System Studies of Fission-Fusion Hybrid Molten Salt Reactors
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University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 12-2013 SYSTEM STUDIES OF FISSION-FUSION HYBRID MOLTEN SALT REACTORS Robert D. Woolley University of Tennessee - Knoxville, rwoolley@utk.edu Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Nuclear Engineering Commons Recommended Citation Woolley, Robert D., "SYSTEM STUDIES OF FISSION-FUSION HYBRID MOLTEN SALT REACTORS. " PhD diss., University of Tennessee, 2013. https://trace.tennessee.edu/utk_graddiss/2628 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact trace@utk.edu. To the Graduate Council: I am submitting herewith a dissertation written by Robert D. Woolley entitled "SYSTEM STUDIES OF FISSION-FUSION HYBRID MOLTEN SALT REACTORS." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Doctor of Philosophy, with a major in Nuclear Engineering. Laurence F. Miller, Major Professor We have read this dissertation and recommend its acceptance: Ronald E. Pevey, Arthur E. Ruggles, Robert M. Counce Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) SYSTEM STUDIES OF FISSION-FUSION HYBRID MOLTEN SALT REACTORS A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Robert D. Woolley December 2013 Copyright © 2013 by Robert D. Woolley All rights reserved ii DEDICATION This study of a Fission-Fusion Hybrid Molten Salt Reactor (FFHMSR) conceptual design is dedicated to Kathryn, love of my life, my wife and partner of the past 45 years, to my daughters Lisa and Eileen who shared the joy and adventures of my younger and middle years and continue to enrich life, to my grandchildren Elliott, Kyra, Alannah and Kathleen, whom I am privileged to know and who are of the generation that may perfect and deploy FFHMSRs, and to their future grandchildren who may enjoy abundant clean energy as a result of the FFHMSR and who may also see the dawn of the fusion era. iii ACKNOWLEDGEMENTS I wish to thank Dr. Laurence F. Miller for patient advice, guidance and encouragement, the other members of my committee, Drs. Ronald E. Pevey, Arthur E. Ruggles, and Robert M. Counce for their critical review, The University of Tennessee's Nuclear Engineering Department for technical excellence and the pioneering use and development of online education, the Oak Ridge National Laboratory researchers of the 1950s on through the 1970s and later, who did so much to develop the Molten Salt Reactor design and who left an excellent trail of relevant technical publications, and to fusion researchers both at the Princeton Plasma Physics Laboratory and worldwide who have persevered through the past six decades on the long path necessary to develop fusion energy. iv ABSTRACT This work proposes and evaluates a Fission-Fusion Hybrid Molten Salt Reactor (FFHMSR), combining two subsystems, a deuterium + tritium (DT) fusion reactor surrounded by a neutron-absorbing Fusion Blanket (FB) and a critical Molten Salt fission Reactor (MSR). The molten salt, which contains dissolved actinides, circulates at a high rate between them. As envisioned the MSR exhibits the large Conversion Ratio of graphite moderated reactors having small fissile and large fertile inventories. DT fusion neutrons irradiating actinides in the molten salt release additional neutrons which increase isotope conversion and fission. Actinide fuel is continually added while fission products are continually removed so the system's operation never requires refueling interruptions. The choice of molten salt as a eutectic mixture of the fluorides of lithium, sodium, and actinide fuel is explained by eliminating other options. System behavior is explored through simulations invoking modules from the Scale 6.1 code package. Modules include ORIGEN which simulates evolution over time of an isotope inventory and others for neutronics transport, criticality and cross section weighting. The simulation automatically adjusts the ratio of fission to fusion power to maintain MSR criticality, implemented through FORTRAN codes and associated files developed as part of this work. Simulations showed actinide inventories stabilizing to steady levels while fresh actinide fuel from feedstocks of Spent Nuclear Fuel or uranium-238 or thorium-232 continued to be added and fissioned. Required fusion was less than 1% of total power and adequate tritium breeding was obtained. The non-removal strategy was also tried with long-lived fission products (FPs) with the mixed results that some inventories stabilized while others did not. FFHMSR benefits of consuming all actinides and some long-lived FPs are that waste issues are ameliorated while available fission energy is increased by two orders of magnitude. Proliferation resistance is enhanced by the absence of fuel reprocessing and related transportation, by low fissile inventories and by denaturing all fissile by nonfissile isotopes. Safety is enhanced by liquid fuel characteristics allowing emergency draining of fuel to a passively cooled safe location while also providing a stronger negative power coefficient than feasible with solid fuel. v TABLE OF CONTENTS CHAPTER 1: COMBINED ADVANTAGES .................................................................... 1 The Problem ................................................................................................................ 1 An Ideal Fission Reactor .............................................................................................. 1 Fuel Enrichment Losses in Existing Power Reactors ................................................... 2 Solid Fuel Materials Damage Sets Burn-up Limits ....................................................... 3 Fast Breeder Reactors ................................................................................................. 4 Fission-Fusion Hybrid Molten Salt Reactor Synergies ................................................. 5 CHAPTER 2: FISSION AND FUSION BACKGROUND ................................................. 8 Fission Reactors .......................................................................................................... 8 Molten Salt Reactor Background ................................................................................. 9 Fusion Background .................................................................................................... 11 Fusion Reactions .................................................................................................... 11 Fusion Energy Gain ................................................................................................ 15 Fusion for Diagnostics via Particle Accelerators ..................................................... 16 Fusion for Energy Production ................................................................................. 16 Inertial Confinement Fusion .................................................................................... 17 Best Fusion Performances to Date ......................................................................... 19 Magnetic Confinement Fusion ................................................................................ 19 CHAPTER 3: FISSION-FUSION HYBRID (FFH) BACKGROUND ............................... 24 CHAPTER 4: FISSION-FUSION HYBRID MOLTEN SALT REACTOR ....................... 37 FFHMSR Configuration Description ........................................................................... 37 vi CHAPTER 5: BENEFITS OF THE FFHMSR ................................................................ 41 Waste Handling Benefits ............................................................................................ 41 Energy Utilization Benefits ......................................................................................... 41 Safety Benefits ........................................................................................................... 43 Proliferation/Diversion Benefits .................................................................................. 45 CHAPTER 6: CHEMISTRY ISSUES ............................................................................ 47 CHAPTER 7: MOLTEN SALT SELECTION ................................................................. 53 CHAPTER 8: MSR NEUTRON ENERGY SPECTRUM CHOICE ................................ 71 CHAPTER 9: FUSION BLANKET THICKNESS ........................................................... 74 CHAPTER 10: SIMULATION OF OPERATION ........................................................... 82 The Problem .............................................................................................................. 82 Constraints on Software Methods .............................................................................. 84 Fundamental Feature Adopted: Time Distortion ....................................................... 84 Fundamental Feature Adopted: Feedback Control by Switching .............................. 85 Labor-intensive manual activities required for running the FFHMSR simulation .......