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The crystal structure of neptunium metal

Description: From abstract: "In this paper the number of displaced atoms in equilibrium in a thin cyclotron-bombarded target is estimated as a function of the bombarding particle energy and target temperature."
Date: January 4, 1952
Creator: Zachariasen, William H.
Partner: UNT Libraries Government Documents Department

Spectrophotometry of Neptunium in Perchloric Acid Solutions

Description: Report discussing a study testing features of the absorption spectra of different oxidation states of neptunium and perchloric acid concentration's effects on the spectra. Data regarding a disproportionation reaction present in neptunium(V) solutions in concentrated acid is included.
Date: April 14, 1950
Creator: Sjoblom, R. K. & Hindman, J. C.
Partner: UNT Libraries Government Documents Department

Isotopes of Neptunium and Plutonium

Description: This report describes work done that originated in an effort to identify previously unknown isotopes of neptunium and plutonium and to characterize a few that were known for extension of the nuclear energy surface. The findings of this work results in two new light plutonium isotopes and one heavy neptunium isotope that were produced by bombardment of uranium with helium and deuteron ions from a 60-inch cyclotron and a 184-inch cyclotron. The chemical and experimental methods are described as well as the results of the bombardment work for each nuclide.
Date: December 1950
Creator: Orth, Donald Alfred
Partner: UNT Libraries Government Documents Department

Heat and Free Energy of the Neptunium (IV)-(V) Couple in Perchloric Acid

Description: Abstract: "The potential of the Np(IV)-Np(V) couple is not directly measurement since the couple does not establish reversible equilibrium at an inert electrode. Reproducible potential measurements were obtainable, however, in solutions containing Np(IV), Np(V), Pe(II), and Pe(III) ions in oxidation-reduction equilibrium. The expected fourth power hydrogen ion dependence of the Np(IV)-Np(V) couple was confirmed over the range 0.25-1.0 molar perchloric acid concentration. The heat of the reaction NpO2+ + 1/2 H2 + 3H+ = Np-(+4) + 2 H2O in 1 molar perchloric acid solution was determined from the electromotive force temperature coefficient to be -36.3 +/- 0.3 kg.-cal. The formal potential of the Np(IV)-Np(V) couple is -0.746 v. at 25 degrees in 1 molar perchloric acid solution."
Date: March 8, 1951
Creator: Magnusson, L. B. & Huizenga, John R.
Partner: UNT Libraries Government Documents Department

Occurrence of the 4n + 1 Series in Nature

Description: "A small quantity of a Np-237, the long-lived ancestor of the 4n + 1 series, has been isolated from a natural source. The Th-229 content of the Th-230 obtained from Belgian Congo pitchblende concentrate and of Th-232 obtained from Brazilian monazite has been determined indirectly through isolation of the Ac-225 daughter. The mass ratio of Np-237 to U-238 in the Belgian Congo pitchblende concentrate has been determined as (1.8 +/- 0.4) x 10-(-12). The mass ratio of U-233 to U-238 in the same ore deposit is found to be (1.3 +/- 0.2) x 10-(-13). The ratio of the respective neutron-capture cross sections of U-238 in the ore body for the (n, 2n) and (n, gamma) reactions is calculated to be (1.3 +/- 0.6) x 10-(-3) on the basis of the relative Np-237 and Pu-239 contents."
Date: April 10, 1952
Creator: Peppard, D. F.; Mason, G. W.; Gray, P. R. & Mech, J. F.
Partner: UNT Libraries Government Documents Department

THERMODYNAMICS OF NEPTUNIUM(V) FLOURIDE AND SULFATE AT ELEVATED TEMPERATURES

Description: Complexation of neptunium(V) with fluoride and sulfate at elevated, temperatures was studied by microcalorimetry. Thermodynamic parameters, including the equilibrium constants and enthalpy of protonation of fluoride and sulfate, and the enthalpy of complexation between Np(V) and fluoride and sulfate at 25-70 C were determined. Results show that the complexation of Np(V) with fluoride and sulfate is endothermic and that the complexation is enhanced by the increase in temperature--a threefold increase in the stability constants of NpO{sub 2}F(aq) and NpO{sub 2}SO{sub 4}{sup -} as the temperature is increased from 25 to 70 C.
Date: March 6, 2006
Creator: Rao, L.; Tian, G.; Xia, Y. & Friese, J.I.
Partner: UNT Libraries Government Documents Department

The Heat of Solution of Neptunium Metal and the Heats of Formation of some Neptunium Chlorides ; A Microcalorimeter for Heat of Solution Measurements

Description: Due to a need of precise thermodynamical and thermochemical data on these elements and their compounds for the understanding and correlation of the chemical behavior of these substances, this report measures the heat of the solution of neptunium metal and the heats of formation of the neptunium chlorides using a microcalorimeter to measure the heat.
Date: August 1950
Creator: Westrum, Edgar F., (Jr.) & Eyring, LeRoy
Partner: UNT Libraries Government Documents Department

Hydrothermal growth kinetics of Np(IV) oxide

Description: Toulouse, France All previous knowledge leading to this estimate is of NpO2(c) is indirect, based on thermodynamic cycles. The phase itself has heretofore not been observed as a precipitate from aqueous solution. Recent attempts (e.g., Nitsche et al., 1993; Efurd et al., 1996) to establish solubility controls on Np in oxidizing groundwaters (including J-13 groundwater) starting from high concentrations (i.e., supersaturation) have shown the formation of one or both of two Np(V) phases, NaNpO2CO3:3.5H2O(c) (with variable stoichiometry) and Np2O5(c). These are both highly soluble, yielding Np concentrations on the order of 1 x 10 -4 to 1 x 10 -3 molal, in accord with existing thermodynamic data for these phases. No evidence was found of the formation of NpO2(c). Under reducing conditions, experiments (Rai et al., 1987 and references cited therein) have shown the formation of Np(IV) polymer, which may be viewed as a hydrated form of NpO2. It is orders of magnitude less soluble than the Np(V) phases, but still orders of magnitude more soluble than NpO2(c). No undersaturation experiments with NpO2(c) are known to have been performed. However, both NpO2(c) and Np(IV) polymer are known to be difficult to dissolve. We have hypothesized that NpO2(c) is simply a phase that is slow to form at low temperature. In this regard, it would be analogous to such minerals as quartz, dolomite, and hematite. It is well known that it is difficult to impossible to demonstrate the formation of such minerals in low temperature experiments on feasible time scales. However, it is possible to demonstrate their formation and measure the kinetics of the process by conducting experiments at elevated temperatures, generally in the range of 150-300 o C (e.g., Rimstidt and Barnes, 1980; Sibley et al., 1984). By developing kinetic models, it should be possible to estimate the appropriate time ...
Date: May 11, 1998
Creator: Palmer, C. E.; Roberts, K. & Wolery, T. J.
Partner: UNT Libraries Government Documents Department

Effect of Precipitation Conditions on the Specific Surface Area of Neptunium Oxide

Description: Neptunium oxalate was precipitated under nominal and bounding HB-Line flowsheet conditions. The nominal case represents expected normal HB-Line operation. The bounding case represents process flowsheet extremes that could occur which are anticipated to decrease particle size and increase surface area. The neptunium oxalate produced under bounding conditions was used to validate the effectiveness of HB-Line calcination conditions. The maximum specific surface area of the neptunium oxide (NpO2) used in gas generation testing was 5.34 m2/g. Experiments were conducted to verify that even under bounding precipitation conditions the SSA of NpO2 produced would remain within the range evaluated during gas generation testing. The neptunium oxalate from nominal and bounding precipitation conditions was calcined at 600 degrees Celsius and 625 degrees Celsius, respectively, to form NpO2. Samples from each batch of neptunium oxalate were calcined for one, two, or four hours. Results indicate that the SSA of NpO2 continues to decrease between one and four hours. After two hours of calcination at 625 degrees Celsius, the SSA of NpO2 from the bounding case meets the surface area requirements for limiting moisture uptake.
Date: June 1, 2004
Creator: HILL, BENJAMINC.
Partner: UNT Libraries Government Documents Department

RECOVERY OF Np$sup 237$ AND Pu$sup 238$ FROM IRRADIATED NEPTUNIUM OXIDE

Description: An ion exchange process was demonstrated for the recovery of Pu/sup 238/ from irradiated neptunium oxide. Three cycles of anion exchange proved adequate for the removal of fission products and for the separation of the neptunium and plutonium from each other. (auth)
Date: November 1, 1959
Creator: Burney, G.A. & Prohaska, C.A.
Partner: UNT Libraries Government Documents Department

Transuranic interfacial reaction studies on manganese oxidemineral surfaces

Description: Several DOE sites have been contaminated by transuranicradionuclide (TRU) discharges including neptunium and plutonium. Theirinteraction with the surrounding geological media can affect thetransport and remediation of these radionuclides in the environment.Manganese based minerals, present as minor phases in the vadose zone, canpreferentially sequester TRU over other minerals present in largerquantities. The objective of this project is to understand theinteractions between plutonium and neptunium and manganese oxyhydroxideminerals to predict potential hazards they represent to the environment,as well as to provide important scientific information for the design ofeffective remediation strategies for contaminated DOE sites.
Date: May 15, 2002
Creator: Shaughnessy, Dawn A.; Nitsche, Heino; Serne, R. Jeffrey; Shuh,David K.; Waychunas, Glenn A.; Booth, Corwin H. et al.
Partner: UNT Libraries Government Documents Department

Gas Generation Testing of Neptunium Oxide Generated Using the HB-Line Phase IIFlowsheet

Description: The hydrogen (H{sub 2}) gas generation rate for neptunium dioxide (NpO{sub 2}) samples produced on a laboratory scale using the HB-Line Phase II flowsheet has been measured following exposure to 75% relative humidity (RH). As expected, the observed H{sub 2} generation rates for these samples increase with increasing moisture content. A maximum H{sub 2} generation rate of 1.8 x 10{sup -6} moles per day per kilogram (mol {center_dot} day{sup -1} kg{sup -1}) was observed for NpO{sub 2} samples with approximately one and one-half times (1 1/2 X) the expected specific surface area (SSA) for the HB-Line Phase II product. The SSA of NpO{sub 2} samples calcined at 650 C is similar to plutonium dioxide (PuO{sub 2}) calcined at 950 C according to the Department of Energy (DOE) standard for packaging and storage of PuO{sub 2}. This low SSA of the HB-Line Phase II product limits moisture uptake to less than 0.2 weight percent (wt %) even with extended exposure to 75% RH.
Date: August 29, 2003
Creator: Duffey, J
Partner: UNT Libraries Government Documents Department

NEPTUNIUM OXIDE PROCESSING

Description: The Savannah River Site's HB-Line Facility completed a campaign in which fifty nine cans of neptunium oxide were produced and shipped to the Idaho National Laboratory in the 9975 shipping container. The neptunium campaign was divided into two parts: Part 1 which consisted of oxide made from H-Canyon neptunium solution which did not require any processing prior to conversion into an oxide, and Part 2 which consisted of oxide made from additional H-Canyon neptunium solutions which required processing to purify the solution prior to conversion into an oxide. The neptunium was received as a nitrate solution and converted to oxide through ion-exchange column extraction, precipitation, and calcination. Numerous processing challenges were encountered in order make a final neptunium oxide product that could be shipped in a 9975 shipping container. Among the challenges overcome was the issue of scale: translating lab scale production into full facility production. The balance between processing efficiency and product quality assurance was addressed during this campaign. Lessons learned from these challenges are applicable to other processing projects.
Date: May 27, 2009
Creator: Jordan, J; Watkins, R & Hensel, S
Partner: UNT Libraries Government Documents Department