Analysis Of Plutonium Research Articles

Challenge to ultra-trace analytical techniques of nuclear materials in environmental samples for safeguards at JAERI: methodologies for physical and chemical form estimation

From a viewpoint of physical and chemical form estimation, ultra-trace analytical techniques of nuclear materials in environmental samples for safeguards have been investigated at Japan Atomic Energy Research Institute. This article deals with (1) an outline of the developed techniques for bulk and particle analyses of uranium and plutonium in the safeguards environmental samples; (2) current R&D on techniques relating to estimation of the physical and chemical form, such as SEM images and EDX spectra for fine particles of nuclear materials and fission track observation applicable to fissile materials; and (3) possible analytical methodologies, as future works, applicable to ultra-trace amounts of nuclear materials in environmental samples.

In search of higher sensitivity: Pu isotopic analysis

Thermal ionization mass spectrometry (TIMS) is an effective method for isotopic and ultra-sensitivity determination of plutonium. This project aims at improving the National Institute of Standards and Technology (NIST) TIMS system sensitivity for the analysis of plutonium from environmental samples. The TIMS detection limits for direct, electrodeposition, and resin bead source loading techniques were determined by systematically varying the amount of plutonium loaded on the rhenium filament. It has been shown in our preliminary work that the resin bead could produce a stable TIMS ion beam for as long as 6 h period with »108 Pu atoms loaded onto a single resin bead.

Sequestered Plutonium: [PuIV{5LIO(Me‐3,2‐HOPO)}2]—The First Structurally Characterized Plutonium Hydroxypyridonate Complex

The first single-crystal X-ray diffraction analysis of a hydroxypyridonate plutonium(IV) complex is presented, that of the tetradentate ligand 5LIO(Me-3,2-HOPO) with Pu(IV). The [Pu(IV){5LIO(Me-3,2-HOPO)}(2)] complex crystallizes in the space group Pna2(1) with the asymmetric unit cell containing two unique eight-coordinate plutonium complexes and one perchlorate anion. According to shape measure analysis, the geometry of both Pu centers is closest to a bicapped trigonal prism (C(2v) symmetry, for Pu 1: S(C(2v))=13.48 degrees , S(D(4d))=15.43 degrees , S(D(4d))=16.10 degrees ). The average bond length for the Pu--O(phenolic) is 2.31(4) A, whereas the Pu--O(amide) distances are slightly longer, averaging 2.40(2) A. The preparative chemistry of this compound and the implications of the structure are discussed.

Development of Rapid Plutonium Analysis for Environmental Samples by Isotope Dilution/Inductively Coupled Plasma Mass Spectrometry with On-line Column

This paper describes our development of a rapid on-line column/ID-ICP-MS technique for the analysis of plutonium (Pu) in environmental samples using an UTEVA extraction chromatograph resin (UTEVA resin) column. It took only 40 min to separate and measure Pu in the sample solution, including the time for conditioning the resin column for the next analysis. In our method, Pu in a 3 M nitric acid solution was fed to the UTEVA resin, and then eluted from the resin by reducing Pu to Pu(III) with 3 M nitric acid mixed with 0.01 M ascorbic acid after washing the resin. The outflow from the resin column was directly introduced to an ICP-MS system. The low concentration of ascorbic acid and the small volume of the eluting solution (0.6 mL) made successive stable analysis possible without any skimmer cone clogging. The chemical recovery of Pu during column operation was 70%, and typical lower detection limits for 239Pu, 240Pu and 242Pu were 9.2, 4.3 and 7.5 fg (21, 36 and 1.1 microBq), respectively. We analyzed five international standard materials for Pu, and obtained good results.

The development of sequential separation methods for the analysis of actinides in sediments and biological materials using anion-exchange resins and extraction chromatography

New, quantitative methods for the determination of actinides have been developed for application to marine environmental samples (e.g., sediment and fish). The procedures include aggressive dissolution, separation by anion-exchange resin, separation and purification by extraction chromatography (e.g., TRU, TEVA and UTEVA resins) with measurement of the radionuclides by semiconductor alpha-spectrometry (SAS). Anion-exchange has proved to be a strong tool to treat large volume samples, and extraction chromatography shows an excellent selectivity and reduction of the amounts of acids. The results of the analysis of uranium, thorium, plutonium and americium isotopes by this method in marine samples (IAEA-384, -385 and -414) provided excellent agreement with the recommended values with good chemical recoveries.

Resonance ionization mass spectrometry for ultratrace analysis of plutonium with a new solid state laser system

Resonance ionization mass spectrometry (RIMS) is well-suited for isotope selective ultratrace analysis of long-lived radioactive isotopes due to its high element and isotope selectivity and good sensitivity. For the analysis of plutonium with a pulsed RIMS apparatus, a powerful, reliable and easy to handle Nd:YAG pumped titanium–sapphire laser system has been developed and combined with a time-of-flight mass spectrometer. Spectroscopic measurements led to an efficient three step excitation and ionization scheme for plutonium with λ 1 = 420.76 nm, λ 2 = 847.28 nm, and λ 3 = 767.53 nm. The isotope shifts in this scheme for the plutonium isotopes 238 Pu through 244 Pu have been determined. An overall efficiency of the RIMS apparatus of 1 × 10 −5 is routinely achieved resulting in a detection limit of 2 × 10 6 atoms of plutonium for single isotope measurements. The application of RIMS for isotope ratio measurements is outlined.

Rapid Method for ICP-MS Analysos of Plutonium in Sediment Samples

AbstractA rapid and reliable method for quantification of transuranium elements in environmental samples is required from the aspect of emergency preparedness. Determination of these elements in e.g. sediment samples includes three steps: sample dissolution, chemical separation and measurement. Different acids were used for leaching of plutonium, americium and neptunium from contaminated sediment (during heating or microwave digestion). Chemical separation was performed by co-precipitation (with Fe(OH)3 or NdF3), by anion exchange or by liquid-liquid extraction (with tributylphosphate, trioctylamine and thenoyl trifluoroacetone, respectively). The following radioisotopes were quantified by quadrupole ICP-MS equipped with an ultrasonic nebulizer (USN): 237Np, 239Pu, 240Pu, 241Pu, 242Pu and 241Am. Data are only given for 239Pu and 240Pu in this paper. Plutonium was also measured by alpha spectrometry in some samples, as well as 137Cs and 241Am by gamma spectrometry. The agreement between concentrations of plutonium obtained by ICP-MS and alpha spectrometry was good, which demonstrates that a simple and rapid procedure for analysis of plutonium by quadrupole ICP-MS is feasible.

Separation of plutonium and neptunium species by capillary electrophoresis-inductively coupled plasma-mass spectrometry and application to natural groundwater samples.

Capillary electrophoresis (CE) was coupled to ICPMS in order to combine the good performance of this separation technique with the high sensitivity of the ICPMS for the analysis of plutonium and neptunium oxidation states. The combination of a fused-silica capillary with a MicroMist AR 30-I-FM02 nebulizer and a Cinnabar small-volume cyclonic spray chamber yielded the best separation results. With this setup, it was possible to separate a model element mixture containing neptunium (NpO2(+)), uranium (UO2(2+)), lanthanum (La3+), and thorium (Th4+) in 1 M acetic acid. The same conditions were also suitable for the separation of various oxidation states of plutonium and neptunium in different aqueous samples. All separations were obtained within less than 15 min. A detection limit of 50 ppb identical with 2 x 10(-7) M (3-fold standard deviation of a blank) was achieved. To prove the negligible disturbance of the plutonium and neptunium redox equilibria during the CE separations, plutonium and neptunium speciation by CE-ICPMS in acidic solutions was compared with the results of UV/visible absorption spectroscopy and was found to be in good agreement. The CE-ICPMS system was also applied to study the reduction of Pu(VI) in a humic acid-containing groundwater at different pH values.

Rapid identification and analysis of airborne plutonium using a combination of alpha spectroscopy and inductively coupled plasma mass spectrometry.

Recent wildland fires near two U.S. nuclear facilities point to a need to rapidly identify the presence of airborne plutonium during incidents involving the potential release of radioactive materials. Laboratory turn-around times also need to be shortened for critical samples collected in the earliest stages of radiological emergencies. This note discusses preliminary investigations designed to address both these problems. The methods under review are same day high-resolution alpha spectroscopy to screen air filter samples for the presence of plutonium and inductively coupled plasma mass spectrometry to perform sensitive plutonium analyses. Thus far, using modified alpha spectroscopy techniques, it has been possible to reliably identify the approximately 5.2 MeV emission of 239Pu on surrogate samples (air filters artificially spiked with plutonium after collection) even though the primary alpha-particle emissions of plutonium are, as expected, superimposed against a natural alpha radiation background dominated by short-lived radon and thoron progeny (approximately 6-9 MeV). Several processing methods were tested to prepare samples for analysis and shorten laboratory turn-around time. The most promising technique was acid-leaching of air filter samples using a commercial open-vessel microwave digestion system. Samples prepared in this way were analyzed by both alpha spectroscopy (as a thin-layer iron hydroxide co-precipitate) and inductively coupled plasma mass spectrometry. The detection levels achieved for 239Pu--approximately 1 mBq m(-3) for alpha spectroscopy screening, and, < 0.1 mBq m(-3) for inductively coupled plasma mass spectrometry analysis--are consistent with derived emergency response levels based on EPA's Protective Action Guides, and samples can be evaluated in 36 to 72 h. Further, if samples can be returned to a fixed-laboratory and processed immediately, results from mass spectrometry could be available in as little as 24 h. When fully implemented, these techniques have the potential to provide useful information and improved operational flexibility to emergency planners and first-responders during radiological emergencies.

Isotopic uranium and plutonium analysis by alpha-particle spectrometry

An isotopic uranium analysis of environmental and man-made samples was performed by alpha-particle spectrometry. A fitting technique using blocks of peaks in the spectra measured with silicon detectors was developed. Samples of natural uranium from conventional mines and from the Bangombé natural nuclear reactor were analysed. The isotope composition of depleted and enriched uranium samples was also determined. The technique was applied to determining the isotope composition of plutonium samples, identifying whether the samples were reactor-grade or weapons-grade plutonium. Spectra of soil samples from Palomares and others from an inter-laboratory comparison exercise were analysed, yielding very good results.

Actinide analysis of a depleted uranium penetrator from a 1999 target site in southern Serbia

Following the detection of 236U in depleted uranium (DU) ammunition used during the Balkans conflict in the 1990s, concern has been expressed about the possibility that other nuclides from the nuclear fuel cycle and, in particular, transuranium nuclides, might be present in this type of ammunition. In this paper, we report the results of uranium and plutonium analyses carried out on a depleted uranium penetrator recovered from a target site in southern Serbia. Our data show the depleted nature of the uranium and confirm the presence of trace amounts of plutonium in the penetrator. The activity concentration of 239+240Pu, at 45.4±0.7 Bq kg –1, is the highest reported to date for any penetrator recovered from the Balkans. This concentration, however, is comparable to that expected to be present naturally in uranium ores and, from a radiological perspective, would only give rise to a very small increase in dose to exposed persons compared to that from the DU itself.

Isotopic analysis of uranium and plutonium using ICP-MS and estimation of burn-up of spent uranium in contaminated environmental samples

Environmental monitoring of actinides and evaluation of the contamination source (nuclear weapons tests, nuclear power plant and nuclear reprocessing plant accidents, etc.) requires precise and accurate isotopic analysis of actinides, especially uranium and plutonium. Double-focusing sector-field inductively coupled plasma mass spectrometry (ICP-SFMS) using a low-flow microconcentric nebulizer with membrane desolvation, “Aridus”, was applied for isotopic measurements of uranium and plutonium at the ultratrace level. The detection limit (3σ) for 236U and 239Pu after chemical extraction was 0.2 pg l−1 in aqueous solution and 0.04 pg g−1 in soil, respectively. 235U/238U, 236U/238U and 240Pu/239Pu isotope ratios were measured in soil samples collected within the 30 km zone around the Chernobyl nuclear power plant. The average 240Pu/239Pu isotope ratio in contaminated surface soil was 0.396 ± 0.014. The burn-up grade and the portion of spent uranium in the spent uranium/natural uranium mixture in soil were calculated using the iteration method. A slight variation in the burn-up grade of spent reactor uranium was revealed by analyzing 235U/238U and 236U/238U isotope ratios. A relationship between the 240Pu/239Pu isotope ratio and burn-up of spent uranium was observed.

Development of rapid bioassay method for plutonium

For the internal dosimetry of plutonium, a urine bioassay method is very useful but requires several days to obtain the result of the analysis. To shorten the time required for the urine bioassay, a rapid method for plutonium analysis using the ICP-MS system was developed. In this chemical procedure, a microwave oven was applied for sample digestion, and an extraction chromatography resin was used for the separation of plutonium. The measurement time was extremely reduced by application of the ICP-MS as compared to alpha-spectrometry. The total analysis time was about 12 hours and the detection limit was 0.3 mBq/sample. The short analysis time and the low detection limit indicate that this method is useful not only for special monitoring but also for routine monitoring.

Analysis of Nuclear Proliferation Resistance of DUPIC Fuel Cycle

This study compares the proliferation resistance of DUPIC (Direct Use of Spent PWR Fuel in CANDU) fuel cycle with other fuel cycle cases. The other fuel cycles considered in this study are PWR of once-through mode (PWR-OT), PWR of reprocessing mode (PWR-MOX), in which spent PWR fuel is reprocessed and recovered plutonium is used for making MOX (Mixed Oxide), CANDU with once-through mode (CANDU-OT), PWR fuel and CANDU fuel in a once- through mode with reactor grid equivalent to DUPIC fuel cycle (PWR-CANDU-OT). This study is focused on intrinsic barriers, especially, radiation field of the diverted material, which could be a significant accessibility barrier, amount of special nuclear material based on 1 GWe-yr that has to be diverted and the quality of the separated fissile material. It is indicated from plutonium analysis of each fuel cycle that the MOX spent fuel is containing the largest plutonium per MTHM but PWR-MOX option based on 1 GWe-yr has the best benefit in total plutonium consumption aspects. The DUPIC option is containing a little higher total plutonium based on 1 GWe-yr than the PWR-MOX case, but the DUPIC option has the lowest fissile plutonium content which could be another measure for proliferation resistance. On the whole, the CANDU-OT option has the largest fissile plutonium as well as total plutonium per GWe-yr, which means negative points in nuclear proliferation resistance aspects. It is indicated from the radiation field analysis that fresh DUPIC fuel could play an important radiation barrier role, more than even CANDU spent fuels. In conclusion, due to those inherent features, the DUPIC fuel cycle could include technical characteristics that comply naturally with the Spent Fuel Standard, at all steps along the DUPIC linkage between PWR and CANDU.

The Physics of Plutonium Fuels—A Review of Organization for Economic Cooperation and Development/Nuclear Energy Agency Activities

In 1993, the Organization for Economic Cooperation and Development/Nuclear Energy Agency first convened the Working Group on the Physics of Plutonium Recycle (WPPR) (now renamed the Working Party on the Physics of Plutonium Fuels and Innovative Fuel Cycles). Since its inception, the WPPR (whose task has now been expanded to include innovative fuel cycles) has published six volumes of detailed results from analyses of plutonium fuel in pressurized water reactors and fast reactors. A seventh volume on the physics of plutonium fuel in boiling water reactors is in preparation. The analyses have been mostly in the form of theoretical benchmark exercises for situations beyond current experience, for which multinational contributions provide a basis for comparison of diverse calculational methods and nuclear data libraries. The overall activities of the WPPR are reviewed and summarized.

Analysis of plutonium in soil samples

Procedures for analysis of plutonium in soil samples were developed using anion exchange as a purification technique. Special attention was paid to removing impurities of 228Th which interferes in 238Pu determination by alpha spectrometry. Two anion-exchange methods were compared. The determination of plutonium in soil involves the conversion of soil samples to acid-soluble form. Two methods for the extraction of plutonium from a natural reference soil were compared. The first method (a direct digestion in nitric acid) is suitable for the determination of plutonium in large amounts of sample. The second method involves microwave digestion of soil (5 g) with a mixture of HNO3, HCl and HF, and is suitable for saving time in routine determinations. Activities calculated with a reference soil matrix were in good agreement with the reference value. The microwave digestion method was applied in a study of different soil samples, and recoveries ranged between 20% and 50%.

Analysis and characterization of plutonium in pyrochemical salt residues

Quantitative measurement of hydrogen produced during salt-catalyzed hydrolysis of plutonium in pyrochemical salt residues show that the metal is present in concentrations of 10 ± 5 mass%. The analytical method is based on stoichiometric reaction of metal with water to form plutonium monoxide monohydride (PuOH) and hydrogen. Results of a kinetic model developed to describe the observed time dependence of the hydrolysis rate shows that metal is present predominately as particles with essentially spherical geometries and diameters near 1 mm. The presence of smaller metallic particles cannot be verified or excluded. Plutonium concentrations measured for residues stored in different configurations suggest that a sizable fraction of the metal has oxidized during storage. Application of the hydrolysis method in determining concentrations and dimensions of metallic plutonium in other nuclear waste forms is proposed.

EXAFS and XANES Analysis of Plutonium and Cerium Edges From Titanate Ceramics for Fissile Materials Disposal

We report x-ray absorption near edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) spectra from the plutonium L{sub III} edge and XANES from the cerium L{sub II} edge in prototype titanate ceramic hosts. The titanate ceramics studied are based upon the hafnium-pyrochlore and zirconolite mineral structures and will serve as an immobilization host for surplus fissile materials, containing as much as 10 weight % fissile plutonium and 20 weight % (natural or depleted) uranium. Three ceramic formulations were studied: one employed cerium as a ''surrogate'' element, replacing both plutonium and uranium in the ceramic matrix, another formulation contained plutonium in a ''baseline'' ceramic formulation, and a third contained plutonium in a formulation representing a high-impurity plutonium stream. The cerium XANES from the surrogate ceramic clearly indicates a mixed III-IV oxidation state for the cerium. In contrast, XANES analysis of the two plutonium-bearing ceramics shows that the plutonium is present almost entirely as Pu(IV) and occupies the calcium site in the zirconolite and pyrochlore phases. The plutonium EXAFS real-space structure shows a strong second-shell peak, clearly distinct from that of PuO{sub 2}, with remarkably little difference in the plutonium crystal chemistry indicated between the baseline and high-impurity formulations.

EELS and Xanes Analysis of Plutonium and Cerium Edges From Titanate Ceramics for Fissile Materials Disposal

Abstract We report x-ray absorption near edge structure (XANES) and extended x-ray fine structure analysis (EXAFS) spectra from the plutonium Llll and cerium Lm edges in prototype titanate ceramic hosts for disposal of surplus fissile materials. These spectra were obtained using the MRCAT beamline at the Advanced Photon Source (APS). The XANES and EXAFS results are compared with electron loss spectra (EELS) determination of oxidation state from the plutonium MlV,V and cerium MlV,V edges [1,2]. The titanate ceramics studied are based upon the hafniumpyrochlore and zirconolite mineral structures and will serve as an immobilization host, containing as much as 10 weight % fissile plutonium, and 20 weight % (natural or depleted) uranium. Similar formulations were composed using cerium as a “surrogate” element, replacing both plutonium and uranium in the ceramic matrix. We find the plutonium to be present almost entirely as Pu (IV), while the cerium is clearly in a mixed III-IV oxidation state in the surrogate ceramic.

Determination of plutonium concentrations and isotope ratios in environmental samples with a double-focusing sector field ICP-MS

An analytical method for the ultratrace and isotopic analysis of plutonium in sediment samples using a double focusing sector field ICP mass spectrometer (ICP-SMS) is described. A detection limit for plutonium in the sub-fg ml −1 range was achieved. The ICP-SMS results were in acceptable agreement with alpha spectrometry. At the low fg ml −1 level a precision in isotope ratio measurements of 2–10% RSD was achieved. Accuracy of the results was assessed by 238 U/ 235 U and 205 Tl/ 203 Tl isotope ratio determinations using isotopic standards and a natural Tl standard solution, respectively. It was shown that correction for 238 UH + and 238 UH + 2 is necessary for both plutonium concentration and isotopic composition determinations. From a practical standpoint, the use of ICP-SMS for plutonium measurements is an attractive alternative to techniques such as alpha spectrometry and thermal ionization mass spectrometry (TIMS) due to its higher throughput and ability to measure both concentration and isotopic ratio on the same sample.