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Reaction studies of hot silicon and germanium radicals. Progress report, September 1, 1981-September 30, 1982

Description: Progress in two areas important to attaining the goals of this research program are briefly reviewed: (a) characterization of the major product-forming intermediate in the reactions of recoiling silicon atoms; (b) time-resolved laser flash spectroscopic studies of the generation and reactions of silicon radicals. 1 figure.
Date: September 30, 1982
Creator: Gaspar, P. P.
Partner: UNT Libraries Government Documents Department

Alumina column Rb-82 generator

Description: The use of an alumina column for the adsorption of radioactive Sr for the generator production of 75-sec /sup 82/Rb was evaluated in both batches and column experiments using /sup 85/Sr and cyclotron-produced /sup 82/Sr. Comparisons of alumina, Bio-Rex 70 and Chelex 100 ion exchangers were made to determine Sr adsorption, /sup 82/Rb elution yield and Sr breakthrough. The adsorption of Sr is similar for alumina and Chelex 100 but different for Bio-Rex 70. Alumina and Chelex 100 exhibit a small fraction of poorly bound Sr which appears as higher breakthrough in the early elution volumes. The remaining Sr activity is strongly bound to these ion exchangers and the breakthrough remains stable at a lower breakthrough value through a large number of elutions. Bio-Rex 70 on the other hand does not exhibit the poorly bound Sr fraction and the breakthrough of Sr remains the lowest of the three ion exchangers through a moderate number of elutions and then the Sr breakthrough gradually increases with each additional elution.
Date: October 1, 1977
Creator: Yano, Y. & Roth, E.P.
Partner: UNT Libraries Government Documents Department

Validation of the atmospheric transport model: comparison of observed krypton-85 concentrations with those computed using a Gaussian plume model

Description: Thirty monthly average /sup 85/Kr concentrations measured at 13 sampling locations between 25 and 150 km from a quasi-continuous point source were used in a validation study of the Atmospheric Transport Model for Toxic Substances (ATM-TOX). Although the computed values tended to overestimate, more than 60% of them fell within a factor of 2 of the observed concentrations.
Date: January 1, 1982
Creator: Raridon, R.J. & Murphy, B.D.
Partner: UNT Libraries Government Documents Department

Iodine-123 generator/iodination kit: a preliminary report

Description: Preliminary results are described of a xenon-123 filled device to serve as a combination iodine-123 generator/iodination kit. Xenon-123 is produced in the Brookhaven Linac Isotope Producer (BLIP) by the reaction /sup 127/I(p, 5n)/sup 123/Xe. The device consists of a small glass ampoule containing an internal glass breakseal and a flanged neck on which is crimped a multi-injection type septum. The ampoule contains a hydrogen sulfide atmosphere to assure that the iodine generated from the decay of the xenon is in the form of iodide. Following an adequate period for xenon-123 to decay (this period can be used for shipment), a needle is forced through the septum breaking the seal and residual gases are pumped off. The iodine-123 in the form of iodide can then be rinsed from the ampoule with any desired solvent or reagent added directly to the device to carry out an iodination in an enclosed environment. Preliminary results of both iodine recovery and iodinations have been promising.
Date: January 1, 1980
Creator: Richards, P; Prach, T; Srivastava, S C & Meinken, G E
Partner: UNT Libraries Government Documents Department

Design of a /sup 18/F production system at ORNL 86-inch cyclotron

Description: A target system for the production of /sup 18/F by proton bombardment of H/sub 2//sup 18/O was designed for the ORNL 86-inch cyclotron facility. The system consists of concentric titanium and aluminum cylinders. Oxygen-18-enriched H/sub 2/O circulates through the inner titanium cylinder and through an external heat exchanger with cooling water flowing in the annulus. Yields of 5.0 curies are expected for a 250-..mu..A proton beam current and 24-min irradiation time.
Date: October 19, 1977
Creator: Shaeffer, M.C.; Barreto, F.; Datesh, J.R. & Goldstein, B.R.
Partner: UNT Libraries Government Documents Department

Development of chemical isolation and concentration techniques for Tc-99 analysis by resin-bead mass spectrometry

Description: A novel, highly sensitive, isotope-dilution analytical technique for the determination of technetium-99 has been developed around single ion-exchange bead mass spectrometry. Mass spectrometry is much more sensitive than direct counting for the low-energy, low-specific activity, Tc-99 isotope. Further, the point source provided by a single ion-exchange bead leads to a greater signal-to-noise ratio in the mass spectrometric measurement than does conventional application of a solution to the source filament. Recent results indicate a sensitivity greater than 0.1 picogram. Isolation of technetium from the samples occurs after addition of Tc-97 as a yield tracer. A combination of ion-exchange chromatography and ion-association solvent extraction provides decontamination from the potential interferences, Mo-97 and Ru-99. Subsequently, the technetium is loaded onto a pair of anion-exchange beads (diameter approx. 0.3 mm). The noncritical isolation and bead-loading scheme typically concentrates the technetium in the sample by a factor of about a million with overall recoveries exceeding 50%. A variety of environmental samples from the Savannah River Plant (SRP) has been analyzed by this method.
Date: January 1, 1979
Creator: Anderson, T.J.
Partner: UNT Libraries Government Documents Department

Kinetics of stimulated Moessbauer emission in neutron-pumped krypton-83

Description: Using an idealized kinetic model for a gamma-ray laser system pumped by a spatially uniform delta-function burst of fast neutrons, a computer study has been made of the growth, decay, and attenuation of resonant 9.3-keV recoil-less gamma radiation from /sup 83/Kr, as a function of neutron-burst intensity, gamma-ray linebreadth, temperature, dilution of krypton in a beryllium host, and nonresonant absorption coefficient of the host. The isomer is formed by neutron capture in a 40-eV resonance, and the 144-ns transition lifetime is short in comparison with the time for neutrons to moderate. The kinetic behavior of this system is therefore determined largely by the time dependence of the neutron spectrum and only slightly by the reciprocal linebreadth of the graser transition. Because the lower state is stable, inversion is rapidly lost, so that, for observable gain, an unrealistically high source intensity is needed. Use of a beryllium host, which increases the Debye temperature, is negated by its parasitic absorption. Although this transition is unsuitable for a graser, these findings help to illustrate useful properties of nuclear isomers and solid hosts for which stimulated emission might be observable.
Date: November 1, 1977
Creator: Baldwin, G.C. & McNeil, L.E.
Partner: UNT Libraries Government Documents Department

/sup 123/I research and production at Brookhaven

Description: The procedures for preparing high purity /sup 123/I at the BLIP using the /sup 127/I(p,5n)/sup 123/Xe reaction on an NaI target are described. The activity is supplied in a glass ampoule with anhydrous /sup 123/I deposited on the interior walls, allowing maximum flexibility in subsequent iodinations. Preliminary experience with a continuous flow target is also described. The results of a series of measurements of specific activity by neutron activation, x-ray fluorescence, uv absorption, and wet chemistry generally showed no detectable carrier. HPLC methods to analyse the chemical form of radioiodine and to characterize various iodinated radiopharmaceuticals have been developed. These methods provide higher sensitivity, speed and resolution than commonly used techniques. 19 refs., 6 figs., 2 tabs.
Date: January 1, 1985
Creator: Mausner, L.F.; Srivastava, S.C.; Mirzadeh, S.; Meinken, G.E. & Prach, T.
Partner: UNT Libraries Government Documents Department

Strategy analysis for krypton-85 waste management

Description: Krypton-85 is a chemically inert, radioactive gas produced by fission of uranium or plutonium isotopes. Depending on the fuel cycle, krypton-85 production in nuclear reactors may range from approx. 200 to approx. 600 kCi/GW/sub e/-year. However, the EPA has published a standard restricting krypton-85 release to 50 kCi/GW/sub e/-year for fuel irradiated after January 1, 1983. To conform with the federal standard, recovery and storage of krypton-85 will be required in some nuclear fuel cycle processes. The long-term waste management of krypton-85 poses unique judgemental problems. Release, recovery, immobilization, and storage (individually, and in combinations), involve a wide range of environmental, economic, and social commitments. The choice of applicable technologies, if such technologies are to be used at all, imposes another set of boundary conditions. This strategy analysis describes the use of a general framework for decision-making in evaluating krypton-85 waste management systems. Such a framework can be further used to provide technical assessment and dose-probability calculations for individual technologies, and to show the interactions among technological options required for the overall waste management scheme.
Date: January 1, 1979
Creator: Knecht, D.A. & Brown, R.A.
Partner: UNT Libraries Government Documents Department

/sup 189/Os and the U(6/12) symmetry scheme

Description: This contribution will consider the extension of the U(6/12) symmetry scheme to the region intermediate between the 0(6) and SU(3) limits and will compare the predicted level structure with that determined empirically for /sup 189/Os.
Date: January 1, 1986
Creator: Bruce, A.M.; Warner, D.D.; Campbell, M.J. & Gelletly, W.
Partner: UNT Libraries Government Documents Department

Near source tracers at Hanford. [Krypton-85]

Description: Atmospheric tracer techniques are reviewed, with emphasis on the Hanford inert gas krypton-85 field technique. This technique is considerably more sophisticated than the visible and particulate tracer techniques. The krypton technique develops histories of concentration at up to 128 field locations; the particulate techniques generate only bulk time integrated samples. The krypton dispersal technique permits release of either a plume or a true puff; the particulate techniques permit continuous releases, but only approximations of puffs through short continuous releases. The Hanford krypton-85 inert gas system offers the advantages of an inert gas tracer, permits release of either puffs or plumes, and presents histories of concentration as opposed to only time-integrated concentrations. However, the approach used has the disadvantages of being usable at only short distances, is a relatively expensive system to deploy and maintain, and is restricted as to locations where it may be used due to the radioactive nature of the tracer.
Date: May 1, 1979
Creator: Nickola, P. W.
Partner: UNT Libraries Government Documents Department

Mapping of functional activity in brain with /sup 18/F-fluoro-deoxyglucose

Description: A model has been designed based on the assumptions of a steady state for glucose consumption, a first-order equilibration of the free /sup 14/C-DG pool in the tissue with the plasma level, and relative rates of phosphorylation of /sup 14/C-DG and glucose determined by their kinetic constants for hexokinase reaction. Using an operational equation based on this model, the metabolic rates of glucose are calculated in various regions of brain (utilizing brain slices and autoradiography). /sup 14/C is a beta emitter and therefore not suitable for noninvasive imaging in man. With the synthesis of /sup 18/F-2-deoxy-2-fluoro-D-glucose (/sup 18/F-DG) all of the requirements for a suitable radiopharmaceutical for the determination of local cerebral metabolism have been met. This agent behaves very similarly to /sup 14/C-DG and therefore, using the above described model and emission tomography, it has become possible to measure regional cerebral metabolism for the first time in man.
Date: January 1, 1981
Creator: Alavi, A.; Reivich, M.; Greenberg, J. & Wolf, A.
Partner: UNT Libraries Government Documents Department

Uptake and distribution of technetium in several marine algae

Description: The uptake or chemical form of technetium in different marine algae (Acetabularia, Cystoseira, Fucus) has been examined and a simple model to explain the uptake of technetium in the unicellular alga, Acetabularia, has been conceptualized. At low concentrations in the external medium, Acetabularia can rapidly concentrate technetium. Concentration factors in excess of 400 can be attained after a time of about 3 weeks. At higher mass concentrations in the medium, uptake of technetium by Acetabularia becomes saturated resulting in a decreased concentration factor (approximately 10 after 4 weeks). Approximately 69% of the total radioactivity present in /sup 95m/Tc labelled Acetabularia is found in the cell cytosol. In Fucus vesiculosus, labelled with /sup 95m/Tc, a high percentage of technetium is present in soluble ionic forms while approximately 40% is bound, in this brown alga, in proteins and polysaccharides associated with cell walls. In the algal cytosol of Fucus vesiculosus, about 45% of the /sup 95m/Tc appears to be present as anionic TcO/sup -//sub 4/ and the remainder is bound to small molecules. 8 references, 5 figures, 1 table.
Date: January 1, 1983
Creator: Bonotto, S.; Gerber, G.B.; Garten, C.T. Jr.; Vandecasteele, C.M.; Myttenaere, C.; Van Baelen, J. et al.
Partner: UNT Libraries Government Documents Department

Modeling and interpretation of two-phase flow and tracer studies from a subbituminous coal seam in the San Juan basin of New Mexico

Description: Field and modeling studies were performed to characterize two-phase flow within the natural cleat structure of an upper Cretaceous subbituminous coal seam. A two borehole pattern with open completion was used in a study of dewatering and tracer residence time distribution. Air was pumped into a five meter thick seam located about 170 meters below the surface. Krypton 85 was used as the airborne tracer. Air inflow and air and water production rates and tracer arrival times were monitored. The field tests were simulated with a two-phase, three component, porous flow code. Results showed that the air inflow and air and water outflow rates and breakthrough times could not be modeled assuming a uniform darcy-type permeability. The use of a pressure dependent permeability did provide, however, a much better match with the field data.
Date: January 1, 1980
Creator: Nuttall, H.E. & Travis, B.J.
Partner: UNT Libraries Government Documents Department

Safety and environmental aspects of HYLIFE-II

Description: The HYLIFE-II inertial confinement fusion reactor uses a Flibe spray for blast chamber protection and tritium breeding. HYLIFE-II is passively safe, having no large sources of energy available to disperse radioactive materials. The dominant activation product is {sup 18}F (half-life 110 minutes). Only a small fraction (< 10{sup {minus}5}) of the Flibe activation products would be mobilized. The offsite dose from a severe accident involving simultaneous failure of the blast chamber and containment building would be < 0.2 mSv (20 mrem), and N-stamp requirements could be avoided in the blast chamber and coolant systems. The required tritium removal efficiencies are quantified. 10 refs., 1 fig.
Date: January 1, 1990
Creator: Dolan, T.J. & Longhurst, G.R. (Idaho National Engineering Lab., Idaho Falls, ID (USA))
Partner: UNT Libraries Government Documents Department

Lifetime measurement of the correlated continuum gamma rays in /sup 170/Hf

Description: Continuum gamma rays are generally emitted at the early stages of the gamma decay of a compound nucleus. These gamma rays are from states with higher angular momentum and excitation energy than the discrete gamma rays. Therefore, from the study of continuum gamma rays it is possible to obtain information on nuclear properties in regions unreachable through studies of discrete transitions. In the current measurements we have applied the Doppler-Shift Attenuation Method to the full gamma-gamma correlation matrix, enabling us to determine the lifetime of the ridge in /sup 170/Hf over a large range of energy. With our Compton Suppression Spectrometer System, it was possible to carry out these measurements with good energy resolution and a high peak-to-Compton ratio. 2 refs., 2 figs.
Date: January 1, 1988
Creator: Lee, I.Y.
Partner: UNT Libraries Government Documents Department

Design and biological properties of iodine-123 labeled. beta. -methyl-branched fatty acids

Description: The synthetic strategy, synthesis, preclinical evaluation and potential clinical applications of 3-methyl-branched radioiodinated iodophenyl- and iodovinyl-substituted fatty acids are reviewed for use as myocardial imaging agents. 50 references, 6 figures. (ACR)
Date: January 1, 1984
Creator: Knapp, F.F. Jr. & Goodman, M.M.
Partner: UNT Libraries Government Documents Department

Experimental and statistical investigation of thermally induced failure in reactor fuel particles

Description: An incomplete experimental study into the failure statistics of fuel particle for the high-temperature gas-cooled reactor (HTGR) is described. Fuel particles failure was induced by thermal ramping from room temperature to temperatures in the vicinity of 2273/sup 0/K to 2773/sup 0/K in 2 to 30 h and detected by the appearance of /sup 85/Kr in the helium carrier gas used to sweep the furnace. The concentration of krypton, a beta emitter, was detected by measuring the current that resulted when the helium sweep gas was passed through an ionization chamber. TRISO fuel particles gave a krypton concentration profile as a function of time that built up in several minutes and decayed in a fraction of an hour. This profile, which was temperature independent, was similar to the impulse response of the ionization chamber, suggesting that the TRISO particles failed instantaneously and completely. BISO fuel particles gave a krypton concentration profile as a function of time that built up in a fraction of an hour and decayed in a fraction of a day. This profile was strongly temperature dependent, suggesting that krypton release was diffusion controlled, i.e., that the krypton was diffusing through a sound coat, or that the BISO coating failed but that the krypton was unable to escape the kernel without diffusion, or that a combination of pre- and postfailure diffusion accompanied partial or complete failure.
Date: October 1, 1980
Creator: Lunsford, J.L.; Imprescia, R.J.; Bowman, A.L. & Radosevich, C.E.
Partner: UNT Libraries Government Documents Department

Positron emission camera for transverse section tomography

Description: A transverse section tomographic positron camera is discussed for quantitative imaging of the heart in gated studies using positron emitters such as /sup 82/Rb, /sup 68/Ga, and /sup 18/F. The system consists of a circular ring of 288 NaI(Tl) crystals 8 mm x 30 mm x 50 mm. The crystals are read out by coded light pipes that permit complete data transfer with only 72 photomultipliers. This and other features lead to an economic design that permits 6 to 9 mm FWHM over sections having 40 cm diameter. Digital image reconstruction can be performed on a small dedicated computer using known algorithms. The device is applicable for either static or dynamic imaging of the brain and other organs as well as gated images of the heart. The major application is for the detection and understanding of cardiac and cerebral vascular disease and physiology.
Date: December 1, 1975
Creator: Derenzo, S. E.; Zaklad, H. & Budinger, T. F.
Partner: UNT Libraries Government Documents Department

Neutron source calibration procedure by activation comparison. [Activation of /sup 56/Mn in MnSo/sub 4/ bath]

Description: The neutron source calibration procedure used in the LLL Hazards Control Calibrations and Standards Facility is described. The source strength is determined by comparing the equilibrium activity of /sup 56/Mn in a MnSO/sub 4/ bath induced by an unknown source to the activity induced by a known source that has been calibrated by the National Bureau of Standards.
Date: August 4, 1976
Creator: Elliott, J. H.
Partner: UNT Libraries Government Documents Department

Recent developments in blood cell labeling research

Description: A number of recent developments in research on blood cell labeling techniques are presented. The discussion relates to three specific areas: (1) a new in vitro method for red blood cell labeling with /sup 99m/Tc; (2) a method for labeling leukocytes and platelets with /sup 99m/Tc; and (3) the use of monoclonal antibody technique for platelet labeling. The advantages and the pitfalls of these techniques are examined in the light of available mechanistic information. Problems that remain to be resolved are reviewed. An assessment is made of the progress as well as prospects in blood cell labeling methodology including that using the monoclonal antibody approach. 37 refs., 4 figs.
Date: September 7, 1988
Creator: Srivastava, S.C.; Straub, R.F. & Meinken, G.E.
Partner: UNT Libraries Government Documents Department

Feeding and decay of superdeformed states

Description: The mechanisms for feeding and decay of superdeformed (SD) bands are examined. Data connected with both processes in [sup 192]Hg are compared with model calculations. The calculations successfully reproduce the data, suggesting that the mechanisms for both processes are understood. Constraints on the energy of the SD band energies and on the well-depths at low and high spins have been obtained. At the point of decay around spin 10, we suggest that the SD band is 3.3--4.3 MeV above the normal yrast line and that the well depths at spin 10 and 40 are 0.5--1.3 and 3.5--4.5 MeV, respectively.
Date: January 1, 1992
Creator: Khoo, T.L.; Lauritsen, T.; Ahmad, I.; Carpenter, M.P.; Fernandez, P.B.; Janssens, R.V.F. et al.
Partner: UNT Libraries Government Documents Department