Radiochemical method for the isolation of protactinium

A simple, yet highly reproducible separation procedure for isolating low levels of protactinium /pico- to micrograms/ from gram quantities of natural or activated soils or sediments has been developed. The reliability is achieved by minimizing the tendency of Pa to hydrolyze or to form colloids by keeping it complexed at all times either by fluoride or sulfate ions. The procedure consistently gives high chemical yields /85+8%/ and the final fractions are not only radiochemically pure, but show little or no visible mass contamination with evaporation.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.     

International cooperation in age-dating uranium standards for nuclear forensics using the 231Pa/235U radiochronometer

Journal of Radioanalytical and Nuclear Chemistry - During 2017–2018 Los Alamos National Laboratory, Lawrence Livermore National Laboratory and the China Institute of Atomic Energy...     

High-energy irradiation of chlorinated hydrocarbons

The Lawrence Livermore National Laboratory (LLNL) and the Idaho National Engineering Laboratory (INEL) are jointly investigating the decomposition of chlorinated hydrocarbons using bremsstrahlung radiation produced by electron accelerators and gamma photons from spent reactor fuel. Experimental results demonstrate an exponential type decay of concentration with dose for volatile organic compounds (VOCs) in ground water and for both polychlorinated biphenyls (PCBs) and insecticides in organic solutions. Experiments were performed at several photon energies and dose rates with various initial concentrations. Mass balance analysis suggests complete mineralization of VOCs in ground water and indicates significant degradation of PCBs and insecticides to VOC type compounds in organic solutions.Work performed under the auspices of the U.S. Department of Energy, DOE Contract Nos. W-7405-ENG-48 and DE-AC07-76IDO1570.     

Isotope ratio determination in microgram levels of osmium by deuteron activation analysis

We have demonstrated the feasibility of determining isotope ratios in very small samples of osmium by deuteron activation in the Livermore Tandem Van de Graaff accelerator. The method involves determination of cross-section ratios by using several osmium isotope mixtures carefully prepared from electromagnetically-enriched osmium isotopes. The accuracy of this method was checked by a determination of the isotope ratios in naturally-occurring osmium. Our analysis demonstrated that an osmium specimen removed from a sample of commercial grade perrhenic acid contained only 0.4% natural osmium, the rest being radiogenic¹⁸⁷Os.Work performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.     

Harnessing the killer micros: Applications from LLNL's massively parallel computing initiative

Recent developments in microprocessor technology have led to performance on scalar applications exceeding traditional supercomputers. This suggests that coupling hundreds or even thousands of these killer-micros (all working on a single physical problem) may lead to performance on vector applications in excess of vector supercomputers. Also, future generation killer-micros are expected to have vector floating point units as well. The purpose of this paper is to present an overview of the parallel computing environment at Lawrence Livermore National Laboratory. However, the perspective is necessarily quite narrow and most of the examples are taken from the author's implementation of a large-scale molecular dynamics code on the BBN-TC2000 at LLNL. Parallelism is achieved through a geometric domain decomposition — each processor is assigned a distinct region of space and all atoms contained therein. As the atomic positions evolve, the processors must exchange ownership of specific atoms. This geometric domain decomposition proves to be quite general and we highlight its application to image processing and hydrodynamics simulations as well.Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract No. W-7405-ENG-48     

Enthalpies and temperatures of transformation for plutonium using a differential scanning calorimeter

The enthalpies and temperatures of transformation of high purity plutonium were measured using a differential scanning calorimeter. The results of our study are presented and compared to values obtained by previous methods.Work performed under the auspices of the U. S. Department of Energy by Lawrence Livermore Laboratory under contract No. W-7405-Eng-48.     

CR-39 Nuclear Track Detectors for identification of Pu-239 and Am-241 alpha contamination

Nuclear Track Detectors (NTD's) are used as passive systems to detect the alpha contamination on flat or semirough surfaces. The procedure for the application of these devices is simple because the detector needs only to be placed on the area to be surveyed for a short period of time, collected and chemically processed to develop the alpha tracks. For the quantification of the results, it is necessary to have a calibration procedure. This paper presents the response of CR-39 (allyl diglycol carbonate), from American Acrylics and Pershore Companies, to alpha particles from Pu-239 (5.15 MeV) and Am-241 (5.48 MeV). The methods of etching and counting are outlined, along with the achievable linearity, efficiency and reproducibility. The sensitivity to low activity levels is also discussed.Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract W-7405-ENG-48.     

The mutual diffusion coefficients of NaCl−H2O and CaCl2−H2O at 25°C from Rayleigh interferometry

The volume-fixed mutual diffusion coefficients of NaCl–H₂O and CaCl₂–H₂O have been measured to an accuracy of 0.1–0.2%, from dilute solutions to high concentrations, by free diffusion Rayleigh interferometry. These diffusion coefficients are compared to other diffusion data for these salts, obtained from Guoy interferometry and the conductometric method. Discrepancies between data in the literature are resolved using the present results. Some diffusion coefficients have also been measured for KCl–H₂O and NH₄Cl–H₂O.Work performed in part under the auspices of the U.S. Department of Energy by the Lawrence Livermore Laboratory under contract number W-7405-ENG-48.Reference to a company or product name does not imply approval or recommendation of the product by the University of California or the U.S. Department of Energy to the exclusion of others that may be suitable.This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Department of Energy, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights.University of Illinois at Urbana-Champaign; tenure served as a participating guest at Lawrence Livermore Laboratory.     

Infrared properties of three plastic bonded explosive binders

Three polymers are routinely used as binders for plastic bonded explosives by Lawrence Livermore National Laboratory, FK-800, Viton A 100, and Oxy 461. Attenuated total reflectance Fourier transform infrared measurements were performed on 10 different lots of FK-800, 5 different lots of Oxy 461, and 3 different lots of Viton A-100, one sample of Viton VTR 5883 and 2 Fluorel polymers of hexafluoropropene and vinylidene fluoride. The characteristic IR bands were measured. If possible, their vibrational modes were assigned based on literature data. Simple Mopac calculations were used to validate these vibrational mode assignments. Somewhat more sophisticated calculations were run using Gaussian on the same structures.     

A critical examination of the salicylaldehyde method for the determination of primary amines in the presence of secondary amines

Summary The salicylaldehyde method for the differentiation of primary and secondary amines in mixtures has been critically evaluated. This method yields best results in acetonitrile. In mixtures of amines one can expect high results for the primary amine with correspondingly low results for the secondary amine. Corrections can be made with known mixtures of the amines.Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore Laboratory under contract number W-7405-ENG-48.     

Trace multielement analysis using high-flux fast-neutron activation

The intense 14-MeV neutron facility at Lawrence Livermore National Laboratory was used for fast-neutron activation analysis (FNAA) of standard fly ash, orchard leaves, and bovine liver supplied by the U.S. National Bureau of Standards. The high flux of 14-MeV neutrons allowed concentration determinations of up to 20 elements from the set of Na, Mg, Al, Si, P, K, Sc, Ti, Fe, Co, Ni, Zn, As, Se, Rb, Sr, Y, Zr, Mo, Sb, Ba, Ce, Tl, and Pb. Interferences and steep flux-gradients were problems, but the elemental profile we obtained is the most complete analysis using FNAA to date.     

Trace-element emissions from Western U. S. coal-fired power plants

The Lawrence Livermore Laboratory program to evalute the trace elements in stack emissions from coal-fired power plants is described. Stack sampling and analysis of fly ash at modern, western U. S. power plants is discussed. Scanning-electron-microscope techniques are shown to be essential for accurate sizing of stack particles sampled with cascade impactors. Particle-size distributions for volatile and nonvolatile trace elements are reported. Comparisons show that the trace elemet enrichment factors of western and eastern U. S. coal-fired power plants are significantly different. This work was performed under the auspices of the U.S. Energy Research and Development Administration, under contract No. W-7405-Eng. 48.     

Dissolution of metallic uranium and its alloys

This review focuses on dissolution/reaction systems capable of treating uranium metal waste to remove its pyrophoric properties. The primary emphasis is the review of literature describing analytical and production-scale dissolution methods applied to either uranium metal or uranium alloys. A brief summary of uranium's corrosion behavior is included since the corrosion resistance of metals and alloys affects their dissolution behavior. Based on this review, dissolution systems were recommended for subsequent screening studies designed to identify the best system to treat depleted uranium metal wastes at Lawrence Livermore National Laboratory (LLNL). This revised version was published online in July 2006 with corrections to the Cover Date.     

Procedures for multielement analysis using high-flux fast-neutron activation

Improvements have been made in the rabbit system used for multielement fast-neutron activation analysis at the Lawrence Livermore National Laboratory Rotating Target Neutron Source, RTNS-I. Procedures have been developed for the analysis of 20–25 elements in samples with an inorganic matrix and 10–15 elements in biological samples, without the need for prohibitively expensive, long irradiations. Results are presented for the analysis of fly ash, orchard leaves, and bovine liver.     

Potentiometric precipitation titrations of selenite,selenate, tellurite and tellurate

Summary Some precipitation titrations have been evaluated for the determination of the oxo anions of selenium and tellurium. Selenite and tellurite can be titrated with sodium diethyldithiocarbamate, using a silver ion-selective electrode as sensor. Tellurite can be titrated with cetylpyridinium chloride, using a poly(vinylchloride)/dioctylphthalate-coated graphite rod as sensor.Silver nitrate can be used to titrate selenite, tellurite, and tellurate. While the sum of tellurite and tellurate can be estimated, no sequential titration is possible. Lead nitrate can be used for the titration of selenite in the presence of selenate, in aqueous solution. In 80% methanolic solution the sum of selenite and selenate is titrated with lead nitrate.This work performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore National Laboratory under contract No. W-7405-ENG-48.     

Potentiometric titration and differentiation of cyano and nitrito complexes of Ir(III), Pt(II), and Pd(II)

Summary The precipitation titration of the nitrito complexes of Ir(III), Pt(II), and Pd(II) vs. cetylpyridinium chloride is reported. The corresponding cyanide complexes of these precious metals are also precipitated by silver nitrate, which does not react with the nitrito complexes. Differentiation of the 2 types of complexes is, therefore, possible. Sequential estimation of the cyanide complexes and some anions such as bromide, cyanide, and aurocyanide is feasible with silver nitrate.

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Potentiometrische Titration und Differenzierung von Cyano- und Nitrito-Komplexen von Ir(III), Pt(II) und Pd(II)

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Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-48     

Radiological Background Levels Found in Glass Fiber Filters Used for Low-Level Environmental Surveillance Air Sampling

Environmental surveillance monitoring of low-level radioactive particles in air requires a thorough understanding of low-level techniques and air sample collection media. High-volume air sampling for radioactive particles around Lawrence Livermore National Laboratory (LLNL) currently employs glass-fiber filters that are analyzed for gross alpha and gross beta activity and for specific isotopes. This study was conducted to determine the activities of radionuclides contained in blank glass-fiber filters. Data from this study provided a partial explanation of differences between current reported concentrations of radionuclides in air and those reported historically when cellulose filters were used in the LLNL monitoring effort.     

Mutual diffusion coefficients of Nal-H2O and LiCl-H2O at 25°C from Rayleigh interferometry

Volume-fixed mutual diffusion coefficients of aqueous NaI have been measured from low concentrations to 10.8 mol-(kg H₂O)^–1 (7.6 mol-dm^–3), and those of LiCl up to 1.6 mol-(kg H₂O)^–1 (1.55 mol-dm^–3), at 25°C using free-diffusion Rayleigh interferometry. The accuracy of these diffusion coefficients is 0.1–0.2%. LiCl-H₂O has some of the lowest diffusion coefficients for alkali halides, whereas NaI-H₂O has some of the highest. The significance of these differences is briefly discussed.Work performed under the auspices of Office of Basic Energy Science (Geosciences) of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-48.     

Neutron interrogation to identify chemical elements with an ion-tube neutron source (INS)

A non-destructive analysis technique using a protable, electric ion-tube neutron source (INS) and gamma ray detector has been used to identify the key constituent elements in a number of sealed munitions, and from the elemental makeup, infer the types of agent within each. The high energy (14 MeV) and pulsed character of the neutron flux from an INS provide a method of measuring, quantitatively, the oxygen, carbon, and fluorine content of materials in closed containers, as well as the other constituents that can be measured with low-energy neutron probes. The braod range of elements that can be quantitatively measured with INS-based instruments provides a capability of verifying common munition fills; it provides the greatest specificity of any portable neutron-based technique for determining the full matrix of chemical elements in completely unrestricted sample scenarios. The specific capability of quantifying the carbon and oxygen content of materials should lead to a fast screening technique which, can discriminate very quickly between high-explosive and chemical agent-filled containers.Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.     

Present and future positron-molecular scattering experiments

Progress to date (June, 1999) of the Oak Ridge positron scattering project is reviewed. Results from our positron time-of-flight mass spectrometer include ionization and fragmentation of some halomethanes, positronium formation below the threshold for double ionization of Ne and the heavier noble gases, and the production of HeH⁺ by positron impact on mixtures of He and H₂. New directions for future experimental work are discussed. These entail the construction and testing of a new spectrometer which measures both the masses and recoil energies of charged products, including secondary electrons. We hope to use an intense positron beam, such as the one at Lawrence Livermore National Laboratory or a similar beam, as the ionizing agent for the new spectrometer, which contains a pulsed supersonic molecular beam. With such an instrument, a range of new phenomena can be studied.