Plutonium in soils, bottom sediments and lichen near peaceful nuclear explosion sites in the Republic of Sakha (Yakutia)

During the 1974–1987 period 12 paceful nuclear explosions were conducted in the Republic of Sakha (Yakutia). For the first time^239,240Pu and²³⁸Pu concentrations were determined in samples of soils, bottom sediments and lichen taken at the Craton-3 and Crystal nuclear explosion sites. At the Craton-3^239,240Pu concentrations in the range 6.2 mBq/g to 5.9 Bq/g samples of soil and^239,240Pu concentrations up to 7.4 Bq/g in samples of lichen were observed.^239,240Pu concentration measurements in bottom sediments of a stream washing out the banking around the borehole of Craton-3 show that plutonium migrates in the direction of the Markha river. At the Crystal site local plutonium concentrations up to 35 Bq/g in soil and 1.8 Bq/g in lichen were observed.     

Plutonium concentration distribution in bed load sediment samples along the Romanian sector of the Danube river and the Black Sea coast

The concentrations of²³⁸Pu and^{239, 240}Pu were determined in 12 sediment samples collected from the bed of the Romanian Danube river and Black Sea coast during June–September 1994. After the sample material has been properly prepared and²⁴²Pu tracer added, plutonium was separated from americium and curium by anion exchange. After electrodeposition on stainless steel discs the elements were counted with an -spectrometry system with silicon surface-barrier detectors. The^{239, 240}Pu concentrations range between 150 and 800 mBq kg^–1 dry, while the²³⁸Pu concentrations rise up to max 150 mBq kg^–1 dry. Although the chemical yields are rather low (51%) we appreciate the results as valuable since they report for the first time the distribution of the plutonium contamination along the Danube river and the Black Sea coast-Romanian sector.     

Determination of the plutonium concentration by isotope dilution mass spectrometry using239Pu as a spike

A method is described for the determination of plutonium concentration in the presence of a bulk of other impurities by isotope dilution mass spectrometry /IDMS/ using²³⁹Pu as a spike. The method involves the addition of²³⁹Pu spike / 90 atom%/ to samples with²³⁹Pu / 70 atom%/ and vice versa. After ensuring chemical exchange between the sample and the spike isotopes, plutonium is purified by conventional anion exchange procedure in 7M HNO₃ medium.²³⁹Pu/²⁴⁰Pu atom ratio in the purified spiked sample is determined with high precision /better than 0.1%/ using a thermal ionization mass spectrometer. Concentration of plutonium in the sample is calculated from the changes in²³⁹Pu/²⁴⁰Pu atom ratio in the spiked mixture. Results obtained on different plutonium samples using²³⁹Pu as a spike are compared with those obtained by the use of²⁴²Pu spike. Precision and accuracy comparable to those achieved by using²⁴²Pu are demonstrated. The method provides an alternative in the event of non-availability of enriched²⁴²Pu or²⁴⁴Pu required in IDMS of plutonium and at the same time, offers certain advantages over the use of²⁴²Pu or²⁴⁴Pu spike.     

Determination of239,240Pu and241Am in environmental samples

An accurate and reliable method has been developed and routinely carried out for the sequential determination of^239,240Pu and²⁴¹Am in environmental samples. After suitable pretreatment.^239,240Pu and²⁴¹Am are separated from other elements by means of the anion exchange resin method. Americium-241 is purified by coprecipitation with calcium oxalate and then ion exchanged in mixed media of the mineral acid-methanol. In the analysis,²⁴²Pu (or²³⁶Pu) and²⁴⁴Cm are used as chemical yield monitors. The recoveries of the yield monitors in the analyses of some kinds of environmental samples were 7080% for plutonium and 7686% for curium. The concentration of^239,240Pu in the coastal sea water were 7.022 Bq/l and that of²⁴¹Am was 1.26.3 Bq/l. The mean concentrations of^239,240Pu in the edible parts of the marine products ranged from 0.22 to 7.4 mBq/kg · fresh and those of²⁴¹Am ranged from 0.11 to 2.6 mBq/kg · fresh.     

Thermal Expansion of Mixed Zirconium Phosphates

A series of framework phosphates with varied ratio of cations Na_5-2x B _x ^IIZr(PO₄)₃, B^II = Mg, Ca, Sr, Ba (0 x 2) and Na_5-3x Fe _x Zr(PO₄)₃ (0 x 1.33) were synthesized and studied under heating. The coefficients of thermal expansion along crystal axes _a and _c were calculated, and their dependences on the cationic composition (nature and concentration) and on the occupancy of out-of-framework structural positions were established.     

The relative permittivity of 1,2-ethanediol+2-methoxyethanol+water ternary mixtures

The relative permittivities for the ternary 1,2-ethanediol (component 1) + 2-methoxyethanol (2) + water (3) solvent system have been measured for 66 mixtures covering the whole mole fraction composition 0X₁/X₂/X₃ 1 range at –10, –5 and 0 °C. The experimental data were used to test some empirical relations stating the dependence of = (X₁, X₂, X₃). A comparison between the calculated and experimental data show that these equations can be usefully employed to predict values in correspondence of the experimental data gaps.     

Field performance test of PASS,an instrument for the rapid assay of plutonium and other γ-ray emitting radionuclides

A field performance test was conducted at the INEL with the mobile Rapid Transuranic Monitoring Laboratory (RTML) that was developed for the analysis of samples from sites or facilities potentially contaminated with plutonium, other actinides, and -ray emitting activation and fission-product radionuclides. The performance test and results are described for the Photon Analysis Spectrometer System (PASS), one of three RTML assay systems. This system consists of a thin-window, n-type Ge spectrometer, that automatically analyzes soil, smear, and air particulate-filter samples for actinides emitting L x rays, and for activation and fission products that emit rays. The measurements were blind and performed with 11-g soil samples gathered from the Cold Test Pit and with spiked samples containing known mixtures of²³⁹Pu,²⁴¹Am⁶⁰Co, and¹³⁷Cs. In the spiked samples the plutonium activity concentrations ranged from 75 to 500 pCi/g while the other radionuclides ranged from 10 to 130 pCi/g. Lower limits of detection (LLDs) were verified to be 1, 5, 5, and 40 pCi/g for²⁴¹Am,⁶⁰Co,¹³⁷Cs, and²³⁹Pu, respectively. Results from the performance test are presented.     

Kinetics and Mechanism of a Reaction of Phenylacetylene with Carbon Monoxide and Butanol in Toluene Catalyzed by a Palladium(0) Complex in the Presence of Trifluoroacetic Acid and Triphenylphosphine

The reaction of phenylacetylene with CO and n-butanol in toluene (363 K) catalyzed by the Pd(dba)₂/m(CF₃COOH)/n(Ph₃P) system (dba is dibenzylideneacetone; 2 m 8; 10 n 30) is studied. The initial rate of the main product (butyl 2-phenylpropenoate) buildup is found to depend on the pressure of CO and the concentrations of reactants and system components. The state of the catalyst under reaction conditions is studied in situby IR spectroscopy. A kinetic model is developed based on the experimental results. This model corresponds to the mechanism that resembles the hydride mechanism in the type of main intermediates in the catalytic cycle.     

Graphite hydrogenation in the presence of a mixture of powdered Ni and Zr

Strong promoting action of Zr in graphite hydrogenation in the presence of catalysts based on physical mixtures of powdered Ni and Zr has been established. The catalytic effect is ascribed to the extent of Zr surface oxidation.

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The position of plutonium/III/ in the lanthanide series in respect to thermodynamic functions of complex formation with nitrates and thiocyanates

The position of Pu/III/ within lanthanides in respect to G⁰, H⁰ and S⁰ of complex formation with nitrate and thiocyanate ligands was determined by the extraction method. It was found that in respect to G⁰, Pu/III/ is a light pseudolanthanide for nitrate ligands and a heavy pseudolanthanide for thiocyanate ligands. A comparison of the positions of Pu/III/ and Am/III/ in respect to G⁰, H⁰ and S⁰ shows that the radius of plutonium is greater than that of americium in the An/NO₃/ ₅ ^2– complex and smaller in the An/NCS/₃/TBP/_n complex. The increase in the radii between plutonium and americium in the thiocyanate complex points out to a contribution from 5f orbitals to bonding.     

Plutonium and americium in sediment samples along the Romanian sector of the Danube river and the Black Sea coast

The concentrations of²³⁸Pu,^239,240Pu and²⁴¹Am were determined in eight sediment samples, collected from the bed of the Romanian sector of the Danube river and the Black Sea coast during 1994 and 1995. Fusion with potassium carbonate was used to achieve complete dissolution of the samples. Tracers,²⁴²Pu and²⁴³Am, were added and the separation of plutonium from americium, uranium and thorium was performed by anion exchange. Americium was separated from uranium in two steps, using a conventional anion exchange resin and an extraction chromatographic resin for transuranics. After electrodeposition on stainless steel discs the nuclides were counted with -spectrometry with -PIPS detectors. The total plutonium concentrations obtained by this method were compared with the acid leachable plutonium concentrations reported for the same samples in a previous paper.     

Photoakustikspektroskopische Untersuchungen an Filtergl?sern

Zusammenfassung Verschiedene Filtergläser wurden mit Hilfe der Photoakustikspektroskopie im Bereich 300800 nm untersucht. Die Ergebnisse zeigten, daß die PAS wertvolle spektroskopische Informationen liefern kann, die die Transmissionsmessungen ergänzen können. Absorptionsmaxima, die durch Transmissionsmessung nicht erfaßbar sind (T10^–5), können bestimmt und den farbgebenden Kationen zugeordnet werden.

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Investigation of filter glasses by photo-acoustic spectroscopy

Summary Various filter glasses were investigated in the range of 300800 nm by photo-acoustic spectroscopy. The results showed that PAS is able to deliver valuable spectroscopic information supplementary to transmission measurements. Absorption maxima which are not detectable by transmission measurements (T10^–5) can be determined and attributed to the dyeing cations.

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Die Arbeit wurde durch Mittel der Deutschen Forschungsgemeinschaft und des Verbandes der Chemischen Industrie — Fonds der Chemie — sowie der Fa. Henkel KGaA unterstützt, wofür wir an dieser Stelle herzlich danken. Den Glaswerken Schott in Mainz danken wir für die Überlassung der untersuchten Filtergläser.     

A toxic reagent-free method for normal-phase matrix solid-phase dispersion extraction and reversed-phase liquid chromatographic determination of aldrin,dieldrin, and DDTs in animal fats

A method for the determination of aldrin, dieldrin, DDT, DDE, and DDD contamination in animal fats (beef tallow, lard, and chicken fat) without using toxic reagents is developed, that uses high-performance liquid chromatography after the sample has been prepared by matrix solid-phase dispersion (MSPD) with acidic alumina oxide. A reversed-phase C₁-silica column with a mobile phase of 50% (v/v) ethanol solution (in water) and a photo-diode array detector were used for the determination. Average recoveries of the target compounds (0.2–5.0 g g^–1) ranged from 84–98%, with coefficients of variation of <5%. The limits of quantitation were 0.16 g g^–1 for AD, 0.10 g g^–1 for DD, 0.06 g g^–1 for DDT, 0.07 g g^–1 for DDE, and 0.05 g g^–1 for DDD. No toxic reagents were used at all.     

Reaction mechanism and principles of choosing catalysts for selective oxidation at C?H bonds

Reaction mechanism for selective oxidation of organic compounds at C–H bonds is discussed. The criteria of selecting catalysts for these reactions have been formulated; 1) fast heterolytic activation of C–H bonds; 2) relatively slow primary activation of oxygen; 3) fast diffusion of oxygen vacancies; 4) fast electron transfer from the adsorbed substrate to catalyst.

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C–H . : 1) C–H ; 2) ; 3) ; 4) .

     

Low temperature crystal and molecular structure of nitrobenzene

The crystal and molecular structure of nitrobenzene was determined at 103 K by X-ray diffraction, yieldingR=0.034 and a highly precise geometry of the molecule (esds of bond lengths 0.001 Å and bond angles 0.1°). The bond angles in the ring agree very well with additive scheme based on angular substituent parameters. X-X electron density maps support the view that the C-N bond does not exhibit-character, and, hence, the nitro group interacts with the ring mostly by inductive effects.     

Gas permeability of block copolymers of styrene and butadiene

The permeability of styrene-butadiene block copolymer foils with different composition prepared by casting and pressing has been investigated for the gases Ar, CO₂, and CH₄ at pressure difference of 400 mbar and at the temperature range 298 T [K] 333.The permeation process can be described by the solution diffusion mechanism. The diffusion coefficients decrease in the sequence of the gases Ar, CO₂, and CH₄ and the solubility coefficients increase in the sequence Ar, CH₄, CO₂.The dependence of the permeability on the composition of the block copolymer can be interpreted by the help of percolation theory and the effective medium theory. It follows the critical volume fraction of the percolation of the transport phase _PB ^c (= 0,23) and the coordination numberz (= 4) giving an information concerning the multiphase structure of the block copolymer.Presented in part at the 33^rd Annual Meeting of the Colloid-Gesellschaft, Graz, Austria, September 14–16, 1987.     

Ionic strength dependence of formation constants. Part 4. Potentiometric study of the system Cu2+-Ni2+-citrate

Summary The ternary Cu²⁺-Ni²⁺-citrate (cit^3–) system was investigated potentiometrically in aqueous solution, at different temperatures, 10t45°C, and ionic strengths, 0.03I0.8 mol dm^–3, using potassium nitrate or tetraethylammonium bromide as background salt. Since the citrate anion forms weak complexes with potassium, the stability constants here reported differ according to whether the potassium association is considered or not. In the presence of both Cu²⁺ and Ni²⁺, the mixed metal species, [CuNi(cit)₂H_–2]^4– is formed with citrate in solution, in addition to the various binary complexes. We have obtained the dependence for all the formation constants on ionic strength and temperature. The previous suggestions concerning a general equation for describing the dependence, log =f(I), are confirmed; from the study of log =f(T) we have obtained the values of thermodynamic parameters. The dependence of H on ionic strength is discussed.     

Thermodynamic data on chalcogenide glasses

The temperature-dependence of the specific heat near to the glass temperature was investigated for several Te- and As-based chalcogenide glasses, the latent heats of melting and crystallization of the former alloys also being measured. No thermal change could be detected in the transformation of the As-based alloys from the solid to the liquid state.

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Zusammenfassung Die Temperaturabhängigkeit der spezifischen Wärme verschiedener Te- und As-Chalkogenid Gläser wurde in der Nähe der Glastemperatur untersucht, indem die latente Schmelzwärme und die Kristallisation gemessen wurden. Bei den Legierungen auf As-Basis konnte nach dem Übergang von dem festen in den flüssigen Zustand keine thermische Veränderung nachgewiesen werden.

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Résumé On a étudié au voisinage de la température de la transition vitreuse la variation de chaleur spécifique en fonction de la température pour différents verres à base de chalcogénures de Te et As, en mesurant la chaleur latente de fusion et de cristallisation. Pour les alliages à base d'arsenic on n'a pas détecté de changement thermique après la transformation de l'état solide à l'état liquide.

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Te As . . As .

     

Dosage de micro quantités de cuivre bivalent par précipitation en picrate de cupritétrammine

Résumé On propose une méthode de dosage de microquantités de cuivre-II par précipitation sous forme de picrate de cupritétrammine. Cette méthode est fondée sur la précipitation du cuivre-II en présence d'un excès de picrate de sodium en milieu ammoniacal et sur le dosage colorimétrique de l'acide picrique résiduel après extraction sous forme de picrate de bleu de méthylène.Cette méthode permet le dosage de 1 à 10 g de cuivre-II, avec une erreur maximale de ± 5%.La présence des cations zinc (jusqu'à 200g), argent (jusqu'à 500g), cobalt (jusqu'à 50g), cadmium (jusqu'à 100g), nickel (jusqu'à 20,g) et chrome (jusqu'à 50 g) ne gêne pas le dosage.Cette méthode peut servir à doser le cuivre dans les cendres végétales.

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Summary A method is suggested for the determination of micro amounts of copper(II) by precipitation as the picrate of cupritetrammine. This method is based on the precipitation of the copper(II) in the presence of an excess of sodium pierate in an ammoniacal milieu and on the colorimetric determination of the residual picric acid, after extraction in the form of the picrate of methylene blue. This procedure permits the determination of from 1 to 10g of Cu(II) with a maximum error of ± 5%.The determination is not impaired by the presence of the cations: zinc up to 200 g), silver (up to 500g), cobalt (up to 50g), cadmium (up to 100g), nickel (up to 20g), and chromium (up to 50g).This method may be employed for determining copper in vegetable ashes.

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Zusammenfassung Bin Verfahren zur Bestimmung von Mikromengen Kupfer(II) durch Fällung als Kupfertetrammin-Pikrat wird vorgeschlagen. Es beruht auf der Fällung von Kupfer in Gegenwart überschüssigen Natriumpikrats in ammoniakhaltiger Lösung und der kolorimetrischen Bestimmung der restlichen Pikrinsäure nach Extraktion als Methylenblaupikrat. 1 bis 10g Cu(II) lassen sich mit einem maximalen Fehler von ± 5% bestimmen. Die Anwesenheit von < 200g Zn, < 500 g Ag, < 50g Co, < 100g Cd, < 2°g Ni und < 50g Cr stört die Bestimmung nicht. Das Verfahren eignet sich zur Bestimmung von Kupfer in Pflanzenasehen.

     

Metallreiche Phasen im ternären System Ni-Se-Te

Zusammenfassung Die metallreichen Phasen im System Ni-Se-Te wurden durch Röntgenaufnahmen bei Zimmertemp. und bei höheren Temperaturen sowie durchDTA untersucht. Bei Zimmertemp. wurden im pseudo-binären Schnitt Ni₃(Se_1-x , Te _x )₂ Phasen mit den folgenden Strukturen gefunden: rhomboedrischer Ni₃S₂-Typ fürx=0; tetragonaler (Ni,Fe)₁₁Se₈-Typ für 0,15x0,35; tetragonaler Rickardit-Typ für 0,50x0,80; Überstrukturen des Rickardit-Typs für 0,95x1. Bei höheren Temperaturen verbreitert sich das Homogenitätsgebiet der Phase mit der tetragonalen Rickardit-Struktur. Über 600–770°C tritt im ganzen Gebiet 0x1 eine kubisch.

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Metal-rich phases in the ternary system Ni-Se-Te

The metal-rich phases in the system Ni-Se-Te have been studied by X-ray diffraction at room temperature and elevated temperatures, and byDTA. At room temperature phases with the following structures were found in the pseudo-binary section Ni₃(Se_1-x , Te _x )₂: rhombohedral Ni₃S₂ type forx=0; tetragonal (Ni,Fe)₁₁Se₈ type for 0,15x0,35; tetragonal rickardite type for 0,50x0,80; superstructures of the rickardite type for 0,95x1. At higher temperatures the homogeneity range of the phase with the tetragonal rickardite structure broadens. Above 600–770°C a face-centered cubic phase exists in the whole range 0x1; a model for the structure of this phase is proposed. The compound Ni_2,6Te₂ is orthorhombic at room temperature; it becomes hexagonal at 720°C and disproportionates at 820°C; by partial substitution of Te by Se the hexagonal form is stabilized at room temperature. Similarly, the compound Ni₆Se₅ which is stable above 440°C only, is stabilized at room temperature by partial substitution of Se by Te. The phase Ni₆(Se_1-x , Te _x )₅ decomposes by a peritectoid reaction at 650° (x=0) to 590°C (x=0,3).

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Herrn Prof. Dr.H. Nowotny gewidmet.