Download or read book The Application of Neutron Multiplicity Counting to the Assay of Bulk Plutonium Bearing Materials at RFETS and LLNL written by and published by . This book was released on 1995 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the past several years, several facilities have identified a need for a large multiplicity counter to support safeguards of excess weapons materials and the measurement control and accountability of large, unusual samples. The authors have designed and fabricated two large thermal neutron multiplicity counters to meet this need at two DOE facilities. The first of these counters was built for Rocky Flats Environmental Test Site for use in the initial inventory inspection of excess weapons plutonium offered to International Atomic Energy Agency safeguards. The second counter was built for the Lawrence Livermore National Laboratory (LLNL) to support their material control and accountability program. For the LLNL version of the counter, a removable, fast-neutron interrogation assembly was added for the measurement of large uranium samples. In the passive mode these counters can accommodate samples in containers as large as a 30-gal. drum. This paper reports on the measured performance of these two counters and the data obtained with them.
Download or read book The Application of Neutron Multiplicity Counting to the Assay of Bulk Plutoniu Bearing Materials at RFETS and LLNL written by and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transactions of the American Nuclear Society written by and published by . This book was released on 1995 with total page 1060 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the International Conference on Facility Operations Safeguards Interface written by and published by . This book was released on 1996 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1996 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Assay of Scrap Plutonium Oxide by Thermal Neutron Multiplicity Counting for IAEA Verification of Excess Materials from Nuclear Weapons Production written by and published by . This book was released on 1996 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The US Nonproliferation and Export Control Policy commits the US to placing under International Atomic Energy Agency (IAEA) safeguards excess nuclear materials no longer needed for the US nuclear deterrent. As of January 1,1996, the IAEA has completed Initial Physical Inventory Verification (IPIV) at the Oak Ridge Y-12 plant, the Hanford Plutonium Finishing Plant, and a plutonium storage vault at Rock Flats. Two IPIVs were performed at Hanford . This paper reports the results of thermal neutron multiplicity assay of plutonium residues during the second IPIV at Hanford. Using the Three Ring Multiplicity Counter (3RMC), measurements were performed on 69 individual cans of plutonium residues, each containing approximately 1 kg of material. Of the 69 items, 67 passed the IAEA acceptance criteria and two were selected for destructive analysis.
Download or read book Application Guide to Neutron Multiplicity Counting written by and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This document is intended to serve as a comprehensive applications guide to passive neutron multiplicity counting, a new nondestructive assay (NDA) technique developed over the past ten years. The document describes the principles of multiplicity counter design, electronics, and mathematics. Existing counters in Department of Energy (DOE) facilities are surveyed, and their operating requirements and procedures and defined. Current applications to plutonium material types found in DOE facilities are described, and estimates of the expected assay precision and bias are given. Lastly, guidelines for multiplicity counter selection and procurement are summarized. The document also includes a detailed collection of references on passive neutron coincidence and multiplicity publications over the last ten to fifteen years.
Download or read book Geometry based Multiplication corrected Analysis for Neutron Coincidence Assay of Impure Plutonium Materials written by and published by . This book was released on 1991 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have developed a technique to assay impure, plutonium-bearing materials using passive neutron coincidence counting. The technique can be applied to any impure, plutonium-bearing material category whose matrix constituents are approximately constant, whose self- multiplication is low-to-moderate, whose plutonium isotopic composition is known and not substantially varying, and whose bulk geometry is measurable or can be derived. The technique requires a set of reference materials with well-characterized plutonium contents. The reference materials are measured once to derive a calibration that is specific to the neutron detector and the material category. This technique has been applied to four categories of material: molten salt extraction residues; plutonium fluoride samples having a variable salt matrix; impure plutonium oxides; and, for comparison, pure plutonium oxides. Assays accurate to 4% (1[sigma]) were obtained for these impure materials measured in an HLNCII. Better results should be obtainable with neutron detectors with better response characteristics. 11 refs., 6 figs., 6 tabs.
Download or read book Standard Test Method for Nondestructive Assay of Plutonium by Passive Neutron Multiplicity Counting written by and published by . This book was released on with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Application of Neutron Multiplicity Counting to Waste Assay written by and published by . This book was released on 1997 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes the use of a new figure of merit code that calculates both bias and precision for coincidence and multiplicity counting, and determines the optimum regions for each in waste assay applications. A tunable multiplicity approach is developed that uses a combination of coincidence and multiplicity counting to minimize the total assay error. An example is shown where multiplicity analysis is used to solve for mass, alpha, and multiplication and tunable multiplicity is shown to work well. The approach provides a method for selecting coincidence, multiplicity, or tunable multiplicity counting to give the best assay with the lowest total error over a broad spectrum of assay conditions.
Download or read book A Large Multiplicity Counter for the Measurement of Bulk Plutonium written by and published by . This book was released on 1994 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors have considered the problem of designing a thermal neutron counter for the neutron multiplicity measurement of large, high-mass plutonium items. Three neutron multiplicity counters have been built at Los Alamos to date; two are used for in-plant applications. The third counter is an experimental prototype and is used for research. The sample cavities of these counters can accommodate only relatively small samples. The largest item that can be measured optimally by the largest of these counters is 20 cm wide by 36 cm high. Now that the multiplicity technique has proven to be accurate and timely for the measurement of plutonium-bearing items, several facilities in the DOE complex have identified the need for larger counters. Several sources have identified a counter that could measure items contained in 30-gal. drums as the most desirable. For a multiplicity measurement to be successful, the neutron counter must have a large detection efficiency independent of changes in the neutron energy of the emitted neutrons, a short die-away time, and a uniform response over the sample cavity. These requirements have been achieved in the smaller counters by using large numbers of 3He tubes placed in concentric rings. This method can be extrapolated to a larger counter but at great expense. The authors have conducted a design study for a 30-gal. drum counter. The goal of this study is to reduce the number of 3He tubes required for such a large counter while still maintaining good measurement performance. This paper will report on the result of this study.
Download or read book Recent Experiences of Scrap and Waste Assay Using Neutron Coincidence Counting of Materials from F B Line at the Savannah River Site written by and published by . This book was released on 1990 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The heterogeneous nature of scrap and waste poses unique problems for quantitative measurement. This is particularly true when the sample to be measured can have significant amounts of plutonium in addition to a variety of matrix components. One approach to addressing these difficulties is to combine gamma-ray and neutron counting techniques. A system combining a segmented gamma-ray scanner and neutron coincidence counter has recently been developed for the non-destructive assay of plutonium-bearing scrap and waste. Experience gained with the neutron coincidence counter portion of the system is described. Results obtained from the measurement of scrap and waste materials containing a few grams to a few hundred grams of plutonium are given. The effects of different matrices are evaluated and the role of special diagnostics is explored. 5 refs., 13 figs., 3 tabs.
Download or read book Neutron Multiplicity Assay of Impure Materials Using Four Different Neutron Counters written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: During an advanced IAEA inspector training course given at Los Alamos in November, 1997, the opportunity existed for an intercomparison study of various neutron detectors to quantify measurement performance using pure and impure plutonium oxide and mixed uranium-plutonium oxide (MOX) items. Because of the cost of counters designed specifically for multiplicity analysis, it was desired to explore the limits of other, less costly and less efficient detectors. This paper presents and intercompares neutron coincidence and multiplicity assay performance for five detectors, which vary widely in detection efficiency. Eight pure plutonium oxide and twelve impure plutonium oxide and MOX working standards were used in the study.
Download or read book Nondestructive Assay Tests of High efficiency Neutron Counter HENC for Waste Assay and Possible Diversion Scenario written by and published by . This book was released on 1998 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: An advanced passive neutron counter, the high-efficiency neutron counter (HENC), has been used to measure plutonium content in 200-L waste drums. The HENC was designed with the 252Cf add-a-source (AS) feature to improve accuracy over a wide range of waste matrix materials. The current implementation allows for passive neutron coincidence counting, AS analysis, and multiplicity analysis. Passive neutron assay of typical waste containers is intrinsically more accurate than active neutron techniques because of the penetrability of the spontaneous fission neutrons originating from within the waste matrix. In addition, the HENC is designed as a slightly undermoderated detector to be less sensitive to low loading of hydrogen-bearing matrices. The following paper considers the applicability of three different nondestructive assay methods for analysis of waste drums and the flagging of possible diversions in waste drums. The 252Cf AS method, multiplicity counting, and a bounded-parameter multiplicity analysis are presented with areas of applicability.
Download or read book Evaluation of the Neutron Self interrogation Approach for Assay of Plutonium in High Cap Alpha N Materials written by and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Neutron self-interrogation is a proposed method for assay of plutonium in bulk materials with very high .cap alpha., n activity. The simple assay approach assumes that neutron multiplication for the calibration standards is the same as that for the bulk items. Efforts to use bulk properties to determine corrections to the calibration for changing multiplication have been initiated. Self-interrogation assays of bulk pyrochemical residues have been performed. Comparison with tag values obtained by difference gives poor agreement. Comparison with tag values obtained by dissolution and destructive analysis gives agreement at the 10% (1sigma) level with no corrections for changing package dimensions or matrix amounts. The agreement improves by a factor of 2 or more if a bulk correction factor (derived from a packaging/matrix study with standards) is applied.
Download or read book Neutron Resonance Transmission Analysis NRTA written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Neutron Resonance Transmission Analysis (NRTA) is an analytical technique that uses neutrons to assay the isotopic content of bulk materials. The technique uses a pulsed accelerator to produce an intense, short pulse of neutrons in a time-of-flight configuration. These neutrons, traveling at different speeds according to their energy, can be used to interrogate a spent fuel (SF) assembly to determine its plutonium content. Neutron transmission through the assembly is monitored as a function of neutron energy (time after the pulse), similar to the way neutron cross-section data is often collected. The transmitted neutron intensity is recorded as a function of time, with faster (higher-energy) neutrons arriving first and slower (lower-energy) neutrons arriving later. The low-energy elastic scattering and absorption resonances of plutonium and other isotopes modulate the transmitted neutron spectrum. Plutonium content in SF can be determined by analyzing this attenuation. Work is currently underway at Idaho National Laboratory, as a part of United States Department of Energy's Next Generation Safeguards Initiative (NGSI), to investigate the NRTA technique and to assess its feasibility for quantifying the plutonium content in SF and for determining the diversion of SF pins from assemblies. Preliminary results indicate that NRTA has great potential for being able to assay intact SF assemblies. Operating in the 1-40 eV range, it can identify four plutonium isotopes (239, 240, 241, & 242Pu), three uranium isotopes (235, 236, & 238U), and six resonant fission products (99Tc, 103Rh, 131Xe, 133Cs, 145Nd, and 152Sm). It can determine the areal density or mass of these isotopes in single- or multiple-pin integral transmission scans. Further, multiple observables exist to allow the detection of material diversion (pin defects) including fast-neutron and x-ray radiography, gross-transmission neutron counting, plutonium resonance absorption analysis, and fission-product resonance absorption analysis. Initial benchmark modeling has shown excellent agreement with previously published experimental data for measurements of individual SF pins where plutonium assays were experimentally demonstrated to have a precision of better than 3%.
Download or read book The Application of the Slowing Down Spectrometer to Nuclear Materials Assay written by J. R. Beyster and published by . This book was released on 1970 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
