Download or read book A High efficiency Neutron Coincidence Counter for Small Samples written by and published by . This book was released on 1991 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The inventory sample coincidence counter (INVS) has been modified to enhance its performance. The new design is suitable for use with a glove box sample-well (in-line application) as well as for use in the standard at-line mode. The counter has been redesigned to count more efficiently and be less sensitive to variations in sample position. These factors lead to a higher degree of precision and accuracy in a given counting period and allow for the practical use of the INVS counter with gamma-ray isotopics to obtain a plutonium assay independent of operator declarations and time-consuming chemicals analysis. A calculation study was performed using the Los Alamos transport code MCNP to optimize the design parameters. 5 refs., 7 figs., 8 tabs.
Download or read book A Neutron Counter for Small Samples written by and published by . This book was released on 1993 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Inventory Sample Counter Model IV is the most recent neutron coincidence counter specifically designed to measure small samples. We used a combination of measurement experience and Monte Carlo modeling to design a neutron counter that can provide measurement results with an accuracy of 0.5% or better. Some applications incorporate a high-resolution detector into the neutron counter. This allows the simultaneous measurement of the plutonium isotopics using the passive gamma-ray emission and the measurement of the [sup 240]Pu effective mass using the passive neutron emission. The two results are then combined to yield the plutonium mass.
Download or read book High efficiency Neutron Counter for Fast Coincidence Measurements written by Thoma M. Snyder and published by . This book was released on 1946 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Systematic Effects in Neutron Coincidence and Multiplicity Counting written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Correlated neutron counting, including neutron coincidence and multiplicity counting, is an important tool in nuclear material accountancy verification. The accuracy of such measurements is of interest to the safeguards community because as the accuracy of NDA improves, the number of samples that are required to undergo destructive analysis (DA) decreases. The accuracy of a neutron mUltiplicity measurement can be affected by a number of variables. Monte Carlo neutron transport simulations with MCNPX have been performed to understand how the properties of the sample affect the count rate. These resultant count rates have been analyzed with the 'point model' in order to determine the effect on the deduced plutonium mass. The sample properties that have been investigated are density, sample position within the detector cavity, moisture content, isotopic composition, plutonium to total actinide ratio and heavy metal fraction. These parameters affect the Singles, Doubles and Triples count rates in different ways. In addition, different analysis methods use these measured quantities in different combinations, so that the final sensitivity of the 24°Pu mass to each parameter also depends on the analysis method used. For example, the passive calibration curve method only used the Doubles rate to produce the 24°Pu mass and so is not sensitive to changes in the Singles rate (to first order). The analysis methods considered here were passive calibration curve (non-multiplication corrected), known alpha (multiplication corrected) and multiplicity with known efficiency. The effects were studied on both a small mass MOX sample (1 g Pu) and a large MOX sample (6000 g Pu) both measured in high efficiency neutron multiplicity counters. In order to determine the final effect of each parameter it is necessary to know not only the sensitivity of the plutonium mass to that parameter, but also the range over which the parameter can realistically vary. Some estimates are given.
Download or read book Handbook of Nuclear Chemistry written by Attila Vértes and published by Springer Science & Business Media. This book was released on 2010-12-10 with total page 3693 pages. Available in PDF, EPUB and Kindle. Book excerpt: This revised and extended 6 volume handbook set is the most comprehensive and voluminous reference work of its kind in the field of nuclear chemistry. The Handbook set covers all of the chemical aspects of nuclear science starting from the physical basics and including such diverse areas as the chemistry of transactinides and exotic atoms as well as radioactive waste management and radiopharmaceutical chemistry relevant to nuclear medicine. The nuclear methods of the investigation of chemical structure also receive ample space and attention. The international team of authors consists of scores of world-renowned experts - nuclear chemists, radiopharmaceutical chemists and physicists - from Europe, USA, and Asia. The Handbook set is an invaluable reference for nuclear scientists, biologists, chemists, physicists, physicians practicing nuclear medicine, graduate students and teachers - virtually all who are involved in the chemical and radiopharmaceutical aspects of nuclear science. The Handbook set also provides further reading via the rich selection of references.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1992 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Ephithermal Neutron Multiplicity Counter Design and Performance Manual More Rapid Plutonium and Uranium Inventory Verifications by Factors of 5 20 written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermal neutron multiplicity counters (TNMCs) assay [sup 240]Pu-effective mass, isolating spontaneous-fission (SF), induced-fission, and ([alpha], n) neutrons emitted from plutonium metal, oxide, scrap, and residue items. Three independent parameters are measured: single, double, and triple neutron-pulse-coincidence count rates. TNMC assays can become precision limited by high ([alpha], n) neutron rates arising from low-Z impurities and [sup 241]Am. TNMCs capture thermal neutrons in 4-atm [sup 3]He tubes after fast-source-neutron moderation by polyethylene. TNMCs are [approximately]50% efficient with [approximately]-[micro]s die-away times. Simultaneously increasing efficiency and reducing die-away time dramatically improve assay precision. Using 10-atm [sup 3]He tubes, they've developed and performance-tested the first of a new generation of neutron assay counters for a wide range of plutonium items. The Epithermal Neutron Multiplicity Counter (ENMC) has an efficiency of 65% and a 22-[micro]s die-away time. The ENMC detects neutrons before thermalization using higher [sup 3]He pressure counters and less moderator than TNMCs. A special insert raises efficiency to 80% for small samples. For five bulk samples containing 50 to 875 g of [sup 240]Pu-effective, ENMC assay times are reduced by factors of 5 to 21, compared with prior state-of-the-art TNMCs. The largest relative gains are for the most impure items, where gains are needed most. In active mode, the ENMC assay times are reduced by factors of 5 to 11, compared with the Active Well Coincidence Counter (AWCC). The ENMC, with high precision and low multiplicity dead time (37 ns), can be used in standards verification mode to precisely and accurately characterize plutonium standards and isotopic sources. The ENMC's performance is very competitive with calorimetry. This report describes the ENMC; presents results of characterization, calibration, and verification measurements; and shows the clear performance and economic advantages of implementing the ENMC for nuclear materials control and accountability.
Download or read book Development of a High efficiency Neutron Counter Using Novel Materials written by and published by . This book was released on 1997 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: Neutron detection efficiency is an important figure of merit for waste assay applications that must measure small quantities of material. It is also important for neutron coincidence counting and multiplicity counting because the detection of double- and triple-correlated events scales as the detection efficiency squared and cubed, respectively. Conventional thermal neutron detection systems typically employ 3He detector tubes embedded in polyethylene. The polyethylene moderates the neutrons so they can be detected by the 3He tubes. However, the hydrogen in the moderator also absorbs neutrons and reduces the diffusion length. We have extensively explored alternate designs that use both polyethylene and other industrial plastics with lower concentrations of hydrogen. In MCNP studies, we have achieved higher detection efficiency by using both polyethylene and other plastics in a hybrid design. In this paper we will present the design of a nominal 30%-efficient, 200-liter neutron counter that uses a hybrid design. We will show comparison results of this design compared to a standard polyethylene design. Finally, this counter has been constructed and tested, and was used in the Los Alamos waste assay course. We will show comparisons of the experimental results from this counter to the MCNP predictions.
Download or read book High efficiency He 3 Proportional Counter for the Detection of Delayed Neutrons written by and published by . This book was released on 1998 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present work examines a high-neutron efficiency detector used to measure delayed neutron techniques. The measurement of delayed neutrons requires a detector system that has high neutron efficiency and a low dead- time. The detection system must also have low gamma-ray sensitivity, and in addition must be insensitive to small sample displacement. The operating characteristics of the high-efficiency He-3 proportional counter used for the measurement of [beta]{sub i}-delayed neutrons is reported here.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1987 with total page 1284 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of a Portable Neutron Coincidence Counter for Field Measurements of Nuclear Materials Using the Advanced Multiplicity Capabilities of MCNPX 2 5 F and the Neutron Coincidence Point Model written by Angela Lynn Thornton and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Neutron coincidence counting is an important passive Nondestructive Assay (NDA) technique widely used for qualitative and quantitative analysis of nuclear material in bulk samples. During the fission process, multiple neutrons are simultaneously emitted from the splitting nucleus. These neutron groups are often referred to as coincident neutrons. Because different isotopes possess different coincident neutron characteristics, the coincident neutron signature can be used to identify and quantify a given material. In an effort to identify unknown nuclear samples in field inspections, the Portable Neutron Coincidence Counter (PNCC) has been developed. This detector makes use of the coincident neutrons being emitted from a bulk sample. An in-depth analysis has been performed to establish whether the nuclear material in an unknown sample could be quantified with the accuracy and precision needed for safeguards measurements. The analysis was performed by comparing experimental measurements of PuO2 samples to the calculated output produced using MCNPX and the Neutron Coincidence Point Model. Based on the analysis, it is evident that this new portable system can play a useful role in identifying nuclear material for verification purposes.
Download or read book Field Test and Calibration of Neutron Coincidence Counters for High mass Plutonium Samples written by Howard O. Menlove and published by . This book was released on 1987 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Annual Report to Congress of the Atomic Energy Commission written by U.S. Atomic Energy Commission and published by . This book was released on 1972 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Annual Report to Congress written by U.S. Atomic Energy Commission and published by . This book was released on 1972 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Operating and developmental functions v 2 Regulatory activities written by U.S. Atomic Energy Commission and published by . This book was released on 1973 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1975 with total page 900 pages. Available in PDF, EPUB and Kindle. Book excerpt: NSA is a comprehensive collection of international nuclear science and technology literature for the period 1948 through 1976, pre-dating the prestigious INIS database, which began in 1970. NSA existed as a printed product (Volumes 1-33) initially, created by DOE's predecessor, the U.S. Atomic Energy Commission (AEC). NSA includes citations to scientific and technical reports from the AEC, the U.S. Energy Research and Development Administration and its contractors, plus other agencies and international organizations, universities, and industrial and research organizations. References to books, conference proceedings, papers, patents, dissertations, engineering drawings, and journal articles from worldwide sources are also included. Abstracts and full text are provided if available.
Download or read book NBS Special Publication written by and published by . This book was released on 1979 with total page 706 pages. Available in PDF, EPUB and Kindle. Book excerpt:
