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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 The Atomic Mass Data Center has released an unpublished version of the present status of the atomic mass values as a private communication. We can not update the Standard Atomic Weight Table at this time based on these unpublished values but we can anticipate how many changes are probably going to be expected in the next few years on the basis of the forthcoming publication of the Atomic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


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


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

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


Description: Measurements of thorium resonance-capture activations relative to those of Au/sup 197/, which were made in the Peach Bottom (HTGR) critical assembly, are analyzed and compared with thorium resonance activations calculated from tabulated values of the resonance parameters. The new vanadium-subtraction method that was applied is shown to measure thorium resonance captures relative to those of Au/sup 197/ to within several per cent in this geometry. The measurements show that the lowest several resonances of thorium capture less strongly than would be predicted by the listed parameters. This reduced capture is such that the thin-limit, epicadmium 1/E-spectrum resonance integral is about 84 b instead of the 96 b predicted by listed parameters; the thorium resonance captures for the critical assembly are about 6% less. The approximations currently used in calculating resonance captures in annular lattices probably underestimate captures by several per cent. The 300 deg K resonance-capture rate of ThO/sub 2/ in the annulus is indicated to be several per cent larger than that of metallic thorium, presumably because of a solid-state effect. 46 references. (auth)
Date: September 14, 1962
Creator: Sampson, J.B.
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

The Determination Thorium Isotopic Ratios by Radiochemical Methods

Description: >A sensitive analytical method was needed to determine the total thorium content and the Th/sup 2//sup 3//sup 0/ isotopic abundance in a number of uranium ore and mill talling samples available in the United States. A procedure was developed using absolute alpha counting to determine Th/sup 2//sup 3//sup 0/ and neutron activation analysis to determine Th/sup 2//sup 3//sup 2/. The method is highly specific with a sensitivity on the order of 10/sup -//sup 1//sup 0/ grams for either isotope and was found to give reliable data for the various sample types of interest. (auth)
Date: January 1, 1960
Creator: Matsumoto, W. Y.
Partner: UNT Libraries Government Documents Department