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Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
A nondestructive gamma-ray technique has been developed to determine plutonium isotopic ratios. The technique is based on the high-intensity, low-energy gamma rays at 43.48, 45.23, 51.63, 59.54, and 64.83 keV for 238Pu, 24°Pu, 239Pu, 241Am, and 241Pu, respectively. The results demonstrate that this technique can accurately measure plutonium samples in a timely manner and in a wide range of masses, isotopic contents, chemical forms, and ages from chemical processing.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
A nondestructive gamma-ray technique has been developed to determine plutonium isotopic ratios. The technique is based on the high-intensity, low-energy gamma rays at 43.48, 45.23, 51.63, 59.54, and 64.83 keV for 238Pu, 24°Pu, 239Pu, 241Am, and 241Pu, respectively. The results demonstrate that this technique can accurately measure plutonium samples in a timely manner and in a wide range of masses, isotopic contents, chemical forms, and ages from chemical processing.
Author: Publisher: ISBN: Category : Languages : en Pages : 12
Book Description
We have developed an analytical method for detection of 239Pu in aqueous samples at concentrations as low as 10−1° M. This nuclear counting technique utilizes the uranium L X-rays, which follow the alpha decay of plutonium. Because L X-rays are specific for the element and not for the individual isotopes, the isotopic composition of the plutonium sample must be known. The counting efficiency in the 11--23 keV range is determined from a plutonium standard, and the concentration of the sample is then calculated from the L X-ray count and the isotopic composition. The total L X-ray count is corrected for possible contributions from other radionuclides present as impurities by measuring the low-energy gamma spectrum for each contaminant to establish specific photon/X-ray ratios. The ratios are important when 241Pu and 242Pu are measured, because the respective decay chain members produce non-U L X-rays. This new method can replace the use of labor-intensive radiochemical separation techniques and elaborate activation methods for analysis of 239Pu in aqueous samples. It is also applicable for assaying plutonium in liquid wastes that pose possible hazards to the environment.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The Gamma-Ray multi-group analysis code MGA developed at Lawrence Livermore National Laboratory has been widely used in the area of gamma-ray non-destructive plutonium assay. This plutonium isotopic analysis code de-convolutes the complicated, 100-keV x-ray and gamma-ray region to obtain the ratio of Pu isotopes. Calibration of the detector efficiency is not required, but is determined intrinsically from the measured spectra. The code can either analyze low-energy gamma-ray spectrum taken using a high-resolution HPGe detector for energies below 300 keV, or analyze the low-energy spectrum combined with a high-energy spectrum (up to 1 MeV) in the two-detector analysis mode. In the latter case, the use of two detectors has been mandated by the conflicting requirements: excellent resolution at low energies (characteristic of small planar detectors) with good high-energy efficiency (characteristic of coaxial detectors). Usually, a high-energy spectrum taken using a coaxial Ge detector will not provide sufficient energy resolution for 100-keV plutonium isotopic analysis, while the small planar used at low energies has inadequate high-energy efficiency. An optimized-geometry ORTEC HPGe detector has been developed which combines good energy resolution at 100 keV combined with acceptable high-energy ((almost equal to) 1 MeV) efficiency in a single detector. It has been used to gather spectra of both low- and high-energy regions of plutonium spectra simultaneously, for analysis by MGA in the two-detector mode. Five Pu gamma-ray calibration standard sources were used in this study of this special detector.
Author: Publisher: ISBN: Category : Languages : en Pages : 8
Book Description
Low-Energy Gamma-ray Spectroscopy (LEGS) is a nondestructive assay (NDA) technique developed in the 1980s. In 1999, it was modified to include a physical-based model for the energy dependent efficiency. It uses the gamma rays in the energy range from approximately 30 keV to 210 keV, except the 100-keV region. This energy region provides intense, well-separated gamma rays from the principal isotopes of plutonium. For applications involving small quantities (mg to g) of freshly separated plutonium in various chemical forms, it is ideally suited for accurate real-time or near real-time isotopic analysis. Since the last modification, LEGS has been incorporated into the FRAM code (Fixed-energy Response-function Analysis with Multiple efficiency), version 4. FRAM v4 is capable of analyzing the peaks in the whole energy range from 30 keV to 1 MeV, including the X-ray region. The new capability of analyzing the peaks in the 100-keV region greatly enhances the plutonium analysis in the 30 keV to 2 10 keV ranges of the traditional LEGS. We now can analyze both the freshly separated and aged plutonium with greater accuracy.
Author: Publisher: ISBN: Category : Languages : en Pages : 10
Book Description
Low-Energy Gamma-ray Spectroscopy (LEGS) is a nondestructive assay (NDA) technique developed in the 1980s. In 1999, it was modified to include a physical-based model for the energy dependent efficiency. It uses the gamma rays in the energy range from approximately 30 keV to 210 keV, except the 100-keV region. This energy region provides intense, well-separated gamma rays from the principal isotopes of plutonium. For applications involving small quantities (mg to g) of freshly separated plutonium in various chemical forms, it is ideally suited for accurate real-time or near real-time isotopic analysis. Since the last modification, LEGS has been incorporated into the FRAM code (Fixed-energy Response-function Analysis with Multiple efficiency), version 4. FRAM v4 is capable of analyzing the peaks in the whole energy range from 30 keV to 1 MeV, including the X-ray region. The new capability of analyzing the peaks in the 100-keV region greatly enhances the plutonium analysis in the 30 keV to 210 keV ranges of the traditional LEGS. We now can analyze both the freshly separated and aged plutonium with greater accuracy.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
We have initiated a feasibility study on the use of nondestructive low-energy gamma-ray spectroscopy for plutonium isotopic analysis on resin beads. Seven resin bead samples were measured, with each sample containing an average of 9 .mu.g of plutonium; the isotopic compositions of the samples varied over a wide range. The gamma-ray spectroscopy results, obtained from 4-h counting-time measurements, were compared with mass spectrometry results. The average ratios of gamma-ray spectroscopy to mass spectrometry were 1.014 +- 0.025 for 238Pu/239Pu, 0.996 +- 0.018 for 24°Pu/239Pu, and 0.980 +- 0.038 for 241Pu/239Pu. The rapid, automated, and accurate nondestructive isotopic analysis of resin beads may be very useful to process technicians and International Atomic Energy Agency inspectors. 3 refs., 1 fig., 3 tabs.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The Lawrence Livermore National Laboratory develops sophisticated gamma-ray analysis codes for the isotopic analysis of nuclear materials based on the principles used in the original MultiGroup Analysis (MGA) code. Over the years, the MGA methodology has been upgraded and expanded far beyond its original capabilities and is now comprised of a suite of codes known as MGA++. The early MGA code analyzed Pu gamma-ray data collected with high-purity germanium (HPGe) detectors to yield Pu isotopic ratios. While the original MGA code relied solely on the lower-energy gamma rays (around 100 keV), the most recent addition to the MGA++ code suite, MGAHI, analyzes Pu data using higher-energy gamma rays (200 keV and higher) and is particulatly useful for Pu samples - that are enclosed in thick-walled containers. The MGA++ suite also includes capabilities to perform U isotopic analysis on data collected with either HPGe or cadmium-zinc-tellutide (CZT) detectors. These codes are commercially available and are known as U235 and CZTU, respectively. A graphical user interface has also been developed for viewing the data and the fitting procedure. In addition, we are developing new codes that will integrate into the MGA++ suite. These will include Pu isotopic analysis capabilities for data collected with CZT detectors, U isotopic analysis with HPGe detectors which utilizes only higher energy gamma rays, and isotopic analyses on mixtures of Pu and U.
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Author: H. W. Kraner
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Author: Shlomo Stefan Yaniv