Individual determination of uranium and plutonium in a single aliquot

Studies on the individual potentiometric determination of uranium and plutonium in a single aliquot have been initiated recently in our laboratory. It was required to adapt the reported procedures (for the precise determination of uranium and plutonium individually when present together in a sample) at various stages to make them suitable for the successive application of the procedures to the same aliquot. Two alternative schemes are proposed in the present work. In the first, plutonium is determined by HClO₄ oxidation followed by the determination of total uranium and plutonium by Zn(Hg) reduction. In the second, plutonium is determined by AgO oxidation following the determination of total uranium and plutonium by Zn(Hg) reduction. Amount of uranium is computed in both cases from the difference of two determinations. Precision for the assay of plutonium and uranium was found to be ±0.25% and ±0.35%, respectively, at milligram levels.     

Recent advances in the determination of low level plutonium in environmental and biological materials

The present paper reviews briefly the recent advance in radioanalysis of low level plutonium in environmental and biological samples. Lots of new radiochemical methods for determination of plutonium in aerosols, natural waters, soil, sediments and various biological materials have been developed. The use and prospects of several radiochemical procedures are discussed.     

A rapid procedure for plutonium separation in large volumes of fresh and saline water by manganese dioxide coprecipitation

A rapid procedure is described for the separation of plutonium radionuclides from large volumes of fresh and saline water by means of a manganese dioxide coprecipitation technique. This procedure has been used in the laboratory and in the field to process 50 to 400 liter water samples. Plutonium is carried through an oxidation and reduction step to insure complete equilibration between added yield tracers and the plutonium present in the water sample. Average recovery under optimum conditions has been 80% for seawater and over 90% for freshwater samples processed in the field with simple equipment. The procedure can be used also to separate plutonium from water samples by direct adsorption on MnO₂-impregnated cartridges. Under laboratory conditions the adsorption on MnO₂ was independent of the oxidation states of plutonium in aqueous samples.     

Assay of an alpha solid waste drum using passive neutron counting

Journal of Radioanalytical and Nuclear Chemistry - A passive neutron based assaying system for plutonium bearing solid wastes has been designed and developed. The assaying of the plutonium in the...     

Electroplating versus microprecipitation of the actinides in alpha-spectroscopic analysis

The recent challenge of the electroplating (EP) method by microprecipitation (MP) methods for alpha-spectroscopic analysis of actinides led us to a comparison study of the two techniques for application to our laboratory workloads. A baseline study was done using filter papers spiked individually with uranium, plutonium and americium. Water and soil samples collected at various field sites were analyzed for uranium and field-collected air filters were analyzed for plutonium. Applicability and attractiveness of both techniques were found to provide good reproducible recoveries adequate for quantifying uranium isotope activity on air filters and in water and soil. Measurement of americium and plutonium on air filters similarly gave good results. Isotope peak resolution was good for both methods and did not contribute to measurement uncertainly over the range of activities studied. Although expanded matrix investigations may still be needed for more depth, we concluded that microprecipitation can be a time saving alternative to the electroplating technique for alpha-spectroscopy of the actinides.     

Contribution to the analysis of plutonium originated from the Chernobyl accident in soil

Four different procedures have been studied for the extraction of plutonium from soil sampled at Bragin, 40 km from Chernobyl. On extraction by leaching with conc. HNO₃ for 2 or 6 h the concentration of^{239, 240}Pu in soil was approximately by 30% lower than on extraction involving treatment with HF or fusion.     

Determination of selenium in nickel and cobalt concentrates applying epithermal neutron activation analysis

The physicochemical association of plutonium in soil near the Subsurface Disposal Area (SDA) at the Idaho National Engineering and Environmental Laboratory (INEEL) has been determined using selective sequential extraction techniques. Our results suggest that plutonium in surface soils is associated primarily with the hydrous oxide coatings of the soil (37±5.3%). Appreciable amounts of plutonium were also removed with the organic matter (22±2.8%) and carbonates (13±3.1%). On the other hand it appears that plutonium association with the soluble and exchangeable components of the soil is relatively small (>4.0%). The remainder of plutonium (21±4.7%) is tightly bound to the refractory silicate residue of the soil. Relatively little plutonium is available for physicochemical mobilization from the soil under the present prevailing conditions of the INEEL site.     

Rapid isolation of plutonium in environmental solid samples using sequential injection anion exchange chromatography followed by detection with inductively coupled plasma mass spectrometry

This paper reports an automated analytical method for rapid determination of plutonium isotopes (²³⁹Pu and ²⁴⁰Pu) in environmental solid extracts. Anion exchange chromatographic columns were incorporated in a sequential injection (SI) system to undertake the automated separation of plutonium from matrix and interfering elements. The analytical results most distinctly demonstrated that the crosslinkage of the anion exchanger is a key parameter controlling the separation efficiency. AG 1-×4 type resin was selected as the most suitable sorbent material for analyte separation. Investigation of column size effect upon the separation efficiency revealed that small-sized (2 mL) columns sufficed to handle up to 50 g of environmental soil samples. Under the optimum conditions, chemical yields of plutonium exceeded 90% and the decontamination factors for uranium, thorium and lead ranged from 10³ to 10⁴. The determination of plutonium isotopes in three standard/certified reference materials (IAEA-375 soil, IAEA-135 sediment and NIST-4359 seaweed) and two reference samples (Irish Sea sediment and Danish soil) revealed a good agreement with reference/certified values. The SI column-separation method is straightforward and less labor intensive as compared with batch-wise anion exchange chromatographic procedures. Besides, the automated method features low consumption of ion-exchanger and reagents for column washing and elution, with the consequent decrease in the generation of acidic waste, thus bearing green chemical credentials.     

Determination of 239,240Pu, 238Pu isotopes in soil samples using molecular recognition technology product AnaLig?Pu-02 gel

Procedure for analysis of plutonium isotopes in soil samples was developed using a new molecular recognition technology product AnaLig^?Pu-02 gel. Extraction chromatography TEVA^? Resin was used for purification of plutonium phase to remove thorium impurities which interfere in Pu determination by alpha spectrometry. The performance of the method was successfully tested by analysis of a sand stimulant sample and a soil sample spiked with known activity of ²³⁹Pu. The results obtained for procedures were compared in terms of activities and recoveries.     

Plutonium speciation: The one-oxidation-state method

The distribution of plutonium oxidation-states in acid solutions can be estimated if the pH and the fraction of one oxidation state can be determined. The approach applies to plutonium in laboratory solutions and to plutonium in water of the environment.     

Recent developments in nonaqueous plutonium coordination chemistry

This account highlights recent research from our laboratory on nonaqueous plutonium coordination chemistry. The preparation of organic-soluble synthons, the reactivity of plutonium with soft donor atom ligands, and initial characterization of resultant complexes are presented. Homoleptic soft donor complexes are targeted, to contrast with the much larger body of actinide chemistry that focuses covalency and reactivity within one to three sites in the coordination sphere. Structural parameters from X-ray structure determination and computation indicate small, yet significant, differences in covalency between isostructural plutonium and lanthanide complexes. Results are discussed in the context of our aim to expand the fundamental chemistry of plutonium, particularly to address challenges in the nuclear industry.     

Electrodeposition and determination of nano-scale uranium and plutonium using alpha-spectroscopy

Summary A simple method was used to design and set up an electrodeposition device for the alpha-emitting nuclides. The designed electroplating facility is leak proof and simple in operation and dismantled. The effect of current, pH of electrolyte, and the plating time on the electrodeposition efficiency have been investigated in a sodium bisulphate, sulphuric acid electrolyte in order to determine the optimum conditions. It was shown that a current of 900-1000 mA, plating time of 80-90 minutes and pH range of 2-2.3 are the best conditions for deposition of nano-scale uranium and plutonium. In these circumstances, it was possible to deposit 0.004 ng ^. g^-1 Pu and 60 ng ^. g^-1 U in an electroplating planchette. The device and modified procedures were successfully applied for soil samples. Prior to electrodeposition of the elements, a column extraction chromatography has been used to separate the Pu and U and eliminate most matrix and interferences in environmental samples.     

Characterization of plutonium contamination at the former nuclear weapons testing range,at Maralinga in South Australia

Re-suspension studies on soils contaminated with plutonium during nuclear weapons tests were performed by use of a mechanical dust-raising apparatus. Airborne dust was analyzed in terms of mass and²⁴¹Am activities for particle sizes less than 7 m. The AMAD was determined as 4.8 to 6 m, for re-suspended soil. Also, surface soil was characterized in the laboratory by means of sieving and microparticle classification, yielding mass and²⁴¹Am activity distributions with respect to size. Data indicate the granularity of plutonium contamination at both major and minor trial sites. Depth profile analyses for undisturbed, areas demonstrate that most (74% on average) of the americium and plutonium activity is found in the top 10 mm of soil. Plutonium and americium activities were found to be enhanced in the inhalable fraction over their values, in the total soil, and the enhancement factors were similar in re-suspended dust and surface soil. Observed enhancement factors ranged from 3.7 to 32.5.     

In search of higher sensitivity: Pu isotopic analysis

Summary 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.     

Determination of plutonium in soil

A procedure for the determination of plutonium isotopes in soil is described. The method involves conversion of plutonium to acid-soluble form, dissolution, purification, electrodeposition and alpha-spectrometric determination. Final recovery is in the range from 27 to 51%. In this work increased attention was paid to the problem of equilibration of the chemical yield monitor with plutonium present in the soil sample.     

Leaching of chlorine from Celotex packaging in stainless steel containers storing plutonium pits

The AL-R8 stainless steel sealed insert that is currently used for interim storage of plutonium pits at the Pantex facility in Amarillo, Texas, is designed to provide an inert storage environment for the plutonium pits for a 50-year service life. There is concern that the high chlorine content and absorbed moisture present in the packaging material, Celotex, may lead to corrosion of the container over time. The main objective of this study was to determine chlorine in the Celotex as well as in the various leaching procedures using neutron activation analysis.     

逆流色谱分离感应耦合等离子质谱在线测量超痕量钚

将逆流色谱（CCC）与感应耦合等离子质谱（ICP-MS）相联,研究了几种两相体系在CCC中的固定相保留率,从中选择1％TNOA-正庚烷作固定相,通过CCC富集分离钚并去除基体及干扰元素,通过研究在线分离条件及定量方法等,建成了CCC分离ICP—MS在线测量超痕量钚的方法。采用该方法分析得到实际土壤样品中^239Pu的含量与由传统的分离方法给出的结果相吻合。     

Extraction chromatography in the TBP-HNO3 system

As an application of a TBP/XAD-4 column for the analytical separation of uranium, neptunium, plutonium and americium, the elution behavior of these elements as a function of their redox reactions has been studied. Subsequently, two effective procedures to carry out a quantitative separation of the actinide elements from each other were established by combining extraction chromatography in the TBP-HNO₃ system and the redox reactions of the actinide elements.     

Solvent Extraction Studies of Gadolinium in Tri-Butyl Phosphate

Fast reactor spent fuel reprocessing plants should be designed for inherent criticality safety due to high plutonium content. Addition of soluble neutron poison is one way to do that. Gadolinium is the best choice based on neutron absorption cross section and chemical compatibility. In this work, using classical thermodynamic approach, the distribution coefficient of gadolinium in tributyl phosphate has been calculated and compared with the experimental data. The influence of acidity and uranium at equilibrium on gadolinium distribution in tributyl phosphate has been investigated. The result establishes the feasibility of employing gadolinium as soluble neutron poison in fast fuel reprocessing.     

Strong association of fallout plutonium with humic and fulvic acid as compared to uranium and137Cs in Nishiyama soils from Nagasaki, Japan

To investigate the formation of mobile organic plutonium, we analyzed the plutonium contents of the fulvic (FA) and humic (HA) acids from the soil samples obtained at Nishiyama, Nagasaki, Japan. The percentages of the plutonium bound strongly to HA and to FA vs. the total plutonium in the soil were 5–10% and 1%, respectively, at the depth of 0–0.1 m, much higher values than those of¹³⁷Cs and uranium. After being weathered for 51 years under a temperate climate, the initial highfired oxides of fallout plutonium have become as chemically reactive plutonium from nuclear fuel reprocessing plants.