Nuclear Fission Reactors : Potential Role and Risks of Converters and Breeders

Nuclear power offers an abundant energy supply for the long term and at reasonable costs. Both are badly needed in this world of limited energy reserves and rising energy prices. On the other hand, there are questions widely discussed in the public on nuclear safety, on acceptable means of nuclear waste disposal, and concern on the proliferation of nuclear weapon capabilities. Public confu­ sion is widespread since facts are often overshadowed by emotions. Recognizing the need for reliable, factual and comprehensive information on nuclear energy, this book on Nuclear Fission Reactors is published .to present the scientific and technical facts of nuclear fission reactors, and to analyse their potential role and risks. The author, Professor Dr. G. Kessler, has worked in nuclear research and project management since 1963. From 1975 to 1978, he acted as project leader for the German/Belgian/Dutch Fast Breeder research and. development activi­ ties. Since then, he has been Director of the Institute of Neutron Physics and Reactor Technology in the Karlsruhe Nuclear Research Centre. The book is part of the series "Topics in Energy" issued by Springer Publish­ ers. The intention of this series of in-depth analyses is to present the facts, inherent problems, trends and prospects of energy demand, resources and tech­ nologies. The vital importance of energy for human activities has become apparent to the public particularly through dramatic events in the area of oil supply.

1 Introduction.- 1.1 TheDevelopmentofNuclear Energy in the World.- 1.2 Technical Applications of Nuclear Fission Energy.- 1.2.1 Nuclear Power for Electricity and Process Heat Generation.- 1.2.2 Nuclear Ship Propulsion.- 1.2.3 Nuclear High Temperature Process Heat.- 1.2.4 Nuclear Power for Hydrogen Generation.- 1.3 Economic Aspects of Nuclear Energy.- 1.3.1 Electricity Generating Costs.- 1.3.2 Load Factors of Nuclear Power Plants.- Selected Literature.- 2 Some Basic Physics of Converter and Breeder Reactors.- 2.1 Basic Nuclear Physics.- 2.1.1 Elastic Scattering.- 2.1.2 Inelastic Scattering.- 2.1.3 Neutron Capture.- 2.1.4 Nuclear Fission.- 2.1.5 Energy Release in Nuclear Fission.- 2.1.6 Decay Constant and Halflife.- 2.1.7 Prompt and Delayed Neutrons.- 2.1.8 Afterheat of the Reactor Core.- 2.2 Neutron Flux and Reaction Rates.- 2.3 Spatial Distribution of the Neutron Flux in the Reactor Core.- 2.4 Fuel Burnup, Fission Product and Actinide Buildup.- 2.5 Conversion Ratio and Breeding Ratio.- 2.6 Conversion Ratio and Fuel Utilization.- 2.7 Radioactive Inventories in Fission Reactors.- 2.8 Inherent Safety Characteristics of Converter and Breeder Reactor Cores.- 2.8.1 Reactivity and Non-steady State Conditions.- 2.8.2 Temperature Reactivity Coefficients.- 2.8.2.1 Fuel Doppler Temperature Coefficient.- 2.8.2.2 Coefficients of Moderator or Coolant Temperatures.- 2.8.2.3 Structural Material Temperature Coefficient.- 2.8.3 Reactor Control and Safety Analysis.- 2.8.3.1 Reactivity Changes During Startup and Full Power Operation.- 2.8.3.2 Qualitative Description of a Reactor Core under Transient Power Conditions.- Selected Literature.- 3 Nuclear Fuel Supply.- 3.1 Introduction (The Nuclear Fuel Cycle).- 3.2 Uranium Resources and Requirements.- 3.2.1Uranium Consumption in Various Reactor Systems.- 3.2.2 Available Uranium and Thorium Reserves.- 3.2.2.1 Worldwide Available Uranium Reserves.- 3.2.2.2 Uranium Production.- 3.2.2.3 Thorium Reserves.- 3.2.3 Uranium Requirement vs. Uranium Reserves.- 3.3 Concentration, Purification and Conversion of Uranium.- 3.4 Uranium Enrichment.- 3.4.1 Introduction.- 3.4.2 Designs of Enrichment Plants.- 3.4.3 Uranium Enrichment by Gaseous Diffusion.- 3.4.4 Gas Ultracentrifuge Process.- 3.4.5 Aerodynamic Methods.- 3.4.6 Advanced Separation Processes.- 3.4.7Effects of Tails Assay and Economic Optimum.- 3.5 Fuel Fabrication.- Selected Literature.- 4 Converter Reactors with a Thermal Neutron Spectrum.- 4.1 Light Water Reactors.- 4.1.1 Pressurized Water Reactors.- 4.1.1.1 Core.- 4.1.1.2 Coolant System.- 4.1.1.3 Containment.- 4.1.1.4 Control Systems.- 4.1.1.5 Protection System.- 4.1.1.5.1 Reactor Scram.- 4.1.1.5.2 Emergency Power Supply.- 4.1.1.5.3 Emergency Feedwater System.- 4.1.1.5.4 Emergency Cooling and Afterheat Removal Systems.- 4.1.1.5.5 Closure of the Reactor Containment.- 4.1.2 Boiling Water Reactors.- 4.1.2.1 Core, Pressure Vessel and Cooling System.- 4.1.2.2 Safety Systems.- 4.1.2.3 Emergency Cooling and Afterheat Removal Systems.- 4.2 Gas Cooled Thermal Reactors.- 4.2.1 Advanced Gas Cooled Reactors.- 4.2.2 High Temperature Gas Cooled Reactors.- 4.2.2.1 HTGR with Prismatic Fuel Elements.- 4.2.2.2 HTR with Spherical Fuel Elements.- 4.2.2.3 General Safety Considerations of HTGR’s and HTR’s.- 4.2.2.3.1 Control and Shutdown Systems.- 4.2.2.3.2 Afterheat Removal and Emergency Cooling.- 4.2.2.3.3 Design Base Accidents.- 4.3 Heavy Water Reactors.- 4.3.1 CANDU Pressurized Heavy Water Reactor.- 4.3.1.1 Fuel Elements.- 4.3.1.2 Reactivity Control.- 4.3.1.3 Shutdown Cooling Systems.- 4.3.1.4 Safety Systems.- 4.4 Near Breeder and Thermal Breeder Reactors.- 4.4.1 Homogeneous Core Thermal Breeders.- 4.4.2 Light Water Breeder Reactors (LWBR’s).- Selected Literature.- 5 Breeder Reactors with a Fast Neutron Spectrum.- 5.1 The Potential Role of Breeder Reactors with a Fast Neutron Spectrum.- 5.2 Brief History of the Development of Fast Breeder Reactors.- 5.3 The Physics of LMFBR Cores.- 5.3.1 LMFBR Core Design.- 5.3.2 Energy Spectrum and Neutron Flux Distribution.- 5.3.3 Breeding Ratio.- 5.3.4 Reactivity Coefficients and Control Stability.- 5.3.5 The Doppler Coefficient.- 5.3.6 The Coolant Temperature Coefficient.- 5.3.7 Fuel and Structural Temperature Coefficients.- 5.3.8 Delayed Neutron Characteristics and Prompt Neutron Lifetime.- 5.4 Technical Aspects of Sodium Cooled FBR’s.- 5.5 SUPERPHENIX -A Commercial Size Demonstration LMFBR.- 5.5.1 Reactor Core and Blankets.- 5.5.2 Reactor Tank and Primary Coolant Circuits.- 5.5.3 Secondary Coolant Circuits and Steam Generators.- 5.6 Safety Design Aspects of LMFBR Plants.- 5.6.1 The Multiple Barrier Principle.- 5.6.2 Control and Shutdown Systems.- 5.6.3 Afterheat Removal and Emergency Cooling of LMFBR Cores.- 5.6.4 Core Instrumentation and Protection against Fault Propagation.- 5.6.5 Design Bases of the Primary System and Containment.- 5.6.6 Sodium Fires.- 5.6.7 Sodium-Water Interactions in Steam Generators 1295.7 Heterogeneous Core Designs of LMFBR’s.- 5.8 LMFBR Cores with Advanced Oxide and Carbide Fuels.- 5.9 Gas Cooled Fast Breeder Reactors.- Selected Literature.- 6 Nuclear Fuel Cycle Options.- 6.1 Fuel Cycle Options for Converter Reactors.- 6.1.1 The Once-Through Fuel Cycle.- 6.1.2 Closed Nuclear Fuel Cycles.- 6.1.2.1 Plutonium Recycling.- 6.1.2.2 The Thorium/Uranium-233 Fuel Cycle.- 6.1.2.3 Comparison of Various Converter Reactors.- 6.2 Fuel Cycle Options for Breeder Reactors.- 6.2.1 The Uranium/Plutonium Fuel Cycle.- 6.2.2 The Thorium/Uranium-233 Fuel Cycle.- 6.3 Natural Uranium Consumption in Various Reactor Scenarios.- Selected Literature.- 7 Technical Aspects of Nuclear Fuel Cycles.- 7.1 Discharge and Storage of Spent Fuel Elements.- 7.1.1 Shipping Spent Fuel Elements.- 7.1.2 Interim Storage of Spent Fuel Elements.- 7.2 The Uranium-238/Plutonium Fuel Cycle.- 7.2.1 Reprocessing Spent UO2 Fuel Elements.- 7.2.1.1 LWR Fuel Element Disassembly and Spent Fuel Dissolution.- 7.2.1.2 Gas Cleaning and Retention of Gaseous Fission Products.- 7.2.1.3 Chemical Separation of Uranium and Plutonium.- 7.2.1.4 Mass Flows of Radioactive Material in a Model LWR Fuel Reprocessing Plant.- 7.2.1.5 Radioactive Inventories of Spent Fuel and Waste.- 7.2.2 Recycling Plutonium and Uranium.- 7.2.2.1 Converting Plutonium Nitrate into Plutonium Oxide.- 7.2.2.2 Converting Uranyl Nitrate into Uranium Oxide.- 7.2.2.3 Mixed Oxide Fuel Fabrication.- 7.2.3 Status of Uranium Fuel Reprocessing Technology.- 7.2.4 Status of Experience in Mixed Oxide Fuel Fabrication and Reprocessing.- 7.2.5 Safety Aspects.- 7.2.5.1 Safety Design Measures in Reprocessing Plants.- 7.2.5.2 Safety Considerations for Mixed Oxide Fuel Fabrication Plants.- 7.3 The Thorium/Uranium-233 Fuel Cycle.- 7.3.1 Fuel Element Disassembly.- 7.3.2 THOREX Process.- 7.3.3 Uranium-233/Thorium Fuel Fabrication.- 7.4 The Uranium/Plutonium Fuel Cycle of Fast Breeder Reactors.- 7.4.1 Ex-core Time Periods of LMFBR Spent Fuel.- 7.4.2 Mass Flow in a Model LMFBR Fuel Cycle.- 7.4.3 Radioactive Inventories of Spent LMFBR Fuel.- 7.4.4 LMFBR Fuel Reprocessing.- 7.4.5 LMFBR Fuel Fabrication.- 7.4.6 Status of LMFBR Fuel Reprocessing and Refabrication.- 7.5 Waste Conditioning.- 7.5.1 Conditioning Waste from Spent LWR Fuel Reprocessing.- 7.5.1.1 Solidification and Storage of Liquid High Level Waste.- 7.5.1.2 Solidification and Storage of Solid High Level Waste.- 7.5.1.3 Treatment of Medium Level Waste.- 7.5.1.4 Treatment of Remaining Wastes.- 7.5.1.5 Waste Volumes to Be Stored from Reprocessing of Spent LWR Fuel.- 7.5.2 Radioactive Waste from Uranium-233/Thorium Fuel Reprocessing.- 7.5.3 Radioactive Waste from Reprocessing Plutonium/Uranium Fuel of LMFBR’s.- 7.5.4 Waste Arising in Other Parts of the Fuel Cycle.- 7.5.4.1 Uranium Ore Processing.- 7.5.4.2 Uranium Refining, Conversion and Enrichment.- 7.5.4.3 Fuel Element Fabrication and Nuclear Power Plants.- 7.6 Nuclear Waste Repositories.- 7.6.1 Waste Disposal in Deep Geological Formations.- 7.6.2 Direct Disposal of Spent Fuel Elements.- 7.6.3 Health and Safety Impacts of Radioactive Waste Disposal.- Selected Literature.- 8 Environmental Impacts and Risks of Nuclear Fission Energy.- 8.1 Radioactivity Releases from Nuclear Power Plants and Fuel Cycle Facilities During Normal Operation.- 8.1.1 Radioactivity Releases and Exposure Pathways.- 8.1.1.1 Exposure Pathways of Significant Radionuclides.- 8.1.1.1.1 Tritium, Carbon-14 and Krypton.- 8.1.1.1.2 Radioisotopes of Iodine.- 8.1.1.1.3 Strontium and Cesium.- 8.1.1.1.4 Plutonium Isotopes.- 8.1.1.1.5 Other Radiobiologically Significant Isotopes.- 8.1.1.2 Radiation Dose.- 8.1.1.3 Permissible Radiation Exposures.- 8.1.2 Radionuclide Effluents and Radiation Exposures from Various Parts of the Fuel Cycle.- 8.1.2.1 Uranium Mining and Milling.- 8.1.2.1.1 Radioactive Effluents from Mining and Milling.- 8.1.2.1.2 Radioactive Exposure Pathways for Uranium Mines and Mills.- 8.1.2.2 UFg Conversion, Enrichment, and Fuel Fabrication.- 8.1.2.3 Nuclear Power Plants.- 8.1.2.3.1 Radioactive Effluents of Nuclear Power Plants.- 8.1.2.3.2 Radioactive Effluents from PWR’s.- 8.1.2.3.3 Comparison of Radioactive Effluents from PWR’s and BWR’s.- 8.1.2.3.4 Radioactive Effluents from LMFBR and Other Nuclear Power Plants (CANDU-PHWR and HTGR).- 8.1.2.3.5 Radiation Exposures Caused by Emissions from Nuclear Power Plants.- 8.1.2.4 Spent Fuel Reprocessing and Waste Treatment Centers.- 8.1.2.4.1 Radioactive Effluents from an LWR Low Enriched UO2 Spent Fuel Reprocessing and Waste Treatment Center.- 8.1.2.4.2 Estimated Radioactive Effluents from a Reprocessing and Waste Treatment Center for Spent PUO2/UO2 Fuel.- 8.1.2.4.3 Radiation Exposure Caused by Reprocessing and Waste Treatment Centers.- 8.1.3 Long Range Accumulation of Tritium, Krypton-85, and Carbon-14.- 8.2 Risk Assessment of Nuclear Fission Reactors.- 8.2.1 Methods and Procedures.- 8.2.1.1 General Procedure.- 8.2.1.2 Event Tree Method.- 8.2.1.3 Fault Tree Analysis.- 8.2.2 Releases of Fission Products from a Reactor Building Following a Core Meltdown Accident.- 8.2.2.1 Initiating Events.- 8.2.2.2 Failure of the Containment.- 8.2.2.3 Releases of Radioactivity.- 8.2.2.4 External Events.- 8.2.3 Accident Consequence Model and Human Exposure.- 8.2.4 ResultsofReactor Safety Studies.- 8.2.4.1 Results of Event Tree and Fault Tree Analysis.- 8.2.4.2 Results of Accident Consequence Models.- 8.2.4.2.1 The German Risk Study.- 8.2.4.2.2 The US Reactor Safety Study.- 8.2.4.2.3 More Recent Improvements in Risk Studies.- 8.2.5 Risk Studies of Other Types of Reactors.- 8.2.6 Risk Studies of Fuel Cycle Plants.- 8.2.7 Comparison with Risks of Other Technical Systems.- 8.3 The Risk of Nuclear Proliferation and Possibilities of Its Mitigation.- 8.3.1 History.- 8.3.2 The IAEA Safeguards System.- 8.3.2.1 Material Balance Measurements.- 8.3.3 Safeguards Techniques.- 8.3.4 Safeguards Implementation.- 8.3.5 Advanced Approaches.- 8.3.5.1 Near-Real Time Accountancy and Extended Containment/Surveillance Systems.- 8.3.5.2 International Plutonium Storage.- 8.3.6 Proliferation Aspects of Different Fuel Cycles.- 8.3.6.1 Quantities of Fissile Nuclear Material.- 8.3.6.2 Technical Measures to Improve Diversion Resistance.- 8.3.7 International Agreements and Institutional Arrangements.- 8.3.8 Remaining Proliferation Risk.- Selected Literature.