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ACCIDENT IN CONTINUOUS-DISSOLVER PILOT PLANT OF FLUORIDE VOLATILITY PROJECT ON MAY 15, 1957

Description: A series of explosions, estimated at five, occurred over a period of ten seconds within the continuous dissolver pilot plant, of the Fluoride Volatility Project on May 15, 1957. The explosive reactions occurred in the dissolver vessels as a result of violent chemical reactions between uranium and an interhalogen mixture. Just what the conditions were which triggered the explosions, have not been definitely established. Nevertheless, based upon the evidence which has been collected, several possible explanations, listed according to probability, are presented. A number of recommendations are included to be followed before operation of the pilot plant is resumed. These recommendations relate to additional laboratory research, equipment design, facility design, and use of a review committee. Safety rules for handling BrF/ sub 3/, BrF/sub 5/, ClF/sub 3/, and Br/sub 2/ are appended. (C.H.)
Date: July 10, 1957
Creator: Strickland, G.; Horn, F.L.; Johnson, R. & Dwyer, O.E.
Partner: UNT Libraries Government Documents Department

Technical bases for the use of CIF{sub 3} in the MSRE reactive gas removal project at Oak Ridge National Laboratory, Oak Ridge, Tennessee

Description: Nearly impermeable, non-volatile deposits in the Molten Salt Reactor Experiment (MSRE) off-gas piping are impeding the removal of reactive gases from that system. The deposits almost certainly consist of reduced uranium fluorides or of uranium oxyfluorides. Treatment with ClF{sub 3} is a non-intrusive method capable of chemically converting these compounds back to UF{sub 6}, which can then be removed as a gas. This report discusses the technical bases for the use of ClF{sub 3} treatments in this system. A variety of issues are examined, and where the necessary information exists or has been developed, the resolution discussed. The more important of these issues include the efficacy of ClF{sub 3} at deposit removal under the conditions imposed by the MSRE system, materials compatibility of ClF{sub 3} and its reaction products, and operational differences in the Reactive Gas Removal System imposed by the presence of ClF{sub 3} and its products.
Date: June 1997
Creator: Trowbridge, L. D.
Partner: UNT Libraries Government Documents Department

THE BEHAVIOR OF URANIUM, THORIUM, AND OTHER SELECTED MATERIALS IN BROMINE TRIFLUORIDE, BROMINE PENTAFLUORIDE, CHLORINE TRIFLUORIDE, AND FLUORINE AT ELEVATED TEMPERATURES

Description: The reactivity of uranium, thorium, aluminum, copper, iron, magnesium, zirconium, and Fluorothene with bromine trifluoride, bromine pentafluoride, chlorine trifluoride, and fluorine was investigated at tempertures ranging from 25 to 410 deg C. The reactivity of platinum with bromine trifluoride was also studied. (auth)
Date: May 1, 1955
Creator: Stein, L. & Vogel, R.C.
Partner: UNT Libraries Government Documents Department

Laboratory tests using chlorine trifluoride in support of deposit removal at MSRE

Description: Experimental trials were conducted to investigate some unresolved issues regarding the use of chlorine trifluoride (ClF{sub 3}) for removal of uranium-bearing deposits in the Molten Salt Reactor Experiment (MSRE) off-gas system. The safety and effectiveness of operation of the fixed-bed trapping system for removal of reactive gases were the primary focus. The chief uncertainty concerns the fate of chlorine in the system and the potential for forming explosive chlorine oxides (primarily chlorine dioxide) in the trapping operation. Tests at the MSRE Reactive Gas Removal System reference conditions and at conditions of low ClF{sub 3} flow showed that only very minor quantities of reactive halogen oxides were produced before column breakthrough. Somewhat larger quantities accompanied breakthrough. A separation test that exposed irradiated MSRE simulant salt to ClF{sub 3} confirmed the expectation that the salt is basically inert for brief exposures to ClF{sub 3} at room temperature.
Date: April 1, 1997
Creator: Williams, D.F.; Rudolph, J.C.; Del Cul, G.D.; Loghry, S.L.; Simmons, D.W. & Toth, L.M.
Partner: UNT Libraries Government Documents Department

Gas-phase decontamination demonstration on PORTS cell X-25-4-2. Final technology status report

Description: The Long-Term, Low Temperature (LTLT) process is a gas-phase in situ decontamination technique which has been tested by LMES/K-25 personnel on the laboratory scale with promising results. The purpose of the Gas-Phase Decontamination Demonstration at PORTS was to evaluate the LTLT process on an actual diffusion cascade cell at conditions similar to those used in the laboratory testing. The demonstration was conducted on PORTS diffusion cell X-25-4-2 which was one of the X-326 Building cells which was permanently shutdown as part of the Suspension of HEU Production at PORTS. The demonstration full-scale test consisted of rendering the cell leak-tight through the installation of Dresser seals onto the process seals, exposing the cell to the oxidants ClF{sub 3} and F{sub 2} for a period of 105 days and evaluating the effect of the clean-up treatment on cell samples and coupons representing the major diffusion cascade materials of construction. The results were extrapolated to determine the effectiveness of LTLT decontamination over the range of historical uranium isotope assays present in the diffusion complex. It was determined that acceptable surface contamination levels could be obtained in all of the equipment in the lower assay cascades which represents the bulk of the equipment contained in the diffusion complex.
Date: September 1, 1997
Creator: Riddle, R.J.
Partner: UNT Libraries Government Documents Department

Evaluation of gas-phase technetium decontamination and safety related experiments during FY 1994. A report of work in progress

Description: Laboratory activities for FY94 included: evaluation of decontamination of Tc by gas-phase techniques, evaluation of diluted ClF{sub 3} for removing U deposits, evaluation of potential hazard of wet air inlekage into a vessel containing ClF{sub 3}, planning and preparation for experiments to assess hazard of rapid reaction of ClF{sub 3} and hydrated UO{sub 2}F{sub 2} or powdered Al, and preliminary evaluation of compatibility of Tenic valve seat material.
Date: May 1, 1995
Creator: Simmons, D.W. & Munday, E.B.
Partner: UNT Libraries Government Documents Department

Thermodynamic stability of complexes of BF{sub 3}, PF{sub 5} and AsF{sub 5} with chlorine fluorides, oxyfluorides, and related compounds

Description: The recent discovery of solid, water sensitive, arsenic-containing deposits in auxiliary process piping in the PGDP led to a search for explanations that could account for such accumulated material. A plausible explanation for the deposits is the formation of complexes of AsF{sub 5} with one or more gases that may have been present as a result of cascade equipment cleanup activities. A literature search was performed. The target of the search was literature that would provide information on the dissociation pressure of complexes of AsF{sub 5} or its hydrolysis products with any gases that may be (at least intermittently) present in the cascade location where the deposits were found. While the precise information sought (namely reliable, accurate dissociation pressures of such complexes at cascade temperatures) was not found in the detail desired. other information on these or similar complexes was obtained which permits prediction of the conditions under which the complexes might form, dissociate, or migrate, and how they might behave in the presence of atmospheric moisture. Information was gathered on potential AsF{sub 5} complexes with ClF, ClF{sub 3}, ClF{sub 5}, ClF{sub 3}O, ClO{sub 2}F, and ClO{sub 3}F. Information was also collected on many other related complexes as it was encountered, particularly for series of complexes which could assist in predicting chemical trends. Thermodynamic analysis and property estimation methods have been used to generate provisional estimates of the dissociation pressures of the two complexes ClF{sub 3}*AsF{sub 5} and ClO{sub 2}F*AsF{sub 5}. In addition, several hydrolysis species have been identified, and stability properties of the most relevant such complex (H{sub 3}O*AsF{sub 6}) have similarly been estimated. While the predicted dissociation pressures are somewhat uncertain. they do lead to a tentative picture of the formation and behavior of such complexes in a cascade cleanup environment.
Date: July 1, 1996
Creator: Trowbridge, L.D.
Partner: UNT Libraries Government Documents Department

BASIC STUDIES OF THE SEPARATION OF URANIUM HEXAFLUORIDE FROM MIXTURES CONTAINING CHLORINE TRIFLUORIDE AND HYDROGEN FLUORIDE

Description: Processes for the conversion of uranium compounds or uranium metal to uranium hexafluoride ordinarily involve the use of a powerful fluorinating agent. Elemental fluorine is used when the scale of operations justifies the construction of a fluorine generating plant, but for smaller operation the use of the interhalogens of fluorine has definite advantages. These compounds provide a high concentration of fluorinating power at moderate temperatures and pressures and are more easily stored and transported than fluorine. In addition, fluorinations in the liquid phase often proceed more smoothly than those with gaseous fluorine. However, the use of . the interhalogens introduces the problem of separating the uranium hexafluoride from the unreacted reagent and from any by-products which may have been formed. The present work is concerned with the determination of the phase equilibrai among the materials uranium hexafluoride, chlorine trifluoride, and hydrogen fluoride. metal with chlorine trifluoride-hydrogen fluoride solutions or as a result of treating many uranium compounds and ores with chlorine trifluoride. These phase equilibria define the physical conditions necessary for separating the components by the processes of crystallization or distillation and have made possinle the successful Operation of a pilot plant for the direct recovery of uranium hexafluoride from spent metallic uranium fuel elements. (auth)
Date: October 31, 1958
Creator: Bernhardt, H.A.; Barber, E.J.; Davis, W. Jr. & McGill, R.M.
Partner: UNT Libraries Government Documents Department

Modeling downwind hazards after an accidental release of chlorine trifluoride

Description: A module simulating ClF{sub 3} chemical reactions with water vapor and thermodynamic processes in the atmosphere after an accidental release has been developed. This module was liked to the HGSYSTEM. Initial model runs simulate the rapid formation of HF and ClO{sub 2} after an atmospheric release of ClF{sub 3}. At distances beyond the first several meters from the release point, HF and ClO{sub 2} concentrations pose a greater threat to human health than do ClF{sub 3} concentrations. For most of the simulations, ClF{sub 3} concentrations rapidly fall below the IDLH. Fro releases occurring in ambient conditions with low relative humidity and/or ambient temperature, ClF{sub 3} concentrations exceed the IDLH up to almost 500 m. The performance of this model needs to be determined for potential release scenarios that will be considered. These release scenarios are currently being developed.
Date: May 1, 1996
Creator: Lombardi, D.A. & Cheng, Meng-Dawn
Partner: UNT Libraries Government Documents Department

Chemical applications of molecular quantum theory

Description: Molecular systems of chemical interest are investigated with the aid of molecular quantum theory. The self-consistent field (SCF) method is used to predict the molecular structures of ClF/sub 2/, ClF/sub 4/ and Cl/sub 3/ radicals, and the ions ClF/sub 2//sup +/, ClF/sub 2//sup -/, ClF/sub 4//sup +/ and ClF/sub 4//sup -/. The ClF/sub 2/ and Cl/sub 3/ radicals are predicted to be bent with bond angles of 145.2/sup 0/ and 158.6/sup 0/, respectively, while the ions ClF/sub 2//sup +/ and ClF/sub 2//sup -/ are predicted to be bent with a bond angle of 97.4/sup 0/ and linear, respectively. The geometry predictions for the ClF/sub 4/ radical and the ClF/sub 4//sup +/ ion are found to be notably basis set dependent. The ClF/sub 4//sup -/ ion is predicted to be square-planar. Multi-configuration self-consistent field (MCSCF) calculations have yielded the dipole moment function for the /sup 1/sigma/sup +/ state of HI, which qualitatively confirms the experimental finding that the dipole derivative at R/sub e/ is negative. The /sup 2/sigma/sup +/ F + H/sub 2/ potential energy surface is studied extensively with the configuration interaction (CI) method. The most complete calculations yield an activation energy of 2.74 kcal/mole and an exothermicity of 30.0 kcal/mole. The production of a potential energy surface of ''chemical accuracy'' for this system is found to be more difficult than previously believed. The simplest hydrophobic model, the water-methane system, is studied with the SCF method in order to determine the nature and magnitude of the interaction. The most favorable geometric arrangement corresponds to an attraction of 0.5 kcal/mole.
Date: September 1, 1977
Creator: Ungemach, S.R.
Partner: UNT Libraries Government Documents Department