LA-14018 Approved for public release; distribution is unlimited. Safeguards Science and Technology Group NIS-5 Nonproliferation and International Security Division Application Guide to Gamma-Ray Isotopic Analysis Using the FRAM Software Edited by Heather L. Edwards, Weirich and Associates, for Group IM-1 Los Alamos National Laboratory, an affirmative action/equal opportunity employer, is operated by the University of California for the United States Department of Energy under contract W-7405-ENG-36. This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the Regents of the University of California, the United States Government nor any agency thereof, nor any of their employees make any warranty, express or implied, or assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represent that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the Regents of the University of California, the United States Government, or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the Regents of the University of California, the United States Government, or any agency thereof. Los Alamos National Laboratory strongly supports academic freedom and a researcher's right to publish; as an institution, however, the Laboratory does not endorse the viewpoint of a publication or guarantee its technical correctness. LA-14018 Issued: September 2003 Application Guide to Gamma-Ray Isotopic Analysis Using the FRAM Software Thomas E. Sampson Thomas A. Kelley Duc T. Vo CONTENTS ABSTRACT ..................................................................................................................................................1 I. INTRODUCTION ................................................................................................................................2 A. Purpose of This Application Guide.........................................................................................2 B. Isotopic Analysis Applications in Nondestructive Assay ....................................................2 1. Calorimetry. ...........................................................................................................................2 2. Neutron Coincidence Counting...........................................................................................3 3. Other Bulk Measurement Techniques. ...............................................................................4 4. Process Control ....................................................................................................................5 5. Treaty Verification.................................................................................................................5 6. Confirmation Measurements ...............................................................................................5 II. BASIC PRINCIPLES OF GAMMA-RAY ISOTOPIC ANALYSIS FOR THE ARBITRARY SAMPLE6 A. Methods for Obtaining Isotopic Fractions Using Gamma Rays ..........................................6 B. Calibrated Absolute Measurements........................................................................................6 C. Ratio Measurements for the Arbitrary Sample—Without Efficiency Corrections..............7 D. The Intrinsic Self-Calibration Technique................................................................................8 1. Isotopic Ratio Measurement................................................................................................8 2. Assumption of Isotopic Homogeneity................................................................................9 E. The Relative Efficiency Concept ...........................................................................................10 F. Relative Efficiency Models.....................................................................................................11 1. Piecewise Linear.................................................................................................................11 2. Spline Fitting .......................................................................................................................13 3. Polynomial Least-squares Fitting .....................................................................................13 4. Physical Model (Gunnink)..................................................................................................13 5. Physical Model (Vo)............................................................................................................14 6. Heterogeneous Relative-Efficiency Models .....................................................................15 III. ISOTOPIC ANALYSIS DEVELOPMENT AT THE LOS ALAMOS NATIONAL LABORATORY ...16 IV. FRAM DEVELOPMENT...................................................................................................................18 A. Factors Influencing Development .........................................................................................18 1. Interferences .......................................................................................................................18 2. Heterogeneous Am/Pu .......................................................................................................18 3. Additional Versatility ..........................................................................................................18 4. Existing Approaches and Development...........................................................................19 B. VAX Version of FRAM.............................................................................................................19 C. PC/FRAM Development..........................................................................................................21 1. Single Detector System......................................................................................................22 2. Choice of Detector Types ..................................................................................................22 3. Shielded Samples ...............................................................................................................22 4. Uranium Isotopic Analysis.................................................................................................23 D. Version/Feature History of PC/FRAM ...................................................................................23 1. Version 1..............................................................................................................................23 2. Version 2..............................................................................................................................23 3. Version 3..............................................................................................................................24 4. Version 4..............................................................................................................................25 v V. HOW FRAM WORKS.......................................................................................................................27 A. Obtain Data..............................................................................................................................27 B. Perform Analysis ....................................................................................................................27 1. Internal Calibrations ...........................................................................................................27 2. Analysis of Spectral Data...................................................................................................29 VI. PARAMETER FILES, THE KEY TO FRAM’S VERSATILITY.........................................................33 A. What are Parameter Files?.....................................................................................................33 B. The Change Parameter Utility................................................................................................33 C. Analysis Parameters...............................................................................................................35 1. Fitting Parameters ..............................................................................................................35 2. Gamma-Ray Peak Data.......................................................................................................37 3. Analysis Region Definition ................................................................................................39 4. Isotope Information ............................................................................................................40 5. Application Constants........................................................................................................40 VII. FRAM USER INTERFACE...............................................................................................................45 A. FRAM Main Menu....................................................................................................................45 B. Main Menu Options.................................................................................................................45