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Description: This is a report to demonstrate use of Non-Scaling Fixed-Field Alternating-Gradient (FFAG) accelerators [1] in acceleration of partially stripped ions of Uranium-238 for Rare Isotopes Production. This example assumes a beam final energy of 500 MeV/u with an average beam output current of 1 {micro}A-particle and a beam average power of 120 kWatt.
Date: June 26, 2006
Partner: UNT Libraries Government Documents Department

Limitations on the precision of 238U/235U measurements and implications for environmental monitoring

Description: The ability to determine the isotopic composition of uranium in environmental samples is an important component of the International Atomic Energy Agency`s (IAEA) safeguards program, and variations in the isotopic ratio {sup 238}U/{sup 235}U provide the most direct evidence of isotopic enrichment activities. The interpretation of observed variations in {sup 238}U/{sup 235}U depends on the ability to distinguish enrichment from instrumental biases and any variations occurring in the environment but not related to enrichment activities. Instrumental biases that have historically limited the accuracy of {sup 238}U/{sup 235}U determinations can be eliminated by the use of the {sup 233}U/{sup 236}U double-spike technique. With this technique, it is possible to determine the {sup 238}U/{sup 235}U in samples to an accuracy equal to the precision of the measurement, ca. 0.1% for a few 10`s of nanograms of uranium. Given an accurate determination of {sup 238}U/{sup 235}U, positive identification of enrichment activities depends on the observed value being outside the range of {sup 238}U/{sup 235}U`s expected as a result of natural or environmental variations. Analyses of a suite of soil samples showed no variation beyond 0.2% in {sup 238}U/{sup 235}U.
Date: August 1, 1997
Creator: Russ III, G.P.
Partner: UNT Libraries Government Documents Department

Spatial variations of particle scavenging rates within the central and northern Adriatic Sea: use of U--Th disequilibria

Description: Dissolved and particlulate Thorium-234 ({sup 234}Th) were measured in near surface waters from the Central and Northern Adriatic Sea in order to gain an insight into the intensity and variability of active scavenging and particle removal processes. Dissolved {sup 234}Th to Uranium-238 ({sup 238}U) activity ratios vary from 0.21 to 0.75 and clearly imply that {sup 234}Th is being actively scavenged from sea water on a timescale of <3 months. The scavenging rate of dissolved {sup 234}Th with respect to scavenging onto particles appears to correlate with primary productivity measurements. Scavenging and rapid removal of particulate {sup 234}Th from the water column is best explained by a mechanism of zooplankton grazing and fecal pellet production. At one sight in the Jabuka Pit, particulate {sup 234}Th residence times below the pycnocline are long (30-40 days) suggesting that particles are being more readily recycled at these depths. By comparison, in a seawater profile collected near the Po outflow region, {sup 234}Th is depleted with respect to {sup 238}U through the entire water column. We conclude from this assessment that particles in waters near the Po River outflow will be more efficiently transported to bottom sediments compared with those in deeper waters over the Jabuka Pit.
Date: April 1, 1998
Creator: Hamilton, T. F.
Partner: UNT Libraries Government Documents Department

Demonstration recommendations for accelerated testing of concrete decontamination methods

Description: A large number of aging US Department of Energy (DOE) surplus facilities located throughout the US require deactivation, decontamination, and decommissioning. Although several technologies are available commercially for concrete decontamination, emerging technologies with potential to reduce secondary waste and minimize the impact and risk to workers and the environment are needed. In response to these needs, the Accelerated Testing of Concrete Decontamination Methods project team described the nature and extent of contaminated concrete within the DOE complex and identified applicable emerging technologies. Existing information used to describe the nature and extent of contaminated concrete indicates that the most frequently occurring radiological contaminants are {sup 137}Cs, {sup 238}U (and its daughters), {sup 60}Co, {sup 90}Sr, and tritium. The total area of radionuclide-contaminated concrete within the DOE complex is estimated to be in the range of 7.9 {times} 10{sup 8} ft{sup 2}or approximately 18,000 acres. Concrete decontamination problems were matched with emerging technologies to recommend demonstrations considered to provide the most benefit to decontamination of concrete within the DOE complex. Emerging technologies with the most potential benefit were biological decontamination, electro-hydraulic scabbling, electrokinetics, and microwave scabbling.
Date: December 1, 1995
Creator: Dickerson, K.S.; Ally, M.R.; Brown, C.H.; Morris, M.I. & Wilson-Nichols, M.J.
Partner: UNT Libraries Government Documents Department


Description: Information is presented in tabular form on the contributions of the individual resonances to the resonance integrals in U and Th. The cases considered are for isolated cylindrical rods and involve U/sup 238/, U/sup 238/O/ sub 2/, Th/ sup 232/, and Th/sup 232/O/sub 2/ (M.C.G.)
Date: October 26, 1961
Creator: Nordheim, L.W.
Partner: UNT Libraries Government Documents Department


Description: ABS>The measurable properties of a critical assembly (e.g.. fission, capture, and leakage rates; neutron-per-fission ratios; bare/Cd-covered reaction rate of-atios; danger eoefficients; etc.), whose judicious use completely defines tbcneutron economy in the assembly, are discussed. Require ments regarding the internal consisteney of these of:deasured quantities are reviewed. lt is concluded that theoretical analysis of the assembly must both reproduce the gross experimental results and reflect the internal consistency of the data. Only thermal systems fueled with U/sup 235/ and U/sup 238/ are considered. (T.F.H.)
Date: January 1, 1962
Creator: Kelber, C.N.
Partner: UNT Libraries Government Documents Department


Description: The theory is presented in detail of an activation method for measuring the ratio of U/sup 238/ absorptions to U/sup 235/ fissions in a nuclear reactor. The origin of the activities is discussed, the equations are given for interpretation of the measurements, and the expected counting rates are computed for a typical experiment in the EGCR. (auth)
Date: August 10, 1962
Creator: Preskitt, C.A.
Partner: UNT Libraries Government Documents Department

Power production and ADS

Description: We describe the power production process in Accelerator Driven Sub-critical systems employing Thorium-232 and Uranium-238 as fuel and examine the demands on the power of the accelerator required.
Date: March 1, 2010
Creator: Raja, Rajendran
Partner: UNT Libraries Government Documents Department


Description: We explore the possibility of using two non-scaling FFAG accelerators for a high power heavy-ion driver as an alternative to a superconducting Linac. Ions of Uranium 238 are accelerated to a kinetic energy of 400 MeVIu and a total power of 400 kWatt. Different modes of acceleration have been studied: at 1 and 10 kHz repetition rate, and for Continuous Wave production. The following is a summary of the study. More details of the study can be found in reference 2.
Date: June 25, 2007
Partner: UNT Libraries Government Documents Department

Measurement of the equivalent fundamental-mode source strength

Description: The steady-state multiplication, M, of a subcritical system that is in equilibrium with an external/intrinsic source is defined as the total neutron-production rate divided by the external/ intrinsic neutron source rate, S. The total neutron-production rate, in this context, is the sum of the fission-production rate plus the source rate. Because the system is in equilibrium, the total neutron-production rate is identically equal to the loss rate from the system due to absorption plus leakage. If the source S is distributed identically to the fission source distribution (i.e., angle, energy, and space), then M will be related to the effective multiplication factor of the system, k{sub eff}, as M = 1/1-k{sub eff}.
Date: January 21, 1997
Creator: Spriggs, G.D.; Busch, R.D.; Sakurai, Takeshi & Okajima, Shigeaki
Partner: UNT Libraries Government Documents Department

Study of parity nonconservation with epithermal neutrons

Description: The authors describe a new generation of experiments studying the weak interaction between nucleons. Measurements of the effect of this interaction are few in number and the significance of the observed effects are generally small. It is well known that the weak interaction violates parity. This was first experimentally established by C.S. Wu through measurement of an asymmetry of electrons emitted in the beta-decay of polarized {sup 60}Co. The measured asymmetry was large because beta decay is a weak interaction process. For a process in which the - strong interaction can contribute, we expect much smaller asymmetries, of order 10{sup -7}.
Date: September 1996
Creator: Seestrom, S. J.; Bowman, J. D.; Knudson, J. N. & Yuan, V.
Partner: UNT Libraries Government Documents Department

Beta and gamma decay heat measurements between 0.1s - 50,000s for neturon fission of {sup 235}U, {sup 238}U and {sup 239}Pu. Progress report, June 1, 1992--December 31, 1994

Description: In the investigations reported here, a helium-jet/tape-transport system was used for the rapid transfer of fission products to a low-background environment where their aggregate beta and gamma-ray spectra were measured as a function of delay time after neutron induced fission of {sup 235}U, {sup 238}U and {sup 239}Pu. Beta and gamma-ray energy distributions have been deduced for delay times as short as 0.2 s and extending out to 100,000s. Instrumentation development during the initial phase of the project included: (1) assembly and characterization of a NaI(Tl) spectrometer for determining aggregate gamma-ray energy distributions, (2) development and characterization of a beta spectrometer (having excellent gamma-ray rejection) for measuring aggregate beta-particle energy distributions, (3) assembly and characterization of a Compton-suppressed HPGe spectrometer for determining gamma-ray intensities of individual fission products to deduce fission-product yields. Spectral decomposition and analysis codes were developed for deducing energy distributions from measured aggregate beta and gamma spectra. The aggregate measurements in the time interval 0.2 - 20s after fission are of special importance since in this region data from many short-lived nuclei are missing and summation calculations in this region rely on model calculations for a large fraction of their predicted beta and gamma decay heat energy spectra. Comparison with ENDF/B-VI fission product data was performed in parallel with the measurements through a close collaboration with Dr. T. England at LANL, assisted by one of our graduate students. Such aggregate measurements provide tests of the Gross Theory of beta decay used to calculated missing contributions to this data base. Fission-product yields deduced from the HPGe studies will check the accuracy of the semi-empirical Gaussian dispersion model used presently by evaluators in the absence of measured yields.
Date: May 1, 1997
Creator: Schier, W.A. & Couchell, G.P.
Partner: UNT Libraries Government Documents Department

Results of the independent radiological verification survey at the former Chapman Valve Manufacturing Company, Indian Orchard, Massachusetts (CIO001V)

Description: The Chapman Valve Manufacturing Company in Indian Orchard, Massachusetts was one of many companies performing work during the 1940s associated with the development of nuclear energy for defense-related projects for the Manhattan Engineer District (MED) and the Atomic Energy Commission (AEC). In 1991, a radiological survey was conducted at the site. The survey report indicated {sup 238}U contamination in excess of the DOE criteria for surface contamination, and some {sup 235}U residues in the west end of the building. Decontamination of the facility to supplemental guidelines, derived by a hazard assessment based on appropriate scenarios for this building, was conducted by subcontractor personnel in 1995 under the direction of Bechtel National Incorporated (BNI), the project management contractor for FUSRAP. The independent radiological verification survey detailed in this report was performed in July and August 1995 under the FUSRAP program by members of ORNL at the request of DOE. The radiological verification survey of the west end of the building included gamma, alpha, and beta-gamma scans for fixed contamination, smear sampling for transferable contamination, and radionuclide analysis of soil samples taken from outside the building and from excavations in the concrete floor inside the building.
Date: May 1, 1997
Creator: Rodriguez, R.E. & Johnson, C.A.
Partner: UNT Libraries Government Documents Department

Factors affecting use of fission foils as dosimetry sensors

Description: Fission foils are commonly used as dosimetry sensors. They play a very important role in neutron spectrum determinations. This paper provides a combination of experimental measurements and calculations to quantify the importance and synergy of several factors that affect the fission response of a dosimeter. Only when these effects are properly treated can fission dosimeters be used with sufficient fidelity.
Date: December 31, 1996
Creator: Griffin, P.J.; Vehar, D.W.; Kelly, J.G. & Holm, C.V.
Partner: UNT Libraries Government Documents Department

Development of a ceramic form for immobilization of excess plutonium

Description: Between 8 and 50 metric tonnes of excess plutonium are currently planned to be immobilized in a glass or ceramic waste form in the US. The immobilized Pu would then be encased in HLW glass (the can-in-canister alternative), which would provide a radiation barrier to enhance the proliferation resistance of the material. Associated with the plutonium are about 15 metric tonnes of uranium primarily {sup 238}U and a variety of other impurities (primarily Ga, Mo, Al, Mg, Si, and Cl) totaling about 1 metric tonne or less. Immobilization of this material is complicated by the fact that the uranium content in the various feed streams varies widely, from 0 to about 95%. The proposed ceramic form is composed of about 90% zirconolite (CaZrTi{sub 2}O{sub 7}) and/or pyrochlore (CaPuTi{sub 2}O{sub 7}) with about 10% other phases, typically hollandite (BaAl{sub 2}Ti{sub 6}O{sub 16}) and rutile (TiO{sub 2}). The form is a variation of Synroc-C, which contains nominally 30% zirconolite, 30% perovskite, 30% hollandite, and 10% rutile and noble metal alloys. Zirconolite and perovskite are the actinide host phases in Synroc-C with zirconolite being the more durable phase. The pyrochlore structure is closely related to zirconolite and forms at higher actinide loadings. Thus, this mineral is of interest for plutonium deposition in ceramic. Pyrochlore has the advantage that it is cubic rather the monoclinic like zirconolite. Cubic mineral swell isotropically when radiation damaged. As a result, differential strain in the microstructure will be minimal, leading to significantly less microcracking of the form after thousands of years in a repository. Zirconolites and pyrochlores containing uranium and.or thorium exist in nature and have demonstrated actinide immobilizations for periods exceeding 100 million years.
Date: April 22, 1997
Creator: Van Konynenburg, R.; Ebbinghaus, B.; Ryerson, F.; Shaw, H. & Curtis, P.
Partner: UNT Libraries Government Documents Department