A gamma-spectrometric method for the determination of plutonium isotope ratios

A gamma-spectrometric method using an intrinsic high resolution germanium detector has been developed for the determination of isotope ratios of plutonium from samples in solution form. The method is based on the assay of low energy gamma-rays of²³⁸Pu,²³⁹Pu,²⁴⁰Pu and²⁴¹Pu and does not require the use of branching intensities or the knowledge of detection efficiencies for different gamma rays. Since low energy gamma-rays are used, the effect of²⁴¹Am has also been studied. It is found that results are not affected up to 0.5 wt% of²⁴¹Am in plutonium samples. An accuracy of 3% is achievable in the determination of²⁴⁰Pu/²³⁹Pu and²⁴¹Pu/²³⁹Pu atom ratios as demonstrated by carrying out measurements on isotopic standards of plutonium.     

Radioanalytical approach to determine 238Pu, 239+240Pu, 241Pu and 241Am in soils

The simultaneous determination of multiple actinide isotopes in samples where total quantity is limited can sometimes present a unique challenge for radioanalytical chemists. In this study, re-determination of ²³⁸Pu, ^239+240Pu, and ²⁴¹Am for soils collected and analyzed approximately three decades ago was the goal, along with direct determination of ²⁴¹Pu. The soils had been collected in the early 1970’s from a shallow land burial site for radioactive wastes called the Subsurface Disposal Area (SDA) at the Idaho National Lab (INL), analyzed for ²³⁸Pu, ^239+240Pu, and ²⁴¹Am, and any remaining soils after analysis had been archived and stored. We designed an approach to reanalyze the ²³⁸Pu, ^239+240Pu, and ²⁴¹Am and determine for the first time ²⁴¹Pu using a combination of traditional and new radioanalytical methodologies. The methods used are described, along with estimates of the limits of detection for gamma-and alpha-spectrometry, and liquid scintillation counting. Comparison of our results to the earlier work documents the ingrowth of ²⁴¹Am from ²⁴¹Pu, and demonstrates that the total amount of ²⁴¹Am activity in these soil samples is greater than would be expected due to ingrowth from ²⁴¹Pu decay.     

Simultaneous determination of plutonium and americium in soils by extraction chromatography

A radiochemical method is described for the determination of²³⁸Pu,^239(240)Pu and²⁴¹Am in a single soil sample. Plutonium is separated from a HNO₃ leaching solution by a Microthene-TNOA column; amcricium is coprecipitated by oxalic acid, decontaminated from polonium by a TNOA-column in HCl medium, separated from the rare earth elements by a Microthene-HDEHP column, eluted with a 0.07M DTPA+1M lactic acid solution and finally purified by a PMBP-TOPO extraction. The method supplies a good decontamination of Am and Pu from natural alpha emitters; starting from 50 g soil, the average yields were 75.1±13.4% for plutonium and 57.7±10.8% for Am.^239(240)Pu,²³⁸Pu and²⁴¹Am concentrations (mBq/kg) in three different kinds of soil were the following: 255, 10.4, 81.3 (uncultivated soils); 236, 11.6, 76.7 (cultivated soils); 46, 1.9, 19.8 (river sediment). The average ratios²³⁸Pu to^239(240)Pu and²⁴¹Am to^239(240)Pu were 0.044 and 0.350, respectively.     

Plutonium, 90Sr and 241Am in human bones from southern and northeastern parts of Poland

The paper presents the results of our study on ²³⁸Pu, ²³⁹Pu, ²⁴⁰Pu, ²⁴¹Am and ⁹⁰Sr concentration in human bones carried out on a set of 88 individual samples of central Europe origin. Bone tissue samples were retrieved under surgery while introducing hip joint implants. The conducted surgeries tend to cover either southern or northeastern parts of Poland. While for the southern samples only global fallout was expected to be seen, a mixed global and Chernobyl fallout were to be reflected in the others. Alpha spectrometry was applied to obtain activity concentration for ²³⁸Pu, ^239+240Pu, ²⁴¹Am, while liquid scintillation spectrometry for ⁹⁰Sr and mass spectrometry to receive ²⁴⁰Pu/²³⁹Pu mass ratio. Surprisingly enough, and to the contrary to our expectations we could not see any significant differences in either Pu activity or Pu mass ratio between the studied populations. In both populations Chernobyl fraction proved marginal. The results on ⁹⁰Sr and ²⁴¹Am confirm similarities between the two examined groups.     

Behavior and distribution of <Superscript>239+240</Superscript>Pu and <Superscript>241</Superscript>Am in the east coast of Peninsular Malaysia marine environment

The present distributions of ^239+240Pu, ²⁴¹Am and activity ratio of ²⁴¹Am/^239+240Pu in surface seawater of the Peninsular Malaysia east coast were studied. The surface seawater samples were collected at 30 identified stations during the expedition conducted in 2008. ^239+240Pu activity concentrations in surface seawater of the studied area were in the range of 2.33 ± 0.20–7.95 ± 0.68 mBq/m³, meanwhile ²⁴¹Am activity concentrations ranged from MDA to 1.90 ± 0.23 mBq/m³. The calculated activity ratios of ²⁴¹Am/^239+240Pu were varied and disperse distributed with the ranged of 0.12–0.53. The relationships between anthropogenic radionuclide and oceanographic parameters such as turbidity and salinity were examined. The linearly relationships between ^239+240Pu and oceanographic parameters are important for better understanding of its transport processes and behavior in the east coast of Peninsular Malaysia marine environment. Thus, the differ of distribution of ^239+240Pu, ²⁴¹Am and ²⁴¹Am/^239+240Pu in the studied area mainly due to high affinity of ^239+240Pu to associate with sinking particles, mobility nature of ²⁴¹Am, degree of particle reactive of both anthropogenic radionuclides, scavenging and removal process; and others.     

Isotopic composition of plutonium immissions in Austria after the Chernobyl accident

Alpha-spectrometric Pu determinations in aerosol samples collected after the Chernobyl accident in Austria show a²³⁸Pu/²³⁹ (240)Pu ratio in the range of 0.33–0.76 with a most reliable value of 0.47. From²⁴¹Am measurements in old Pu preparations and air filter analyses also²⁴¹Pu activities have been calculated. The ratio²⁴¹Pu/^{239 (240)}Pu during the main contamination period is 74.6±5.7, when maximum²⁴¹Pu concentrations in air achieved 4.5–6.0 mBq/m³.     

238Pu, 239+240Pu, 241Am, 90Sr and 137Cs in mountain soil samples from the Tatra National Park (Poland)

Activity concentrations and inventory for ²³⁸Pu, ^239+240Pu, ²⁴¹Am, ⁹⁰Sr, and ¹³⁷Cs in soil from Tatra Mountains of Poland are presented. Soil samples were collected using 10 cm diameter cores down to 10 cm and sliced into 3 slices. Details of the applied procedure are described with the quality assurance program. The maximum activity concentrations found for various samples were: 1782±13 Bq/kg, 17.4±0.9 Bq/kg, 3.4±0.3 Bq/kg and 84±7 Bq/kg for ¹³⁷Cs, ^239+240Pu, ²⁴¹Am and ⁹⁰Sr, respectively. The maximum cumulated deposition of ^239+240Pu is 201±8 Bq/m². The origin of radionuclides is discussed, based mostly on the observed isotopic ratio of Pu. Significant correlations were found between ^239+240Pu, ²⁴¹Am and ¹³⁷Cs. The effective vertical migration rate seems to be in the order of: ⁹⁰Sr≫Pu>Am>Cs.     

Presence of 137Cs, Pu isotopes and 241Am in ligurian and Tyrrhenian Seas sediments

During the last ten years, the Italian Universities of Parma and Urbino collaborated on a special radioecological program having the aim to study the levels and the distribution of long-lived radionuclides in different marine and terrestrial matrixes. This paper summarizes the results concerning the concentrations of ^239+240Pu and ²³⁸Pu, ²⁴¹Am and ¹³⁷Cs in sediments collected in the Ligurian and South Tyrrhenian Seas (Rapallo Harbour, Vado Ligure Canyon, Eolie Islands). Superficial sediments and sediment cores were collected. For cores the vertical distribution was calculated and the sedimentation rate obtained. ¹³⁷Cs was determined directly by gamma-spectrometry, while ^239+240Pu, ²³⁸Pu and ²⁴¹Am were separated by extraction chromatography, electroplating and determined by alpha-spectrometry. This revised version was published online in August 2006 with corrections to the Cover Date.     

Reverse isotope dilution alpha spectrometry using plutionium-239 spike for determining plutonium concentration in high burn-up fuel samples without purification from americium-241 and a bulk of other impurities

A reverse isotope dilution alpha spectrometric /R-IDAS/ method using²³⁹Pu as a spike is described for the determination of plutonium concentration in high burn-up fuel samples wth²³⁸Pu/(²³⁹Pu+²⁴⁰Pu) alpha activity ratio >0.5, without resorting to any purification from²⁴¹Am and a bulk of other impurities. It involves the addition of a pre-clibrated spike solution to a known aliquot of the plutonium sample solution followed by source preparation using TEG as a spreading agent. The results obtained on a number of plutonium samples containing 20–80% of²⁴¹Am /alpha activity wise/ using this method are compared with those achieved by R-IDAS using purification with TTA, with respect to precision and accuracy. Precision and accuracy of 0.5% are demonstrated. This method eliminates the need of any separation and purification of plutonium from²⁴¹Am and a bulk of other impurities like uranium.     

Determination of plutonium,americium and curium in airborne effluents of nuclear power plants

A radiochemical method has been developed for the determination of²³⁸Pu,^{239, 240}Pu,²⁴¹Am,²⁴²Cm and²⁴⁴Cm in airborne effluents of nuclear power plants. The method involves conversion of transuranium elements to acid-soluble forms, dissolution, purification, electrodeposition and alpha spectrometric determination. Final recovery ranged from 69.0 to 75.4% for plutonium and from 26.8 to 68.3% for americium and curium.     

Sequential separation and determination of plutonium, americium-241 and strontium-90 in soils and sediments

A sensitive and reliable metbod for the sequential separation and determination of plutonium,²⁴¹Am and⁹⁰Sr in soil samples was developed. Plutonium was separated by a Microthene-TNOA column. Then⁹⁰Y (for⁹⁰Sr determination) was separated from americium by a HDEHP column after elimination of large amounts of interfering stable or radioactive nuclides (iron,²¹⁰Bi and²¹⁰Po etc.) by an oxalate precipitation and a Microthene-TNOA column. Finally americium was purified by another HDEHP column and a PMBP-TOPO extraction. A special attention was paid to the decontamination of Pu and Am from²¹⁰Po and of⁹⁰Y from²¹⁰Bi; the relevant decontamination factors resulted greater than 10⁵, 10⁶ and 10⁴ respectively. The detection limits were 1.2 mBq/kg for Pu and 1.7 mBq/kg for²⁴¹Am and 0.32 Bq/kg for⁹⁰Sr. The procedure was checked by analyzing three certified samples supplied by IAEA. Some Italian soil samples were also analyzed giving average yields of 84.9±7.2% for Pu, 57.8±3.2%for Am and 96.7±1.6% for Y; the^239+240Pu,²³⁸Pu,²⁴¹Am and⁹⁰Sr contents (Bq/kg) ranged from 0.347 to 1.53, from 0.013 to 0.048, from 0.126 to 0.556 and from 2.89 to 11.6 respectively and the average ratios were 0.037±0.017 for²³⁸Pu/^239+240Pu, 0.357±0.040 for²⁴¹Am/^239+240Pu and 7.0±1.2 for⁹⁰Sr/^239+240Pu.     

Measurements of actinide nuclides in water samples from the primary circuit of a nuclear power plant

Weekly, consecutive primary coolant samples from a boiling water reactor have been analyzed for^{239, 240}Pu,²³⁸Pu+²⁴¹Am,²⁴²Cm and²⁴⁴Cm for about two years, and for²³⁸Pu,²⁴¹Pu and²⁴¹Am for one year. Concentration ranges are reported. Samples were prepared for counting either directly by evaporation or by chemical separation on BioRad AG 1×4 resin and subsequent electrolysis, and were counted in 20 cm dia Frish grid ionization chambers. Procedures are described. For most actinide nuclides, activity ratios in primary coolant were found to be different from those in worldwide fallout, thus allowing an identification of origin in the case, that actinides should be detected in the vicinity of a nuclear power station.     

Age determination of single plutonium particles after chemical separation

Age determination of single plutonium particles was demonstrated using five particles of the standard reference material, NBS 947 (Plutonium Isotopic Standard. National Bureau of Standards, Washington, D.C. 20234, August 19, 1982, currently distributed as NBL CRM-137) and the radioactive decay of ²⁴¹Pu into ²⁴¹Am. The elemental ratio of Am/Pu in Pu particles found on a carbon planchet was measured by wavelength dispersive X-ray spectrometry (WDX) coupled to a scanning electron microscope (SEM). After the WDX measurement, each plutonium particle, with an average size of a few μm, was picked up and relocated to a silicon wafer inside the SEM chamber using a micromanipulator. The silicon wafer was then transferred to a quartz tube for dissolution in an acid solution prior to chemical separation. After the Pu was chemically separated from Am and U, the isotopic ratios of Pu (²⁴⁰Pu/²³⁹Pu, ²⁴¹Pu/²³⁹Pu and ²⁴²Pu/²³⁹Pu) were measured with a thermal ionization mass spectrometer (TIMS) for the calculation of Pu age. The age of particles determined in this study was in good agreement with the expected age (35.9 a) of NBS 947 within the measurement uncertainty.     

Sensitivity of DF-ICP-MS,PERALS and alpha-spectrometry for the determination of actinides: A comparison

We applied three techniques (DF-ICP-MS, PERALS and alpha-spectrometry) for the determination of minor actinides at environmental levels. For each method the limit of detection and the resolution were estimated in order to study the content and isotopic composition of the actinides. Two international reference materials, IAEA-135 (Irish Sea Sediment) and IAEA-300 (Baltic Sea sediment) were analyzed for activity concentrations of ²³⁸Pu, ²³⁹Pu, ²⁴⁰Pu, ²⁴¹Pu and ²⁴¹Am. The sensitivities of the three determination techniques were compared.     

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.     

Gamma-emitters 90Sr, 238,239+240Pu and 241Am in bones and liver of eagles from Poland

Summary The present study focused on analyzing samples of bones, livers and kidneys of European white-tailed eagles (Halia?tus albicilla) and lesser-spotted eagle (Aquila pomarina). Bone samples were collected for both species, from 7 and 2 individuals, respectively, whereas liver and kidney samples for white-tailed eagle species only, 2 and 1 individuals, respectively. The samples were analyzed for the presence of gamma-emitters and then for ⁹⁰Sr, ²³⁸Pu, ^239+240Pu and ²⁴¹Am. The applied radiochemical method is presented. Activity concentration in ashen bones (600 °C) for ⁹⁰Sr ranged from 4.6±1.2 to 31.0±2.5 Bq/kg, for ^239+240Pu from <1.7 to 21±4 mBq/kg, for ²³⁸Pu from <2.7 to 6.5±1.3 mBq/kg and for ²⁴¹Am from <1.2 to 6.5±4.4 mBq/kg. Relatively high ^239+240Pu activity concentration of 78±9 mBq/kg (for fresh weight) was recorded in a single kidney sample. The liver samples showed activities of magnitude at least one order lower. No clear correlations were found between the activities of different radionuclides.     

241Pu in the biggest Polish rivers

In the paper the results of ²⁴¹Pu activity concentration determination in the biggest Polish rivers are presented. The analysis of more than 100 river water samples showed the Vistula and the Odra as well as three Pomeranian Rivers are important sources of ²⁴¹Pu in the southern Baltic Sea. There were differences in ²⁴¹Pu activities depending on season and sampling site and the plutonium contamination came mainly from the global atmospheric fallout as well as the Chernobyl accident, which is confirmed by plutonium activity ratios of ²⁴¹Pu/^239+240Pu and ²³⁸Pu/^239+240Pu.     

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.     

137Cs, 40K, 90Sr, 238, 239+240Pu, 241Am and 243+244Cm in forest litter and their transfer to some species of insects and plants in boreal forests: Three case studies

Results for ¹³⁷Cs, ⁴⁰K, ⁹⁰Sr, ^238,239+240Pu, ²⁴¹Am and ^243+244Cm measurements in plant, insects and forest litter samples collected at three sites in Poland are presented. New results are compared with some existing data for locations examined during previous studies. Insect samples were introduced now for the first time. Relatively high activities of ⁹⁰Sr were noticed for spruce bark beetle (Ips typographus) and those for ¹³⁷Cs, plutonium and ²⁴¹Am for forest dung beetle (Anoplotrupes stercorosus). Faster than caused by physical decay decrease of radiocesium activity was noticed for the majority of plant and litter samples. The results for ^239+240Pu for litter were similar to previous results, but the activities of ²³⁸Pu were smaller. The activity ratio between ²⁴¹Am and ^239+240Pu was found lower than expected for known proportions between global and Chernobyl fallout. Thus a kind of dynamic behavior of Pu and Am in the forest ecosystem is concluded. Transfer factors and aggregation coefficients were estimated and discussed for both plants and insects as well as between insects and the part of plants (or litter) they feed on. Many of them were never presented before.The authors are thankful to the Polish State Committee for Scientific Research for financial support of this investigation, Grant No. PG04 07520.