Analysis Of Plutonium Research Articles

New capabilities of the PAT plutonium analysis program

The Plutonium Attribute Test (PAT) is a software program originally developed for determining the category of a plutonium sample. The premise for its development was that, to assign Pu samples to particular categories, it is not necessary to determine the abundance of all its isotopes. Rather, it is sufficient to determine only 239Pu abundance, which is universally used to establish a category assignment, i.e., >90 wt% 239Pu is low burnup (LBPu), <70 wt% is high burnup (HBPu), and the abundances in between could be considered medium burnup (MBPu) plutonium grade. In contrast to previous Pu isotopic analysis programs which analyse spectra taken with HPGe detectors, the algorithms developed in PAT analyses use spectra taken with medium resolution detectors such as LaBr3(Ce) and CZT detectors. As demonstrated by initial tests, PAT was found capable of not only assigning the material category, but also accurately determining 239Pu abundance, with several per cent typical relative combined standard uncertainty. Furthermore, an advanced algorithm (A-PAT) was added to allow full isotopic characterization of samples. This paper presents further enhancements of the PAT/A-PAT algorithms towards analysis of heavily shielded samples, samples with varied size and age, as well as mixed oxide (MOX) materials.

Rapid radiochemical analysis of uranium and plutonium in emergency urine samples

Rapid radiochemical analysis of uranium and plutonium in emergency urine samples

Initial Characterization and Optimization of the Liquid Sampling-Atmospheric Pressure Glow Discharge Ionization Source Coupled to an Orbitrap Mass Spectrometer for the Determination of Plutonium.

Plutonium measurements are essential to the nuclear forensics and safeguards community. The liquid sampling-atmospheric pressure glow discharge (LS-APGD) microplasma ionization source coupled with an Orbitrap mass spectrometer is a proven platform for uranium isotope ratio determinations. This work expands the LS-APGD-Orbitrap platform capabilities by reporting the first-ever analysis of plutonium with the LS-APGD and the first-ever measurement of elemental plutonium with an Orbitrap mass spectrometer. This coupling has the potential to dramatically reduce the complex sample manipulations required for traditional analysis techniques employed for actinide isotope ratio determinations. As a first step toward the goal of simultaneous uranium and plutonium isotope ratio determinations, the initial characterization and optimization of the platform for the detection of plutonium are reported. Collision-induced dissociation modality settings were optimized to reduce water-related and other molecular clusters containing plutonium, maximizing 242Pu16O2+ responses. A design of experiments study was conducted to optimize the discharge conditions of the dual-electrode LS-APGD toward the responsivity of 242Pu16O2+. The measurement sensitivity was determined from a Pu response curve, yielding a limit of detection of 10 fg (absolute) of total analyte when data was collected and processed with a Spectroswiss FTMS Booster X2 data acquisition system. Additionally, plutonium and uranium were measured in a simultaneous acquisition, and each analyte remained unaffected by the other. It is believed that the LS-APGD-Orbitrap platform could be a valuable addition to the nuclear forensics' toolbox and, indeed, other scientific disciplines and regulatory communities in which rapid, high-resolution plutonium determinations are paramount.

Burn-Up Analysis of Plutonium and Minor Actinide Recycling on Gas Cooled Fast Reactor (GCFR) Using SRAC COREBN

Research on the analysis of recycling, plutonium, and minor actinides in the Gas Cooled Fast Reactor (GFCR) using SRAC COREBN has been done. This research uses a fuel mixture of uranium, plutonium, and minor actinides. The analysis was conducted with computational simulation using the COREBN code, an additional code to SRAC. The purpose of this research is to find out the influence of the addition of plutonium and actinide on the composition of nuclear fuel at the end of reactor operation and the limitation of the value of the multiplication factor (keff at the end of the reactor burn up period). Found in this research is the final value, the multiplication factor (keff) of 1.19964, and the conversion ratio value of 0.766813 in the burn-up period of 1515 days as well as the maximum power density value of 125.85 watts/cm³, the relative power density value at the radius y of 1,230263 and radius x equal to 1.19737 the atomic density value experienced a change in the number of nuclides in the types of nuclides U235, U238, Pu239, Pu241, Np237, and Am243 at the end of the burn-up period.

Optimisation of plutonium separations using TEVA cartridges and ICP-MS/MS analysis for applicability to large-scale studies in tropical soils.

The analysis of plutonium (Pu) in soil samples can inform the understanding of soil erosion processes globally. However, there are specific challenges associated for analysis in tropical soils and so an optimal analytical methodology ensuring best sensitivity is critical. This method aimed to demonstrate the feasibility of sample preparation and analysis of Pu isotopes in African soils, considering the environmental and cost implications applicable to low-resource laboratories. The separation procedure builds upon previous work using TEVA columns, further demonstrating their usefulness for the reduction of uranium (U) interference in ICP-MS analysis with enhanced selectivity for Pu. Here several steps were optimised to enhance Pu recovery, reducing method blank concentration, and improving the separation efficiency through the determination of the elution profiles of U and Pu. The elimination of the complexing agent in the eluent, increased the spike recovery by improving matrix tolerance of the plasma, and simplified the separation procedure, improving throughput by 20%. The subsequent method was validated through the analysis of Certified Reference Material IAEA-384, where high accuracy and improved precision of measurement were demonstrated (measured value 114 ± 12 versus certified value 108 ± 13 Bq kg-1). Optimisation of the column separation, along with the analysis of the samples using O2 gas in ICP-MS/MS mode to mass shift Pu isotopes away from interfering molecular U ions provided a simple, robust, and cost-effective method with low achievable method detection limits of 0.18 pg kg-1 239+240Pu, applicable to the detection of ultra-trace fallout Pu in African soils.

Rapid isotopic analysis of uranium, plutonium, and americium in post-detonation debris simulants by RIMS

Uranium interference is a major problem in conventional 238Pu analysis. In RIMS, a slight detuning of the resonance laser extinguishes the Pu signal so that the 238U interference can be accurately quantified and subtracted.

Multivariate chemometric methods and Vis-NIR spectrophotometry for monitoring plutonium-238 anion exchange column effluent in a radiochemical hot cell

The Plutonium-238 Supply Program at Oak Ridge National Laboratory has developed the capability to inform process decisions during full-scale 238Pu anion exchange column runs using multivariate chemometrics and visible-near infrared (Vis-NIR) absorption spectroscopy. Multivariate analytical methods provided a suitable option for real-time analysis of complex neptunium (Np) and plutonium (Pu) absorption spectra. Thousands of spectra from multiple production campaigns were analyzed by principal component analysis and Kennard-Stone sample selection to select a training set composed of 60 spectra. Multivariate curve resolution–alternating least squares analysis (MCR-ALS) identified spectral components and component concentrations. A partial least squares regression (PLSR) model was built using the spectra and concentration values determined by these virtually unsupervised methods. Next, a supervised PLSR model was built by scaling the MCR-ALS–selected concentration matrix using molar epsilon values. Both PLSR models predicted the concentrations of Np(IV), Np(V), Pu(III), Pu(IV), and Pu(VI) in the column effluent and identified nearly identical product cut decisions. The time-dependent Np and Pu concentration profiles provided valuable insight into column dynamics and the predictions agreed with traditional methods including alpha spectrometry and inductively coupled plasma mass spectrometry. These results establish a resourceful avenue for modeling multicomponent systems with convoluted absorption bands without significant user input. It is particularly advantageous for production-oriented radiochemical applications in restrictive hot cell environments.

Distribution and source of plutonium in sediments from the southern Gulf of Mexico

Here, we report on new data (75 analyses) of plutonium (Pu) isotopes to elucidate activity concentrations, inventories, sources, and their transport from the ocean surface to the seafloor from a collection of six deep-sea sediment cores (depths ranging from 257 to 3739 m) in the southern Gulf of Mexico. Sediment cores collected from the continental shelf and upper slope region of the Gulf of Mexico showed 240Pu/239Pu ratios of 0.15 to 0.26, and 239+240Pu-inventories ranging from 14.7 to 33.0 Bq m−2. Inventories and ratios are consistent with global fallout Pu for this tropical region. In contrast, sediment cores collected from the lower slope region and abyssal plain showed low 240Pu/239Pu ratios of 0.07 to 0.13 and much lower 239+240Pu inventories below 6.8 Bq m−2. This implies that only a small fraction of the expected global fallout Pu has reached the deep-sea sediments. The low 240Pu/239Pu isotope ratios indicate that fallout from the Nevada testing site was an important source of Pu in deep-sea sediments, and that this Pu was likely more efficiently scavenged from the water column than Pu from global fallout. We estimated that up to 44% of the total inventory of 239+240Pu in deep-sea sediments is due to the Nevada source. Low values and a progressive decrease of 240Pu/239Pu ratios and 239+240Pu inventories with increasing water depth have been previously reported for the Gulf of Mexico. Analysis of Pu isotopes in two sediment traps from the upper slope regions shows 240Pu/239Pu ratios comparable to those observed in global fallout. These results indicate that global fallout Pu is currently the main source of Pu in sinking particles in the water column. Therefore, a significant fraction of global fallout Pu must still be present, either in a dissolved phase, or as biologically recycled material in the water column, or scavenged on the shelf and shelf break. Our results bring to light important questions on the application of Pu isotopes to establish sediment chronologies in deep-sea sediments, since global fallout features such as the 1963 maximum are not available.

The Development of a rapid method for Plutonium separation by extraction chromatography and its application for environmental samples

This research aims to develop a rapid method of plutonium analysis from sediment samples using the extraction chromatography method with TRU resin. This approach will be compared with the anion exchange method with DOWEX resin previously conducted in the BATAN radioecology laboratory. Plutonium measurements was carried out using an alpha spectrometer with a PIPS detector after the separation processes. The results showed that recovery using extraction chromatography followed by the microprecipitation method resulted in an average recovery of 71.22 percent, compared to anion exchange using the electrodeposition method, which obtained about 58.89 percent. Since a combination of chromatographic extraction with electro-deposition, the recovery is still low, about 27.56 percent. The chromatographic extraction method with microprecipitation method to sediment samples from the coast of Merak resulted in an average activity of 0.14 Bq/kg dry. The activities obtained are comparable with the previous data from the Merak coastal sediment study. The advantages of using the extraction chromatography method compare to using the anion exchange method to separate plutonium from sediment samples are the shorter separation time and the less acid waste produced. Another advantage is that it is more selective to separate plutonium from other actinides. This approach is very suitable for emergency preparedness when there is an emergency response.

Decay heating power of various types of plutonium

Analysis of the influence of the decay heating power of plutonium is one of the important tasks of the process in design of nuclear reactors, nuclear waste disposal or mechanical analysis of nuclear explosive devices. The paper simulated the decay heating power of some isotopes by means of cascade decay dynamics, then numerical regression was done and some formulae were obtained describing the heating power of the isotopes respectively. Furthermore, the paper reached to a common formula describing the heating power of all kinds of plutonium, and the heating powers of various types of plutonium used in fields of nuclear energy, nuclear waste disposal or military were obtained. Comparing with other calculation methods, calculating the heating power of various types of plutonium using this common formula raised in the paper could result in higher precision and more efficient, and because of the time-dependence, the common formula could also be used in thermal-related analysis of plutonium considering the storage time.

Development of ‘on-site’ measurement methods for assay of plutonium isotopes

Over the past decades, radioanalytical methods for environmental monitoring of plutonium (Pu) isotopes from contaminated soils were developed to respond in case of a nuclear accident but also for routine analyses. In this paper we prove the possibility of on-site analysis of plutonium using alpha particle spectrometry. Tests are performed with two types of soils: a “brown” soil and a “sandy” soil, both spiked with 242Pu. The proposed method starts with leaching the soil, then separating the radionuclides of interest through a TEVA column and finally preparing counting planchets for alpha-spectrometry analyses. The aim of this work was to obtain a fast and reliable procedure, from the sample preparation to the analysis, applicable directly in the field and lasting no longer than a working day. The testing involved several parameters, such as the soil-to-liquid ratio, the acid molarity, the influence of a purification step, the source preparation. For each procedure defined, the time and the recovery rates of 242Pu were recorded and compared. Results have proven that the recovery rates increase with the solid-to-liquid ratio, with the acid molarity, with the purification step but decrease with the mixing time. The two methods used for source preparation showed similar results and the sources were measured by alpha spectrometry, using two different counting devices. The final selected sample preparation procedure has a throughput of 3 h, with recovery rates of 33.8 ± 3.1% for the “brown” soil and 77.3 ± 9.2% for the “sandy” soil and is suitable for a field application.

A simple microanalytical method for trace elemental determination in plutonium samples using energy dispersive X-ray fluorescence

A simple microanalytical method for trace elemental determinations in plutonium (Pu) solution samples was developed using Energy Dispersive X- Ray Fluorescence (EDXRF) spectrometry. A very small sample volume (200 μL) of Pu solution was taken for analysis and the major matrix Pu was separated using the extractant, Tri n-Butyl Phosphate (TBP), in 4 M HNO3 medium. Aliquot of 5 μL of the aqueous phase containing only the trace elements were deposited on a thin transparent mylar film inside the PVC (Poly Vinyl Chloride) EDXRF sample container and dried in ambient atmosphere inside a radioactive fume hood. After drying, the container was sealed with PVC lids. Two pure Pu solutions spiked with different trace elements having concentration of 6.25 and 23.25 μg/mL, were analyzed with RSD (Relative Standard Deviation) of 6.6 and 4.2% (1 σ, n = 3), and the average deviation from the expected values calculated on the basis of sample preparation were 8.9 and 6.6%, respectively. The developed methodology requires small amount of sample, extractant, and therefore generates less radioanalytical waste. Moreover, due to the requirement of small amount of sample, sealed inside a PVC container, the measurements could be carried out in ambient atmosphere without putting the instrument inside glove box. Further, the simple instrumentation of EDXRF, made this methodology very much ideal for the routine analysis of plutonium based samples.

Plutonium (IV) Quantification in Technologically Relevant Media Using Potentiometric Sensor Array.

The quantification of plutonium in technological streams during spent nuclear fuel (SNF) reprocessing is an important practical task that has to be solved to ensure the safety of the process. Currently applied methods are tedious, time-consuming and can hardly be implemented in on-line mode. A fast and simple quantitative plutonium (IV) analysis using a potentiometric sensor array based on extracting agents is suggested in this study. The response of the set of specially designed PVC-plasticized membrane sensors can be related to plutonium content in solutions simulating real SNF-reprocessing media through multivariate regression modeling, providing 30% higher precision of plutonium quantification than optical spectroscopy.

Reference materials for quality assurance of environmental plutonium analysis

Reference materials (RMs) are very important for method development and validation. In order to quickly and reliably select the suitable RM for validating the determination of plutonium (Pu), we reviewed the RMs of Pu and prepared extensive Pu datasets in this study. After data treatment and a series of statistical analyses, we obtained the statistical values of 238−241Pu activity and Pu isotopic ratio for RMs. The statistical value of 239+240Pu activity is consistent with the certified value, indicating these measured values are highly reliable. We anticipate that, after further independent work at different laboratories, the statistical values of the Pu isotopic ratios are very important to validate analysis methods and calibrate the mass bias for environmental Pu analysis.

Development of an online measurement system using an alpha liquid scintillation counter and a glass-based microfluidic solvent extraction device for plutonium analysis

An online measurement system using an alpha liquid scintillation counter (α-LSC) coupled to microchip solvent extraction has been developed. A flow-through cell of α-LSC has been prepared by packing PTFE tube into glass tube to combine microchip. Two-phase flow in microchannel has been stabilized by using coiled tube. The Pu in organic phase has been mixed with scintillation cocktail by T-junction connectors. The system separates and detects Pu by online with detection limit of 6.5 Bq/mL, generating only μL-level wastes.

Optimization of a primary X‐ray filter for X‐ray fluorescence analysis of uranium and plutonium

When workers are wounded at a nuclear fuel handling facility, it is difficult to quantify actinide contamination through α‐particle counting because these particles are shielded by blood. To overcome this problem, we used X‐ray fluorescence (XRF) analysis with a handheld‐type device that is useful in cases where sampling is not allowed, such as in this study. In XRF analysis, a primary X‐ray filter made of metal foil is generally inserted between the X‐ray tube and the sample to attenuate the incident X‐ray at the energy region of the XRF signal for the target element. Doing so can reduce the background signal originating from the scattered radiation of the incident X‐ray. In this study, we aimed to optimize a primary X‐ray filter that facilitates simultaneous high‐sensitivity analysis of uranium and plutonium in a wound. For this purpose, XRF measurements were performed for a needle‐puncture wound model contaminated by U and Pu, and the relationship between the filter material/thickness and the detection limit was investigated. Optimizing the filter material/thickness of a given target element was found to improve the detection limit of the measurement by ~10%.

The use of carbon dioxide as the reaction cell gas for the separation of uranium and plutonium in quadrupole inductively coupled plasma mass spectrometry (ICP-MS) for nuclear forensic samples

The use of carbon dioxide (CO2) as a reaction cell gas for separation and trace analysis of uranium and plutonium by inductively coupled plasma mass spectrometry was investigated. For the analysis of the resultant UO2+ product ion, it was shown that quantitative determination of uranium concentration was achievable within ± 7% uncertainty for samples containing plutonium. In addition, uranium isotope ratios were measured within ± 12% for standard reference materials of several enrichments. This was achieved in both nitric acid and digested cellulose filter paper solutions—a common nuclear forensic sample substrate. However, non-linearity and long term signal instability was observed for plutonium at the high flow rate of CO2 and tuning parameters required to minimise uranium interferences. Therefore, plutonium analysis was not achievable.

Sequential analysis of uranium and plutonium in environmental matrices by extractive liquid scintillation spectrometry

Abstract A methodology for sequential separation of uranium (U) and plutonium (Pu) followed by their estimation, using extractive liquid scintillation spectrometry was standardized for matrices like soil, fish and sediment. Various parameters for selective and efficient extraction and separation of Pu and U in the presence of interfering matrix elements with HDEHP bis(2-ethylhexy1) phosphoric acid as an extracting agent were investigated. Quenching effect of the various extracting reagents on resolution of α spectrum of analytes and reduction in these interferences is discussed in the current study. Standardized procedure gave about 91% of extraction of spiked Pu into the organic phase. Performance of the method was tested by separating and estimating U and Pu in International Atomic Agency (IAEA) certified reference materials like soil/sediment/fish.

Accurate determination of minor isotope ratios in individual plutonium–uranium mixed particles by thermal ionization mass spectrometry

Abstract Isotopic analyses of plutonium and low-enriched uranium mixtures with particle sizes of 0.6–3.3 μm were performed using thermal ionization mass spectrometry with a continuous heating method to verify its effectiveness for the accurate analysis of minor isotopes without sample pretreatment. The mixed particles used in this study were prepared from a mixed solution of plutonium (SRM 947) and uranium (U010, 235U 1% enriched) reference materials. The isotope ratios for plutonium in the individual mixed particles, including 238Pu/239Pu, 241Pu/239Pu as well as 240Pu/239Pu, and 242Pu/239Pu, were in good agreement with the certified values despite the isobaric interference of 238U and 241Am. The isotope ratios for uranium in the mixed particles also agreed well with the certified values within the range of error. However, the isotope ratios for minor isotopes, such as 234U and 236U, in the particles with diameters of less than approximately 1.8 μm could not be measured because numbers of 234U and 236U atoms in analyzed particles are too low. These results indicate that thermal ionization mass spectrometry with a continuous heating method is applicable for the analysis of trace amounts of plutonium isotopes, including 238Pu and 241Pu, despite the presence of the respective isobars 238U and 241Am in the microsamples.

Anion-Exchange Fibers for Improved Sample Loading in Ultra-Trace Analysis of Plutonium by Thermal Ionization Mass Spectrometry.

A new sample loading procedure was developed for isotope ratio measurements of ultratrace amounts of plutonium with thermal ionization mass spectrometry (TIMS). The goal was to determine the efficacy of a polymer fiber architecture for TIMS sample loading by following similar sample loading procedures as those used in bead loading. Fibers with diameter of approximately 100 μm were prepared from triethylamine-quaternized-poly(vinylbenzyl chloride) cross-linked with diazabicyclo[2.2.2]octane. Fiber sections (2.5 mm) were loaded with 10 pg of New Brunswick Laboratory certified reference material (NBL CRM) 128 from an 8 M HNO3 matrix and affixed to rhenium filaments with collodion. A single filament assembly was used for these analyses. Total ion counts (239Pu + 242Pu) and isotope ratios obtained from fiber-loaded filaments were compared to those measured by depositing Pu amended resin beads on the filament. Fiber loading was found to improve sensitivity, accuracy, and precision of isotope ratio measurements of plutonium when compared to the established resin bead loading method, while maintaining its simplicity. The average number of detected Pu+ counts was 180% greater, and there was a 72% reduction in standard deviation of ratio measurements when using fiber loading. An average deviation of 0.0012 (0.117%) from the certified isotope ratio value of NBL CRM Pu128 was measured when fiber loading versus a deviation of 0.0028 (0.284%) when bead loading. The fiber formation method presented in this study can be extended to other anion-exchange polymer chemistries and, therefore, offers a convenient platform to investigate the efficacy of novel polymer chemistries in sample loading for TIMS.