Combined procedure for the determination of90Sr,241Am and Pu radionuclides in soil samples

A combined procedure for sequential determination of low level activity concentrations of⁹⁰Sr,²⁴¹Am and Pu radionuclides is described. The analysis of -emitters is performed by isotope dilution -spectrometry using²⁴²Pu or²³⁶Pu and²⁴³Am tracers. Strontium-90 is analyzed by liquid scintillation counting using the double energetic windows method. The method combines the well established, procedure for Pu analysis based on anion exchange, the powerful and selective method for Sr isolation based on extraction chromatography using Sr-Spec resin and finally it includes the application of the TRU-Spec column for separation and purification of the Am fraction. The radiochemical procedure was tested using IAEA reference and intercomparison materials. Major parameters of the procedure as well as advantages and drawbacks are discussed in detail.     

Increasing the sensitivity of241Pu determination for emission and immission control of nuclear installations by aid of liquid scintillation counting

A radiochemical procedure was developed and optimized which allows sensitive²⁴¹Pu measurement in various sample materials. As a first step, Pu isotopes are separated from matrix elements, purified radiochemically, electroplated, and measured by -spectrometry. The electrodeposited Pu is then redissolved in nitric acid and extracted with trioctylphosphinic oxide/cyclohexane. The organic phase is mixed with scintillator cocktail (PPO/Xylene) and Pu is measured with a liquid scintillation counter. The detection limit of the optimized procedure for a counting time of 100 minutes is 50 mBq²⁴¹Pu per sample at a 95% confidence level.     

Simultaneous determination of238Pu,239+240Pu,241Pu,241Am,242Cm,244Cm,89Sr,and90Sr in vegetation samples,and application to Chernobyl-fallout contaminated grass

A radiochemical procedure is described for the simultaneous determination of²³⁸Pu,^239+240Pu,²⁴¹Pu,²⁴¹Am,²⁴²Cm,²⁴⁴Cm,⁸⁹Sr, and⁹⁰Sr in vegetation samples. The method was applied for the determination of these, radionuclides in grass, collected near Munich after the fallout from the reactor accident at Chernobyl, USSR. The specific activities observed were (in Bq kg^–1 dry weight):²³⁸Pu, 0.077;^239+240Pu, 0.15;²⁴¹Pu, 3.9;²⁴¹Am, 0.031;²⁴²Cm, 3.0;²⁴⁴Cm, 0.008;⁸⁹Sr, 2000;⁹⁰Sr, 99.     

Determination of Np,Pu and Am in high level radioactive waste with extraction-liquid scintillation counting

A new method for the determination of transuranium elements, Np, Pu and Am with extraction-liquid scintillation counting has been studied systematically. Procedures for the separation of Pu and Am by HDEHP-TRPO extraction and for the separation of Np by TTA-TiOA extraction have been developed, by which the recovery of Np, Pu and Am is 97%, 99% and 99%, respectively, and the decontamination factors for the major fission products (⁹⁰Sr,¹³⁷Cs etc.) are 10⁴–10⁶. Pulse shape discrimination (PSD) technique has been introduced to liquid scintillation counting, by which the counting efficiency of -activity is >99% and the rejection of -counts is >99.95%. This new method, combining extraction and pulse shape discrimination with liquid scintillation technique, has been successfully applied to the assay of Np, Pu and Am in high level radioactive waste.     

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.     

Kinetics of the 2,2′-bipyridyl catalyzed Cr(VI)?I? reaction

The kinetics of 2,2-bipyridyl catalyzed Cr(VI)–I^– reaction has been studied. The order with respect to Cr(VI) is one and fractional with respect to bipyridyl. The order in [I^–] changes from unity to zero. Plots of 1/k_obs vs. 1/[bipy] and 1/k_obs vs. 1/[I^–] are straight lines with positive slopes and intercepts.

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2,2-, Cr(VI)–I^–. Cr(VI) , -. [I^–] 1 0. 1/k_obs 1/[bipy] 1/k_obs 1/[I^–] .

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IICT Publication NO. 2586     

Procedures to define Pu isotopic ratios characterizing a contaminated area in Palomares (Spain)

Plutonium isotopic ratios have been calculated in soils contaminated by the Palomares accident which occurred in 1966 (Almería, Southeastem Spain). Contrasted techniques have been used to determine the radionuclide activities:²³⁸Pu and^238+240Pu were analysed by -spectrometry prior purification on anion-exchange resins, the ratio²³⁹Pu/²⁴⁰Pu was estimated by -spectra deconvolution and²⁴¹Pu was directly measured by liquid scintillation counting and indirectly through quantification of in-grown²⁴¹Am from aged plutonium discs. The mean activity ratios²³⁸Pu/²³⁹Pu,²³⁹Pu/²⁴⁰Pu,²⁴¹Pu/²³⁹Pu, backdated to 1966, were 0.027±0.002 (1), 4.5±0.2 (1) and 8.2±0.8 (1), respectively, characterizing the accident of Palomares as the source term of the measured plutonium.     

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.     

Simultaneous liquid scintillation determination of239Pu and241Am in tissue

A liquid scintillation counting method for the simultaneous determination of Pu and Am, with a two-phase cocktail, has been applied to the analysis of a tissue sample from an accidental exposure incident. The sample contained²³⁹Pu,²⁴¹Pu, and²⁴¹Am. In addition to analysis by two liquid scintillation counting techniques, analysis of the sample was performed by -spectroscopy and ZnS scintillation techniques, and the results were compared. The presence of²⁴¹Pu interfered with the liquid scintillation determination of²⁴¹Am when the two-phase cocktail was used, but the results were in agreement sufficient to be useful in determining what course of treatment, if any, might be necessary for the patient.     

Separation of actinide and fission product elements by means of thermochromatography and fractional sublimation of their β-diketonates

The heterogeneous ligand exchange synthesis of volatile -diketonates of some actinides /²³⁰Th,²³³U,²³⁹Pu,²⁴¹Am/ and fission product elements /⁹⁰Sr,⁹⁰Y,¹¹³Sn,^113mIn/ and their separation by means of thermochromatography and fractional sublimation are reported. The methods are efficient for the separation of elements of different oxidation states.     

Energy resolution of liquid scintillator for α-particles and internal conversion electrons at lower temperatures

The energy resolution of -particles from²⁴¹Am,²²²Rn,²¹⁸Po and²¹⁴Po and internal conversion electrons from^131mXe with a liquid scintillation system has been studied at temperatures from 13 °C to –65 °C. At lower temperatures the liquid scintillation system has shown to give better energy resolutions both for -particles and internal conversion electrons compared with the values obtained at ordinary temperature. The phenomena were explained by the increase in light output of liquid scintillator at lower temperatures.     

Syntheses and properties of mixed dinuclear copper(II) complexes with heterocyclic dithiocarbamates and a cyclic octadentate tertiary amine

Five new Cu^II complexes of general formula [Cu₂(Rdtc)tpmc](ClO₄)₃, (1)–(5), where tpmc and Rdtc ^– refer to N,N,N,N-tetrakis(2-pyridylmethyl)-1,4,8,11-teraazacyclotetradecane and piperidine- (Pipdtc), 4-morpholine- (Morphdtc), 4-thiomorpholine- (Timdtc), piperazine- (Pzdtc) or N-methylpiperazine- (N-Mepzdtc) dithiocarbamates, respectively, have been prepared. Elemental analyses, conductometric and magnetic measurements, u.v./vis, i.r., e.p.r. and mass spectroscopy have been employed to characterize them. The complexes adopt an exo coordination of Cu^II ions and tpmc. The dithiocarbamate ion joins both the sulphur and the copper atoms acting as a bridging ligand The presence of different heteroatoms in the piperidine ring influences the (C=N) and (C=S) vibrations which decrease in the order of the complexes: Pipdtc>N-Mepipdtc>Pzdtc>Morphdtc>Timdtc ligands. Attention has been paid to the detailed mechanism of the mass spectral fragmentation of the complexes. The g _eff factors of the complexes have been also estimated by e.p.r. spectra. Finally, the complexes obtained demonstrate microbiologycal activity against some bacteria.     

Investigation of the interaction between zinc oxide and phosgene

It has been shown that in the interaction of zinc oxide and phosgene, the most active are the samples having oxygen vacancies. A mechanism for this process is suggested.

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Thermal effects of contamination,adsorbed water and annealing on the DTA of powdered quartz

During the grinding of quartz, water is adsorbed from the atmosphere, but this water gave no detectable thermal effect on DTA because it was evolved uniformly up to 1000°. However, in conjunction with an iron contaminant, the adsorbed water was involved in an oxidation reaction causing noticeable thermal effects for quartz powdered in a vibration mill constructed of steel parts. When powdered so finely that the - inversion peak at 573° had disappeared, annealing caused a partial redevelopment of the peak but recrystallization of disrupted quartz was too small an effect to give any detectable exothermic peak on DTA.

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Zusammenfassung Während des Vermahlens von Quartz wird Wasser aus der Atmosphäre adsorbiert, jedoch ergab dieses Wasser keinen nachweisbaren thermischen Effekt in der DTA, da es bis zu 1000° gleichmässig freigesetzt wird. Im Zusammenhang mit einer Eisen-Verunreinigung wurde jedoch das adsorbierte Wasser in eine Oxidationsreaktion einbezogen, welche beim in einer aus Stahlteilen gefertigten Vibrationsmühle zerpulvertem Quartz nachweisbare thermische Effekte verursachten. Wenn so fein pulverisiert wurde, daß der --Inversions-Peak bei 573° verschwunden war, verursachte eine Wärmebehandlung eine teilweise Wiederentwicklung des Peaks, jedoch war die Rekristallisation des zerstörten Quartzes zu geringfügig um einen nachweisbaren exothermen Peak in der DTA-Kurve zu ergeben.

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Résumé Lors du broyage du quartz, il se produit une adsorption de l'eau atmosphérique mais cette eau ne donne pas d'effet thermique décelable par ATD car elle se dégage régulièrement jusqu'à 1000°. Cependant, en présence de fer comme contaminant, l'eau adsorbée intervient dans une réaction d'oxydation qui donne des effets thermiques perceptibles dans le cas de quartz pulvérisé dans un vibrobroyeur en acier. Si le quartz est en poudre assez fine pour que le pic d'inversion - à 573° disparaisse, le recuit provoque la réapparition partielle du pic. La recristallisation du quartz est cependant trop faible pour donner un effet exothermique décelable par ATD.

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, , 1000°. , , . - 573° , , , - .

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We are grateful to the Science Research Council for supporting this work.     

90Sr and 137Cs radioisotopes and heavy metal concentrations in pharmaceutical herbal plants from the Lublin (Poland) region

Radioactivity of ⁹⁰Sr and ¹³⁷Cs in several species of herbs collected at Fajsawice and Góra Puawska located in Lublin (Poland) region was examined. Depending on the type of herb the radioactivity of strontium ranged from 0.004 to 1.808 Bq/kg dry weight whereas that from cesium varied from 0.053 to 9.853 Bq/kg. Calculated transfer factors of the radioisotopes in the plants studied revealed much stronger accumulation of strontium than cesium. Concentration of calcium and potassium in these plants has no influence on the concentration of measured radioisotopes.     

Results of three years of monitoring239,240Pu and238Pu concentrations in airborne effluents from the V-1 nuclear power plant with VVER 440 reactors in Jaslovské Bohunice in Czechoslovakia

The concentration of^239,240Pu and²³⁸Pu in airborne effluents in the years 1985–1987 from two reactors VVER 440/total power of 880 MW/ of a nuclear power plant V-1 in Jaslovské Bohunice in Czechoslovakia, was determined. The concentration of^239,240Pu in effluents ranged from 1.0 to 30.8 Bq.m^–3 and of²³⁸Pu from 1.6 to 41.1 Bq.m^–3. The activity ratio²³⁸Pu/^239,240Pu in airborne effluents kept within the range of 1.0–2.4. Total annual discharged activities of^239,240Pu in 1985, 1986 and 1987 were 28.5, 12.7 and 12.2 kBq, respectively. Total annual discharged activities of²³⁸Pu in 1986 and 1987 were 16.6 and 15.1 kBq, respectively.     

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.     

Environmental radioactivity in Romania Danube river area during 1986–1990

This paper presents the results of radioactivity studies of environmental factors such as surface water, sediment, aquatic vegetation and soil. The concentrations of¹³⁷Cs,⁹⁰Sr,³H, U, Ca, and Mg in water samples were determined by radiochemical and chemical methods. Gamma-spectrometric analyses were performed for all the samples. The analysis showed a decrease in concentrations of¹³⁷Cs in water, aquatic vegetation and sediment, but a constant level of¹³⁷Cs activity in soil (0–5 cm depth). The average concentrations of⁹⁰Sr,³H, U, Ca and Mg were about 7 mBq/l, 11 Bq/l, 0.6 g/l 60 mg/l and 11 mg/l, respectively.     

89,90Sr fallout from Chernobyl in the Bucharest-Magurele area

⁸⁹Sr and⁹⁰Sr were determined in the fallout of May 1986. The maximum values of 335 Bq/(m².6 h) and 110 Bq/(m².6 h) were observed on May 2 and 5. Throughout May 1986 a quantity of 860 Bq/m² of⁹⁰Sr, deposited from the fallout in the Bucharest-Mgurele area, was estimated.     

Determination of 241Pu in marine samples using co-precipitation with rare earth fluoride and liquid scintillation spectrometry

²⁴¹Pu was measured in reference materials and marine samples using a novel method based on rare earth fluoride co-precipitation followed by liquid scintillation spectrometry (LSS). Disc sources used for -spectrometry of ²³⁸Pu and ^239+240Pu were leached with concentrated nitric acid before neodymium fluoride co-precipitation to scavenge plutonium in the lower oxidation states was carried out. After the determination of the chemical recovery by -spectrometry, the precipitate was recovered in a H₃BO₃/HNO₃ based dissolver and mixed with Packard Insta-Gel^Ò Plus cocktail before LSS. Reasonable agreement has been obtained between the results obtained using this methods and the data obtained by direct disc analysis by LSS and ICP-MS. The ²⁴¹Pu/^239+240Pu ratios were coherent with the expected origin of the Pu contaminant in the marine environment showing the validity of the method.This revised version was published online in November 2005 with corrections to the Cover Date.