herein to any specific commercial product, process, or service by trade name, trade mark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the U.S. Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the U.S. Government or any agency thereof. INL/EXT-11-21097 HTGR Dust Safety Issues and Needs for Research and Development P. W. Humrickhouse June 2011 Idaho National Laboratory Next Generation Nuclear Plant Project Idaho Falls, Idaho 83415 http://www.inl.gov Prepared for the U.S. Department of Energy Office of Nuclear Energy Under DOE Idaho Operations Office Contract DE-AC07-05ID14517 ABSTRACT This report presents a summary of high temperature gas-cooled reactor dust safety issues. It draws upon a literature review and the proceedings of the Very High Temperature Reactor Dust Assessment Meeting held in Rockville, MD in March 2011 to identify and prioritize the phenomena and issues that characterize the effect of carbonaceous dust on high temperature reactor safety.
    [Show full text]
  • Reactor Technology Safety and Siting
    XA0101477-5/I5* IAEA-TC-389.26 LIMITED DISTRIBUTION REACTOR TECHNOLOGY SAFETY AND SITING REPORT OF A TECHNICAL COMMITTEE MEETING ORGANIZED BY THE INTERNATIONAL ATOMIC ENERGY AGENCY AND HELD IN DIMITROVGRAD, USSR, 21-23 JUNE 1989 Reproduced by the IAEA Vienna, Austria, 1990 NOTE The material in this document has been supplied by the authors and has not been edited by the IAEA. The views expressed remain the responsibility of the named authors and do not necessarily reflect those of the govern- ments) of the designating Member State(s). In particular, neither the IAEA nor any other organization or body sponsoring this meeting can be held responsible for any material reproduced in this document. FOREWORD On the invitation of the Government of the Union of Soviet Socialist Republics, the Eleventh International Conference on the HTGR and the IAEA Technical Committee Meeting on Gas-Cooled Reactor Technology, Safety and Siting were held in Dimitrovgrad, USSR, on June 21-23, 1989. The meetings complemented each other. Due to the large worldwide interest, the conference attracted approximately 60 participants from 18 countries and 130 Soviet delegates. About 50 foreign participants and 100 Soviet delegates stayed over for the Technical Committee Meeting. The Technical Committee Meeting provided the Soviet delegates with an opportunity to display the breadth of their program on HTGR's to an international audience. Nearly one-half of the papers were presented by Soviet participants. Among the highlights of the meeting were the following: - The diverse nature and large magnitude of the Soviet research and development program on high temperature gas-cooled reactors.
    [Show full text]
  • Deployability of Small Modular Nuclear Reactors for Alberta Applications Report Prepared for Alberta Innovates
    PNNL-25978 Deployability of Small Modular Nuclear Reactors for Alberta Applications Report Prepared for Alberta Innovates November 2016 SM Short B Olateju (AI) SD Unwin S Singh (AI) A Meisen (AI) DISCLAIMER NOTICE This report was prepared under contract with the U.S. Department of Energy (DOE), as an account of work sponsored by Alberta Innovates (“AI”). Neither AI, Pacific Northwest National Laboratory (PNNL), DOE, the U.S. Government, nor any person acting on their behalf makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by AI, PNNL, DOE, or the U.S. Government. The views and opinions of authors expressed herein do not necessarily state or reflect those of AI, PNNL, DOE or the U.S. Government. Deployability of Small Modular Nuclear Reactors for Alberta Applications SM Short B Olateju (AI) SD Unwin S Singh (AI) A Meisen (AI) November 2016 Prepared for Alberta Innovates (AI) Pacific Northwest National Laboratory Richland, Washington 99352 Executive Summary At present, the steam requirements of Alberta’s heavy oil industry and the Province’s electricity requirements are predominantly met by natural gas and coal, respectively. On November 22, 2015 the Government of Alberta announced its Climate Change Leadership Plan to 1) phase out all pollution created by burning coal and transition to more renewable energy and natural gas generation by 2030 and 2) limit greenhouse gas (GHG) emissions from oil sands operations.
    [Show full text]
  • Exelon Generation Introduction to the Pebble Bed Modular Reactor
    Exekn.m Exelon Generation Telephone 610.765.5661 Generati on 200 Exelon Way Fax 610.765.5545 KSA3-N www.exeloncorp.com Kennett Square, PA 19348 Project No.: 713 August 30, 2001 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 Subject: "Introduction to the Pebble Bed Modular Reactor" Dear Sir/Madam, a general Transmitted here with is a copy of the subject document, which provides presents an description of the Pebble Bed Modular Reactor (PBMR). This document safety analysis, and overview of the PBMR; the concept, the basic principles of design, operation. It is not intended to be used (or maintained) as a design document. Sincerely, Manager, Licensing PBMR Introduction to the Pebble Bed Modular Reactor (PBMR) Doc. No. 009949-185 PBMR Introduction to the Pebble Bed Modular Reactor (PBMR) Doc. No. 009949-1 85 INTRODUCTION TO THE PEBBLE BED MODULAR REACTOR (PBMR) DOCUMENT No.: 009949-185 Revision: 1 Document Status: Approved 1 Page 1 0179 ©@ Copyright 20012001 by PBMR 22/08/200122108/2001 Revision 1 Page 1 of 79 PBMVR Introduction to the Pebble Bed Modular Reactor (PBMR) Doc. No. 009949-185 CHANGE HISTORY Configuration Control Project: PBMR Title: Introduction to the Pebble Bed Modular Reactor (PBMR) Doc. Reference: 009949-185 Created By: A P George Creation Date: August 2001 Classification: Confidential Document History Revision History Revision Date Changes A August 2001 New document 1 August 2001 Document updated after review I Page 2of79 Q© Copyright 2001 byby PB3MRPBMR 22/08/200122108/2001 Revision I Page 2 of 79 PBMVR Introduction to the Pebble Bed Modular Reactor (PBMVR) Doc.
    [Show full text]
  • Annual Report 2015 Forschungszentrum Jülich at a Glance Contents
    Annual Report 2015 Forschungszentrum Jülich at a glance Contents U 2 Facts and Figures 0 2 Highlights 0 4 Board of Directors 0 5 Preface 0 6 60 Years of Research R e s e a r c h at the Centre 22 Climate Research Climate goals. Climate Records. Climate Models. 1 4 Chronology 28 Nanoelectronics Insights into the Resistance Generation 32 Energy Research Breaking New Ground in the Hydrogen World 36 Materials Research The Slipperiness Formula 38 Structural Biochemistry New Light Switch for Nerve Cells 40 Electron Tomography Nanoworld in 3D 42 Brain Research Changes in the Brain Caused by Depression 44 Climate Research A Chance Discovery for Climate Research 46 Computer Simulation The Birth of Elements 48 Materials Research New Steel for Energiewende 5 0 Research in Brief 5 2 Publications Cooperation 5 4 The Computer Diplomat 5 8 International Cooperations (EU) 59 National Cooperations 6 0 Collaborations with Industry 6 1 JARA – Combined Expertise 6 4 Cooperations in Brief 6 8 Research for Practical Applications 7 0 Patents and Licenses P e o p l e 7 2 The Tinkerer and the Networker 7 4 Promoting Young Talent 8 2 Personnel 8 4 Accolades 8 6 Professorial Appointments Campus 8 8 Strategy Process of Forschungszentrum Jülich 98 Finances 9 0 Jülich’s Sustainable Campus 1 0 2 Bodies and Committees 9 1 Excellent Platforms 1 0 4 Organization Chart 9 4 Work at Other Locations 1 0 6 Contact Information/ Publication Details U3 Impressions from 60 Years of Research Forschungszentrum Jülich Annual Report 2015 1 Highlights 2015 Forschungszentrum Jülich is focused on use-inspired basic research.
    [Show full text]
  • Preliminary Failure Modes and Effects Analysis of the US DCLL Test Blanket Module
    INL/EXT-07-13115 Preliminary Failure Modes and Effects Analysis of the US DCLL Test Blanket Module Lee C. Cadwallader August 2007 The INL is a U.S. Department of Energy National Laboratory operated by Battelle Energy Alliance INL/EXT-07-13115 Preliminary Failure Modes and Effects Analysis of the US DCLL Test Blanket Module Lee C. Cadwallader August 2007 Idaho National Laboratory Advanced Nuclear Energy Systems Department Idaho Falls, Idaho 83415 Prepared for the U.S. Department of Energy Office of Fusion Energy Sciences Under DOE Idaho Operations Office Contract DE-AC07-05ID14517 ABSTRACT This report presents the results of a preliminary failure modes and effects analysis (FMEA) of a small tritium-breeding test blanket module design for the International Thermonuclear Experimental Reactor. The FMEA was quantified with “generic” component failure rate data, and the failure events are binned into postulated initiating event families and frequency categories for safety assessment. An appendix to this report contains repair time data to support an occupational radiation exposure assessment for test blanket module maintenance. iii iv CONTENTS ABSTRACT.................................................................................................................................................iii ACRONYMS................................................................................................................................................ 1 1. INTRODUCTION.............................................................................................................................
    [Show full text]
  • The High Temperature Gas-Cooled Reactor
    The High Temperature Gas-cooled Reactor Safety considerations of the (V)HTR-Modul Kugeler, K., Nabielek, H., Buckthorpe, D. Editors: Scheuermann, W., Haneklaus, N., Fütterer, M. 2017 EUR 28712 EN KJ - NA - 28712 - EN - C This publication is a Book with editorship by the Joint Research Centre (JRC), the European Commission’s science and knowledge service. It aims to provide evidence-based scientific support to the European policymaking process. The scientific output expressed does not imply a policy position of the European Commission. Neither the European Commission nor any person acting on behalf of the Commission is responsible for the use that might be made of this publication. Contact information Name: Fütterer, M. Address: European Commission, DG Joint Research Centre – JRC, Directorate G, Unit G.I.4 – Nuclear Reactor Safety & Emergency Preparedness; P.O. Box 2, NL-1755 ZG Petten, Netherlands Email: [email protected] Tel.: +31 22456-5158 JRC Science Hub https://ec.europa.eu/jrc JRC107642 EUR 28712 EN PDF ISBN 978-92-79-71311-8 ISSN 1831-9424 doi:10.2760/270321 Print ISBN 978-92-79-71312-5 ISSN 1018-5593 doi:10.2760/970340 Luxembourg: Publications Office of the European Union, 2017 © European Atomic Energy Community, 2017 Reuse is authorised provided the source is acknowledged. The reuse policy of European Commission documents is regulated by Decision 2011/833/EU (OJ L 330, 14.12.2011, p. 39). For any use or reproduction of photos or other material that is not under the EU copyright, permission must be sought directly from the copyright holders.
    [Show full text]
  • R. HÜPER Fast Breeder Project, Kernforschungszentrum Karlsruhe
    STATUS OF FAST BREEDER REACTOR DEVELOPMENT 500 °C. After several years of operation with a thermal reactor core (KNK I), IN THE FEDERAL REPUBLIC OF GERMANY, the plant has been run with fast, i.e. unmoderated, reactor cores since 1978 (KNK II). BELGIUM AND THE NETHERLANDS February 1987* While the fuel assemblies of the first fast core, KNK II/l, were identical with those of the Mk.Ia first core of the SNR 300 in their key parameters, the fuel assemblies of the second core loading, KNK 11/2 , correspond to the SNR 300 Mk.II R. HÜPER type, which is characterized by a high fuel density, 7.6 mm fuel rod diameter, Fast Breeder Project, and spark eroded spacer grids which, in the fuel assemblies of the test zone, Kernforschungszentrum Karlsruhe GmbH, are attached to the wrapper tube by means of flow aprons. Karlsruhe, Federal Republic of Germany The first fast core had been unloaded in 1982 after a peak burnup of 100.000 MWd/te. The fuel assemblies of the second core, which was commissioned iri mid-1983, have meanwhile reached an average burnup of 47.000 MWd/te. One test Abstract fuel assembly transferred from the first to the second core has reached an average burnup of 125.000 MWd/te by late 1986. In 1967 and 1968, the Federal Republic of Germany, the Kingdom of Belgium, and the Kingdom of the Netherlands ("DeBeNe") agreed in a joint program to develop In the course of the burnup of the second core so far, a change in the outlet breeder reactors.
    [Show full text]
  • Core Physics of Pebble Bed High Temperature Nuclear Reactors
    Core Physics of High Temperature Pebble Bed Nuclear Reactors Pebble of High Temperature Physics Core Uitnodiging Voor het bijwonen van de openbare Core Physics of Pebble Bed verdediging van het proefschrift High Temperature Core Physics of Nuclear Reactors Pebble Bed High Temperature Nuclear Reactors Gert Jan Auwerda door Gert Jan Auwerda 22 december 12:30 Aula, TU Delft, Mekelweg 5 Gert Jan Auwerda Voorafgaand, om 12:00, is een presentatie over het onderzoek Faculty of Applied Sciences Department of Radiation Science & Technology Faculty: Applied Sciences Department: RS&T ISBN 978-94-6295-047-4 Group: NERA Propositions accompanying the dissertation CORE PHYSICSOF PEBBLE BED HIGH TEMPERATURE NUCLEAR REACTORS by Gert Jan AUWERDA 1. Non-isotropic models are required to accurately simulate heat and mass transfer next to the wall in a pebble bed reactor. (This thesis.) 2. In a pebble bed reactor, the higher porosity near the boundaries than in the centre of the randomly stacked pebble bed can be ignored when calculating the neutron flux distribution, but cannot be ignored when calculating the ke f f or the power distribution. (This thesis.) 3. In annular pebble bed designs, the wall-channelling effect results in a significantly lower maximum fuel temperature during both normal operation and during a pres- surized loss of forced cooling accident. (This thesis.) 4. A grid convergence study based on Richardson extrapolation to evaluate the grid convergence index (GCI) should be mandatory to evaluate the mesh quality when solving equations using numerical analysis. (P.J.Roache. Verification and validation in com- putational science and engineering, Hermosa Publishers, USA, 1998.) 5.
    [Show full text]
  • Nuclear Energy of the Future: What Research for Which Objectives?
    MonoCEA GB 5/04/06 15:30 Page 3 Commissariat à l’énergie atomique e-den A monograph of the Nuclear Energy Directorate Nuclear energy of the future: what research for which objectives? Éditions techniques MonoCEA GB 5/04/06 15:30 Page 2 DEN monographs A monograph of the Nuclear Energy Directorate Commissariat à l’énergie atomique, 31-33, rue de la Fédération 75752 Paris Cedex 15 Tél. : +33-1 40 56 10 00 Scientific comitee Michel Alexandre, Michel Beauvy, Georges Berthoud, Mireille Defranceschi, Gérard Ducros, Yannick Guérin, Yves Limoge, Charles Madic, Gérard Santarini, Jean-Marie Seiler, Pierre Sollogoub, Étienne Vernaz, Research Directors. The following people participated in this work: Fanny Bazile, Patrice Bernard, Bernard Bonin, Jacques Bouchard, Jean-Claude Bouchter, Bernard Boullis, Franck Carré, Jean Cazalet, Alain Marvy, Valérie Moulin, Emmanuel Touron, Yves Terrien. Publishing Supervisor: Philippe Pradel. Editorial Board: Bernard Bonin (Managing Editor), Bernard Bouquin, Martine Dozol, Michel Jorda, Jean-Pierre Moncouyoux, Alain Vallée. Administrator: Fanny Bazile. Editor: Jean-François Parisot. Graphic concept: Pierre Finot. Cover illustration: Véronique Frouard. Correspondence: all correspondence can be addressed to the Editor or to CEA / DEN Direction scientifique, CEA Saclay 91191 Gif-sur-Yvette Cedex. Tél. : + 33-1 69 08 16 75. © CEA Saclay and Groupe Moniteur (Éditions du Moniteur), Paris, 2006 The information contained in this document can be freely reproduced, with the agreement of the Editorial Board and due mention of its origin. MonoCEA GB 5/04/06 15:30 Page 5 Preface After a dazzling start in the 1950s as a promising, inexhaustible, cost-effective energy source, nuclear energy was rejected by majority opinion in several countries in North America and Western Europe three to four decades later, suddenly bringing its development to a halt.
    [Show full text]