Systematic errors in vacuum and inert gas fusion analysis for oxygen in metals

Determinations of oxygen in metals by conventional vacuum or inert gas fusion are usually based on the assumption that oxygen is extracted from the melt wholly as carbon monoxyde. A qualitative thermodynamic approach is used to demonstrate that whilst this is true for most metals in the Periodic Table, a significant number of them can yield oxygen partially as gaseous species other than carbon monoxide, so that systematic errors are obtained. Practical suggestions are made to overcome this inconvenience. Vacuum fusion and neutron activation results on different metals are given.     

The velocity distribution of clusters generated by inert gas condensation

The velocity distribution of sodium chloride clusters produced by inert gas condensation is determined by means of a mechanical chopping technique. It is found to be the same for all cluster sizes between 1 and more than 200 molecular units per cluster, ruling out the possibility of cluster mass separation by velocity filters. This is explained by an adiabatic expansion occuring during the cluster's exit from the condensation chamber into the high vacuum of the mass spectrometer.     

Recovery of plutonium from carbonate wash solutions

A novel method has been developed for recovery of plutonium and uranium from carbonate wash solutions generated during solvent wash process involved in the reprocessing of high burn up FBTR fuel. The proposed method involves a selective coprecipitation of Pu and U by adding ammonium hydroxide to the pre acidified carbonate wash solution. Substantial removal of DBP by successive steps of coprecipitation, completely eliminates the possibility of undesired solid formation which is mainly due to the presence of high content of DBP. By adopting this method, an excellent decontamination factor for DBP has been achieved without any crud/solid formation. Phosphate content in the final oxide product meets the product specifications. Flowsheet condition necessary for the recovery process for plutonium from the aqueous carbonate solution is formulated and adopted in the CORAL facility.     

Recovery of plutonium and cerium from alumina crucible

Journal of Radioanalytical and Nuclear Chemistry - Plutonium recovery is inevitable from plutonium bearing alumina crucibles generated over the years as part of carbon analysis during chemical...     

惰气熔融-红外吸收光谱法测定镧铈稀土钢中氧含量

高品质稀土钢要求进行精确低氧含量控制,而依据现有GB/T11261-2006标准进行氧含量测定,检测结果具有较大的不准确性。本研究以具有不同镧、铈稀土元素含量的稀土钢为对象,以其氧含量精确测定为目标,基于惰气熔融-红外吸收法,开展了分析功率、助熔剂和称样量对镧铈稀土钢中氧含量分析结果的影响研究。结果表明,对于不同镧、铈元素含量的稀土钢,需要采用不同的分析方法：当稀土钢中的镧、铈含量较低时,通过降低分析功率即可较为精确的测定稀土钢中的氧含量;对于镧、铈含量较高的稀土钢,在调控分析功率（分析功率在4000W～4500W）的基础上,需同时采用锡作为助熔剂,并将助熔剂与样品比例设定为1:1（称样量为0.3g～0.6g）,即可实现氧含量的精确测定。精密度验证实验结果显示,采用本研究所建立的方法,氧含量测试结果相对标准偏差（RSD）小于8.0%;采用钢标样进行回收率实验,回收率值在97%～108%,而加标回收率略有升高的原因在于助熔剂Sn降低了合金熔点,使少量难熔氧化物中的氧得到更充分释放。本研究所建立的分析方法可准确测定不同镧、铈元素含量稀土钢中的氧含量。     

Simultaneous microdetermination of water and oxygen in metal halides by reductive fusion in an inert gas

The carrier-gas technique has been used for the simultaneous determination of water and oxygen impurities in metal halides. In a hot carbon crucible these impurities are converted to hydrogen and carbon monoxide, which are separated on a MS 5A column and determined with a zirconia solid electrolyte detector with a coupled feedback circuit. The measuring range is 1–1000 p.p.m. in samples of 1–20 mg.     

Quantitative analysis of trace bulk oxygen in silicon wafers using an inert gas fusion method.

This paper describes a method for removing oxide film from the surface of silicon wafers using an inert gas fusion impulse furnace and precise determination of bulk oxygen within the wafer. A silicon wafer was cut to about 0.35 g (6 x 13 x 2 mm) and dropped into a graphite crucible. The sample was then heated for 40 s at 1300 degrees C. The wafer's oxide film was reduced by carbon and removed as carbon monoxide. The treated silicon sample was taken out of the graphite crucible and maintained again with the holder of the oxygen analyzer. The graphite crucible was then heated to 2100 degrees C. The treated silicon sample was dropped into the heated graphite crucible and the trace bulk oxygen in the wafer was measured using the inert gas fusion infrared absorption method. The relative standard deviations of the oxygen in silicon wafer samples with the removed surface oxide film were determined to be 0.8% for 9.8 x 10(17) atoms/cm3, and 2.7% for 13.0 x 10(17) atoms/cm3.     

Recovery of plutonium from aqueous waste solutions using porous zirconia spherical particles

Based on the Linssi database and UniSampo/Shaman software, an automated analysis platform has been setup for the analysis of large amounts of gamma-spectra from the primary coolant monitoring systems of a CANDU reactor. Thus, a database inventory of gaseous and volatile fission products in the primary coolant of a CANDU reactor has been established. This database is comprised of 15,000 spectra of radioisotope analysis records. Records from the database inventory were retrieved by a specifically designed data-mining module and subjected to further analysis. Results from the analysis were subsequently used to identify the reactor coolant half-life of ¹³⁵Xe and ¹³³Xe, as well as the correlations of ¹³⁵Xe and ⁸⁸Kr activities.     

Calculation of diatomic van der Waals systems inert gas Atom-Halogen type inert gas ion in the ground state

Interatomic potentials are calculated for the systems inert gas ion in the ground state-inert gas atom Ne⁺, Xe⁺ -Ne, Ar, Kr, Xe, Fr. The calculation is performed by the effective pseudopotential method using the new form of the polarization interaction potential obtained by calculating the most important polarization diagrams of perturbation theory in the Thomas-Fermi approximation. The quasimolecular states of these van der Waals systems are calculated to refine the available data; some data are obtained for the first time. Translated fromZhumal Strukturnoi Khimii, Vol. 39, No. 4, pp. 591–595, July–August, 1998.     

Spectroscopy of large molecules in inert gas clusters

Aromatic hydrocarbons provide nucleation centers for the formation of clusters of inert gases in high-flow supersonic beams. Large clusters of Ar, each containing a single tetracene (T) molecule, were prepared by supersonic expansion of the seeded gas at pressures p = 3000–13000 Torr and interrogated by laser-induced fluorescence spectroscopy Evidence is reported for homogeneous line broadening of large TAr_n clusters prepared at p? 8000 Torr.     

Formation of plutonium/IV/ colloid from plutonyl cations

Solutions of plutonyl cations in dilute acids gradually form Pu/IV/ polymer under the influence of alpha radiations. These systems have properties that can be illuminated by assuming conditions to be near equilibrium and constrained by mass conservation.Mound is operated by Monsanto Research Corporation for the U.S. Department of Energy under Contract DE-AC04-76-DP00053.     

Recovery and purification of plutonium in lean plutonium product stream obtained during reprocessing of fast reactor spent fuels

A method has been developed for final purification of plutonium from uranium and fission products of high beta gamma activity. This method involves selection of a suitable ion exchange resin for the purification of plutonium in order to deliver a quality PuO₂ product. The effect of the concentration of uranium and plutonium, effect of increased loading of uranium and number of bed volumes for effective washing, which are some of the parameters that generally affect the recovery and purification of plutonium were investigated. An excellent decontamination factor for fission products has been achieved by this anion exchange process which in turn delivered an excellent PuO₂ product quality in terms of purity and associated beta gamma activity with low personnel radiation exposure.     

Quantitative determination of oxygen in silicon by combination of FTIR-spectroscopy,inert gas fusion analysis and secondary ion mass spectroscopy

Analytical and Bioanalytical Chemistry - VLSI devices are almost exclusively fabricated on Czochralski (CZ) silicon containing high concentrations of interstitially dissolved oxygen ([Oi] ∼...     

Comparison of a modified Kjeldahl and a vacuum fusion technique for determination of nitrogen in tantalum alloys

Results obtained for the determination of nitrogen in the tantalum alloys T-111 (Ta-8 W-2 Hf) and T-222 (Ta-10 W-2.5 Hf-0,1C) by Kjeldahl and vacuum fusion procedures are compared. Results obtained by each technique are shown for the determination of nitrogen m the MAB T-111 sample, two commercial T-111 samples and a commercial sample of T-222 alloy. In the 5-25 ppm range, the relative standard deviation was 3-9% by the Kjeldahl procedure and 4-8% by vacuum fusion. This is a measure of the homogeneity of the material as well as of the reproducibility of the results. The agreement of the results obtained by these two techniques increases confidence in the vacuum fusion results for nitrogen in tantalum.     

Recovery of plutonium from phosphate containing aqueous analytical waste solutions using macroporous anion exchange resin

Distribution ratios of Pu(IV) between 7.5M HNO₃+0.75M H₃PO₄+0.3M H₂SO₄ media and a macroporous anion-exchange resin Amberlyst A-26 (MP) increased from 40 to 250 when 1M aluminium nitrate was added to the aqueous medium. When 1M ferric nitrate was used in place of aluminium nitrate the distribution ratio further increased to 850. The 10% Pu(IV) breakthrough capacities with a 5 ml bed resin column, using synthetic feed solutions containing 1M aluminium nitrate, were 1.4 g l^–1, 3.2 g l^–1 at flow rates of 30 ml per hour and 10 ml per hour, respectively. The corresponding 10% Pu(IV) breakthrough capacities in the presence of 1M ferric nitrate were 8.5 g l^–1 and 12.8 g l^–1. More than 97% of plutonium could be recovered from actual analytical phosphate waste solutions.     

Recovery of plutonium from oxalate supernatant using 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone

Summary Extraction of Pu(IV) from oxalate supernatant was carried out employing 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) in xylene as extractant. The conditions for quantitative extraction were determined by the variation of ligand, oxalic acid and nitric acid concentration. Quantitative stripping was achieved using a mixture of 0.4M oxalic acid and 0.4M ammonium oxalate. Extraction of Pu(IV) from synthetic oxalate supernatant solution containing 3M nitric acid and 0.2M oxalic acid was investigated under various loading conditions employing 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone in xylene as extractant. Under uranium loading conditions the Pu extraction decreased significantly while with increased Pu loading whereas the D_Pu value was influenced marginally. The effect of a redox reagent on Pu extraction was also investigated.     

Recovery of americium from analytical solid waste containing large amounts of uranium,plutonium and silver

Trace metallic impurity analysis by spectroscopic techniques is one of the important steps of chemical quality control of nuclear fuel materials. Depending on the burn-up and the storage time of the fuel, there is an accumulation of ²⁴¹Am in plutonium based fuel materials due to β decay of ²⁴¹Pu. In this paper, attempts were made to develop a method for separation of ²⁴¹Am from 1.2 kg of analytical solid waste containing 70% U, 23% Pu, 5% Ag and 1–2% C as major constituents along with other minor constituents generated during trace metal assay of plutonium based fuel samples by d. c. arc carrier distillation atomic emission spectrometry. A combination of ion exchange, solvent extraction and precipitation methods were carried out to separate ~45 mg of ²⁴¹Am as Am(NO₃)₃ from 15 L of the analytical waste solution. Dowex 1×4 ion exchange chromatographic method was used for separation of Pu whereas 30% TBP–kerosene was utilized for separation of U. Am was separated from other impurities by fluoride precipitation followed by conversion to nitrate. The recovery of Pu from ion exchange chromatographic separation step was ~93% while the cumulative recovery of Am after separation process was found to be ~90%.     

Investigation of cocrystallization of diamond and graphite from the gas phase

Conclusions A procedure was developed for separate determination of the rates of growth of diamond and graphite during their cocrystallization on diamond seed powders during thermal decomposition of methane, using the Kolmogorov theory for the change in the electric conductivity of the powder layer during growth.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 983–987, May, 1980.The authors thank Yu. N. Tolmachev and V. L. Bukhovets for carrying out the etching of the powders overgrown in the glow-discharge plasma.