Identification of the contamination source of plutonium in environmental samples with isotopic ratios determined by inductively coupled plasma mass spectrometry and alpha-spectrometry

Concentrations of^239+249Pu in environmental samples were detemined by ICP-MS and spectrometry, showing consistent results, which suggests an applicability of ICP-MS to²³⁹Pu and²⁴⁰Pu measurement. The activity ratios of²³⁸Pu/^239+240Pu and²⁴⁰Pu/²³⁹Pu were significantly different in samples from the general environment and near Sellafield reprocessing plants, indicating the usefulness of these ratios for identification of the Pu contamination source.     

Improved separation method for determining actinides in soil samples

Radionuclides have been identified as a significant source of contamination at many United States Department of Energy (DOE) sites. As a result, reliable and accurate methods to determine actinide content in environmental samples have become increasingly important. Therefore, an improved analytical scheme using a series of actinide-selective extraction chromatography (Tru-Spec, Teva-Spec) and ion-exchange (Diphonix) resins was designed to satisfy the requirements of both alpha spectrometry and inductively coupled plasma mass spectrometry (ICP-MS). Alpha spectrometry required the sequential isolation of the actinides, whereas ICP-MS required only a group separation of the actinides. The separation schemes were designed to allow analysis of the actinides in soil, whether the soils were acid leached or totally dissolved through fusion. For those analytes present as contaminants (^239/240Pu,²⁴¹Am), the laboratory results agreed favorably with the accepted values for several reference soils. However, for the acid digestion procedure, the results for matrix constitutents (²³⁸U,²³⁴U,²³²Th) were quite low because the silicate matrix was not decomposed. The sodium hydroxide fusion technique described allowed accurate analysis of both matrix constituents and contaminants because a total dissolution was achieved.     

Determination of environmental actinide nuclides and210Pb(210Po) by low-energy photon spectrometry with alpha-spectrometry

Low-energy photon spectrometry with -spectrometry was used to determine the environmental concentrations of low-level actinides and other nuclides, especially²¹⁰Pb and²¹⁰Po. The isotopic ratio of²⁴⁰Pu/²³⁹Pu was successfully determined by measuring L_x-ray/-ray counting ratio. A reliable method has been developed for the determination of extremely low-level²³⁷Np global fallout in environmental samples. The non-destructive determination by Ge-LEPS for natural²¹⁰Pb in various samples (tobacco leaves, commercially available tobacco, etc.) was also carried out with the determination of²¹⁰Po by -spectrometry using²⁰⁹Po as a yield tracer.     

Alpha-emitting radionuclide contents in food samples as related to the Chernobyl accident

As a preliminary survey to establish intake of -emitting nuclides, in particular^239,240Pu, from a daily diet for inhabitants living near the Chernobyl reactor site, some kinds of food samples including total diet samples were collected in the Chernobyl (Ukraine) area and in the Ibaraki prefecture (Japan). Plutonium-239 and 240 were determined together with naturally occurring -emitters²²⁶Ra and U isotopes (²³⁴U,²³⁵U and²³⁸U) by -spectrometry after chemical separation. In most of the samples studied,^239,240Pu was less than the detectable amount, but in some mushrooms from the Ukraine it was found to be 41.6 mBq kg^–1 (wet mass) with a high activity ratio(0.58±0.08) of²³⁸Pu/^239,240Pu, indicating that nearly 100% of the^239,240Pu was attributable to the accident. Concentrations of²²⁶Ra and²³⁸U varied largely, depending on the samples. The measured activity ratios of²³⁵U/²³⁸U for some samples showed the isotopic composition of natural uranium.     

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.     

The measurement of the isotopic composition of plutonium in an Irish Sea sediment by mass spectrometry

Samples from sediment cores, collected from a site close to the Sellafield outfall and dated using conventional - and -spectrometry, have been analysed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Thermal Ionisation Mass Spectrometry (TIMS). This has provided information on the isotopic composition of plutonium in the liquid discharges from Sellafield; such information is not available using conventional -spectrometry alone. There was very good agreement between the²⁴⁰Pu/²³⁹Pu ratios obtained by the two MS methods. More recent discharges have been characterised by a progressive decrease in the relative proportion of²³⁹Pu.     

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.     

Dosimetric measurement of the disintegration rate of fission products

Investigations on the disintegration rate of fission products of²³⁸U and²³⁹Pu are presented. The intensity of the - and -radiation of fission products were measured continuously in an interval of 1–1300 hours following the fission, offering the possibility for determining the general and specific characteristics of the individual fission products. A universal measuring procedure was elaborated for the rapid in situ determination of the dosimetric features of fission products, which is suitable for the accurate evaluation and prediction of external absorbed dose even in case of fission products of various origin and unknown composition.     

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.     

Distribution of137Cs,40K,238U and232Th in soils from Northern Venezuela

More than one hundred undisturbed soil samples from Northern Venezuela and the islands of Margarita and Los Roques have been analyzed for¹³⁷Cs,⁴⁰K,²³⁸U and²³²Th by -ray spectroscopy. The specimens were taken from between 5–10 cm below the earth's surface. Thus, they are valid not only for the¹³⁷Cs deposition studies but also for the estimation of the natural -ray dose from primordial radionuclides that form the terrestrial component. The concentration of⁴⁰K was directly determined from its 1461 keV -ray, while those of¹³⁷Cs,²³⁸U and²³²Th were performed using a -ray from one of their daughter radionuclides: the 661 keV -ray of^137mBa for¹³⁷Cs, the 1760 keV -ray of²¹⁴Bi for²³⁸U and the 2620 keV -ray of²⁰⁸Tl for²³²Th. Finally, the concentration values were compared with those of global estimates.     

Die Bestimmung von Uran und Plutonium im Rahmen der Ausscheidungsanalyse

Zusammenfassung Eine in der Praxis angewandte Analysenmethode zur Bestimmung von Plutonium in Harnproben wurde mit Hilfe von Tracerversuchen mit²³⁶Pu,²³³U und²⁴¹Am hinsichtlich ihrer radiochemischen Ausbeute und ihrer Trenneffizienz überprüft. Dabei zeigte sich, daß die Pu-Bestimmung mit einer Ausbeute von 95% praktisch quantitativ erfolgt. Im allgemeinen ist es nicht notwendig, vom Restgehalt an Uran, der 25% beträgt, weiter abzutrennen. Bei Uranmengen bis zu 100g U (nat.) sind die Meßproben alphaspektrometrisch zur qualitativen und zur quantitativen Auswertung geeignet. Auf diese Weise kann neben der Pu-Bestimmung aus demselben Alphaspektrum einer Harnprobe auch eine Aussage über die Isotopenzusammensetzung des Urangehaltes und eine mengenmäßige Abschätzung getroffen werden.Die Abtrennung des²⁴¹Am erfolgt dagegen vollständig. Der Restgehalt an²⁴¹Am in der durch Elektrodeposition hergestellten Pu-Meßprobe wurde mit weniger als 0,3% ermittelt und ermöglicht eine Auswertung des Alphaspektrums auch auf²³⁸Pu.Die Ergebnisse von Routinemessungen im Rahmen der Personenüberwachung zeigten einen normalen Urangehalt im Harn von <0,3g U/l und einen normalen Plutoniumgehalt von 0,05 pCi²³⁹Pu/24 h-Harn.

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The determination of uranium and flutonium in excretion analysis

Summary A routine method for the determination of Pu in urine samples was tested with tracer amounts of²³⁶Pu,²³³U and²⁴¹Am for its recovery and for efficiency of radiochemical separation. Pu recovery was 95%, uranium about 25%, which in generally does not need to be separated for-spectrometric determination of Pu. With uranium content up to 100g U_(nat.) counting sources are suitable for qualitative and quantitative evaluation of-spectra. In this way additionally information about the isotopic composition and the amount of uranium in the urine sample can be achieved from the same measurement.Separation from²⁴¹Am, however, can be assumed quantitatively. The activity of²⁴¹Am in such counting sources prepared by electrodeposition was less than 0,3% which enables evaluation of²³⁸Pu too. Results of routine determinations in personnel monitoring show normal background levels of uranium concentration in urine samples of less than 0,3g U (nat.)/l and for plutonium of 0,05 pCi²³⁹Pu/24-hr urine samples.

     

Speciation of239U and238Np produced by radiative neutron capture

Various simple and complex compounds of²³⁸U and²³⁷Np have been irradiated in a neutron flux. The chemical state of²³⁹U and²³⁸Np formed in (n, ) reactions has been determined as a function of the initial oxidation state of the actinide elements and of the nature of ligands. A scheme for the chemical reactions following neutron capture is proposed.     

Oxidation states of239,240Pu in global fallout

Oxidized Pu species [Pu(V+VI)] have been found in surface waters and rainfall both from atmospheric and surface nuclear test debris. This paper presents experimental data which suggests that this oxidized Pu may be a memory of the oxidation state of^239,240U formed during thermonuclear explosions, and which -decayed to^239,240Pu through^239,240Np following condensation on atmospheric particles.Research sponsored by the Office of Health and Environmental Research, U. S. Department of Energy, under Contract No. DE-AC05-840R21400 with Martin Marietta Energy Systems, Inc.     

Activity concentrations of238U and226Ra in agricultural samples

Distributions of²³⁸U and²²⁶Ra in agricultural samples and cultivated soils have been studied over ten years. The crops are rice, spinach and Chinese cabbage. Two investigated areas have been selected (35° 18 N, 113° 35 E). The agricultural samples and soils were collected annually from May 1982 through October 1991. The activity concentrations of²²⁶Ra in agricultural samples are greater than those of²³⁸U. The transfer factors of²³⁸U,²²⁶Ra are from 0.06·10^–3 to 1.2·10^–3. The²²⁶Ra/²³⁸U ratios for three agricultural samples have their characteristic values.     

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.     

Adsorbed oxygen species formed by reaction with N2O on CaO

A considerable amount of adsorbed oxygen species is formed by the reaction of N₂O on CaO. It is suggested that these adsorbed species were practically held on 5-coordinated sites.

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- N₂O CaO. , 5-- .

     

Thermal decomposition of metal polyacrylates

Results of thermal and pyrolysis-GC/MS analyses of Na, Ca and Mg polyacrylates are presented. It was confirmed that the main decomposition reactions of the Na salt take place in the temperature range 420 – 470 and those of the other two polymers in the range 450–490. It was found that the solid residue after decomposition was the metal carbonate or oxide, while the volatile products consisted of H₂, CO, CO₂, saturated and unsaturated hydrocarbons (including cycloolefins and aromatic hydrocarbons) and aliphatic ketones. This suggests that the thermal decomposition of the metal polyacrylates proceeds via side-chain splitting and breaking of the main chain of the polymer, without retropolymerization.

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Zusammenfassung Die Ergebnisse der Thermo- und Pyrolyse-GC/MS-analysen von Na-, Ca- und Mg-Polyacrylaten werden beschrieben. Es wurde bestÄtigt, dass die Hauptzersetzungsreaktionen des Natriumsalzes im Temperaturbereich von 420 bis 470, jene der anderen zwei Polymeren im Bereich von 450 bis 490 ablaufen. Es wurde nach der Zersetzung ein fester Rückstand von Metallkarbonat oder -oxid gefunden, wÄhrend die flüchtigen Produkte aus N₂, CO, CO₂, gesÄttigten und ungesÄttigten Kohlenwasserstoffen (darunter Zykloolefinen und aromatischen Kohlenwasserstoffen) und aliphatischen Ketonen bestanden. Dies lÄsst darauf schliessen, dass sich die thermische Zersetzung der Metallpolyacrylate über die Abspaltung der Seitenkette und der Spaltung der Hauptkette des Polymers ohne Retropolymerisation vollzieht.

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Résumé On présente les résultats des analyses thermiques et des produits de décomposition pyrolytique par chromatographie en phase gazeuse et spectrométrie de masse (GC/MS) des polyacrylates de Na, Ca et Mg. On confirme que la réaction de décomposition principale du sel de sodium a lieu entre 420 et 470 et celle des deux autres polymères entre 450 et 490. On trouve que le résidu solide après décomposition est le carbonate ou l'oxyde du métal, tandis que les produits volatils consistent en N₂, CO, CO₂, en hydrocarbures saturés et non-saturés (y compris les cyclooléfines et hydrocarbures aromatiques) et en cétones aliphatiques. Cela permet de supposer que la décomposition thermique des polyacrylates métalliques s'effectue par coupure de la chaÎne latérale et par rupture de la chaÎne principale du polymère, sans rétropolymérisation.

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-- -- Na, Ca Mg. , 420–470, — 450–490. , . H₂, CO, CO₂, , , . , .

     

Role of three phonon normal processes in the analysis of the thermal conductivity of solid HD at low temperatures

The role of the three phonon normal processes in the analysis of the lattice thermal conductivity of the solid HD has been studied in the entire temperature range 0.2–4 K. The study is made by calculating the contribution of the correction term due to the three phonon normal processes towards the total lattice thermal conductivity of the pure sample of the solid HD in the temperature range stated above. The study is also made for the different values of the three phonon normal processes scattering relaxation rate. The considerable contribution due to the correction term is found compared to the total phonon conductivity above 1 K.

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Zusammenfassung Die Rolle der Drei-Phonon-Normalprozesse in der Analyse der Gitter-Wärmeleitung von festem HD wurde im Temperaturbereich von 0.2 bis 4 K untersucht. Die Untersuchung wurde durch Berechnung des Beitrages des den Drei-Phonon-Normalvorgängen zuzuschreibenden Korrekturterms an der totalen Gitter-Wärmeleitung der reinen Probe des festen HD im o.a. Temperaturbereich durchgeführt. Diese Betrachtung wurde auch für die verschiedenen Werte der Streuungsrelaxationsgeschwindigkeit der Drei-Phonon-Normalvorgänge durchgeführt. Ein wesentlicher Beitrag des Korrekturglieds wurde im Vergleich zu der totalen Phononleitfähigkeit oberhalb von 1 K gefunden.

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Résumé On a étudié, dans tout l'intervalle des températures comprises entre 0.2 et 4 K, le rôle des processus normaux à trois phonons dans l'analyse de la conductivité thermique du réseau de HD solide. L'étude s'est effectuée en calculant la contribution du terme de correction dû aux processus normaux à trois phonons, à la conductivité thermique totale du réseau de l'échantillon pur de HD solide, dans l'intervalle de températures considéré. On a, de même, effectué l'étude pour les différentes valeurs de la vitesse de relaxation de dispersion des processus normaux à trois phonons. On a trouvé une contribution considérable due au terme de correction comparé à la conductivité totale de phonon au-dessus d'1 K.

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0.2–4 . , , . . , 1 .

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The author wishes to express his thanks to Dr. R. A. Rashid, Dr. R. H. Misho and Dr. G. S. Verma for their interests in the present project.     

Seasonal variation of activity ratios for natural uranium in surface waters

The uranium concentration, and²³⁴U/²³⁸U and²³⁵U/²³⁸U activity ratios were measured by alpha spectrometry of surface water from the neighbourhood of the uranium mines El Lobo and El Pedregal (Badajoz, Spain) before and after the rainy season. Changes were observed in all the three parameters studied. Leaching and dilution are the probable mechanisms for the seasonal changes in the concentration and in the²³⁴U/²³⁸U activity ratio as measured in open and dynamic systems (rivers).     

Effect of the solvent on selective hydrogenation of 6, 10-dimethylundeca-3,5,9-trien-2-one

Reaction mechanism for selective hydrogenation of pseudo-ionon on Raney-Ni in the presence of n- and iso-alcohols has been studied. From the analysis of ESR spectra, the dependence of selectivity on the solvent is concluded.

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- Ni- . .