High Temperature Gas Cooled Reactor Fuels and Materials
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High Temperature Gas Cooled Reactor Fuels and Materials The following States are Members of the International Atomic Energy Agency: AFGHANISTAN GHANA NORWAY ALBANIA GREECE OMAN ALGERIA GUATEMALA PAKISTAN ANGOLA HAITI PALAU ARGENTINA HOLY SEE PANAMA ARMENIA HONDURAS PARAGUAY AUSTRALIA HUNGARY PERU AUSTRIA ICELAND PHILIPPINES AZERBAIJAN INDIA POLAND BAHRAIN INDONESIA PORTUGAL BANGLADESH IRAN, ISLAMIC REPUBLIC OF QATAR BELARUS IRAQ REPUBLIC OF MOLDOVA BELGIUM IRELAND ROMANIA BELIZE ISRAEL RUSSIAN FEDERATION BENIN ITALY SAUDI ARABIA BOLIVIA JAMAICA BOSNIA AND HERZEGOVINA JAPAN SENEGAL BOTSWANA JORDAN SERBIA BRAZIL KAZAKHSTAN SEYCHELLES BULGARIA KENYA SIERRA LEONE BURKINA FASO KOREA, REPUBLIC OF SINGAPORE BURUNDI KUWAIT SLOVAKIA CAMBODIA KYRGYZSTAN SLOVENIA CAMEROON LATVIA SOUTH AFRICA CANADA LEBANON SPAIN CENTRAL AFRICAN LESOTHO SRI LANKA REPUBLIC LIBERIA SUDAN CHAD LIBYAN ARAB JAMAHIRIYA SWEDEN CHILE LIECHTENSTEIN SWITZERLAND CHINA LITHUANIA SYRIAN ARAB REPUBLIC COLOMBIA LUXEMBOURG TAJIKISTAN CONGO MADAGASCAR THAILAND COSTA RICA MALAWI THE FORMER YUGOSLAV CÔTE D’IVOIRE MALAYSIA REPUBLIC OF MACEDONIA CROATIA MALI TUNISIA CUBA MALTA TURKEY CYPRUS MARSHALL ISLANDS UGANDA CZECH REPUBLIC MAURITANIA UKRAINE DEMOCRATIC REPUBLIC MAURITIUS UNITED ARAB EMIRATES OF THE CONGO MEXICO UNITED KINGDOM OF DENMARK MONACO GREAT BRITAIN AND DOMINICAN REPUBLIC MONGOLIA NORTHERN IRELAND ECUADOR MONTENEGRO EGYPT MOROCCO UNITED REPUBLIC EL SALVADOR MOZAMBIQUE OF TANZANIA ERITREA MYANMAR UNITED STATES OF AMERICA ESTONIA NAMIBIA URUGUAY ETHIOPIA NEPAL UZBEKISTAN FINLAND NETHERLANDS VENEZUELA FRANCE NEW ZEALAND VIETNAM GABON NICARAGUA YEMEN GEORGIA NIGER ZAMBIA GERMANY NIGERIA ZIMBABWE The Agency’s Statute was approved on 23 October 1956 by the Conference on the Statute of the IAEA held at United Nations Headquarters, New York; it entered into force on 29 July 1957. The Headquarters of the Agency are situated in Vienna. Its principal objective is “to accelerate and enlarge the contribution of atomic energy to peace, health and prosperity throughout the world’’. IAEA-TECDOC-1645 High Temperature Gas Cooled Reactor Fuels and Materials INTERNATIONAL ATOMIC ENERGY AGENCY VIENNA, 2010 COPYRIGHT NOTICE All IAEA scientific and technical publications are protected by the terms of the Universal Copyright Convention as adopted in 1952 (Berne) and as revised in 1972 (Paris). The copyright has since been extended by the World Intellectual Property Organization (Geneva) to include electronic and virtual intellectual property. Permission to use whole or parts of texts contained in IAEA publications in printed or electronic form must be obtained and is usually subject to royalty agreements. Proposals for non-commercial reproductions and translations are welcomed and considered on a case-by-case basis. Enquiries should be addressed to the IAEA Publishing Section at: Sales and Promotion, Publishing Section International Atomic Energy Agency Vienna International Centre PO Box 100 1400 Vienna, Austria fax: +43 1 2600 29302 tel.: +43 1 2600 22417 email: [email protected] http://www.iaea.org/books For further information on this publication, please contact: Nuclear Fuel Cycle and Materials Section International Atomic Energy Agency Vienna International Centre PO Box 100 1400 Vienna, Austria email: [email protected] HIGH TEMPERATURE GAS COOLED REACTOR FUELS AND MATERIALS IAEA, VIENNA, 2010 IAEA-TECDOC-1645-CD ISBN 978-92-0-153110-2 ISSN 1684-2073 © IAEA, 2010 Printed by the IAEA in Austria March 2010 FOREWORD At the third annual meeting of the technical working group on Nuclear Fuel Cycle Options and Spent Fuel Management (TWG-NFCO), held in Vienna, in 2004, it was suggested “to develop manuals/handbooks and best practice documents for use in training and education in coated particle fuel technology” in the IAEA’s Programme for the year 2006–2007. In the context of supporting interested Member States, the activity to develop a handbook for use in the “education and training” of a new generation of scientists and engineers on coated particle fuel technology was undertaken. To make aware of the role of nuclear science education and training in all Member States to enhance their capacity to develop innovative technologies for sustainable nuclear energy is of paramount importance to the IAEA Significant efforts are underway in several Member States to develop high temperature gas cooled reactors (HTGR) based on either pebble bed or prismatic designs. All these reactors are primarily fuelled by TRISO (tri iso-structural) coated particles. The aim however is to build future nuclear fuel cycles in concert with the aim of the Generation IV International Forum and includes nuclear reactor applications for process heat, hydrogen production and electricity generation. Moreover, developmental work is ongoing and focuses on the burning of weapon-grade plutonium including civil plutonium and other transuranic elements using the “deep-burn concept” or “inert matrix fuels”, especially in HTGR systems in the form of coated particle fuels. The document will serve as the primary resource materials for “education and training” in the area of advanced fuels forming the building blocks for future development in the interested Member States. This document broadly covers several aspects of coated particle fuel technology, namely: manufacture of coated particles, compacts and elements; design-basis; quality assurance / quality control and characterization techniques; fuel irradiations; fuel failure mechanisms; accident testing; fuel and fission product chemistry; fuel cycles; fission product transport; spent fuel management; and nuclear hydrogen production. This knowledge base was gained over nearly fifty years of fuel materials research and development in the international HTGR community. The primary intent of this effort is that this documented experience will provide the basis for further development of HTGR fuels and reactor systems. In many ways this book is a unique source of past experience, and hopefully, it will serve as an important part of future development of nuclear energy worldwide for the new generation scientists and engineers. The authors for the preparation of this report were drawn from a large number of countries involved today in HTGR research and development. Subsequently, consultancy meetings in December 2006 (Vienna), December 2007 (NRG, Petten) and November, 2008 (Vienna) were held to review and finalize this report. The IAEA is grateful to the experts who contributed to this publication (listed at the end of this publication). Special thanks to H. Nabielek of Germany for chairing this working group and to Ü. Colak of Turkey and M.J. Kania of the USA for their critical review of this report. The IAEA officer responsible for this publication was H.P. Nawada of the Division of Fuel Cycle and Waste Technology. CONTENTS 1. INTRODUCTION 1.1. HTGR technology 1.1.1. History of HTGR development and concepts 1.1.2. Characteristics and utilization of HTGRs 1.2. Fuels for HTGRs 1.2.1. Conventional fuels for HTGRs 1.2.2. Advanced fuels for HTGRs 2. MANUFACTURE OF TRISO COATED PARTICLES 2.1. Historic development 2.2. Manufacture of UO2 kernels 2.2.1. Process schematic 2.2.2. Preparation of the feed solution 2.2.3. Casting of microspheres 2.2.4. Ageing, washing and drying 2.2.5. Calcining 2.2.6. Reduction and sintering 2.2.7. Sieving and sorting 2.3. Manufacture of UCO kernels 2.4. Manufacture of TRISO coated particles 2.4.1. Process schematic 2.4.2. Coating process 2.4.3. Sieving and sorting 3. MANUFACTURE OF SPHERICAL FUELS 3.1. Fabrication technology 3.1.1. Preparation of resinated graphitic matrix powder 3.1.2. Overcoating of TRISO coated particles 3.1.3. Molding and pressing of fuel spheres 3.1.4. Lathing the elements 3.1.5. Carbonization and removal of impurities 4. QUALITY ASSURANCE / QUALITY CONTROL AND THE CHARACTERIZATION OF TRISO COATED PARTICLES 4.1. Quality assurance 4.2. Statistical quality control 4.3. QC and characterization test methods 4.3.1. TRISO particle size and shape analysis (PSA) 4.3.2. Optical anisotropy 4.3.3. Kernel, buffer and layer density determination 4.3.4. Layer thickness determination: Micro-radiography 4.3.5. SiC layer integrity: Burn-leach testing 4.3.6. Thermal conductivity 4.3.7. Elasticity modulus 5. FABRICATION OF FUEL COMPACTS 5.1. The Japanese process 5.2. The French process 5.3. The US process 5.3.1. Graphite matrix material formulation 5.3.2. Overcoating TRISO coated fuel particles 5.3.3. Compact fabrication 6. IN-CORE STRUCTURAL MATERIALS AND COMPONENTS 6.1. Hexagonal block fuel elements for the prismatic HTGR design 6.2. In-core graphitic materials 6.3. In-core ceramic and ceramic composite materials 7. TRISO-COATED PARTICLE FUEL IRRADIATIONS 7.1. Past irradiation performance 7.2. State of the art in TRISO-coated particle fuel irradiations 7.2.1. Reactor considerations 7.2.2. Thermal and physics analysis considerations 7.2.3. Gas control system considerations 7.2.4. Statistical considerations 7.2.5. Fission product monitoring considerations 8. FUEL FAILURE MECHANISMS 8.1. Overpressure 8.2. Irradiation-induced IPyC cracking 8.3. Debonding between IPyC and SiC 8.4. Kernel migration 8.5. Fission product attack 8.6. Matrix-OPyC interactions and OPyC irradiation-induced cracking 8.7. Non-retentive SiC 8.7.1. Diffusive release through intact layers 8.7.2. SiC degradation resulting in permeability to fission products 8.8. Creep failure of PyC 8.9. SiC thermal decomposition 8.10. Kernel-coating mechanical interaction (KCMI) 8.11. Summary 9. ACCIDENT TESTING 9.1. Test background 9.2. Description of the cold finger apparatus 9.2.1. General 9.2.2. Measurement of the fission gases release 9.2.3. Solid fission products release 9.2.4. Typical tests 9.3. Fission product release in accidents 9.3.1. Bare fuel release 9.3.2. Release from irradiated spherical fuel elements 10. FUEL CHEMISTRY 10.1. Introduction 10.2. Unirradiated fuel 10.3. Irradiated fuel 10.3.1. Particle composition and fission product behavior 10.3.2. Urania (UO2) kernel oxygen potential 10.3.3. CO/CO2 formation and particle pressurization 10.3.4.