532 Matching Results

Search Results

Advanced search parameters have been applied.

Workshop on dating old ground water

Description: A workshop on methods which might be used to date very old ground water was held on March 16--18, 1978, in Tucson, Arizona. The workshop was sponsored by the Office of Waste Isolation of Union Carbide Corporation as part of studies supported by the United States Department of Energy which are designed to evaluate the safety of proposed subsurface repositories for nuclear waste. The workshop was convened by the College of Earth Sciences of the University of Arizona with the cooperation of other university departments, particularly the Department of Physics. The dating of ground water in the vicinity of nuclear repositories is a critical aspect of the safety evaluation of these repositories. The age of the water gives an indication of past rates of water movement which in turn will help evaluate the likelihood of future migration of radionuclides from a given repository. Despite this rather obvious practical application, most of the workshop time was devoted to difficult technical questions related to the actual dating of the water.
Date: January 1, 1978
Partner: UNT Libraries Government Documents Department

Analysis of low energy beta-emitters

Description: A survey was made of the instruments used for the determination of low energy beta radioactivity. Techniques commonly used are gas flow proportional counting, liquid scintillation counting, solid scintillation counting, and internal ionization chamber counting, solid state detector counting, and radiochemical separation followed by counting using one of the preceeding techniques. The first four techniques were examined and compared with each other. The sensitivities of the techniques were compared on the basis of the detection limits quoted for instruments described in the technical and reviewed literature. The detection limits were then related to the occupational and public individual maximum levels for air and water. Attention is focused primarily on the continuous monitoring of air for /sup 3/H and /sup 85/Kr, a medium energy ..beta..-emitter. It is clear that several continuous air monitoring instruments are readily available for measuring low energy ..beta.. concentrations, even in presence of certain other activity, at occupational levels. However, these instruments do not typically have sensitivities comparable to the public individual levels. Moreover, their capabilities for giving results in real time and for differentiating among the radionuclides actually present is limited.
Date: October 1, 1979
Creator: Murphy, D.L.
Partner: UNT Libraries Government Documents Department

Giant resonances excited by heavy-ions

Description: The potential of heavy-ion inelastic scattering as a method for studying giant resonance spectroscopy is investigated and compared to results obtained with the (..cap alpha..,..cap alpha..') reaction. Optical model calculations reveal a strong dependence of the excitation cross sections upon bombarding energy. Differences between the backgrounds encountered in light and heavy hadron scattering experiments are discussed. 35 references.
Date: January 1, 1979
Creator: Sandorfi, A.M.
Partner: UNT Libraries Government Documents Department

ENDF/B-V neutron cross section evaluation for the krypton isotopes. [10/sup -5/ eV to 20 MeV]

Description: The evaluation of the neutron cross-section data for the six stable isotopes of Kr from 10/sup -5/ eV to 20 MeV is described. These evaluations incorporate all the new data on these isotopes, including those on the resonance parameters, level schemes of the various isotopes and residual nuclei, and reaction data. Evaluation procedures adopted to assess experimental data and the nuclear model calculations used are described. 67 figures, 6 tables.
Date: January 1, 1979
Creator: Prince, A.
Partner: UNT Libraries Government Documents Department

Hydrogen absorption in the niobium--vanadium system

Description: The effect of dilute vanadium additions to niobium on hydrogen absorption has been studied by measuring equilibrium pressure--composition--temperature data for a Nb + 6 at.% V alloy and by constructing a theoretical model of the effect of hydrogen trapping on phase equilibria in such systems. The results indicate the H--V binding energy is substantially smaller than thought previously. A depression of the ..cap alpha..--..cap alpha..' critical temperature is observed which, if interpreted in terms of trapping, leads to a H--V binding energy of approx. 0.04 eV.
Date: January 1, 1979
Creator: Pick, M A & Welch, D O
Partner: UNT Libraries Government Documents Department

Hyper fuse: a novel inertial confinement system utilizing hypervelocity projectiles for fusion energy production and fission waste transmutation

Description: Parametric system studies of an inertial confinement fusion (ICF) reactor system to transmute fission products from an LWR economy have been carried out. The ICF reactors would produce net power in addition to transmuting fission products. The particular ICF concept examined is an impact fusion approach termed HYPERFUSE, in which hypervelocity pellets, traveling on the order of 100 to 300 km/sec, collide with a target in a reactor chamber and initiate a thermonuclear reaction. The DT fusion fuel is contained in a shell of the material to be transmuted, e.g., /sup 137/Cs or /sup 90/Sr. The 14 MeV fusion neutrons released during the pellet burn cause transmutation reactions (e.g., (n, 2n), (n, ..cap alpha..), etc.) that convert the long lived fission products (FP's) either to stable products or to species that decay with a short half-life to a stable product.
Date: January 1, 1979
Creator: Makowitz, H; Powell, J R & Wiswall, R
Partner: UNT Libraries Government Documents Department

Organic radiopharmaceuticals: recent advances

Description: Organic radiopharmaceuticals are considered in light of accelerator and nuclide production requirements, special problems relating to the carrier-free state, including terminology, of the special technology required to prepare and manipulate these compounds and new trends in compound design and synthesis. The emphasis is on medical cyclotrons and the positron-emitting radionuclides, carbon-11, nitrogen-13, oxygen-15, and fluorine-18. New routes to synthetic precursors and organic compounds of high specific activity labeled with carbon-11, fluorine-18, and iodine-123 including monosaccharides, aromatic amines, neuroleptics, fatty acids, steroids, and other classes of compounds are discussed. Some compounds are considered in terms of the development and evaluation of structure-activity relationships and including some newer concepts such as metabolic trapping. 67 references.
Date: January 1, 1979
Creator: Wolf, A.P. & Fowler, J.S.
Partner: UNT Libraries Government Documents Department

Subcellular site and nature of intracellular cadmium in plants

Description: The mechanisms underlying heavy metal accumulation, toxicity and tolerance in higher plants are poorly understood. Since subcellular processes are undoubtedly involved in all these phenomena, it is of interest to study the extent of, subcellular site of and nature of intracellularly accumulated cadmium in higher plants. Whole plants supplied /sup 109/CdCl/sub 2/ or /sup 112/CdSO/sub 4/ accumulated Cd into roots and aerial tissues. Preparation of protoplasts from aerial tissue followed by subcellular fractionation of the protoplasts to obtain intact vacuoles, chloroplasts and cytosol revealed the presence of Cd in the cytosol but not in vacuoles or chloroplasts. Particulate materials containing other cell components were also labeled. Of the /sup 109/Cd supplied to plants, 2 to 10% was recovered in both cytosol preparations and in particulate materials. Cytosol contained proteinaceous--Cd complexes, free metal and low molecular weight Cd complexes. Labeling of protoplasts gave similar results. No evidence was obtained for the production of volatile Cd complexes in tobacco.
Date: January 1, 1979
Creator: Wagner, G.J.
Partner: UNT Libraries Government Documents Department

Status of radiative widths, neutron strength functions and improved evaluation using the Lane-Lynn theory

Description: The s- and p-wave neutron strength functions and average radiative widths of fission product nuclides are reviewed. The direct capture mechanism of Land and Lynn is quantitatively varified for the two reactions /sup 42/Ca(n,..gamma..) /sup 43/Ca and /sup 136/Xe(n,..gamma..) /sup 137/Xe. Thermal capture cross sections of /sup 132/Te and /sup 126/Sn are estimated with the aid of the Lane-Lynn theory. 7 figures, 1 table.
Date: January 1, 1979
Creator: Mughabghab, S.
Partner: UNT Libraries Government Documents Department

Shell-model origins of collective effects in light- and medium-weight nuclei. [Preliminary results]

Description: Two independent investigations are discussed illustrating possible interesting collective features in some f-p shell nuclei which are generated from the motion of valence nuclei and that the structure of the states in question is consistent with interacting boson model theory. Also further studies of shell-model wave functions in the s-d and light f-p shell nuclei are discussed which also offer some support to the studied model. It is emphasized that these results are preliminary. Nine references. (JFP)
Date: January 1, 1977
Creator: McGrory, J.B.
Partner: UNT Libraries Government Documents Department

(n,p) reaction at 60 MeV on ND-2 targets. [M1 strength, angular distribution, transitions, giant resonance, cross sections]

Description: Various results are presented on energy levels of the isobaric analog resonances produced in the (n,p) reaction on /sup 7/Li, /sup 9/Be, /sup 27/Al, /sup 58/ /sup 60/ /sup 62/ /sup 64/Ni, /sup 90/Zr, and /sup 209/Bi targets. The emphasis is on qualitative features of the data through a comparison with existing results from other nuclear probes as well as observed properties of the isovector transitions anticipated from known isospin selection rules. 21 references. (JFP)
Date: January 1, 1979
Creator: King, N.S.P. & Ullmann, J.L.
Partner: UNT Libraries Government Documents Department

Fast neutron total and scattering cross sections of chromium, iron and /sup 60/Ni. [50 to 100 keV]

Description: Neutron total cross sections are measured with broad resolutions (50 to 100 keV) from approx. = 1.0 to 4.5 MeV at intervals of less than or equal to 50 keV and to accuracies of approx. = 1%. Differential elastic scattering cross sections are measured at greater than or equal to 10 scattering angles distributed between 20 and 160/sup 0/ from approx. = 1.5 to 4.0 MeV at intervals of less than or equal to 50 keV. Angle-integrated elastic scattering cross sections are deduced from the measured values to accuracies of greater than or equal to 5%. Inelastically scattered neutrons are observed up to incident neutron energies of 4.0 MeV at scattering angles distributed between 20 and 160/sup 0/. Cross sections are determined corresponding to the excitation of observed states at: Chromium - 1433, 2377, 2665, 2778, and 2970 keV; Iron - 853, 1389, 2097, 2579, 2677, 2974, and 3152 keV; and /sup 60/Ni - 1342, 2168, 2304, 2509, 2636, and 3164 keV. The experimental results are discussed in terms of conventional optical-statistical models and in the context of direct-scattering processes. The experimental and calculational results are compared with the corresponding evaluated quantities given in the ENDF/B file. 21 references.
Date: January 1, 1979
Creator: Smith, A B; Guenther, P T & Whalen, J F
Partner: UNT Libraries Government Documents Department

In-situ verification techniques for fast critical assembly cores

Description: Active and passive autoradiographic techniques were used to obtain piece counts of fuel plates in fast critical assembly drawers and to verify the assembly loading pattern. Active autoradiography using prompt-fission and fission-product radiation was more successful with uranium fuel while passive autoradiography was more successful with plutonium fuel. A source multiplication technique was used to measure changes in reactivity when small quantities (2-2.5 kg) of fissile material were removed from a subcritical reference core of the Zero Power Plutonium Reactor. Efforts to compensate for unsuccessful. Some compensation was achieved by replacing U-238 with polyethylene. The sensitivity for detection of partially compensated fuel removed from minimum worth regions was approximately 2.5 kg (fissile) for a core containing 2600 kg (fissile). Substitution of polyethylene was detected with a spectral index which was the ratio of the rate of the In-115 (n,..gamma..) reaction to the rate of the In-115 (n,n') reaction. This spectral index was sensitive to the presence of an 0.64-cm-thick, 5.08-cm-high polyethylene column 10-15 cm away from the indium foil. The reactivity worth of Pu-239 was also obtained as a function of location in the reactor core with the use of an inverse kinetics technique. Reactivity worths for Pu-239 varied from a maximum of 58.67 Ih/kg near the core center to a minimum of 14.86 Ih/kg at the core edge.
Date: January 1, 1979
Creator: Brumbach, S.B.; Amundson, P.I. & Roche, C.T.
Partner: UNT Libraries Government Documents Department

Grain-boundary diffusion: structural effects, models and mechanisms

Description: Grain boundary diffusion phenomena were considered including: anisotropy, effect of orientation, crystallographic transformation, boundary type, dislocation dissociation, pressure, and isotope effects. Diffusivity is different for various boundaries. Dissociated dislocations and stacking faults are not efficient paths for grain boundary diffusion. Results suggest a vacancy mechanism along the dislocation core, and involves atomic jumps away from the back towards the dislocation as well as jumps along the core. Measurements were made on nickel and silver. (FS)
Date: January 1, 1979
Creator: Peterson, N L
Partner: UNT Libraries Government Documents Department

Level densities in nuclear physics

Description: In the independent-particle model nucleons move independently in a central potential. There is a well-defined set of single- particle orbitals, each nucleon occupies one of these orbitals subject to Fermi statistics, and the total energy of the nucleus is equal to the sum of the energies of the individual nucleons. The basic question is the range of validity of this Fermi gas description and, in particular, the roles of the residual interactions and collective modes. A detailed examination of experimental level densities in light-mass system is given to provide some insight into these questions. Level densities over the first 10 MeV or so in excitation energy as deduced from neutron and proton resonances data and from spectra of low-lying bound levels are discussed. To exhibit some of the salient features of these data comparisons to independent-particle (shell) model calculations are presented. Shell structure is predicted to manifest itself through discontinuities in the single-particle level density at the Fermi energy and through variatons in the occupancy of the valence orbitals. These predictions are examined through combinatorial calculations performed with the Grover (Phys. Rev., 157, 832(1967), 185 1303(1969)) odometer method. Before the discussion of the experimenta results, statistical mechanical level densities for spherical nuclei are reviewed. After consideration of deformed nuclei, the conclusions resulting from this work are drawn. 7 figures, 3 tables. (RWR)
Date: January 1, 1978
Creator: Beckerman, M
Partner: UNT Libraries Government Documents Department

Environmental monitoring at Argonne National Laboratory. Annual report for 1978

Description: The results of the environmental monitoring program at Argonne National Laboratory for 1978 are presented and discussed. To evaluate the effect of Argonne operations on the environment, measurements were made for a variety of radionuclides in air, surface water, Argonne effluent water, soil, grass, bottom sediment, and foodstuffs; for a variety of chemical constituents in air, surface water, and Argonne effluent water; and of the environmental penetrating radiation dose. Sample collections and measurements were made at the site boundary and off the Argonne site for comparison purposes. Some on-site measurements wee made to aid in the interpretation of the boundary and off-site data. The results of the program are interpreted in terms of the sources and origin of the radioactive and chemical substances (natural, fallout, Argonne, and other) and are compared with applicable environmental quality standards. The potential radiation dose to off-site population groups is also estimated.
Date: March 1, 1979
Creator: Golchert, N W; Duffy, T L & Sedlet, J
Partner: UNT Libraries Government Documents Department

Spontaneous unscheduled DNA synthesis in human lymphocytes

Description: The rate of spontaneous unscheduled DNA synthesis in human lymphocytes was estimated from measurements of tritiated thymidine incorporation into double-stranded DNA (ds-DNA) during incubation of cells in vitro. The contribution of scheduled DNA synthesis to the observed incorporation was reduced by inhibiting replication with hydroxyurea and by separating freshly replicated single-stranded DNA (ss-DNA) from repaired ds-DNA by column chromatography. The residual contribution of scheduled DNA synthesis was estimated by observing effects on thymidine incorporation of: (a) increasing the rate of production of apurinic sites, and alternatively, (b) increasing the number of cells in S-phase. Corrections based on estimates of endogenous pool size were also made. The rate of spontaneous unscheduled DNA synthesis is estimated to be 490 +- 120 thymidine molecules incorporated per cell per hour. These results compare favorably with estimates made from rates of depurination and depyrimidination of DNA, measured in molecular systems if we assume thymidine is incorporated by a short patch mechanism which incorporates an average of four bases per lesion.
Date: January 1, 1979
Creator: Forell, B.; Myers, L.S. Jr. & Norman, A.
Partner: UNT Libraries Government Documents Department

Theoretical analysis and preliminary experiments on the feasibility of removing CO/sub 2/ containing /sup 14/C selectively with a Ca(OH)/sub 2/ slurry from a /sup 85/Kr-contaminated HTGR reprocessing plant off-gas stream

Description: Exploratory experiments were conducted to find methods of removing /sup 14/C-contaminated CO/sub 2/ with a Ca(OH)/sub 2/ slurry from off-gas streams without removal of /sup 85/Kr. Purging the product CaCO/sub 3/ slurry, created by reacting CO/sub 2/ and Ca(OH)/sub 2/, with a small amount of gas appears effective in the removal of any residual krypton from the CaCO/sub 3/. It therefore appears feasible to remove /sup 14/C-contaminated CO/sub 2/ before removal of /sup 85/Kr from HTGR off-gas streams and hence reduce the volume flow rate to the /sup 85/Kr removal equipment with significant cost savings.
Date: October 1, 1977
Creator: Forsberg, C. W.
Partner: UNT Libraries Government Documents Department

Splenic sequestration of Tc-99m labeled heat treated red blood cells. [Feasibility of use for spleen imaging]

Description: The rate of blood clearance and spleen uptake as well as the total spleen uptake of heat damaged red blood cells labeled with Tc-99m was determined in eight patients, six of whom had chronic lymphatic leukemia, one had polycythemia vera and one had eosinophilia of unknown origin. Spleen uptake at 2 hrs was 72.0 +- 18.5%. Approximately 82.6% of the initial radioactivity was cleared from the blood by 2 hrs with a rapid T 1/2 component of 6.3 +- 4.7 min. The T 1/2 of splenic uptake was 8.3 +- 4.6 min with a plateauing of splenic radioactivity by 30 min. The preliminary results indicate that the method of preparation is reliable but the usefulness of the method for evaluating spleen function remains to be determined.
Date: January 1, 1979
Creator: Atkins, H L; Goldman, A G; Fairchild, R G; Oster, Z H; Som, P; Richards, P et al.
Partner: UNT Libraries Government Documents Department

Physiopathology of blood platelets and development of platelets substitutes. Progress report, August 1, 1976--October 31, 1977. [/sup 51/Cr]

Description: Progress is reported on the following research projects: the effect of estrogen on platelet aggregability and thrombus formation; the antithrombotic effect of platelet inhibiting agents in a bench model of artificial kidney; the arrest of hemorrhage in severely alloimmunized thrombocytopenic patients; and in vivo elution of /sup 51/Cr from labeled platelets induced by antibody. (HLW)
Date: July 31, 1977
Creator: Baldini, M G
Partner: UNT Libraries Government Documents Department

Evaluation of an in-situ x-ray fluorescence analyzer for inorganic pollutants in sediments and water columns

Description: The applicability of an energy dispersive x-ray fluorescence spectrometer for measurement of trace elements in sediments and in water columns from Coast Guard vessels has been investigated. This investigation was conducted in both freshwater and saltwater areas and included Puget Sound, Lake Washington, Lake Union, and the ship canal in the State of Washington. The spectrometer system consisted of a solid cryogen-cooled Si(Li) detector and a /sup 109/Cd excitation source. Sediments and water columns were viewed through a 0.2 mm Be window. This study showed the feasibility of measuring trace elements at concentrations ranging from 20 to about 100 ppM. Measurements of this sensitivity with a 100 mCi /sup 109/Cd source are possible for time intervals as short as 5 minutes. This in-situ measurement capability permits the on-site mapping of pollution and avoids the problem of sediment disturbance which is inherent in the collection of grab samples of the sediment surface. Recommendations for an improved analyzer system included a detector assembly which could be towed, or allow continuous sediment surface analysis thereby recording the average composition of a large area.
Date: September 1, 1979
Creator: Wogman, N.A.
Partner: UNT Libraries Government Documents Department

Sediment and radionuclide transport in rivers. Phase I: field sampling program during mean flow Cattaraugus and Buttermilk Creeks, New York

Description: A field sampling program was conducted on Cattaraugus and Buttermilk Creeks, New York during November and December 1977 to investigate the transport of radionuclides in surface waters as part of a continuing program to provide data for application and verification of Pacific Northwest Laboratory's (PNL) sediment and radionuclide transport model, SERATRA. Suspended sediment, bed sediment, and water samples were collected during mean flow conditions over a 45 mile reach of stream channel. Radiological analysis of these samples included primarily gamma ray emitters; however, some plutonium, strontium, curium, and tritium analyses were also included. The principal gamma emitter found during the sampling program was /sup 137/Cs where, in some cases, levels associated with the sand and clay size fractions of bed sediment exceeded 100 pCi/g. Elevated levels of /sup 137/Cs and /sup 90/Sr were found downstream of the Nuclear Fuel Services Center, an inactive plutonium reprocessing plant and low level nuclear waste disposal site. Based on radionuclide levels in upstream control stations, /sup 137/Cs was the only radionuclide whose levels in the creeks downstream of the site could confidently be attributed to the site during this sampling program. This field sampling effort is the first of a three phase program to collect data during low, medium and high flow conditions.
Date: August 1, 1979
Creator: Ecker, R.M. & Onishi, Y.
Partner: UNT Libraries Government Documents Department

Environmental status of the Hanford site for CY 1978

Description: Continued compliance of Hanford operations with all applicable state and federal environmental regulations, with the exception of suspended particulates from several steam power plants, was demonstrated by the environmental and effluent data collected during 1978. Included in the environmental data collected were measurements of external radiation, and radionuclide analyses of air samples, Columbia River water, other surface waters, wildlife, soil, and vegetation. Periodically all roadways, railways, and active as well as retired waste disposal sites were surveyed to detect any abnormal levels of radioactivity.
Date: August 1, 1979
Creator: Houston, J.R. & Blumer, P.J.
Partner: UNT Libraries Government Documents Department

Quarterly report on the strontium heat source development program, Advanced Nuclear Systems and Projects Division for April-June 1979.

Description: Metallographic examination of the 20,000-hr /sup 90/SrF/sub 2/ compatibility test specimens has been completed. Evaluation of the photomicrographs obtained is now under way. The 30,000-hr compatibility tests with nonradioactive SrF/sub 2/ have also been completed, and metallographic examination of the test specimens is now under way. Experimentally determined collapse pressures for the AISI-1018 steel stand-in outer capsules did not agree with theoretical values predicted by various models. Additional mechanical properties measurements on the capsule material have shown that the differences between the experimental collapse values and the theoretical predictions cannot be reconciled by a refinement in the mechanical property data. Additional drop tests with the AISI-1018 steel stand-in capsules have shown that the capsule material must have a minimum impact energy of greater than 5 ft-lb but less than 30 ft-lb to meet the drop test requirement.
Date: July 1, 1979
Creator: Fullam, H.T.
Partner: UNT Libraries Government Documents Department