Papers by Bartley Ebbinghaus
High temperature oxide melt solution calorimetry was used to derive standard enthalpies of format... more High temperature oxide melt solution calorimetry was used to derive standard enthalpies of formation, AHf (kJ/mol), for three pyrochlore phases: Ca0.93Ce1.00Ti2.035O7.00 (-3656.0 +/- 5.6), Ca1.46U0.234+U0.466+Ti1.85O7.00 (-3610 +/- 4.1) and Gd2Ti2O7 (-3822.5 +/- 4.9). Enthalpy of drop solution data, DeltaH(ds), were used to calculate enthalpies of formation with respect to an oxide/perovskite phase assemblage AH(f-ox)(0): CaO + MO2 + 2TiO(2) = CaMTi2O7 or Gd2O3 + 2TiO(2) = Gd2Ti2O7, and an oxide/perovkite phas assemblage AH(f-pv+ox)(0): CaTiO3 + MO2 + TiO2 = CaMTi2O7, where M = Ce or U. All three pyrochlore samples were stable in enthalpy relative to an oxide assemblage with DeltaH(f-ox)(0) (kJ/mol) (Gd2Ti2O7) = -113.4 +/- 2.8; DeltaH(f-ox)(0)(Ca1.46U0.234+U0.466+Ti0.85O7.00) = -123.1 +/- 3.4; DeltaH(f-ox)(0)(Ca0.93Ce1.00Ti2.035O7.00) = -54.1 +/-5.2. U pyrochlore was stable in enthalpy relative to an oxide/perovskite assemblage (DeltaH(f-pv-ox)(0) = -5.1 +/- 4.0 kJ/mol). Ce-pyrochlo...
We present volume, density, and tensile property change observed from both naturally and accelera... more We present volume, density, and tensile property change observed from both naturally and accelerated aged plutonium alloys. Accelerated alloys are plutonium alloys with a fraction of Pu-238 to accelerate the aging process by approximately 18 times the rate of unaged weapons-grade plutonium. After thirty-five equivalent years of aging on accelerated alloys, the dilatometry shows the samples at 35 C have
This paper reports the continued evaluation of the attractiveness of materials mixtures containin... more This paper reports the continued evaluation of the attractiveness of materials mixtures containing special nuclear materials (SNM) associated with thorium based nuclear fuel cycles. Specifically, this paper examines a thorium fuel cycle in which a pressurized heavy water reactor (PHWR) is fueled with mixtures of natural uranium/233U/thorium. This paper uses a PHWR fueled with natural uranium as a base fuel cycle, and then compares material attractiveness of fuel cycles that use 233U/thorium salted with natural uranium. The results include the material attractiveness of fuel at beginning of life (BoL), end of life (EoL), and the number of fuel assemblies required to collect a bare critical mass of plutonium or uranium. This study indicates what is required to render the uranium as having low utility for use in nuclear weapons; in addition, this study estimates the increased number of assemblies required to accumulate a bare critical mass of plutonium that has a higher utility for use...
Acta Crystallographica Section C Crystal Structure Communications, 1988
Rh(CTHT)(ClsH40P2)), M r = 512.50, tri- clinic, Pi, a=9.5973(8), b=10.4471(15), c= 14.3667 (15)A,... more Rh(CTHT)(ClsH40P2)), M r = 512.50, tri- clinic, Pi, a=9.5973(8), b=10.4471(15), c= 14.3667 (15)A, ~=88.46 (1), fl=83.92 (1), y= 67.95 (1) °, V= 1327.5 (3)A 3, Z = 2, D m =- 1.29, D x = 1.283 g cm -3, Mo Ka (2 = 0.7107 A), ~t = 7.59 cm -l, F(000) = 544, T= 295 K, R = 0.022, wR =0.033 for 3152 independent reflections with Fo> 3a(Fo). The Rh atom is in a distorted square-planar environment in which two coordination sites are occupied by an allylic bond to the benzyl ligand. The benzyl ligand is unsymmetrically bound: the Rh-C(6) and Rh-C(7) distances are 2.371 (2) and 2.162 (2)/~, respectively. The non-allylic portion of the ligand exhibits the expected bond-length alternation.
Facilities to support development of modified nitride-based reactor fuel pellets have been activa... more Facilities to support development of modified nitride-based reactor fuel pellets have been activated and are now in operation at Lawrence Livermore National Laboratory. These facilities provide the controls and monitored laboratory conditions required to produce, evaluate, and verify quality of the nitride-based product required for this fuel application. By preserving the high melting point, high thermal conductivity, and high actinide density properties of nitride fuel while enhancing stoichiometry, density, and grain structure, and by applying inert matrix (ZrN) and neutron absorbing (HfN) additives for improved stability and burn-up characteristics, the requirements for a long-life fuel to support sealed core reactor applications may be met. This paper discusses requirements for producing the modified nitride powders for sintering of fuel pellets, translation of these requirements into facility specifications, and implementation of these specifications as facility capabilities.
Acta Crystallogr C Cryst Str, 1988
Unclassified Comparison will use the following Figure of Merit (FOM). The FOM is applicable to ... more Unclassified Comparison will use the following Figure of Merit (FOM). The FOM is applicable to an adversary intending to build a stockpile of nuclear weapons without purifying the materials: • M-bare critical mass in unpurified metal form (kg) • h-heat content in unpurified metal form (W/kg) • D-dose rate of 0.2•m @ 1 m (rad/h) The FOM only addresses the attractiveness of the material to make a stable threshold nuclear device capable of being stockpiled.
The purpose of this study is to evaluate the volatilities of U, Pu, and Am in thermal treatment p... more The purpose of this study is to evaluate the volatilities of U, Pu, and Am in thermal treatment processes for mixed wastes. The thermodynamics of vaporization U and Pu oxides in the presence of oxygen and water vapor and of U oxide in the presence of oxygen and chlorine were studied. Experimental studies of U oxide volatilities by previous authors have also been reviewed. For species where data are unavailable estimation methods were used to obtain free energies of formation of the gaseous species, The data are applied to thermal treatment processes in general and then more specifically to conditions representative of the Rocky Flats Plant Fluidized Bed Unit. (RFP FBU), molten salt oxidizer, and an incinerator. U volatilities are greatest ranging from 2.67 x 10{sup -7} gU/h in the RFP FBU to 4. 00 gU/h for typical incinerator conditions. Pu volatilities are almost 5 orders of magnitude less than U and Am volatilities are about 3 orders of magnitude less than Pu.
We report development and bench-scale testing of an electrolytic process for reduction of LiOH to... more We report development and bench-scale testing of an electrolytic process for reduction of LiOH to lithium metal through an amalgam intermediate. The amalgam is formed in an aqueous-electrolyte cell and stripped in a molten salt cell using a LiI-CsI eutectic at 225 C. Total energy efficiency is >70%. The process obviates high temperature materials problems, chlorine evolution and anhydrous feedstocks. While the principle is proven, sustained operation of the cell is now needed to obtain statistical data on reliability and maintainability.
MRS Proceedings, 2002
ABSTRACTBaseline formulation titanate ceramics for surplus Pu disposition are based upon a target... more ABSTRACTBaseline formulation titanate ceramics for surplus Pu disposition are based upon a target mineralogy of 95 wt.% pyrochlore (Ca0.89Gd0.22Hf0.23Pu0.22U0.44Ti2O7) plus 5 wt.% Hf-doped rutile (∼ Ti0.9Hf0.1O2), where Ce is used as an analogue for Pu and U, and Th for Pu. Typically, Pu/U, Th/U and Ce/U-baseline samples form major pyrochlore, plus minor brannerite (AnTi2O6) and rutile. Ce/Ce-baseline ceramics were similar but did not form brannerite. Sintering in air produced more U5+ in the ceramics than sintering in Ar. In the pyrochlore the charge compensation for U5+ principally occurred by an increase in Ca2+ and decrease in Ti4+ and Th4+. In the matrix these phase compositional changes result in an increase in brannerite content of the ceramic at the expense of pyrochlore in the air sintered ceramic relative to the Ar sintered sample. Sintering in reducing 3.7% H2 in Ar atmospheres eliminates the brannerite and rutile and results in 2M-zirconolite and perovskite in addition t...
DISCLAIMER This document was prepared as an account of work sponsored by an agency of the United ... more DISCLAIMER This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of 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. Referena herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. a. DISCLAIMER Portions of this document may be illegible in efectronic image products. Images are produced from the best available original document.
This report has been reproduced directly from the best available copy.
List of Figures 3.1 Secondary electron image (SEI) of zirconolite-rich form 3.2 Backscattered ele... more List of Figures 3.1 Secondary electron image (SEI) of zirconolite-rich form 3.2 Backscattered electron image (BEI) of pyrochlore-rich form 4.1 Linkages between tasks and sample test matrices 30 5.1 Depiction of the processing regime 5.2 Recommended process for preparing ceramic precursors 5.3 The ceramic immobilization process flow diagram 5.4 The overall baseline firing schedule 51
Uploads
Papers by Bartley Ebbinghaus