225 Matching Results

Search Results

Advanced search parameters have been applied.

Recent Developments in the Field of the TransplutoniumElements

Description: The author tells about some of the most interesting aspects of recent research on the synthetic transplutonium elements. The amount of recent information on these elements is obviously too much to cover completely in the time that has been placed at my disposal. Therefore, in planning my talk, I have attempted to choose those topics which have the broadest implications for the whole transuranium field of research. Although much important and interesting research is, of course, being done in many laboratories, I have chosen examples mainly from the work in our own laboratory, the Radiation Laboratory at the University of California in Berkeley. I shall cover this information about the known transplutonium elements, listed in Slide No. 1, by discussing them in order of increasing atomic number, and I shall conclude with some thoughts concerning the prospects for elements with higher atomic numbers than any that have been produced and identified up to the present time. For purposes of orientation, Slide No. 2 shows the position in the periodic table of the presently known and the future transuranium elements. The transplutonium elements through element 103, together with the five preceding elements, are members of the 'heavy rare earth', or actinide transition series, which is analogous to the lighter rare easth, or lanthanide, transition series. The undiscovered 'trans-103' elements will fit into the periodic table as shown. I shall, of course, refer in my talk to the important unifying principle embodied in the periodic table.
Date: September 10, 1958
Creator: Seaborg, Glenn T.
Partner: UNT Libraries Government Documents Department

Single-particle states in transcurium nuclei.

Description: Identification of single-particle states in the heaviest known nuclei is important because their energies can be used to test the single-particle potential in these high-Z elements. These states can be identified by studying the decay schemes of very heavy odd-mass nuclides. For neutrons, the heaviest odd-mass nuclide available in milliCurie quantities is the 20-h {sup 255}Fm and for protons the heaviest nuclide available is the 20-d {sup 253}Es. These two isotopes were obtained from the Transplutonium Element Production Program at Oak Ridge and their spectra were measured with high-resolution germanium spectrometers. From the results of these measurements we have identified states in {sup 251}Cf and {sup 249}Bk up to 1 MeV excitation energy.
Date: September 30, 1999
Creator: Ahmad, I.
Partner: UNT Libraries Government Documents Department

Safety Analysis Report for Packaging (SARP) of the Oak Ridge National Laboratory TRU Californium Shipping Container

Description: An analytical evaluation of the Oak Ridge National Laboratory TRU Californium Shipping Container was made in order to demonstrate its compliance with the regulations governing off-site shipment of packages that contain radioactive material. The evaluation encompassed five primary categories: structural integrity, thermal resistance, radiation shielding, nuclear criticality safety, and quality assurance. The results of this evaluation demonstrate that the container complies with the applicable regulations.
Date: January 1, 1980
Creator: Box, W.D.; Shappert, L.B.; Seagren, R.D.; Klima, B.B.; Jurgensen, M.C.; Hammond, C.R. et al.
Partner: UNT Libraries Government Documents Department

Frontiers of chemistry for americium and curium

Description: The discoveries of americium and curium were made only after Seaborg had formulated his actinide concept in order to design the chemistry needed to separate them from irradiated /sup 239/Pu targets. Their discoveries thus furnished the first clear-cut evidence that the series exists and justified Seaborg's bold assumption that even though Th and Pa appeared to presage a following 6d series, the pattern established by the periodic table after Cs and Ba would be repeated exactly after Fr and Ra. That is to say, a new 5f element rare earth series (the actinides) would follow Ac in the same way the 4f rare earth series (the lanthanides) follows La. The consequences of the resulting half-filled 5f/sup 7/ shell at Cm were originally presented by Seaborg as a test of his hypothesis. Recent research is outlined that substantiates Seaborg's predictions in new and definitive ways. 15 references, 4 figures.
Date: January 1, 1984
Creator: Keller, O.L. Jr.
Partner: UNT Libraries Government Documents Department

New look at the atomic volumes of the. beta. -form of the transplutonium metals

Description: The atomic volumes of the beta-form of the first four transplutonium metals were evaluated using data for samples prepared by thermal and by pressure treatment. The volumes derived for curium, berkelium, and californium metals quenched from elevated temperatures were found to be consistently larger than those for ''pressure-quenched'' samples, whose volumes were in good agreement with values for the alpha-forms. The cubic lattice parameters from ''pressure-quenched'' samples also provided a more consistent trend than those obtained from thermally quenched samples when compared to the parameters for the mononitrides of the metals.
Date: January 1, 1986
Creator: Haire, R.G.; Benedict, U.; Peterson, J.R.; Dufour, C. & Dabos, S.
Partner: UNT Libraries Government Documents Department

Symposium commemorating the 25th anniversary of elements 99 and 100. [Lawrence Berkeley Lab. , January 23, 1978]

Description: Separate abstracts were prepared for five of the contributions to this symposium. The four remaining ones have already been cited in ERA and may be located by reference as the entry CONF-780134-- in the Report Number Index. (RWR)
Date: April 1, 1979
Creator: Seaborg, G.T. & Webb, C. (eds.)
Partner: UNT Libraries Government Documents Department

CPD`s potential for processing the higher transuranics

Description: Hanford`s potential has been evaluated for producing higher transuranic isotopes, particularly curium-242 and curium-244. This document outlines the concepts visualized, and estimates the potential impact on CPD`s development, construction, and production programs. The irradiation program would proceed in 3 steps: production of fuel-grade plutonium, its burning to higher isotopes and alloying with Al for use in one reactor, and the separated americium irradiated to form curium-242. Disposition of higher Pu isotopes and alternative production of curium-244 are discussed.
Date: March 14, 1963
Creator: Tomlinson, R. E.
Partner: UNT Libraries Government Documents Department

Chemistry of berkelium: a review

Description: Element 97 was first produced in December 1949, by the bombardment of americium-241 with accelerated alpha particles. This new element was named berkelium (Bk) after Berkeley, California, the city of its discovery (Thompson, Ghiorso, and Seaborg, Phys. Rev. 77, 838 (1950); 80, 781 (1950)). In the 36 years since the discovery of Bk, a substantial amount of knowledge concerning the physicochemical properties of this relatively scarce transplutonium element has been acquired. All of the Bk isotopes of mass numbers 240 and 242 through 251 are presently known, but only berkelium-249 (..beta../sup -/ decay, 0.125 MeV, t/sub 1/2/ = 325 days) is available in sufficient quantities for bulk chemical studies. About 0.7 gram of this isotope has been isolated at the HFIR/TRU Complex in Oak Ridge, Tennessee in the last 18 years. Over the same time period, the scale of experimental work using berkelium-249 has increased from the tracer level to bulk studies at the microgram level to solution and solid state investigations with milligram quantities. Extended knowledge of the physicochemical behavior of berkelium is important in its own right, because Bk is the first member of the second half of the actinide series. In addition, such information should enable more accurate extrapolations to the predicted behavior of heavier elements for which experimental studies are severely limited by lack of material and/or by intense radioactivity.
Date: January 1, 1985
Creator: Hobart, D.E. & Peterson, J.R.
Partner: UNT Libraries Government Documents Department

Table of isotopes for the 1998/99 handbook of chemistry and physics

Description: Non-neutron nuclear data have been reviewed and recommended values are presented in the Table of the Isotopes to be published in the Chemical Rubber Company`s 1998--1999 Handbook of Chemistry and Physics. The information, which is presented in the Isotopes Table for each known chemical element and for each ground state and long-lived isomeric state nuclide of each element includes the atomic weight of the element and the atomic mass of the ground state nuclide, isotopic abundance value (if the nuclide is stable) or the radioactive half-life (if the nuclide is not stable), the mode of decay, branching ratio and the total disintegration energy, the discrete energies of the alpha particles, protons or neutrons and end point energies of beta transitions and their respective intensities. The following additional information is also included, the nuclear spin and parity, the magnetic dipole moment and the electrical quadrupole moment and the gamma ray energies and intensities.
Date: March 1, 1998
Creator: Holden, N.E.
Partner: UNT Libraries Government Documents Department

Richland Five-year 02 R&D Program

Description: This program is directed to the production of higher weight plutonium isotopes and transplutonium isotopes from the irradiation of transuranic elements, particularly plutonium. Since production of Pu-238 from the irradiation of Np-237 and Am-241 is the subject of Mission 4, Pu-238 Program, it is excluded from this Mission. Specific products which are of prime interest are Cm-244 and plutonium containing a high concentration of either the Pu-240 isotope or the Pu-242 isotope. Because of the potential interest in Cm-244 as a heat source in the 1970`s, the main emphasis has been to provide the capability for producing this isotope. In support of this program, irradiations have been performed to obtain isotopic buildup rates, and a production and economic calculational model has been prepared for determining production methods and costs of producing Cm-244 in the Richland complex. The Richland production reactors have particular advantages in producing higher weight plutonium isotopes from the irradiation of plutonium because of a desirable neutron flux spectrum and a high heat removal capability. Specifically, the high temperature thermal neutron flux maximizes the capture-to-fission ratio of the Pu-239 and Pu-241 isotopes; the high heat removal capability provides for the large decrease in heat generation in the plutonium elements with minimum effect on reactor power levels and efficiency.
Date: June 30, 1968
Partner: UNT Libraries Government Documents Department

Application of pressurized ion exchange to separations of transplutonium elements

Description: High-pressure ion exchange chromatography, used first for nucleic acid separations, was applied to the production of the heavier actinides, particularly the transcurium elements. Its use at the TRU plant is described. Future developments are considered briefly. (DLC)
Date: January 1, 1980
Creator: Campbell, D.O.
Partner: UNT Libraries Government Documents Department

Actinide recovery from pyrochemical residues

Description: We demonstrated a new process for recovering plutonium and americium from pyrochemical waste. The method is based on chloride solution anion exchange at low acidity, or acidity that eliminates corrosive HCl fumes. Developmental experiments of the process flow chart concentrated on molten salt extraction (MSE) residues and gave >95% plutonium and >90% americium recovery. The recovered plutonium contained <500 ppM americium and <2500 ppM magnesium. The process operates by sorbing PuCl/sub 6//sup 2 -/ from high-chloride low-acid solution. Americium and other metals are washed from the ion exchange column with lN HNO/sub 3/-4.8M NaCl. After elution, plutonium is recovered by hydroxide precipitation, and americium is recovered by NaHCO/sub 3/ precipitation. All filtrates from the process can be discardable as low-level contaminated waste. Production-scale experiments are in progress for MSE residues. Flow charts for actinide recovery from electro-refining and direct oxide reduction residues are presented and discussed.
Date: May 1, 1985
Creator: Avens, L.R.; Clifton, D.G. & Vigil, A.R.
Partner: UNT Libraries Government Documents Department

Glove box operations for transplutonium element production

Description: Glove boxes are used in the Transuranium Processing Plant (TRU) at Oak Ridge National Laboratory for (1) completing the final chemical processing steps to isolate and purify the transplutonium elements, (2) packaging transplutonium elements for shipment, (3) preirradiation and postirradiation processing of samples used to produce special transplutonium isotopes in the High Flux Isotope Reactor (HFIR), and (4) conducting special projects, which include providing highly purified transplutonium products in special chemical forms and/or in experimental devices as requested by researchers. During 20 years of operation, the quantities of transplutonium elements produced, and thus the amount of radioactivity handled, have continually increased. At the same time, substantial effort has been expended to reduce personnel radiation exposures. Equipment and techniques have been developed to maintain the desired operational capabilities in the glove boxes while keeping radiation exposures to operating personnel as low as reasonably achievable. Developments have included the design and fabrication of product handling and collection devices, product storage containers, and laminated exterior shields of lead glass, lead acrylic, acrylic sheets, polyethylene, and lead.
Date: January 1, 1986
Creator: Knauer, J.B.; Alexander, C.W. & Wiggins, J.T.
Partner: UNT Libraries Government Documents Department

Direct spectrophotometric assay of americium

Description: Americium is determined by a simple, direct spectrophotometric assay. The sample is dissolved in acid, diluted to volume, and the Am(III) absorbance is measured at 503 nm. Absorbances with respect to concentration are linear to an absorbance of 0.7, corresponding to 0.5 mg/ml Am. The effects of HNO/sub 3/, HC1, H/sub 3/PO/sub 4/ and HF, and temperature on the absorbance are discussed.
Date: January 1, 1981
Creator: Harmon, A.W.; Dahlby, J.W.; Marshall, T.K.; Baughman, W.J. & Bonner, A.S.
Partner: UNT Libraries Government Documents Department

Electronic and magnetic properties of Am and Cm

Description: A review of the present status of the analyses of the optical spectra of Am and Cm in various oxidation states is given. From these analyses, the magnetic properties of the ground states of these ions can be determined. These predicted values are compared with the various magnetic measurements available.
Date: February 1, 1985
Creator: Edelstein, N.
Partner: UNT Libraries Government Documents Department

Outlooks of HLW Partitioning Technologies Usage for Recovering of Platinum Metals from Spent Fuel

Description: The existing practice of management of high level waste (HLW) generated by NPPs, call for a task of selective separation of the most dangerous long-lived radionuclides with the purpose of their subsequent immobilization and disposal. HLW partitioning allows to reduce substantially the cost of vitrified product storage owing to isolation of the most dangerous radionuclides, such as transplutonium elements (TPE) into separate fractions of small volumes, intended for ultimate storage. By now numerous investigations on partitioning of HLW of various composition have been carried out in many countries and a lot of processes permitting to recover cesium, strontium, TPE and rare earth elements (REE) have been already tested. Apart from enumerated radionuclides, a fair quantity of palladium and rhodium presents in spent fuel, but the problem of these elements recovery has not yet been decided at the operating radiochemical plants. A negative effect of platinum group metals (PGM) occurrence is determined by the formation of separate metal phase, which not only worsens the conditions of glass-melting but also shortens considerably the service life of the equipment. At the same time, the exhaustion of PGMs natural resources may finally lead to such a growth of their costs that the spent nuclear fuel would became a substituting source of these elements industrial production. Allowing above mentioned, it is of interest to develop the technique for ''reactor'' palladium and rhodium recovery process which would be compatible with HLW partitioning and could be realized using the same facilities. In the report the data on platinum metals distribution in spent fuel reprocessing products and the several flowsheets for palladium separation from HLW are presented.
Date: February 24, 2003
Creator: Pokhitonov, Y. A.; Estimantovskiy, V.; Romanovski, v.; Zatsev, B. & Todd, T.
Partner: UNT Libraries Government Documents Department

Chemical properties of the heavier actinides and transactinides

Description: The chemical properties of each of the elements 99 (Es) through 105 are reviewed and their properties correlated with the electronic structure expected for 5f and 6d elements. A major feature of the heavier actinides, which differentiates them from the comparable lanthanides, is the increasing stability of the divalent oxidation state with increasing atomic number. The divalent oxidation state first becomes observable in the anhydrous halides of californium and increases in stability through the series to nobelium, where this valency becomes predominant in aqueous solution. In comparison with the analogous 4f electrons, the 5f electrons in the latter part of the series are more tightly bound. Thus, there is a lowering of the 5f energy levels with respect to the Fermi level as the atomic number increases. The metallic state of the heavier actinides has not been investigated except from the viewpoint of the relative volatility among members of the series. In aqueous solutions, ions of these elements behave as a normal trivalent actinides and lanthanides (except for nobelium). Their ionic radii decrease with increasing nuclear charge which is moderated because of increased screening of the outer 6p electrons by the 5f electrons. The actinide series of elements is completed with the element lawrencium (Lr) in which the electronic configuration is 5f/sup 14/7s/sup 2/7p. From Mendeleev's periodicity and Dirac-Fock calculations, the next group of elements is expected to be a d-transition series corresponding to the elements Hf through Hg. The chemical properties of elements 104 and 105 only have been studied and they indeed appear to show the properties expected of eka-Hf and eka-Ta. However, their nuclear lifetimes are so short and so few atoms can be produced that a rich variety of chemical information is probably unobtainable.
Date: January 1, 1981
Creator: Hulet, E.K.
Partner: UNT Libraries Government Documents Department

Technique for fission measurements of highly active and weak cross-section actinides

Description: The Rensselaer Intense Neutron Spectrometer (RINS) system provides an intense neutron source that is well suited for measuring the fission cross sections of microgram quantities of highly-active actinides and gram quantities of nuclei with very weak cross sections. The system consists of a 75-ton lead assembly driven by the RPI electron linac, and the neutron fluxes are three-to-four orders of magnitude more intense than those available in conventional time-of-flight measurements. Examples of measured cross sections of curium isotopes /sup 238/U and /sup 232/Th are presented. 17 refs., 10 figs., 1 tab.
Date: January 1, 1989
Creator: Block, R.C.; Slovacek, R.E.; Hoff, R.W. & Nakagome, Yoshihiro
Partner: UNT Libraries Government Documents Department

Safety analysis report for packaging (SARP) of the Oak Ridge National Laboratory. TRU curium shipping container

Description: An analytical evaluation of the Oak Ridge National Laboratory Transuranium (TRU) Curium Shipping Container was made to demonstrate its compliance with the regulations governing offsite shipment of packages containing radioactive material. The evaluation encompassed five primary categories: structural integrity, thermal resistance, radiation shielding, nuclear criticality safety, and quality assurance. The results of the evaluation show that the container complies with the applicable regulations.
Date: June 1, 1980
Creator: Box, W.D.; Klima, B.B.; Seagren, R.D.; Shappert, L.B. & Aramayo, G.A.
Partner: UNT Libraries Government Documents Department

Feasibility studies of thermonuclear neutron capture synthesis of SHE

Description: A variety of thermonuclear neutron sources and neutron capture targets were investigated for their potential of allowing signigicant production of heavy, perhaps superheavy, isotopes. The neutron sources considered range from inertial confinement microexplosives to (underground) macroexplosives. Optimal capture targets appear to be composites containing uranium and protactinium. 1 figure.
Date: April 10, 1978
Creator: Meldner, H.W.
Partner: UNT Libraries Government Documents Department

Shifted homologous relationships between the transplutonium and early rare-earth metals

Description: The physico-chemical properties of the late actinide metals americium through einsteinium are compared with their rare-earth counterparts. Localization of the 5f electrons beginning at americium signals the appearance of true rare-earth-like properties, but the homologous relationship is shifted to place americium below praseodymium, einsteinium then below europium. The comparison of crystal structure, phase transitions, vapor pressures and heats of vaporization reveals remarkable similarities, especially for Sm-Cf and Eu-Es, where the stability of the divalent metal becomes established and divalent chemistry then follows. There is of course a major perturbation at the half-filled shell at curium, and it may be argued that americium is the anomaly in the so-called second rare-earth series. However, the response of americium, berkelium and californium under pressure reveals the true perturbation to be a thermodynamic one, occurring at curium.
Date: January 1, 1984
Creator: Ward, J.W.
Partner: UNT Libraries Government Documents Department