We have designed and built a gamma-ray spectrometer system that measures the relative plutonium isotopic abundances of plutonium oxide enriched in 238Pu. The first system installed at Westinghouse Savannah River Company was tested and evaluated on plutonium oxide in stainless steel EP60/61 containers. 238Pu enrichments ranged from 20% to 85%. Results show that 200 grams of plutonium oxide in an EP60.61 container can be measured with {plus minus}0.3% precision and better than {plus minus}1.0% accuracy in the specific power using a counting time of 50 minutes. 3 refs., 2 figs.

This software manual is addressed to the Westinghouse Hanford's Radioisotope Power Systems Facility personnel (programmers and supervisors) who maintain the software on the Pu-238 isotopic analysis system. The document is divided into two parts. Part 1 describes the computer codes that control the system, analyze the spectral data, and determine the relative plutonium abundances. Part 2 contains the software listing of the analysis codes.

This user's manual is addressed to the Savannah River Site personnel (routine operators and supervisors) who perform measurements with the Pu-238 isotopic analysis system. Each chapter begins with a table of contents that lists the section title, illustrations, and tabular data presented in that chapter. The first chapter in this manual is an introduction to the system. Chapter 2 lists required settings for the system's commercial nuclear instrument modules. System operating procedures are given in Chapter 3. Chapter 4 contains routine and supervisorial operator interactions. Chapter 5 describes the system's short- and long-printout output formats. Chapter 6 gives instructions for changing system parameters. Error messages are listed and described Chapter 7. Chapter 8 contains a reference article on measuring relative plutonium isotopics in plutonium samples enriched in Pu-238. All commercial items mentioned in this manual are assumed to be functioning correctly for the purposes of system operation. Users are referred to individual equipment manufacturers' manuals for details of operation, trouble-shooting, and maintenance of this commercial equipment.

This user's manual is addressed to the Hanford Site personnel (routine operators and supervisors) who perform measurements with the Pu-238 isotopic analysis system. Each chapter begins with a table of contents that lists the section titles, illustrations, and tabular data presented in that chapter. The first chapter in this manual is an introduction to the system. Chapter 2 lists required settings for the system's commercial nuclear instrument modules. System operating procedures are given in Chapter 3. Chapter 4 contains routine and supervisorial operator interactions. Chapter 5 describes the system's short- and long-printout output formats. Chapter 6 gives instructions for changing system parameters. Error messages are listed and described in Chapter 7. Chapter 8 contains reference articles on measuring relative plutonium isotopics in solid samples.

An automated at-line plutonium isotopic analysis system for small-product plutonium samples in the range of 10 to 1000 .mu.g has been developed. The analysis is based on low-energy gamma rays at 43.48 keV (238Pu), 45.23 keV (24°Pu), 51.63 keV (239Pu), 64.83 keV (241Pu-237U), 129.3 keV (239Pu), and 148.6 keV (241Pu). Within a 20-ks counting time, we demonstrated that for plutonium masses> 600 .mu.g the precision is

The gamma-ray data analysis methodology originally developed for the MGA code to determine the relative detection efficiency curve may also be used to determine the relative amounts of the isotopes being measured. This analysis approach is based on the fact that the intensity of any given gamma ray from a sample is determined by the amount of the emitting isotope present in the sample, the emission probability for the gamma ray being measured, the sample self attenuation, the attenuation due to absorbers between the sample and detector, and the detector efficiency. An equation can be written that describes a measured gamma-ray peak intensity in terms of these parameters. By selecting appropriate gamma-ray peaks from the isotopes of interest, we can solve a set of equations for the values of the parameters in any particular measurement including the relative amounts of the selected isotopes. The equations representing the peak intensities are very nonlinear and require an iterative least squares method to solve. We have developed software to ensure that during the iterative process the parameters stay within their appropriate ranges and converge properly in solving the set of equations under various measurement conditions. We have utilized and reported on this approach for determining the plutonium isotopic abundances in samples enriched in Pu-238 and to determine the U-235 enrichment of uranium samples in thick-walled containers. Recently, we have used this approach to determine the plutonium isotopic abundances of plutonium samples in thick-walled containers. We will report on this most recent application, and how this general approach can be adapted quickly to any isotopic analysis problem.