VERIFICATION AND VALIDATION OF ATMOSPHERIC TRANSPORT MODELS USING THE UNIVERSITY OF FLORIDA TRAINING REACTOR By GABRIEL ALFREDO SANDLER A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2019 1 © 2019 Gabriel A. Sandler 2 To my partner, family, and friends 3 ACKNOWLEDGMENTS To begin, I want to thank my adviser Dr. James Baciak for guiding me for the past four and a half years. As a graduate student under Dr. Baciak, I truly learned how to work independently at a high level. I would also like to thank Dr. Andreas Enqvist who was my first research adviser as an undergraduate student and has been an amazing source of help throughout my time as a graduate student. I would also like to thank Brian Shea, Dan Cronin, and Matt Berglund from the University of Florida Training Reactor for helping me accomplish tasks essential for my research. I have also furthered my knowledge and abilities outside the University of Florida. I would like to thank Dr. Scott Kiff from Sandia National Laboratory and Dr. Micah Lowenthal from the National Academies of Science for helping me develop new skillsets which I will carry on as I continue my career. Additionally, I would like to thank the National Nuclear Security Administration for providing funding throughout my graduate career as part of the Consortium for Verification Technology. My educational path would not have been the same without my mom, dad, and brother. Their support and love throughout the entirety of my life has allowed me to follow my passions and become the person I am today. Also, I would like to thank all the friends I have made in high school, undergrad, and graduate school. My time as a student would not have been the same without you all. Lastly, I would like to thank my partner Hannah Kaufman for providing constant support and pushing me to always be the best version of myself. 4 TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................. 4 LIST OF TABLES ............................................................................................................ 7 LIST OF FIGURES ........................................................................................................ 11 LIST OF ABBREVIATIONS ........................................................................................... 14 ABSTRACT ................................................................................................................... 16 CHAPTER 1 INTRODUCTION AND MOTIVATION..................................................................... 18 Introduction to Atmospheric Transport Models ....................................................... 18 Impact of Atmospheric Transport Models in the Nuclear Field ................................ 21 Utilizing the University of Florida Training Reactor ................................................. 26 Objective of Research............................................................................................. 30 2 THEORY ................................................................................................................. 32 Atmospheric Dispersion Theory .............................................................................. 32 Atmospheric Transport Models ............................................................................... 34 The Gaussian Dispersion Model ...................................................................... 37 The Lagrangian Model ..................................................................................... 40 The Puff Model ................................................................................................. 41 The Eulerian Model .......................................................................................... 42 Computational Fluid Dynamics Modeling ......................................................... 43 Comparison of Models ..................................................................................... 43 Radiation Detection ................................................................................................ 45 Gas-filled Detectors .......................................................................................... 46 Scintillators ....................................................................................................... 47 Semiconductors ................................................................................................ 48 Selection of Detector for Measurements .......................................................... 49 3 VERIFICATION AND VALIDATION PROCESS ..................................................... 51 Experimental Measurements .................................................................................. 51 Instrumentation ................................................................................................. 51 Measurement Setups ....................................................................................... 53 Proving the Detectability of the 41Ar Plume ............................................................. 58 Coupling ATMs with MCNP .................................................................................... 59 UF Developed MATLAB Gaussian Model ........................................................ 62 AERMOD .......................................................................................................... 64 5 FLEXPART ....................................................................................................... 68 Summary of Weather Data Sources ................................................................. 71 4 HIGH VELOCITY PLUME STACK .......................................................................... 73 Measurement Results for May 2018 and March 2019 Trials ................................... 73 Simulation Results for May 2018 and March 2019 Trials ........................................ 84 Discussion and Analysis of Results ........................................................................ 94 5 LOW VELOCITY PLUME STACK ......................................................................... 100 Measurement Results for November 2018 and January 2019 Trials .................... 100 Simulation Results for November 2018 and January 2019 Trials ......................... 111 Discussion and Analysis of Results ...................................................................... 125 6 SENSITIVITY ANALYSIS OF COUPLED MODELS ............................................. 130 Overview of Proposed Sensitivity Analyses .......................................................... 130 One-factor-at-a-time Sensitivity Analysis .............................................................. 131 Wind Speed .................................................................................................... 132 Wind Orientation ............................................................................................. 136 Atmospheric Stability ...................................................................................... 141 Plume Length and Resolution ........................................................................ 141 7 CONCLUSION AND FUTURE WORK .................................................................. 145 APPENDIX: 10 MINUTE AVERAGED MEASUREMENT AND SIMULATION DATA .. 150 LIST OF REFERENCES ............................................................................................. 185 BIOGRAPHICAL SKETCH .......................................................................................... 193 6 LIST OF TABLES Table page 1-1 August 2017 measurement and low velocity plume stack info ........................... 28 1-2 Air sampling information #1 ................................................................................ 28 1-3 Air sampling information #2. ............................................................................... 29 2-1 Stability classifications for Gaussian model based on wind speed and solar irradiation. ........................................................................................................... 39 2-2 Stability classifications for Gaussian model based on atmospheric lapse rate ... 39 2-3 Summary of ATM code selection for various applications and dispersion distances. ........................................................................................................... 45 3-1 Proposed detectors surrounding UFTR .............................................................. 54 3-2 Detector location coordinates. ............................................................................ 54 3-3 Elevations of selected locations. ......................................................................... 56 3-4 Modified Pasquill stability scheme in the daytime ............................................... 63 3-5 Parameters used to solve vertical dispersion coefficient (σz). ............................ 64 3-6 Parameters used to solve horizontal dispersion coefficient (σy). ........................ 64 4-1 May 8th, 2018 measurement 41Ar count rates and count rate ratios. .................. 80 4-2 March 20th, 2019 measurement 41Ar count rates and count rate ratios. ............. 81 4-3 March 22nd, 2019 measurement 41Ar count rates and count rate ratios. ............. 82 4-4 May 8th, 2018 wind information (averaged hourly) .............................................