Download or read book Measurement of 235 U Content and Flow of UF 6 Using Delayed Neutrons Or Gamma Rays Following Induced Fission written by and published by . This book was released on 1996 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of 235U Content and Flow of UF6 Using Delayed Neutrons Or Gamma Rays Following Induced Fission written by and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Determining 235U Enrichment Using a Dual energy Approach for Delayed Neutron Measurements written by Angela Lynn Lousteau and published by . This book was released on 2017 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bulk uranium items are often measured using active neutron interrogation systems to take advantage of the relatively high penetrability of neutrons, providing the ability to quickly and accurately measure uranium masses in large, dense configurations. Active techniques employ an external neutron source to induce fission in the uranium and subsequently measure emitted prompt fission or delayed neutrons. Unfortunately, the emitted neutrons from 235U [uranium-235] and 238U [uranium-238] are, for all practical purposes, indistinguishable; therefore, commonly used systems such as the Active Well Coincidence Counter, the 252Cf [californium-252] Shuffler, and other systems based on measurement of prompt or delayed fission neutrons require many representative calibration standards and/or well-known isotopic information to interpret the results (i.e., extract an isotopic mass from the effective fissionable mass), thus limiting these techniques for safeguards applications. The primary objective of this research was to develop and demonstrate a dual-energy neutron interrogation technique using a 252Cf Shuffler measurement chamber for determination of uranium enrichment, thus eliminating the need for a (traditionally separate) gamma isotopic measurement. This new technique exploits the change in fission rates as a function of interrogating neutron energy to independently determine the 235U and 238U content in the measurement item. Dual neutron interrogation energies were achieved by adding a deuterium- tritium (D-T) neutron generator into the measurement chamber of the Oak Ridge National Laboratory 252Cf Shuffler. Results from traditional 252Cf measurements and the new D-T measurements were then used to develop a relationship between uranium enrichment and the ratio of the two delayed neutron count rates. Parameter studies were performed to optimize the measurements for each source using a combination of modeling/simulation and experimental measurements. This dissertation presents the detailed development of this novel dual-energy neutron interrogation technique. The results are promising and with engineering refinements could be deployed for routine assay of certain types of materials.

Download or read book Delayed Neutron Equilibrium Spectra of U 235 U 238 and Pu 239 written by Eric S. Jacobs and published by . This book was released on 1991 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ratio of Capture to Fission in Pu 239 at Kev Neutron Energies written by and published by . This book was released on 1967 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Delayed Fission Gamma Characteristics of U 235 U 238 Pu 239 written by and published by . This book was released on 2014 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Confirmatory Measurements of UF6 Using the Neutron Self interrogation Method written by and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A passive neutron counting method has been developed for measurement of the 235U mass in Model 5A cylinders of UF6. The unique neutronic properties of UF6 containing highly enriched uranium (HEU) permit 235U assay using only passive neutron counting. The sample effectively assays itself by self-interrogation. Shipped from enrichment plants and received at fuel fabrication and conversion facilities, 5A UF6 cylinders hold up to approx. 17 kg of 235U each. Field measurements at the Portsmouth Gaseous Diffusion Plant (GDP) showed an average assay accuracy of 6.8% (1sigma) for 44 cylinders with enrichments from 6 to 98% and with a range of fill heights. Further measurements on 38 cylinders containing 97%-enriched material yielded an accuracy of 2.8% (1sigma). Typical counting times for these measurements were less than 5 min. An in-plant instrument for receipts confirmation measurements of 5A UF6 cylinders has been developed for the Savannah River Plant. The Receipts Assay Monitor (RAM) is currently being tested and calibrated. It is designed to confirm declared fissile mass in all incoming 5A cylinders containing HEU in the form of UF6. One of the computer-controlled features is a removable cadmium liner for the sample cavity. The liner allows a sample fill-height correction, which significantly improves assay accuracy.

Download or read book 235U Determination Using In Beam Delayed Neutron Counting Technique at the NRU Reactor written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes a collaborative effort that saw the Royal Military College of Canada (RMC)'s delayed neutron and gamma counting apparatus transported to Canadian Nuclear Laboratories (CNL) for use in the neutron beamline at the National Research Universal (NRU) reactor. Samples containing mg quantities of fissile material were re-interrogated, and their delayed neutron emissions measured. This collaboration offers significant advantages to previous delayed neutron research at both CNL and RMC. This paper details the determination of 235U content in enriched uranium via the assay of in-beam delayed neutron magnitudes and temporal behavior. 235U mass was determined with an average absolute error of ± 2.7 %. This error is lower than that obtained at RMCC for the assay of 235U content in aqueous solutions (3.6 %) using delayed neutron counting. Delayed neutron counting has been demonstrated to be a rapid, accurate, and precise method for special nuclear material detection and identification.

Download or read book Measurement of the Ratio of Fissions in U238 to Fissions in U235 Using 1 60 Mev Gamma Rays of the Fission Product La140 written by John R. Wolberg and published by . This book was released on 1963 with total page 14 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 700 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Delayed neutron Energy Spectra for Thermal Fisson of U 235 written by Robert Steven Tanczyn and published by . This book was released on 1985 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Beta Decay Heat Following U 235 U 238 and Pu 239 Neutron Fission written by Shengjie Li and published by . This book was released on 1997 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Non destructive Field Measurement of the Ratio 235U written by and published by . This book was released on 1977 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The exploration of a natural reactor site is expedited by prompt measurement of 235U to 238U ratios near the mining operation. An instrument has been constructed which uses the relative fission rates of 235U and 238U in fast and moderated neutron spectra to measure the isotopic ratio. This device can be placed in the field and allows continuous monitoring of ore as a rich deposit of uranium is mined. With rapid return of isotopic information to the operator it is possible to locate a fossil reactor before it has been destroyed. The relative fast neutron and slow neutron fission rates induced in uranium which is depleted to moderately enriched in 235U may be used to measure the isotopic ratio 235U/238U quickly and nondestructively with a relative error of a few percent. When a neutron source such as 252Cf is used, the measurements may be made in the field.

Download or read book Conceptual Ideas for New Nondestructive UF6 Cylinder Assay Techniques written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nondestructive assay (NDA) measurements of uranium cylinders play an important role in helping the International Atomic Energy Agency (IAEA) safeguard uranium enrichment plants. Traditionally, these measurements have consisted of a scale or load cell to determine the mass of UF6 in the cylinder combined with a gamma-ray measurement of the 186 keV peak from 235U to determine enrichment. More recently, Los Alamos National Laboratory (LANL) and Pacific Northwest National Laboratory (PNNL) have developed systems that exploit the passive neutron signal from UF6 to determine uranium mass and/or enrichment. These include the Uranium Cylinder Assay System (UCAS), the Passive Neutron Enrichment Meter (PNEM), and the Hybrid Enrichment Verification Array (HEVA). The purpose of this report is to provide the IAEA with new ideas on technologies that may or may not be under active development but could be useful for UF6 cylinder assay. To begin, we have included two feasibility studies of active interrogation techniques. There is a long history of active interrogation in the field of nuclear safeguards, especially for uranium assay. Both of the active techniques provide a direct measure of 235U content. The first is an active neutron method based on the existing PNEM design that uses a correlated 252Cf interrogation source. This technique shows great promise for UF6 cylinder assay and is based on advanced technology that could be implemented in the field in the near term. The second active technique is nuclear resonance fluorescence (NRF). In the NRF technique, a bremsstrahlung photon beam could be used to illuminate the cylinder, and high-resolution gamma-ray detectors would detect the characteristic de-excitation photons. The results of the feasibility study show that under certain measurement geometries, NRF is impractical for UF6 cylinder assay, but the 'grazing transmission' and 'secant transmission' geometries have more potential for this application and should be assessed quantitatively. The next set of techniques leverage scintillator detectors that are sensitive to both neutron and gamma radiation. The first is the BC-523A capture-gated organic liquid scintillator. The detector response from several different neutron energies has been characterized and is included in the study. The BC-523A has not yet been tested with UF6 cylinders, but the application appears to be well suited for this technology. The second detector type is a relatively new inorganic scintillator called CLYC. CLYC provides a complementary detection approach to the HEVA and PNEM systems that could be used to determine uranium enrichment in UF6 cylinders. In this section, the conceptual idea for an integrated CLYC-HEVA/PNEM system is explored that could yield more precision and robustness against systemic uncertainties than any one of the systems by itself. This is followed by a feasibility study on using alpha-particle-induced reaction gamma-rays as a way to estimate 234U abundance in UF6. Until now, there has been no readily available estimate of the strength of these reaction gamma-rays. Thick target yields of the chief reaction gammas are computed and show that they are too weak for practical safeguards applications. In special circumstances where long count times are permissible, the 1,275 keV F([alpha], x[gamma]) is observable. Its strength could help verify an operator declaration provided other knowledge is available (especially the age). The other F([alpha], x[gamma]) lines are concealed by the dominant uranium line spectrum and associated continuum. Finally, the last section provides several ideas for electromagnetic and acoustic nondestructive evaluation (NDE) techniques. These can be used to measure cylinder wall thickness, which is a source of systematic uncertainty for gamma-ray-based NDA techniques; characterize the UF6 filling profile inside the cylinder, which is a source of systematic uncertainty for neutron-based NDA techniques; locate hidden objects inside the cylinder ...

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1996 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of Uranium Enrichment for Gaseous Uranium at Low Pressure written by and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: X-ray fluoresence determines the amount of total uranium present in gaseous UF6 inside cascade header pipes of a uranium centrifuge enrichment facility. A highly collimated source, highly collimated detector, and a very rigid, reproducible geometry are required. Two measurements of the 185.7-keV gamma ray from 235U using two collimators determine the amount of 235U present only in the gas phase. The ratio of the gas-only 235U signal to the total uranium gas-only signal is directly proportional to the enrichment of the process UF6 gas. This measurement technique is independent of the deposit that forms on a surface in contact with UF6. This measurement technique is independent of the pressure of the gaseous UF6. This technique has the required sensitivity to determine whether the process gas is of uranium enrichment less than or equal to 20% or>20%. 6 refs., 4 figs., 4 tabs.

Download or read book 235U Enrichment Determination Using 4He Proportional Counters written by and published by . This book was released on 1973 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Two independent techniques --one passive and one active --for determining 235U enrichment in UF6 have been developed utilizing /sup 4/He proportional counters. Enrichment value precisions with both techniques on the order of 3- to 5-% have been demonstrated during three field trials at the Oak Ridge and Goodyear Atomic Gaseous Diffusion Plants. With the prototype system used during field trials statistical precisions of better than 2% were obtained for typical type 30 and 48 UF6 cylinders in count periods of 300 seconds or less for both techniques. The same portable electronics package and / sup 4/He counter system are used for both techniques. The principle of the active technique is that of thermal neutron-induced fission of 235U followed by fast prompt neutron detection. (auth).