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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: The distribution of the kinetic energy of fragments emitted as a result of the neutron-induced fission of Th/sup 232/ has been determined. Incident neutron energies of 1475 plus or minus 35 kev and l600 plus or minus 35 kev were used. The distributions determined at the two incident neutron energies are identical. The measured total average fragment kinetic energy was l55 plus or minus 4.5 Mev. The most probable fragment mass ratio is 1.47 plus or minus 0.05, and the average kinetic energies of the light and heavy fragments are 95 plus or minus 2 and 60 plus or minus 3 Mev, respectively. The experimental results were related to the known systematics of neutron-induced and spontaneous fission. The effect of collective nuclear rotations at the saddle point is discussed, with particular emphasis on fission from specific rotational bands. (auth)
Date: November 1, 1960
Creator: Smith, A.B.; Nobles, R.G. & Friedman, A.M.
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

Forecast of Standard Atomic Weights for the Mononuclidic Elements – 2011

Description: In this short report, I will provide an early warning about potential changes to the standard atomic weight values for the twenty mononuclidic and the so-called pseudo-mononuclidic ({sup 232}Th and {sup 231}Pa) chemical elements due to the estimated changes in the mass values to be published in the next Atomic Mass Tables within the next two years. There have been many new measurements of atomic masses, since the last published Atomic Mass Table. The Atomic Mass Data Center has released an unpublished version of the present status of the atomic mass values as a private communication. We can not update the Standard Atomic Weight Table at this time based on these unpublished values but we can anticipate how many changes are probably going to be expected in the next few years on the basis of the forthcoming publication of the Atomic Mass Table. I will briefly discuss the procedures that the Atomic Weights Commission used in deriving the recommended Standard Atomic Weight values and their uncertainties from the atomic mass values. I will also discuss some concern raised about a proposed change in the definition of the mole. The definition of the mole is now connected directly to the mass of a {sup 12}C isotope (which is defined as 12 exactly) and to the kilogram. A change in the definition of the mole will probably impact the mass of {sup 12}C.
Date: July 27, 2011
Creator: Holden, N.E.; Holden, N. & Holden,N.E.
Partner: UNT Libraries Government Documents Department

Cost-based optimizations of power density and target-blanket modularity for {sup 232}Th/{sup 233}U-based ADEP

Description: A cost-based parametric systems model is developed for an Accelerator-Driven Energy Production (ADEP) system based on a {sup 232}Th/{sup 233}U fuel cycle and a molten-salt (LiF/BeF{sub 2}/ThF{sub 3}) fluid-fuel primary system. Simplified neutron-balance, accelerator, reactor-core, chemical-processing, and balance-of-plant models are combined parametrically with a simplified costing model. The main focus of this model is to examine trade offs related to fission power density, reactor-core modularity, {sup 233}U breeding rate, and fission product transmutation capacity.
Date: July 1, 1995
Creator: Krakowski, R.A.
Partner: UNT Libraries Government Documents Department

Results of the radiological survey of the Excelsior Steel Ball Company, Tonawanda, New York (TNY005)

Description: At the request of the US Department of Energy (DOE), a team from Oak Ridge National Laboratory conducted two radiological surveys of property belonging to the Excelsior Steel Ball Company, which is surrounded on three sides by the former site of the Linde Uranium Refinery, Tonawanda, New York. The surveys were performed in September 1997 and February 1998. The purpose of the first survey was to determine if radioactive residuals were present from previous activities at the former Linde site. The Linde Air Products Division of Union Carbide Corporation, Tonawanda, New York, had used radioactive materials at that location for work performed under government contract from 1942 through 1948. The purpose of the second survey was to collect additional biased samples from an area of the site where biased sample results showed slightly elevated levels of thorium-232.
Date: July 1998
Creator: McKenzie, S. P. & Brown, K. S.
Partner: UNT Libraries Government Documents Department

Thorium in occupationally exposed men.

Description: Higher than environmental levels of {sup 232}Th have been found in autopsy samples of lungs and other organs from four former employees of a thorium refinery. Working periods of the subjects ranged from 3 to 24 years, and times from end of work to death ranged from 6 to 31 years. Examination of the distribution of thorium among the organs revealed poor agreement with the distribution calculated from the dosimetric models in Publication 30 of the International Commission on Radioprotection (ICRP). Concentrations in the lungs relative to pulmonary lymph nodes, bone or liver were much higher than calculated from the model for class Y thorium and the exposure histories of the workers. Much better agreement was found with more recently proposed models in Publications 68 and 69 of the ICRP. Radiation doses estimated from the amounts of thorium in the autopsy samples were compatible with health studies that found no significant difference in mortality from that of the general population of men in the US.
Date: February 24, 1999
Creator: Stehney, A. F.
Partner: UNT Libraries Government Documents Department

Treatment methods and comparative risks of thorium removal from waste residues

Description: This study was done to examine the risks of remediation and the effectiveness of removal methods for thorium and its associated radioactive decay products from various soils and wastes associated with DOE`s Formerly Utilized Sites Remedial Action Program (FUSRAP). Removal of {sup 230}Th from uranium process residues would significantly reduce the buildup of {sup 226}Ra (half-life of 1600 years), and since {sup 230}Th concentrations at most of the important sites greatly exceed the {sup 226}Ra concentrations, such removal would reduce the accumulation of additional radiation risks associated with {sup 226}Ra and its products; and, if treatment also removed {sup 226}Ra, these risks could be mitigated even further. Removal of {sup 232}Th from thorium process residues would remove the source material for {sup 228}Ra, and since {sup 228}Ra has a half-life of 5.76 years, its control at FUSRAP sites could be done with land use controls for the 30--50 years required for {sup 228}Ra and the risks associated with its decay products to decay away. It must be recognized, however, that treatment methods invariably require workers to process residues and waste materials usually with bulk handling techniques. These processes expose workers to the radioactivity in the materials, therefore, workers would incur radiological risks in addition to industrial accident risks. An important question is whether the potential reduction of future radiological risks to members of the public justifies the risks that are incurred by remediation workers due to handling materials. This study examines, first, the effectiveness of treatment and then the risks that would be associated with remediation.
Date: July 1, 1997
Creator: Porter, R.D.; Hamby, D.M. & Martin, J.E.
Partner: UNT Libraries Government Documents Department

Experiments on parity violation in the compound nucleus

Description: Results from experiments that measure parity-violating longitudinal asymmetries in the scattering of epithermal neutrons from compound-nuclear resonances at the Manuel Lujan Neutron Scattering Center at Los Alamos are discussed. Parity non-conserving asymmetries have been observed for many p-wave resonances in a single target. Measurements were performed on several nuclei in the mass region of A-100 and A-230. The statistical model of the compound nucleus provides a theoretical basis for extracting mean-squared matrix elements from the experimental asymmetry data, and for interpreting the mean-squared matrix elements. The constraints on the weak meson-exchange couplings calculated from the compound-nucleus asymmetry data agree qualitatively with the results from few-body and light-nuclei experiments. For all nuclei but {sup 232}Th measured asymmetries have random signs. For {sup 232}Th eight of eight measured asymmetries are positive. This phenomenon is discussed in terms or doorway models.
Date: September 1, 1996
Creator: Bowman, J.D.
Partner: UNT Libraries Government Documents Department

Evaluation of possible physical-chemical processes that might lead to separations of actinides in ORNL waste tanks

Description: The concern that there might be some physical-chemical process which would lead to a separation of the poisoning actinides ({sup 232}Th, {sup 238}U) from the fissionable ones ({sup 239}Pu, {sup 235}U) in waste storage tanks at Oak Ridge National Laboratory has led to a paper study of potential separations processes involving these elements. At the relatively high pH values (>8), the actinides are normally present as precipitated hydroxides. Mechanisms that might then selectively dissolve and reprecipitate the actinides through thermal processes or additions of reagents were addressed. Although redox reactions, pH changes, and complexation reactions were all considered, only the last type was regarded as having any significant probability. Furthermore, only carbonate accumulation, through continual unmonitored air sparging of the tank contents, could credibly account for gross transport and separation of the actinide components. From the large amount of equilibrium data in the literature, concentration differences in Th, U, and Pu due to carbonate complexation as a function of pH have been presented to demonstrate this phenomenon. While the carbonate effect does represent a potential separations process, control of long-term air sparging and solution pH, accompanied by routine determinations of soluble carbonate concentration, should ensure that this separations process does not occur.
Date: September 1, 1997
Creator: Del Cul, G.D.; Toth, L.M.; Bond, W.D. & Dai, S.
Partner: UNT Libraries Government Documents Department

The positron peak puzzle - recent results from APEX

Description: Results are presented from a new experiment, APEX, designed to study the previously reported sharp lines in sum-energy spectra of positrons and electrons produced in collisions of very heavy ions. Data have been collected for {sup 238}U+{sup 181}Ta and {sup 238}U+{sup 232}Th. No evidence is found for narrow structures similar to those previously reported. For the specific case of the isolated decay of a neutral particle of mass 1.4-2.1 MeV/c{sup 2}, the upper limits on cross sections obtained are significantly less than previously reported. Data are also presented for internal pair conversion in {sup 206}Pb. These results are used to set limits for the possible contribution to the pair yield of a 1780 keV transition in {sup 238}U observed in heavy-ion gamma-ray coincidence measurements.
Date: December 31, 1995
Creator: Ahmad, I.; Back, B.B. & Kutschera, W.
Partner: UNT Libraries Government Documents Department

A new look at positron production from heavy-ion collisions: Results from apex

Description: A new solenoidal spectrometer, designed to study the production mechanism of electrons and positrons in heavy-ion collisions, has been constructed at Argonne National Laboratory. The spectrometer has been used to study the {sup 238}U + {sup 181}Ta system at 5.95, 6.10, and 6.30 MeV/u and the {sup 238}U + {sup 232}Th system at 5.95 MeV/u. These bombarding energies cover the energy region where previous experiments have reported sharp sum-energy lines. No evidence is found for sharp peaks in the present data. For the specific case of the isolated decay of a neutral particle of mass 1.4--2.1 MeV/c{sup 2} the upper limits on cross sections obtained from the present data are significantly less than the previously reported cross sections.
Date: December 31, 1995
Creator: Ahmad, I.; Back, B.B. & Austin, S.M.
Partner: UNT Libraries Government Documents Department


Description: This paper discusses some of the unique regulatory conditions and operational challenges facing a team performing a thorium-232 cleanup in a commercially active environment, as well as the implemented and proposed solutions that can be applied to other programs, particularly those operating in an OSHA-regulated environment.
Date: February 27, 2003
Creator: Winters, Michael S. & Hays, David C. Jr.
Partner: UNT Libraries Government Documents Department


Description: A direct numerical integration of the integral equation for the average collision density in the absorber was previously suggested in a discussion of resonance absorption. The implementation of this program is considered. The method of calculation, comparison with experimental data, and the computer code developed are described. The method of integration, computation of cross sections, selection of mesh size, integration interval, outside correction, the Dancoff correction, and unresolved resonances are discussed. Resonance integrals for U/sup 235/ and Th2/sup >/s3>s/sup 2/ were calculated and compared with experiment. (M.C.G.)
Date: August 28, 1961
Creator: Nordheim, L.W.
Partner: UNT Libraries Government Documents Department


Description: A preliminary study was made of the nuclear stability of reactors in which particles containing U/sup 233/ and Th/sup 232/ are fluidized by liquid water. D/sub 2/O moderated reactors were found to be least sensitive to changes in bed height at thorium concentrations in the range 80 to 120 g/liter, H/sub 2/O reactors in the rarnge 1500 io 2400 g Th/ liter, and mixed H/sub 2/O-D/sub 2/O reactors at thorium concentrations between those for pure moderators. A reactor operated at the thorium concentration at which it is least sensitive to change in bed height was found to be stable in response to a cyclical variation in height. (auth)
Date: January 12, 1959
Creator: Benumof, R. & Rosenthal, M.W.
Partner: UNT Libraries Government Documents Department