SPECTRAL CHARACTERIZATION AND TRANSMUTATION OF ACTINIDES IN GASEOUS CORE REACTORS By CINDY FUNG A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ENGINEERING UNIVERSITY OF FLORIDA 2006 Copyright 2006 by Cindy Fung ACKNOWLEDGMENTS I thank the members of my supervisory committee Dr. Samim Anghaie, Dr. Edward T. Dugan, and Dr. Jacob N. Chung for their guidance, encouragement, and support. Their scientific knowledge, dedication to their students, and kindness make the learning experience a pleasure. I would like to show deep gratitude for the financial support provided by the Department of Energy and the Office of Nuclear Energy, Science and Technology through the Advanced Fuel Cycle Initiative. I am fortunate to have Dr. Anghaie as the chair of my supervisory committee. His great vision for the future of the nuclear industry and his pragmatic attitude are the foundations of this research. I am touched by his compassion and respect for his students, and most of all by his honesty. It has been enlightening working with Dr. Dugan. His expertise in Gas Core Reactors was essential to the success of this research. I am very appreciative of Dr. Dugan’s professionalism and dedication to his role as supervisory committee member. I am grateful to have the support and love of my family and all those who love me; without them my accomplishments would be meaningless. I want to especially thank a close friend who encouraged me to do my best and helped me through times of doubt. His unconditional support was essential to the completion of this project. iii TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................................................................................. iii LIST OF TABLES........................................................................................................... viii LIST OF FIGURES ........................................................................................................... xi ABSTRACT..................................................................................................................... xiv CHAPTER 1 INTRODUCTION ........................................................................................................1 The Fuel Cycle..............................................................................................................2 Mining and Milling of Uranium Ore.....................................................................2 Conversion of Yellowcake to Uranium-Hexafluoride ..........................................3 Enrichment of Uranium.........................................................................................3 Fabrication of Nuclear Fuel...................................................................................3 Power Production ..................................................................................................4 Spent Fuel Characteristics ............................................................................................4 Nuclear Waste History..................................................................................................6 Nuclear Waste Treatment .............................................................................................8 Reprocessing and Recycling..................................................................................8 Advantages of the closed cycle ......................................................................9 Disadvantages of the closed cycle..................................................................9 Storage and Disposal ...........................................................................................10 Low level waste............................................................................................10 High level waste...........................................................................................12 Advantages of the open cycle.......................................................................14 Disadvantages of the open cycle ..................................................................14 Nuclear Waste Challenges..........................................................................................15 Permanent Repository not Available...................................................................15 More Repositories are Needed ............................................................................16 MRS not Available..............................................................................................16 Reprocessing Facility not Available....................................................................17 Waste Must be Isolated for 10,000 Years ...........................................................18 Current Technology....................................................................................................19 Boiling Water Reactor.........................................................................................20 Pressurized Water Reactor ..................................................................................21 iv Developing Technologies ...........................................................................................22 Accelerator Driven Systems (ADS) ....................................................................23 Gaseous Core Reactor (GCR) .............................................................................24 Thesis Objectives........................................................................................................25 2 THE GASEOUS CORE REACTOR..........................................................................26 GCR Description And Modeling................................................................................26 Reactor Geometry................................................................................................26 Reactor Materials.................................................................................................27 Gaseous fuel .................................................................................................28 Reflector/moderator .....................................................................................31 Assumptions ........................................................................................................34 Power Conversion Systems ........................................................................................35 GCR Characteristics ...................................................................................................36 Safety and Feedback............................................................................................36 Reactivity Control ...............................................................................................38 Core Neutronics...................................................................................................38 Advantages Of The GCR............................................................................................39 Computational Tools ..................................................................................................41 MCNP..................................................................................................................41 ORIGEN..............................................................................................................44 MONTEBURNS..................................................................................................45 3 ACTINIDES AND FISSION PRODUCTS................................................................47 Origins ........................................................................................................................48 Actinides..............................................................................................................50 92-Uranium (U)............................................................................................50 93-Neptunium (Np) ......................................................................................51 94-Plutonium (Pu) ........................................................................................53 95-Americium (Am).....................................................................................57 96-Curium (Cm)...........................................................................................58 Fission Products...................................................................................................62 38-Strontium (Sr) .........................................................................................62 43-Technetium (Tc)......................................................................................63 53-Iodine (I) .................................................................................................63 55-Cesium (Cs) ............................................................................................64 Applications................................................................................................................65 Nuclear Fuel ........................................................................................................66 Radioisotope Thermoelectric Generator (RTG)..................................................68 Improving Proliferation Resistance of Fissile Material.......................................70 Nuclear Medicine: Diagnostic and Treatment.....................................................72 Spectral Influence