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Abstract  

Porous zirconia spherical particles have been prepared by internal gelation process. During preparation of these spherical particles, a cationic surfactant, cetrimide was added in the feed broth to increase the surface area and porosity of the particles. The sorption behavior of plutonium was investigated on this material from different complexing aqueous media from the recovery point of view. Distribution ratio studies have been carried out to investigate the effect of varying concentrations of oxalic acid, phosphoric acid, sulphuric acid, nitric acid, sodium carbonate and sodium bicarbonate to optimize the conditions of sorption of plutonium on this ion exchange material.

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Abstract  

The calorimetry exchange (CALEX) program is administered by New Brunswick Laboratory (NBL). The main objective of the program is to provide an independent verification of the internal quality control practices in nuclear material safeguards facilities making plutonium accountability measurements by non-destructive calorimetry/gamma spectrometry techniques. Facilities measure the calorimetric power, and plutonium and 241Am isotope abundances of CALEX program standards using routine accountability procedures. The measurement results as well as two other quantities (effective specific power and plutonium mass) calculated from these results are evaluated for accuracy (or bias) and precision. In this paper, a limited number of measurement results of a CALEX program standard (identified as Calex I) are evaluated with specific goals to identify a suitable method for uncertainty estimation and to identify the major contributors to the uncertainties. In order to achieve the goals, the Calex I measurement results were evaluated using two different methods: the first method confined to uncertainty estimation from random variations of the measurement results alone, and the second method providing a more comprehensive evaluation of uncertainties from both the measurements and the characterized values of the measured standard according to the Guide to the Expression of Uncertainty in Measurement (GUM). The results of this study, and a subsequent study extended to a larger number of results in the CALEX program database, are expected to provide relevant input for developing the International Target Values for plutonium measurements by the calorimetry/gamma spectrometry method.

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Abstract  

This paper deals with the studies on decontaminations of spent ion exchange resin used for purification of plutonium in PUREX process stream. Studies were carried out to optimize the chemical procedure for removal of plutonium and fission products activities form spent Ion Exchange resin. Different metal complexing reagents were tested for leaching out of radionuclides entrapped in irradiated spent ion exchange resin. The experimental results indicate that 0.01 M NaF solution was found the most suitable for removal of plutonium. The mixture of Na2CO3 and sodium salt of EDTA solution was found to be better for decontamination of spent ion exchange resin from beta and gamma activities. Optimized mixture of 0.5 M Na2CO3 and 0.1 M sodium salt of EDTA solution was found to be the most effective for fission product activities removal. After successive multiple contacts using these suitable reagents, the Pu and fission product activities in spent ion exchange resin were brought down to a minimum possible level, making it quite suitable for its long term storage.

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Abstract  

Minimizing plutonium measurement uncertainty is essential to nuclear material control and international safeguards. In 2005, the International Organization for Standardization (ISO) published ISO 12183 “Controlled-potential coulometric assay of plutonium,” 2nd edition. ISO 12183:2005 recommends a target of ±0.01% for the mass of original sample in the aliquot because it is a critical assay variable. Mass measurements in radiological containment were evaluated and uncertainties estimated. The uncertainty estimate for the mass measurement also includes uncertainty in correcting for buoyancy effects from air acting as a fluid and from decreased pressure of heated air from the specific heat of the plutonium isotopes.

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Abstract  

A flow injection-based electrochemical detection system coupled to a solid-phase extraction column was developed for the determination of trace amounts of plutonium in low-active liquid wastes from spent nuclear-fuel reprocessing plants. The oxidation state of plutonium in a sample solution was adjusted to Pu(VI) by the addition of silver(II) oxide. A sample solution was made up in 3 mol L−1 HNO3 and loaded onto a column packed with UTEVA® with 3 mol L−1 HNO3 as the carrier. Plutonium(VI) was adsorbed onto the resin, and interfering elements were removed by rinsing the column with 3 mol L−1 HNO3. Subsequently, the adsorbed Pu(VI) was eluted with 0.01 mol L−1 HNO3, and then introduced directly into the flow-through electrolysis cell with boron-doped diamond electrode. The eluted Pu(VI) was detected by an electrochemical amperometric method at a working potential of 0.1 V (vs. Ag/AgCl). The current produced on reduction of Pu(VI) was continuously monitored and recorded. The plutonium concentration was calculated from the relationship between the peak area and concentration of plutonium. The relative standard deviation of ten analyses was 1.1% for a plutonium solution of 25 μg L−1 containing 50 ng of Pu. The detection limit calculated from three-times the standard deviation was 0.82 μg L−1 (1.6 ng of Pu).

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Abstract  

Uranium (U) and plutonium (Pu) isotopes in coral soils, contaminated by nuclear weapons testing in the northern Marshall Islands, were isolated by ion-exchange chromatography and analyzed by mass spectrometry. The soil samples were spiked with 233U and 242Pu tracers, dissolved in minerals acids, and U and Pu isotopes isolated and purified on commercially available ion-exchange columns. The ion-exchange technique employed a TEVA® column coupled to a UTEVA® column. U and Pu isotope fractions were then further isolated using separate elution schemes, and the purified fractions containing U and Pu isotopes analyzed sequentially using multi-collector inductively coupled plasma mass spectrometer (MCICP-MS). High precision measurements of 234U/235U, 238U/235U, 236U/235U, and 240Pu/239Pu in soil samples were attained using the described methodology and instrumentation, and provide a basis for conducting more detailed assessments of the behavior and transfer of uranium and plutonium in the environment.

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Abstract  

Plutonium and americium are radionuclides particularly difficult to measure in environmental samples because they are α-emitters and therefore necessitate a careful separation before any measurement, either using radiometric methods or ICP-SMS. Recent developments in extraction chromatography resins such as Eichrom® TRU and TEVA have resolved many of the analytical problems but drawbacks such as low recovery and spectral interferences still occasionally occur. Here, we report on the use of the new Eichrom® DGA resin in association with TEVA resin and high pressure microwave acid leaching for the sequential determination of plutonium and americium in environmental samples. The method results in average recoveries of 83 ± 15% for plutonium and 73 ± 22% for americium (n = 60), and a less than 10% deviation from reference values of four IAEA reference materials and three samples from intercomparisons exercises. The method is also suitable for measuring 239Pu in water samples at the μBq/l level, if ICP-SMS is used for the measurement.

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Abstract  

The anthropogenic plutonium isotopes are important geochemical tracers for environmental studies. The distributions and sources of the Pu isotopes in water column or sediments of the North Pacific have been intensively studied. However, knowledge on the distribution of Pu isotopes in sediments of the Central Pacific, when available, is limited. To study the composition of Pu isotopes in the ocean, thus to identify the sources of radioactive pollution, sediment core samples were collected in the Central Pacific by R/V Hakuho Maru in the KH-04-5 cruise. The activity concentrations of 239+240Pu and the 240Pu/239Pu atom ratio were determined using a sector-field inductively coupled mass spectrometry (SF-ICP-MS) combined with a high efficiency sample introduction system (APEX-Q). Possible sources and sedimentation behavior of Pu isotopes are discussed.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: Lav Tandon, Kevin Kuhn, Patrick Martinez, Joseph Banar, Laurie Walker, Terry Hahn, David Beddingfield, Donivan Porterfield, Steven Myers, Stephen LaMont, Daniel Schwartz, David Gallimore, Scott Garner, Khalil Spencer, Lisa Townsend, Heather Volz, Russ Gritzo, Rodney McCabe, Ramiro Pereyra, Dominic Peterson, Mark Scott, Christy Ruggiero, Diana Decker, and Amy Wong

Abstract  

This paper presents results from the examination of a number of archived neutron-irradiated uranium targets used for past plutonium production testing. Three of these targets were destructively characterized using Los Alamos National Laboratory actinide analytical chemistry capabilities. A validated conduct-of-operations protocol was followed for this characterization effort. Chemical analyses included measurements for radionuclides, uranium assay, uranium isotopic abundances, trace actinides, trace metals, and non-metals. Material scientists also examined materials for morphological and microstructural properties and individual particles were examined for trace impurities. After characterization of the targets was completed, a reactor modeling effort was undertaken to corroborate target details in historical records. Time since irradiation calculations utilized both activation and fission products. The described examination of uranium targets has a tremendous impact from a safeguards verification and nuclear forensics perspective.

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Abstract  

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.

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