Determination of Separated Plutonium,Americium and Curium in Environmental Samples by Sequential Extraction Techniques

A simple, reliable and practical radiochemical method for sequential isolation and determination of plutonium, americium and curium in a wide variety of environmental samples including soils, river sediments and water was developed. The isotopes determined are: ²³⁸Pu, ^239,240Pu, ²⁴¹Am, ²⁴²Cm and ²⁴⁴Cm. The methods involve leaching of soil or sedimental samples with concentrated nitric acid using a pressure digestion technique. Subsequent concentration and separation of nuclides of interest from major matrix elements and other interfering alpha-emitters are carried out by coprecipitation with ferric hydroxide and solvent extractions. Sources suitable for alpha-spectrometry are prepared by electrodeposition from acidic ammonium chloride solution. ²⁴²Pu and ²⁴³Am are used as tracer isotopes of plutonium and americium-curium elements, respectively. Some results of analysis of soils, sediments and water are given. The alpha peaks from ²³⁸Pu, ^239,240Pu and ²⁴²Pu as well as ²⁴¹Am, ²⁴⁴Cm, ²⁴²Cm and ²⁴³Am are well resolved. The entire analytical procedures for plutonium, americium and curium are completed in less than sixteen hours.     

Recent status of radiochemical analysis of irradiated trans-uranium targets

We have developed a sequential radiochemical separation method (SRCS) in order to isolate each trans-uranium element (TRU) contained in a TRU target (or fuel) irradiated in the experimental fast reactor JOYO. The chemical separation procedures for SRCS consist of the following steps:

Cesium, americium and plutonium isotopes in ground level air of vilnius

Systematic observations of radionuclide composition and concentration in the atmosphere have been carried out at the Institute of Physics in Vilnius since 1963. Increases in activity concentration of radionuclides in the atmosphere were observed after nuclear weapon tests and the Chernobyl NPP accident. At present the radiation situation in Lithuania is determined by two main sources of radionuclides, forest fire and resuspension products transferred from highly polluted region of the Ukraine and Belarus. The activity concentrations of ¹³⁷Cs were measured in two to three days samples while plutonium and americium in monthly samples. The extremely high activity concentrations of ²³⁸Pu, ^239,240Pu, ²⁴¹Am determined in the atmosphere during the Chernobyl accident can be explained by transport of “hot particles” of different composition. Activity concentration in 1995–2003 of ²⁴¹Am and ^239,240Pu isotopes ranged from 0.3 to 500 and from 1 to 500 nBq/m³, respectively. ²³⁸Pu/^239,240Pu activity ratio in measured samples differs from 0.03 to 0.45. A decrease in ²⁴⁰Pu/²³⁹Pu atomic ratio from 0.30 to 0.19 was observed in 1995–2003.     

Cesium,americium and plutonium isotopes in ground level air of Vilnius

Systematic observations of radionuclide composition and concentration in the atmosphere have been carried out at the Institute of Physics in Vilnius since 1963. Increases in activity concentration of radionuclides in the atmosphere were observed after nuclear weapon tests and the Chernobyl NPP accident. At present the radiation situation in Lithuania is determined by two main sources of radionuclides, forest fire and resuspension products transferred from highly polluted region of the Ukraine and Belarus. The activity concentrations of ¹³⁷Cs were measured in two to three days samples while plutonium and americium in monthly samples. The extremely high activity concentrations of ²³⁸Pu, ^239,240Pu, ²⁴¹Am determined in the atmosphere during the Chernobyl accident can be explained by transport of “hot particles” of different composition. Activity concentration in 1995–2003 of ²⁴¹Am and ^239,240Pu isotopes ranged from 0.3 to 500 and from 1 to 500 nBq/m³, respectively. ²³⁸Pu/^239,240Pu activity ratio in measured samples differs from 0.03 to 0.45. A decrease in ²⁴⁰Pu/²³⁹Pu atomic ratio from 0.30 to 0.19 was observed in 1995–2003.     

Pu and Am determination in the environment—method development

A high resolution inductively coupled plasma mass spectrometric (HR-ICP-MS) method for the determination of plutonium isotopes, Am and the ²⁴⁰Pu/²³⁹Pu isotope ratio utilising modification of Pu-02-RC Plutonium in Soil Samples, Pu-03-RC Plutonium in Soil Residue—Total Dissolution Method, Pu-11-RC Plutonium Purification—Ion Exchange Technique, Pu-12-RC Plutonium and/or Americium in Soil or Sediments, HASL-300 was developed. Total plutonium concentrations (^239+240Pu) measured in environmental samples by this HR-ICP-MS method were in good agreement with recommended data obtained from a-spectrometry. It was achieved the decreasing of the time to analyze the samples over than 33%.     

Retention of cesium,plutonium and americium by engineered and natural barriers

Safety assessment of low and intermediate level waste repository requires sorption parameters and understanding of the radionuclides sorption-desorption mechanism. In order to obtain realistic sorption data for safety relevant radionuclides present in cement (concrete) based near surface repository, some preliminary studies have been carried out. Batch sorption experiments were conducted with two clay samples to determine K_d values of Cs, Pu and Am under a wide range of geochemical conditions. Cs, Pu and Am K_d values were determined for rainwater, groundwater and cement-water of different chemical compositions. Cs, Pu, Am Kd values ranged from 450 to 9700, from 15000 to 21000 and from 15000 to 80000 ml/g, respectively. Iron speciation was determined using Mössbauer spectrometry.     

Retention of cesium, plutonium and americium by engineered and natural barriers

Safety assessment of low and intermediate level waste repository requires sorption parameters and understanding of the radionuclides sorption-desorption mechanism. In order to obtain realistic sorption data for safety relevant radionuclides present in cement (concrete) based near surface repository, some preliminary studies have been carried out. Batch sorption experiments were conducted with two clay samples to determine K_d values of Cs, Pu and Am under a wide range of geochemical conditions. Cs, Pu and Am K_d values were determined for rainwater, groundwater and cement-water of different chemical compositions. Cs, Pu, Am Kd values ranged from 450 to 9700, from 15000 to 21000 and from 15000 to 80000 ml/g, respectively. Iron speciation was determined using Mössbauer spectrometry.     

Production of neutron-deficient nuclei around N = 126 by proton-induced spallation

Many isotopes of Np, Pu, Am, and Cm around the N = 126 shell still have not been produced in the laboratory. This study aims to investigate the cross sections and yields of the neutron-deficient nuclei of Np, Pu, Am, and Cm produced in the proton-induced spallations of transuranium elements. The isospin-dependent quantum molecular dynamics (IQMD) model is applied to study the dynamical process of reaction, and the subsequent decay process is simulated by the GEMINI++ model. The IQMD-GEMINI++ model is applied to calculate the cross section, kinetic energy, and angular distribution of the isotopic productions around N = 126. The Lindhand, Scharff, and Schiott theory is applied to calculate the energy loss of different heavy nuclei in the target material. A comparison between the data and the calculations shows that the IQMD-GEMINI++ model can reproduce the production cross sections of the neutron-deficient nuclei in spallation within approximately 1.5 orders of magnitude. The maximum cross section of the undiscovered isotopes of Np, Pu, Am, and Cm is about 10^?5 mb, while the kinetic energies of the productions are all less than 16 MeV. The angular distribution shows that the emission direction of production is mostly at a backward angle. The range of production in the target is within the range of 10^?7 to 10^?5 cm. This range is the effective target thickness for the online identification of undiscovered isotopes. Based on the effective thickness of the target and assuming an intensity of 120 μA for the proton beam, the yields of the undiscovered neutron-deficient nuclei are calculated. Productions of the undiscovered isotopes of Np, Pu, Am, and Cm by the proton-induced spallations of transuranium elements are feasible. However, experimental techniques for online identification of neutron-deficient nuclei produced in proton-induced spallation should be developed.     

Alphaspektrometrische Isotopenverdünnungsanalyse von Plutoniumisotopen in Kernbrennstofflösungen

In einer bestrahlten Kernbrennstofflösung wurde die Plutoniumaktivität mit Hilfe der Isotopenverdünnungsanalyse bestimmt. Dabei wurde ²³⁸Pu als Tracerisotop verwendet. Die Abtrennung des Plutoniums wurde durch Extraktion und die Aktivitätsmessung mit Hilfe der Alphaspektrometrie unter Verwendung von Si-Halbleiterdetektoren vorgenommen. Die Störung durch ²⁴¹Am wurde durch gammaspektrometrische Messung berücksichtigt. Die Genauigkeit der ²³⁸Pu-Aktivitätsmessung und die der Messung der Gesamtaktivität beträgt ungefähr 1,5%. Die Bestimmung des ²³⁹Pu zu ²⁴⁰Pu Verhältnisses war nur mit einem groβen Fehler möglich, entsprechend der nahezu gleichen Alphaenergien dieser Isotope und der komplizierten Peakform. ²⁴¹Pu wurde durch alphaspektrometrische Differenzmessung der nachgebildeten ²⁴¹Am Aktivität bestimmt.

In irradiated nuclear fuel solution plutonium isotops were determined with the help of isotope dilution analysis. ²³⁸Pu was used as a tracer isotope. Plutonium was separated by extraction and the activity was measured by alphaspectroscopy using silicon detectors. Interfering ²⁴¹Am was recognized by gamma spectroscopic measurements. The accuracy of ²³⁸Pu determination and the determination of the total activity amounts to about 1-5%. For the ²³⁹Pu ratio we obtained a value with a large systematic error due to the similar alpha energies of these isotopes in the complicated shape of the peaks. The ²⁴¹Pu activity was determined by alphaspectroscopic difference measurement, and was calculated from the ingrown of ²⁴¹Am activity.     

A new neutron-deficient isotope, 235Am

The new transuranium neutron-deficient isotope ²³⁵Am was produced by bombarding of ²³⁸Pu with 35-MeV protons beam via the (p,4n) reaction. The reaction products were transported by a helium-jet system. A rapid radiochemical method was employed for separating the americium isotopes from the complex products. From the observed Kx-rays of Np, γ-ray of ²³⁵Pu and x-γ coincidence measurements, the new neutron-deficient isotope ²³⁵Am with a half-life 15±5min was definitely identified for the first time.     

Innovative separation method for advanced spent fuel reprocessing based on tertiary pyridine resin

Radiochemical separation experiments have been performed in order to realize a novel reprocessing method based on chromatography techniques using a novel pyridine resin. The newly synthesized tertiary pyridine resin with two functions of ion exchanger and soft-donor was dedicated to the experiments, where highly irradiated mixed oxide fuel from the experimental fast reactor JOYO was used as a reference spent fuel. With a 3-step separation, pure Am and Cm were individually obtained as minor actinide products, and ¹⁰⁶Ru group, lanthanides with ¹³⁷Cs group and Pu group were fractionated, respectively. The decontamination factor of ¹³⁷Cs and trivalent lanthanides (¹⁵⁵Eu, ¹⁴⁴Ce) against the Am product exceeded 3.9 × 10⁴ and 1.0 × 10⁵, respectively. The decontamination factor as the mutual separation of ²⁴³Cm was larger than 2.2 × 10³ against the Am product. Moreover, the content of ¹³⁷Cs, trivalent lanthanides and ²⁴³Cm in Am product did not exceed 2 ppm. The tertiary pyridine resin method is a candidate separation system for an “advanced ORIENT process”, where enhanced separation, transmutation and utilization of actinides, long-lived fission products and rare metal fission product would be oriented.     

平均场加区分质子和中子的邻近轨道对力模型及对超铀区核的统一描述

利用严格可解的平均场加区分质子和中子的邻近轨道相互作用对力模型,对超铀区部分大形变核进行了统一的描述.计算了^227—233Th,^232—239U,^236—243Pu同位素和同中异质素²²⁸Ra-²²⁹Ac-²³⁰Th-²³¹Pa-²³²U,²³²Th-²³³Pa-²³⁴U-²³⁵Np-²³⁶Pu,²³⁶U-²³⁷Np-²³⁸Puv-²³⁹Am的结合能,对激发能和奇偶能差并与相应核的实验值进行了比较     

Determination of plutonium isotopes in low activity waste of NPP origin

The inventory analysis of the alkaline low level liquid radioactive waste collected during more than 30 years of NPP “Kozloduy” operation requires determination of eighteen radioactive isotopes with different decay properties. Plutonium isotopes of interest are Pu-238, Pu-239/Pu-240, and Pu-242. The preliminary investigations of the supernatant phase of model and authentic waste samples showed essential challenges for determination of plutonium due to its various oxidation states and low concentration in the complex matrix. Plutonium concentration was determined in precipitate and supernatant after the calcium phosphate precipitation and in the different fractions of the anion exchange steps. The separation by anion exchange and final purification of plutonium fraction by extraction chromatography on TEVA resin (EiChroM Industries) was studied by variation of plutonium oxidation states. The sources were prepared by micro precipitation with NdF₃ and counted by alpha spectrometry. As a result from the performed experiments, plutonium determination procedure was optimized and applied to real waste samples.     

大孔吸附树脂分离纯化巫山淫羊藿总黄酮

筛选适合分离纯化巫山淫羊藿总黄酮的大孔吸附树脂并确立纯化工艺参数。以对总黄酮的吸附容量、解吸附率、吸附速率为指标,筛选D101、DM301、AB-8 3种大孔吸附树脂,并对最适树脂进行洗脱液浓度和洗脱液用量的工艺参数考察。结果AB-8型大孔树脂对巫山淫羊藿总黄酮的吸附容量、解吸附率、吸附速率均大于其他两种树脂,洗脱液以50%乙醇最佳,洗脱液用量3.6BV即可,纯化后总黄酮含量可达70.20%。该工艺简便、成本低,可用于工业化生产。     

Spectral interferences from polyatomic barium ions in inductively coupled plasma mass spectrometry

For the Element2 (a relatively new high-sensitivity magnetic sector ICP MS), we have studied spectral interferences from barium arising as a result of polyatomic barium ions, which have a considerable effect on the intensity of lines for rare-earth isotopes. We have shown that the parameters characterizing the interferences (the ratios of the signals from oxygen-containing, chlorine-containing, and fluorine-containing BaX⁺ ions to the Ba⁺ signal, and the apparent rare-earth concentrations C_{app j} resulting when overlap from polyatomic Ba occurs) are higher for the Element2 than for a quadrupole instrument (PQ2⁺). However, it is possible to solve many spectral overlap problems when using the Element2 by using the medium-resolution (MR) or high-resolution (HR) modes. We have estimated the resolutions needed to completely separate the masses of the polyatomic barium ions and the rare-earth isotopes in the spectrum. For cases when it is impossible to use the high-resolution mode due to the ∼100-fold decrease in sensitivity, we recommend preliminary separation of Ba from the rare earths. In this work, we have used extraction chromatography to determine low rare-earth concentration levels in Lake Baikal water. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 813–818, November–December, 2006.     

双水相萃取技术的应用研究进展

双水相萃取技术作为一种新型的分离技术日益受到重视,与传统的萃取及其他分离技术相比具有操作条件温和、处理量大、易于连续操作等优点,从而使其能广泛应用于生物工程、药物分析和金属分离等方面。目前,双水相萃取技术的研究进展集中表现在:廉价双水相体系的开发、新的双水相体系探索、双水相萃取技术同其他技术集成化、双水相萃取相关理论的进展等方面。本文简单介绍了双水相萃取技术及其原理、特点,综述了双水相体系在生物工程(其中包括萃取分离抗生素、酶、分离提纯蛋白质和萃取其他生物活性物质)、药物分析和金属分离等方面的应用,展望了双水相体系的应用前景。     

Photofission of americium isotopes in the energy range 6–12 MeV

By means of the reference method, the cross sections for the fission of the ²⁴¹Am, ^242m Am, and ²⁴³Am isotopes were measured at the microtron of the Institute of Physics and Power Engineering (Obninsk). These measurements, which employed the cross section for ²³⁸U photofission as a reference, covered the energy range 6–12 MeV scanned with a variable step of 50 to 200 keV. Data on ^242m Am photofission in the energy range 6–12 MeV and ²⁴³Am photofission in the region between 6 and 7 MeV were obtained for the first time. New results for ²⁴¹Am reveal that the cross sections for ²⁴¹Am photofission from previous studies of the present author were exaggerated. The new results for this isotope comply well with data of other authors. It is not confirmed that the fissility of ²⁴¹Am is less than the fissility of ²⁴³Am. The energy dependences of the fissilities of the americium isotopes from photofission data are compared with those that were obtained for these fissilities from data on direct reactions like ²⁴⁰Pu(³He, df)²⁴¹Am. The results of this comparison show that the observed fission thresholds and the plateaulike dependences at energies above 7.5 MeV from the two types of studies comply well. The present data show evidence that, in the energy region around 6 MeV, the photofission cross section has a maximum, which is associated, in all probability, with the low-energy resonance structure in the cross section for dipole photoabsorption.     

Determination of the fission barrier of232Pu from β-delayed fission and the problem of the first barrier

A delayed fission activity with a half-life of (55±7) s and a production cross section of (5±1)nb has been observed in the irradiation of²³⁷Np with 104 MeVα particles. It is tentatively assigned to the electron capture decay of²³²Am followed by fission of²³²Pu With a probability of (1.3 _?0.8 ⁺⁴ )· 10^?2 A barrier height of (5.3±0.4) MeV is extracted for²³²Pu exceeding theoretical barrier heights by about 2MeV. Systematic deviations between experimental and theoretical barrier heights previously observed in particular for U and Th isotopes are now also established for neutron deficient Pu isotopes indicating severe defects in the procedure of calculating static fission barriers.     

Plutonium isotopes concentration in the ground level air and rain samples from Kraków

The aim of the present work was to look at the background levels of plutonium in air and rain samples. Two sets of Petryanov type filters through which ca. 0.5 Mm³ each of air had passed and two large samples of collected rain (170 L and 182 L) were analysed for the content of plutonium alpha-emitters. In the article the radiochemical procedure applied to these samples is described. Obtained Pu activities in air were 0.5±0.1 nBqm^?3 and 0.7±0.1 nBqm^?3 for²³⁸Pu and 3.1±0.2 nBqm^?3 and 8.3±0.6 nBqm^?3 for^239+240Pu. Activities of rain samples were 7.5±0.7 mBqm^?3 and 14.3±0.8 mBqm^?3 for^239±240Pu and 0.4±0.1 mBqm^?3 and 2.1±0.2 mBqm^?3 for²³⁸Pu, respectively, for the two samples. The most interesting finding is the largely different²³⁸Pu to^239+240Pu activity ratios (from 0.03±0.01 to 0.18±0.01) measured in the samples. This result needs conformation, but as now it suggests different origins of plutonium isotopes in incoming to Kraków air.     

Direct Radioimmunoassay of Proinsulin and Insulin in Human Plasma by Chromatographic Technique

Specific method for direct radioimmunoassay of IRP and IRI separately in human plasma has been described. The method is used for extraction of total insulin and separation of IRP from IRI by paper chromatography to be assayed separately. The separation of the two components are indentified and confirmed by column chromatography, paper chromatography and U.V. spectral analysis in comparison with the standard compounds.

134 plasma samples of different cases were, investigated for determination of IRI, IRP and IRT, of which 39 normals, 16 normal obes, 21 juvinil diabetes, 18 adult oncet diabetes, 10 recent adult diabetes, 12 hypothroid and 18 bilharzial hepatosplenomegaly to evaluate the levels of the test in comparison with blood sugar concentration.