PNNL-18531 Prepared for the U.S. Department of Energy under Contract DE-AC05-76RL01830 Coupled Multi-Group Neutron Photon Transport for the Simulation of High-Resolution Gamma-Ray Spectroscopy Applications KA Burns August 2009 DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor Battelle Memorial Institute, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. 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Box 62, Oak Ridge, TN 37831-0062; ph: (865) 576-8401 fax: (865) 576-5728 email: [email protected] Available to the public from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Rd., Springfield, VA 22161 ph: (800) 553-6847 fax: (703) 605-6900 email: [email protected] online ordering: http://www.ntis.gov/ordering.htm This document was printed on recycled paper. (9/2003) COUPLED MULTI-GROUP NEUTRON PHOTON TRANSPORT FOR THE SIMULATION OF HIGH-RESOLUTION GAMMA-RAY SPECTROSCOPY APPLICATIONS A Dissertation Presented to The Academic Faculty By Kimberly Ann Burns In Partial Fulfillment of the Requirements for the Degree Doctoral of Philosophy in Nuclear Engineering Georgia Institute of Technology August 2009 COUPLED MULTI-GROUP NEUTRON PHOTON TRANSPORT FOR THE SIMULATION OF HIGH-RESOLUTION GAMMA-RAY SPECTROSCOPY APPLICATIONS Approved by: Dr. Nolan E. Hertel, Advisor Dr. L. Eric Smith Nuclear and Radiological Engineering Radiation Detection and Nuclear Sciences Georgia Institute of Technology Pacific Northwest National Laboratory Dr. Farzad Rahnema Dr. Richard Pagh Nuclear and Radiological Engineering Nuclear Materials and Engineering Georgia Institute of Technology Analysis Pacific Northwest National Laboratory Dr. Chris Wang Dr. Eva Lee Nuclear and Radiological Engineering Industrial and Systems Engineering Georgia Institute of Technology Georgia Institute of Technology Dr. Bojan Petrovic Dr. William David Kulp III Nuclear and Radiological Engineering Physics Georgia Institute of Technology Georgia Institute of Technology Date Approved: June 12, 2009 ACKNOWLEDGEMENTS First and foremost, I would like to thank my family. Since I was a little girl, you have always told me I can be anything I want. Your faith in me and the belief that I can achieve anything by setting goals for myself has helped me reach this point in my life. I would not be here if not for your support. Thank you. I would like to thank the entire RADSAT team – Eric Smith, Christopher Gesh, Michael Batdorf, Mark Shaver, Edward Ellis, Erin Miller, Andrei Valsan, Richard Wittman, Jacob Benz and Andrew Casella, particularly Eric Smith, for entrusting such a large section of the project to me. The aid and support of the team has helped to guide and shape the task at hand. The collaboration with the RADSAT team has made working on this project an enjoyable task. I would also like to give a special thanks to Michael Batdorf for helping me turn my algorithms for the cross section collapsing into a fully functional code. He is responsible for all of the computer programming implemented in conjunction with this work. Without his help, the cross section development would not have reached the maturity it has. Thank you to my committee – Dr. Nolan Hertel, Dr. Eric Smith, Dr. Richard Pagh, Dr. Farzad Rahnema, Dr. Chris Wang, Dr. Eva Lee, Dr. Bojan Petrovic, and Dr. William David Kulp – for their time and contributions. I would particularly like to thank Dr. Nolan Hertel, my advisor, for his support and guidance. Eric Smith and Richard Pagh also deserve special thanks for their contributions to the project and for their patience with me. iii I would also like to acknowledge a few people who helped me with some technical issues and thank them for their individual contributions. Ian Davis of Transpire, Inc. and Christopher Gesh of Pacific Northwest National Laboratory provided guidance for the application of Attila. John Mattingly of Sandia National Laboratories provided the Kynea3 cross-section library. A.C. Kahler and Morgan White of Los Alamos National Laboratory answered a number of questions on NJOY. Jeffrey Favorite, also of Los Alamos National Laboratory, converted the Kynea3 cross-section library to a format compatible with Attila. Gus Caffrey of Idaho National Laboratory and the United States Army provided some funding and motivation for this project through the PINS (Portable Isotopic Neutron Spectroscopy) Project. Thank you to everyone. I could not have done this without everyone’s help and support. iv TABLE OF CONTENTS Page ACKNOWLEDGEMENTS iii LIST OF TABLES viii LIST OF FIGURES x LIST OF SYMBOLS xiii LIST OF ABBREVIATIONS xv SUMMARY xvi CHAPTER 1 BACKGROUND 1 1.1 Computational Methods 2 1.1.1 Monte Carlo Methods 2 1.1.2 Deterministic Methods 5 1.2 Coupled Stochastic-Deterministic Methods 9 1.3 Applications of Coupled Method 14 1.3.1 Interrogation of Cargo Containers 14 1.3.2 UF6 16 1.3.3 Prompt Gamma Neutron Activation Analysis 17 CHAPTER 2 METHODS 19 2.1 Experimental Design for Testing Methods 19 2.2 Methods Discussion 21 2.2.1 Neutron Transport Calculation 23 2.2.2 Generation of Neutron-Induced Photon Spectrum 44 2.2.3 Photon Transport 56 2.2.4 Detector Response Calculation 60 v CHAPTER 3 RESULTS 62 3.1 Polyethylene 62 3.1.1 Cross Sections 63 3.1.2 Detector Response 67 3.2 Phosphorus 69 3.2.1 Neutron Flux Comparison 69 3.2.2 Cross Sections 72 3.2.3 Photon Flux within Detector 75 3.3 Nitrogen 77 3.3.1 Neutron Flux Comparison 77 3.3.2 Cross Sections 79 3.3.3 Photon Flux within Detector 84 3.4 Oxygen 85 3.4.1 Neutron Flux Comparison 86 3.4.2 Cross Sections 88 3.4.3 Photon Flux within Detector 92 3.5 Iron 94 3.5.1 Neutron Flux Comparison 94 3.5.2 Cross Sections 95 3.5.3 Photon Flux within Detector 102 CHAPTER 4 CONCLUSIONS 105 CHAPTER 5 RECOMMENDATIONS 108 APPENDIX A Example Attila Input File for Neutron Transport Problem in C2H4 110 APPENDIX B Radion15, SCALE44 and Kynea3 Group Structure 119 APPENDIX C MCNP5 Input File for C2H4 Cube 122 vi APPENDIX D Summary of NJOY99.259 Modules Used in Calculations 127 APPENDIX E NJOY99.259 Input File to Produce ACER file for Hydrogen 129 APPENDIX F RADSAT-NG Cross Section Example Format 130 APPENDIX G NJOY99.259 Input File to Produce GROUPR file for Hydrogen 133 APPENDIX H Example RADSAT “Pseudo-Isotope” File for Phosphorus 137 REFERENCES 147 vii LIST OF TABLES Page Table 1. Comparison of MCNP and RADSAT Computational Times for Simple Cube Problems ................................................................................................................. xix Table 2. Reaction Rates Calculated using Attila Flux and Kynea3, SCALE44 and Radion15 Cross Sections and Compared to Reaction Rates Calculated Using MCNP. .............................................................................................................................. 32 Table 3. Comparison of the Scalar Flux (γ/cm2-sec-source particle) in Each Photopeak inside the Detector from the Irradiation of Polyethylene ................................ 35 Table 4. Comparison of Total Cross Section for RADSAT-NG and Cross Sections Produced by GROUPR for Hydrogen, Deuterium and Carbon ........................................ 66 Table 5. Comparison of Attila and MCNP Total Neutron Flux for the Irradiation of Phosphorus.................................................................................................................... 72 Table 6. Discrete Gamma Rays Produced by 31P ............................................................. 73 Table 7. Comparison of Total Cross Section for RADSAT-NG and Cross Sections Produced by GROUPR for Phosphorus ............................................................................ 75 Table 8. Comparison of Photon Flux for Top 2 Most Intense Peaks Produced by the Neutron Irradiation of Phosphorus .............................................................................. 76 Table 9. Comparison of Attila and MCNP Total Neutron Flux for the Irradiation of Nitrogen ........................................................................................................................ 78 Table 10. Discrete Gamma Rays Produced by 14N ........................................................... 80 Table 11. Comparison of Total Cross Section for RADSAT-NG and Cross Sections Produced by GROUPR for 14N .......................................................................... 83 Table 12. Comparison of Photon Flux for Top 5 Most Intense Peaks Produced by the Neutron Irradiation of Nitrogen .................................................................................