RSICC CODE PACKAGE PSR-542

 

1.  NAME AND TITLE

                 MGA8:  Determine Pu Isotope Abundances from Multichannel Analyzer Gamma Spectra.

 

2.  CONTRIBUTORS

                Lawrence Livermore National Laboratory, Livermore, California, through the Energy Science and Technology Software Center, Oak Ridge, Tennessee.

 

3.  CODING LANGUAGE AND COMPUTER

                Fortran 77; PC and DEC VAX series 8810 (P00542MNYCP00).

 

4.  NATURE OF PROBLEM SOLVED

            The MGA (Multiple Group Analysis) program determines the relative abundances of plutonium and other actinide isotopes in different materials. The program analyzes spectra taken of such samples using a 4096-channel germanium (Ge) gamma-ray spectrometer. The code can be run in a one or two detector mode. The first spectrum, which is required and must be taken at a gain of 0.075 Kev/channel with a high resolution planar detector, contains the 0-300Kev energy region. The second spectrum, which is optional, must be taken at a gain of 0.25 Kev/channel; it becomes important when analyzing high burnup samples (concentration of Pu241 greater than one percent). Isotopic analysis precisions of one percent or better can be obtained, and no calibrations are required. The system also measures the abundances of U235, U238, Np237, and Am241. A special calibration option is available to perform a one-time peak-shape characterization when first using a new detector system.

 

5.  METHOD OF SOLUTION

            The basic method for determining the relative abundance of the isotopes of plutonium is to measure the intensity of two or more peaks from gamma rays of similar energy, but arising from different isotopes. Since the gamma-ray emission probabilities and half-lives are known, the atom ratios can be calculated provided relative detection efficiencies for the peaks can be estimated.

 

6.  RESTRICTIONS OR LIMITATIONS

            None noted.

 

7.  TYPICAL RUNNING TIME

                Analysis time is typically less than one minute.

 

8.  COMPUTER HARDWARE REQUIREMENTS

MGA runs on personal computers and on DEC VAX series under VMS.

 

9.         COMPUTER SOFTWARE REQUIREMENTS

            The package contains the Fortran-77 source code and executables for Windows and VAX VMS. The included PC executable was compiled with Microsoft Fortran 77. The Windows release was tested by RSICC on Pentium PC's running the Microsoft® Windows XP™ and Vista™ operating systems with MS FORTRAN 5.1.

 

10. REFERENCES

            10.a included in documentation:

                R. Gunnink, “MGA - A Gamma-Ray Spectrum Analysis Code for Determining Plutonium Isotopic Abundances, Volume 1, Methods and Algorithms,” UCRL-LR-103220, Vol.1 (April 3, 1990).

R. Gunnink, “MGA - A Gamma-Ray Spectrum Analysis Code for Determining Plutonium Isotopic Abundances, Volume 2, A Guide to Using MGA,” UCRL-LR-103220, Vol.2 (Sept. 1, 1990).

 

10.b background information

R. Gunnink, “MGA2 - A One-Detector Code for Rapid High-Precision Plutonium Measurements UCRL-96016 Rev. 1, Preprint (July 1987).

            R. Gunnink, “A New One-Detector Analysis Method for Rapid High-Precision Plutonium Isotopic Measurements            Reprinted from the Proceedings of the 9th ESARDA Symposium on Safeguards and Nuclear Material Management, London, UK., pp. 167-171 (May 12-14, 1987).

 

11. CONTENTS OF CODE PACKAGE

Included are the referenced documents listed above in 10.a and a CD containing the Fortran 77 source code and executables for Windows and VAX VMS.

 

12. DATE OF ABSTRACT

September 2008.

This code system was developed in the early 1990’s, and no changes were made when it was transmitted from ESTSC and released by RSICC in September 2008.

 

KEYWORDS: GAMMA-RAY SPECTRUM ANALYSIS; PLUTONIUM