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Optimization of Transcurium Isotope Production in the High Flux Isotope Reactor

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Optimization of Transcurium Isotope Production in the High Flux Isotope Reactor University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 12-2012 Optimization of Transcurium Isotope Production in the High Flux Isotope Reactor Susan Hogle [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Nuclear Engineering Commons Recommended Citation Hogle, Susan, "Optimization of Transcurium Isotope Production in the High Flux Isotope Reactor. " PhD diss., University of Tennessee, 2012. https://trace.tennessee.edu/utk_graddiss/1529 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 [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Susan Hogle entitled "Optimization of Transcurium Isotope Production in the High Flux Isotope Reactor." 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. G. Ivan Maldonado, Major Professor We have read this dissertation and recommend its acceptance: Lawrence Heilbronn, Howard Hall, Robert Grzywacz 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.) Optimization of Transcurium Isotope Production in the High Flux Isotope Reactor A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Susan Hogle December 2012 © Susan Hogle 2012 All Rights Reserved ii Dedication To my father Hubert, who always made me feel like I could succeed and my mother Anne, who would always love me even if I didn’t. iii Acknowledgements This research is supported by the Isotopes Program, Office of Nuclear Physics of the Oak Ridge Nuclear Laboratory, U.S. Department of Energy. ORNL is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725. This dissertation would not have been possible without the backing I have received from my advising team of G. Ivan Maldonado, Chuck Alexander and Julie Ezold. I would like to thank my advising professor Ivan Maldonado for seeing potential in me; for providing me with the chance to pursue my studies and research under his guidance and always ensuring his students are given every opportunity to succeed. I would like to thank my technical advisor Chuck Alexander for giving me access to his astounding mind; for always being available to trade ideas, and for pointing out possibilities that I could not have envisioned. I would like to thank my mentor Julie Ezold for her overwhelming support, both personal and professional. Nearly any problem encountered can, if not be solved, be at least soothed, by a trip to Julie’s office. I would like to thank the members of my dissertation committee: Dr. Lawrence Heilbronn, Dr. Howard Hall and Dr. Robert Gryzwicz; for their guidance during my dissertation work which has helped bring this dissertation to its final form. I would like to thank all the staff at the Radiochemical Engineering Development Center, as well as at the University Of Tennessee Department Of Nuclear Engineering for their tireless support of their students. I would also like to thank my fellow students for keeping me sane over the past years. For making me wake up in the morning happy to come into work, even if I was looking at a tedious day of coding. I will miss my 6’ by 4’ cube in the graduate student office. Finally I would like to thank my family, who has always given me their unconditional encouragement and support. To my parents Anne and Hubert, who did not balk at my plan to move 1000 miles away for graduate school any more than they did when I professed my undying desire to attend theatre school at the age of 12, I cannot thank you enough for all you have done for me. To my siblings Janet, Karen and Jeff, I am sorry I have missed seeing your children grow up and become the lovely people I am sure they will be. Thank you for being there to lend an ear when home seemed so far away. iv Abstract The Radiochemical Engineering Development Center at Oak Ridge National Laboratory is the world's leader in production of californium-252. This and other heavy actinides are produced by irradiation of mixed curium/americium targets in the High Flux Isotope Reactor. Due to the strong dependence of isotopic cross sections upon incoming neutron energy, the efficiency with which an isotope is transmuted is highly dependent upon the neutron flux energy spectrum and intensities. There are certain energy ranges in which the rate of fissions in feedstock materials can be minimized relative to the rate of (n, γ) absorptions. This work shows that by perturbing the flux spectrum, it is possible to alter the net consumption of curium feedstock, as well as the yields of key isotopes for the heavy element research program, such as 249 Bk and 252 Cf. This flux spectrum perturbation is accomplished by means of focused resonance shielding through the use of filter materials. This work further shows that these perturbations can alter the target yields in a significant way, increasing the amount of 252 Cf produced per unit curium consumption. All materials with isotopes containing appropriate energy level resonances are examined and extensive data has been obtained on the filtering effects of these materials. Neural networks and genetic algorithms are used to develop an optimization framework for evaluating the performance of filter materials. This algorithm allows for customized optimization and selection of filter materials depending upon the need of the user and the campaign conditions. v Table of Contents 1. Introduction ............................................................................................................................. 1 1.1 Motivation ........................................................................................................................ 4 1.2 Research Objective and Scope ......................................................................................... 5 2. Background ............................................................................................................................. 6 2.1 The High Flux Isotope Reactor and the Radiochemical Engineering Development Center .......................................................................................................................................... 6 2.2. Californium-252 and other Heavy Actinide Isotopes ...................................................... 9 2.3. Actinide Radiochemistry ................................................................................................ 11 2.4. Transmutation and Losses .............................................................................................. 12 2.5. Resonance Shielding ...................................................................................................... 18 2.6. Heavy Actinide Feedstock ............................................................................................. 20 2.7. Flux Spectrum Filtering ................................................................................................. 20 2.8. Benefits of Optimized Production .................................................................................. 22 3. Literature Review.................................................................................................................. 23 3.1 HFIR modeling capabilities ........................................................................................... 23 4. Methodology ......................................................................................................................... 24 4.1 Solving the Boltzman Transport Equation ..................................................................... 25 4.1.1 Monte Carlo Methods ............................................................................................. 25 4.1.2 Diffusion Theory ..................................................................................................... 26 4.1.3 Discrete Ordinates Methods .................................................................................... 27 4.1.4 Bondarenko Method................................................................................................ 27 4.1.5 Matrix Exponentiation ............................................................................................ 28 4.1.6 Neural Networks ..................................................................................................... 28 4.1.7 Genetic Algorithms ................................................................................................. 30 4.2 Computer Codes and Modules ....................................................................................... 31 vi 4.2.1 CSAS....................................................................................................................... 31 4.2.2 KENO-VI ................................................................................................................ 31 4.2.3 BONAMI ................................................................................................................ 31 4.2.4 CENTRM
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