Sequential isotopic determination of plutonium,thorium, americium and uranium in the air filter and drinking water samples around the WIPP site

The simultaneous determination of actinides in air filter and water samples around the WIPP site have been demonstrated. The analytical method is based on the selective separation and purification by anion exchange and Eichrome-TEVA, TRU and DGA-resin followed by determination of actinides by alpha spectrometry. Counting sources for alpha spectrometric measurements were prepared by microcoprecipitation on neodymium fluoride (NdF₃). Radiochemical yields were determined using ²⁴²Pu, ²²⁹Th, ²⁴³Am and ²³²U as tracers. The validation of the method is performed through the analysis of reference materials or participating in laboratory intercomparison programs. The plutonium concentrations in aerosols varied seasonally, being highest in spring and summer due to the spring-time enhanced wind-storm transportation of radioactive aerosols from the stratosphere to the troposphere. The ²³⁸Pu/^239+240Pu activity ratio in the aerosol samples is typically close to that of global fallout from historic above-ground nuclear weapons testing. The results presented here indicate that the source of plutonium in the WIPP environment results mainly from global nuclear fallout and there is no evidence of increases in radiological contaminants in the region that could be attributed to releases from the WIPP.     

Airborne plutonium monitoring

Methods of monitoring low plutonium concentration in the inner and outer atmosphere are analyzed and compared. It is shown that monitors based on the gross alpha counting of air filters are not sensitive enough to measure reliably plutonium activities below 1 MPC. A spectrometric discontinuously operating monitor using a gridded ionization chamber and a membrane filter having 70 cm² active area is described. Plutonium activities of the order of 0.01 MPC /1 mBq.m^–3/ can be measured by the spectrometer at 1 h sampling and 1 h counting time.     

Concentration of plutonium in squids collected from Japanese inshore measured by HR-ICP-MS, 1981–2000

In order to obtain the information about plutonium contamination in ocean environment, plutonium in the internal organs of squid collected from Japanese inshore were determined by HR-ICP-MS. Although the plutonium was detected in all samples collected in 1980"s, the concentration is almost the same level as the detection limit (1 to 3 mBq/kg wet) in recent years. The atomic ratio of ²⁴⁰Pu/²³⁹Pu in all samples was slightly higher than the value of global fallout.     

Concentration of239, 240Pu in human bone

Some results of the plutonium determination for bone ash samples collected in Japan are presented. Mean^239,240Pu concentration in the adult vertebra was 0.53 pCi/kg of ash during the period 1978 through 1983. The data are roughly in coincidence with estimated plutonium concentrations in the trabecular bone from reported air plutonium concentrations using the ICRP model and metabolic data, and weight of bone in Reference Japanese Man.     

Analysis of nuclear materials by energy dispersive X-ray fluorescence and spectral effects of alpha decay

Energy dispersive X-ray fluorescence (EDXRF) spectra collected from alpha emitters are complicated by artifacts inherent to the alpha decay process, particularly when using portable instruments. For example, ²³⁹Pu EDXRF spectra exhibit a prominent uranium L X-ray emission peak series due to sample alpha decay rather than source-induced X-ray fluorescence. A portable EDXRF instrument was used to collect qualitative spectra from plutonium and americium, and metal alloy identification was performed on a Pu-contaminated steel sample. Significant alpha decay-induced X-ray fluorescence peaks were observed in spectra obtained from the plutonium and americium samples due to the ²³⁵U and ²³⁷Np daughters, respectively. The plutonium sample was also analyzed by wavelength dispersive XRF (WDXRF) to demonstrate that alpha decay-induced X-ray emission has a negligible effect on WDXRF spectra.     

Presence of uranium and plutonium in marine sediments from gulf of tehuantepec, mexico

Uranium and plutonium were determined in the Tehua II-21 sediment core collected from the Gulf of Tehuantepec, Mexico. The analyses were performed using radiochemical separation and alpha spectroscopy. Activity concentrations of alpha emitters in the sediment samples were from 2.56 to 43.1 Bq/kg for ²³⁸U, from 3.15 to 43.1 Bq/kg for ²³⁴U and from 0.69 to 2.95 Bq/Kg for ^239+240Pu. Uranium activity concentration in marine sediment studied is generally high compared with those found in sediments from other marine coastal areas in the world. The presence of relatively high concentrations of anthropogenic plutonium in the sediments from the Gulf of Tehuantepec suggests that anthropogenic radionuclides have been incorporated and dispersed into the global marine environment.     

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.     

Plutonium isotopes in the surface air in Japan: Effect of Chernobyl accident

Plutonium isotope concentrations in the surface air at Tsukuba, Japan are reported during the period from 1981 to the end of 1986. The^239,240Pu concentration in the surface air, which showed a marked seasonal variation with a spring maximum and fall minimum, decreased until the end of 1985 according to the stratospheric residence time of 1.15 years. In May 1986, elevated^239,240Pu concentrations with high²³⁸Pu/^239,240Pu activity ratios were observed. The serial trend of plutonium concentration in the surface air is similar to the concentrations of the Chernobyl-released radionuclides. These findings suggest that a significant part of the plutonium in the surface air in May 1986 was due to the Chernobyl fallout. The size distribution of plutonium bearing particles indicates that plutonium isotopes were mechanically released in the Chernobyl accident. The surface air concentration of plutonium from the Chernobyl accident was much lower than the concentrations of the volatile fission products, and increased the monthly mean^239,240Pu concentration by only 0.03 Bqm^–3.     

Determination of atmospheric iodine species using a system of specifically prepared filters and IDMS

Summary A system was developed which allowed the determination of four different atmospheric iodine species by preparing glass microfibre filters, which were arranged in consecutive order, in a specific way. Particulate iodine was collected by a particle filter, HI and I₂ by a NaOH impregnated filter, HOI was adsorbed on a TBAH impregnated filter and organoiodine was adsorbed on a filter loaded with activated charcoal. These behaviours were checked by extensive model experiments. Two or more filters of the same type were used in series to show the degree of collection of one iodine species. Two European samples, one of continental and one of marine origin, and two Antarctic samples were analysed by this filter system using isotope dilution mass spectrometry (IDMS) for quantification. The distribution pattern for the different iodine species is similar for the two European samples. Organoiodine is found to be the most abundant species whereas in Antarctica the HI/I₂ fraction is up to nearly 50% of the total iodine. The particulate iodine fraction is higher in Europe than in Antarctica, which is due to the low particle concentration in the remote area of Antarctica. The higher HI/I₂ and HOI fractions found at the North Sea compared with the continental sample indicate that the ocean is a primary source of these species. Concentrations in the range of (0.3–3.1) ng I/m³ were analysed for particulate iodine, (0.4–1.3) ng I/m³ for HI/I₂, (0.2–1.8) ng I/m³ for HOI and (0.4–7.6) ng I/m³ for organoiodine. The detection limits varied with the variances of the blank values of the different filters and lay between 0.02 ng I/m³ and 0.24 ng I/m³ using sample volumes of 70 m³ air.     

<Superscript>239, 240, 241</Superscript>Pu fingerprinting of plutonium in western US soils using ICPMS: solution and laser ablation measurements

Sector field inductively coupled plasma mass spectrometry (SF-ICPMS) has been used with analysis of solution samples and laser ablation (LA) of electrodeposited alpha sources to characterize plutonium activities and atom ratios prevalent in the western USA. A large set of surface soils and attic dusts were previously collected from many locations in the states of Nevada, Utah, Arizona, and Colorado; specific samples were analyzed herein to characterize the relative contributions of stratospheric fallout vs. Nevada Test Site (NTS) plutonium. This study illustrates two different ICPMS-based analytical strategies that are successful in fingerprinting Pu in environmental soils and dusts. Two specific datasets have been generated: (1) soils are leached with HNO₃-HCl, converted into electrodeposited alpha sources, counted by alpha spectrometry, then re-analyzed using laser ablation SF-ICPMS; (2) samples are completely dissolved by treatment with HNO₃-HF-H₃BO₃, Pu fractions are prepared by extraction chromatography, and analyzed by SF-ICPMS. Optimal laser ablation and ICPMS conditions were determined for the re-analysis of archived alpha spectrometry “planchette” sources. The best ablation results were obtained using a large spot size (200 μm), a defocused beam, full repetition rate (20 Hz) and scan rate (200 μm s⁻¹); LA-ICPMS data were collected with a rapid electrostatic sector scanning experiment. Less than 10% of the electroplated surface area is consumed in the LA-ICPMS analysis, which would allow for multiple re-analyses. Excellent agreement was found between ^239+240Pu activities determined by LA-ICPMS vs. activity results obtained by alpha spectrometry for the same samples ten years earlier. LA-ICPMS atom ratios for ²⁴⁰Pu/²³⁹Pu and ²⁴¹Pu/²³⁹Pu range from 0.038–0.132 and 0.00034–0.00168, respectively, and plot along a two-component mixing line (²⁴¹Pu/²³⁹Pu = 0.013 [²⁴⁰Pu/²³⁹Pu] – 0.0001; r ² = 0.971) with NTS and global fallout end-members. A rapid total dissolution procedure, followed by extraction chromatography and SF-ICPMS solution Pu analysis, generates excellent agreement with certified ^239+240Pu activities for standard reference materials NIST 4350b, NIST 4353, NIST 4357, and IAEA 385. ^239+240Pu activities and atom ratios determined by total dissolution reveal isotopic information in agreement with the LA-ICPMS dataset regarding the ubiquitous mixing of NTS and stratospheric fallout Pu sources in the regional environment. For several specific samples, the total dissolution method reveals that Pu is incompletely recovered by simpler HNO₃-HCl leaching procedures, since some of the Pu originating from the NTS is contained in refractory siliceous particles.     

Pre-concentration and separation of thorium, uranium, plutonium and americium in human soft tissues by extraction chromatography

An extraction chromatographic method is described for the pre-concentration and separation of thorium, uranium, plutonium and americium in human soft tissues. Tissues such as lung and liver are oven dried at 120°C, ashed at 450°C and the ashed sample is alternately wet (HNO₃/H₂O₂) and dry ashed, and then dissolved in 8M HCl. Because of the complex matrix and large sample samples (up to 1500 g), the actinides were preconcentrated from the tissue solution using the TRU^TM resin (EIChroM) prior to elemental separation by extraction chromatography and determination of americium, plutonium, uranium and thorium by alpha spectrometry. The actinides were eluted from the preconcentration column and each actinide was individually eluted on TEVA^TM and TRU^TM resin columns in a tandem configuration. Actinide activities were then determined by alpha spectrometry after electrodeposition from a sulfate medium. The method was validated by analyzing human tissue samples previously analyzed for americium, plutonium, uranium and thorium in the United States Transuranium and Uranium Registries (USTUR). Two National Institute of Standards and Technology (NIST) Standard Reference Materials, SRM 4351-Human Lung and SRM 4352-Human Liver were also analyzed. United States Transuranium and Uranium Registries, Washington State University, Pullman, WA, 99163, USA.     

Physical and chemical forms of radionuclides of 38S, 38Cl, 39Cl, and 82Br, produced at a high-energy proton accelerator facility

High-energy protons and neutrons produce various radionuclides in the air, mainly through the nuclear spallation of atmospheric elements. Air samples were collected from the EP-2 tunnel of the KEK 12 GeV proton synchrotron facility with a filter pack, which consisted of a membrane filter for aerosols, a Na₂CO₃-impregnated filter for acidic gases, and an activated carbon fiber filter for non-acidic gases. Sulfur-38 was found on the membrane and Na₂CO₃-impregnated filters, ³⁸Cl and ³⁹Cl were on the membrane, Na₂CO₃-impregnated, and ACF filters, and ⁸²Br was only on the ACF filter. The results on the relative abundances of aerosol and gaseous acidic components have indicated that ³⁸Cl produced by thermal neutron capture, which is the main reaction for ³⁸Cl production in the EP-2 tunnel air, are likely not to be present as aerosol or acidic gas. This was similar to the case of ⁸²Br produced by thermal neutron capture.     

Determination of soluble and insoluble nickel compounds in airborne particulate matter by graphite furnace atomic absorption spectrometry and inductively coupled plasma mass spectrometry

An extraction procedure for the determination of soluble and insoluble nickel and its compounds in ambient air dust was investigated employing a special device for the generation of test aerosols and using water-soluble NiCl₂, partly water-soluble NiCO₃ and water-insoluble NiO as model compounds. Additionally, results of the separation and determination of different nickel species down to some ng/m³ in ambient aerosols are discussed. The extraction was carried out with a solution containing 0.01 mol/L EDTA in order to determine partly water-soluble compounds such as NiCO₃ and water-soluble, non-toxic nickel compounds in one step. Airborne dust was sampled on filters at locations close to two metallurgical plants in Northrhine-Westphalia (Germany), and first results on the nickel concentration (mean (median) values over a period of 4 months: 8.6 ± 6.5 ng/m³ (6.7 ng/m³) and 27.7 ± 36 ng/m³ (10.8 ng/m³), respectively) in the collected dust are presented. For EDTA-soluble nickel compounds the maximum and mean fractions of total nickel were found to be 77.1% and 18.6 ± 12%, respectively.     

Transfer of selected heavy metals and radionuclides from calcareous peat to saw sedge (Cladium mariscus) in eastern Poland

Summary The level of artificial and natural radionuclide concentration as well as heavy metal content were determined in samples of saw sedge and peat collected in the Special Protection Area of peat bogs near Chelm (Poland). Gamma- and alpha-spectrometry with proper sample preparation were used to determine natural gamma-emitters, artificial ¹³⁷Cs and alpha-radiating plutonium (²³⁸Pu and ^239,240Pu). Non radioactive elements were determined by AAS. Rather low level of heavy metal concentration in all samples was found, however, the transfer factors were significant. Peat contamination with artificial radionuclides (¹³⁷Cs and plutonium) was low. Contrary, the concentration of these isotopes in saw sedge was higher than normally observed in non contaminated areas, what is a result of a significant transfer factor.     

Study of the winter and summer changes of the air composition in the church of Szalowa, Poland, related to conservation

The St. Michael Archangel’s Church in Szalowa, Poland, was selected for closer investigation with respect to the indoor/outdoor air exchange and its influence on the air quality and work arts preservation. Chemical composition, size and abundance of particulate matter and concentration of gases NO₂, SO₂, O₃ inside and outside the church were determined. To study seasonal variation of the weather condition (temperature, inversion level, wind direction) and the influence of seasonal sources of the air pollution (like heating of the nearby houses), samples were collected in winter and summer time. It was stated that suspended particulate matter inside the wooden church has in general an outdoor source. Several groups of particles were distinguished such as the organic ones, soil dust, nitrates and sulphates. In case of organic and soil dust particles, the concentration inside was higher than outside. From the results, in comparison to literature data, one can conclude that accumulation of particulate suspended matter in the church is more intense than in other types of buildings. Gaseous pollutants were detected but their concentration was negligible.     

Characterisation of nuclear fuel by spectroscopic evaluation of alpha autoradiographs

New methods for estimation of concentration and distribution of plutonium in (Th,Pu)O₂ MOX fuel samples have been attempted by spectroscopic analysis of SSNTD based alpha images using UV–Vis spectrophotometry and photoluminescence spectroscopy. (Th,Pu)O₂ MOX fuel samples having a large range of PuO₂ concentration, were subjected to this study and found beneficial when compared with the conventional analysis of alpha autoradiographs. UV–Vis absorbance and photoluminescence of the alpha autoradiograph showed linear decrease proportionally to PuO₂% in the fuel sample. Optical band gap was found to proportionally increase with PuO₂% in the fuel sample which was revealed in UV–Vis spectrophotometry.

     

The effect of physicochemical parameters on the separation recovery of plutonium and uranium from aqueous solutions by cation exchange

The effect of physicochemical parameters such as pH, salinity (e.g. [NaCl]) and competitive cation (e.g. Ca²⁺ and Fe³⁺) concentration on the separation recovery of plutonium and uranium from aqueous solutions by cation exchange has been investigated. The investigation was performed to evaluate the applicability of cation exchange as separation and pre-concentration method prior to the radiometric analysis of uranium and plutonium isotopes in natural water samples. Application of the method to test solutions of constant radionuclide concentration and variable composition (0.1, 0.5 and 1 M NaCl; 0.1 and 0.5 M Ca(NO₃)₂; 0.1 and 1 mM FeCl₃; 10) has generally shown that: (1) the optimum pH is 4.5 for uranium and plutonium, (2) increasing salinity results in slightly lower for uranium and significantly higher chemical recovery plutonium and (3) the presence of Ca(II) cations doesn’t significantly affect the chemical recovery of both radionuclides. Contrary, the presence of Fe(III) cations ([Fe(III)] > 0.1 mM) results in significantly lower chemical recovery for both radionuclides (<50%). The later is attributed to the formation of Fe(III) colloids, which present increased chemical affinity for uranium and plutonium and hence compete with the radionuclide binding by the resin. Nevertheless, the results indicate that the method could be successfully applied to a wide range of natural waters.     

Electrospun Polyacrylonitrile Nanofibrous Membranes for Point-of-Use Water and Air Cleaning

Novel electrospun polyacrylonitrile (PAN) nanofibrous membranes were prepared by using heat-press lamination under various conditions. The air permeability and the burst-pressure tests were run to select the membranes for point-of-use air and water cleaning. Membrane characterization was performed by using scanning electron microscopy, contact angle, and average pore size measurements. Selected membranes were used for both air dust filtration and cross-flow water filtration tests. Air dust filter results indicated that electrospun PAN nanofibrous membranes showed very high air-dust filtration efficiency of more than 99.99 % in between PM_0.3 and PM_2.5, whereas cross-flow filtration test showed very high water permeability over 600 L/(m²hbar) after 6 h of operation. Combining their excellent efficiency and water permeability, these membranes offer an ideal solution to filter both air and water pollutants.     

Source identification and long-term monitoring of airborne particulate matter (PM<Subscript>2.5</Subscript>/PM<Subscript>10</Subscript>) in an urban region of Korea

Summary For the identification of air pollution sources, about 500 airborne particulate matter (PM_2.5and PM₁₀) samples were collected by using a Gent air sampler and a polycarbonate filter in an urban region in the middle of Korea from 2000 to 2003. The concentrations of 25 elements in the samples were measured by using instrumental neutron activation analysis (INAA). Receptor modeling was performed on the air monitoring data by using the positive matrix factorization (PMF2) method. According to this analysis, the existence of 6 to 10PMF factors, such as metal-alloy, oil combustion, diesel exhaust, coal combustion, gasoline exhaust, incinerator, Cu-smelter, biomass burning, sea-salt, and soil dust were identified.     

Simultaneous determination of lead-210, gross beta and gross alpha activities of air filters by pulse shape discrimination liquid scintillation counting

A chemical procedure for transferring deposited solid matter from a cellulose filter into the liquid scintillation cocktail has been described. The influence of chemical and color quenching on alpha and beta detection efficiency, as well as on misclassification of beta and alpha pulses was corrected by an external standard method. Under the chosen pulse shape discrimination level (PSD), the alpha and beta detection efficiencies were above 85% and spillovers of alpha and beta pulses were below 10% and 2% respectively. Determination limits for samples containing up to 200 mg of mineral matter were 0.015 mBq m^–3 for alpha, 0.055 mBq.m^–3 for²¹⁰Pb and 0.055 mBq.m^–3 for beta activity (counting time 12000 s and volume of filtered air 1000 m³). The method has been applied for routine monitoring of²¹⁰Pb as well as for gross alpha and beta activities of longer-living radionuclides (T_1/2.>11 hrs) in suspended air matter.