Characterization of electrodeposited uranium targets

In this paper, detection techniques of electrodeposited uranium targets were investigated. Plating yield was measured by ultraviolet spectrometry, and surface morphology, composition and structure of electrodeposited layers were analyzed and characterized by scanning electron microscope, Fourier infrared and X-ray spectroscopy, respectively. The firmness of uranium targets was detected by the vibration test with a small frequency. Considering that uranium targets should be transferred to the reactor safely, the exothermic quantity of the target was calculated. Besides, the uniformity of uranium targets was measured by γ spectroscopy. The results will provide reliable technical basis for the detection and preparation of uranium targets.     

Round Robin “Impurities in Uranium Matrix”: A Success for CETAMA and IAEA

The safeguard of nuclear material is of paramount importance to the IAEA which increasingly uses this information for characterization purposes in order to strengthen the verification of declared nuclear material and to identify the origin of samples from mines. IAEA tasked CETAMA to conduct a round robin with objective to evaluate the capability of laboratories to measure impurities in uranium with concentration levels between 1 and 500 ppm relative to uranium. This round robin was attended by 17 international laboratories from the nuclear industry and safeguards community. The results are mainly obtained by ICP-MS (14) and ICP-AES (3). The synthesis of this round robin were helpful in identifying anomalies and will allow the IAEA to better set realistic measurement performance targets for ICP-MS and ICP-AES.     

色谱分离ICP-AES法测定高纯度八氧化三铀中的13种微量杂质

采用磷酸三丁酯（TBP）萃淋树脂色层分离铀，用电感耦合等离子体-原子发射光谱法测定分离后的离纯度铀氧化物的杂质元素Al、Ca、Cr、Cu、Fu、Mn、Mo、Ni、P、Ti、V、Zn、Zr，除Al、Fe、Mo外的其余10种元素的测定结果符合标准物质定值的要求。     

Synthesis of chitosan resin possessing a phenylarsonic acid moiety for collection/concentration of uranium and its determination by ICP-AES

A chitosan resin possessing a phenylarsonic acid moiety (phenylarsonic acid type chitosan resin) was developed for the collection and concentration of trace uranium prior to inductively coupled plasma (ICP) atomic emission spectrometry (AES) measurement. The adsorption behavior of 52 elements was systematically examined by packing it in a minicolumn and measuring the elements in the effluent by ICP mass spectrometry. The resin could adsorb several cationic species by a chelating mechanism, and several oxo acids, such as Ti(IV), V(V), Mo(VI), and W(VI), by an anion-exchange mechanism and/or a chelating mechanism. Especially, U(VI) could be adsorbed almost 100% over a wide pH region from pH 4 to 8. Uranium adsorbed was easily eluted with 1 M nitric acid (10 mL), and the 25-fold preconcentration of uranium was achieved by using a proposed column procedure, which could be applied to the determination of trace uranium in seawater by ICP-AES. The limit of detection was 0.1 ng mL⁻¹ for measurement by ICP-AES coupled with 25-fold column preconcentration.     

Determination of sulphur in uranium matrix by total reflection X-ray fluorescence spectrometry

The possibility of sulphur determination in uranium matrix by total reflection x-ray fluorescence spectrometry (TXRF) has been studied. Calibration solutions and samples of sulphur in uranium matrix were prepared by mixing uranium in form of a standard uranyl nitrate solution and sulphur in the form of Na₂SO₄ standard solution, prepared by dissolving Na₂SO₄ in Milli-Q water. For major element analysis of sulphur, it was determined without separation of uranium whereas for the trace level determinations, uranium was first separated by solvent extraction using 30% tri-n-butyl phosphate (TBP) in dodecane as an extractant. In order to countercheck the TXRF results, a few samples of Rb₂U(SO₄)₃, a chemical assay standard for uranium, were diluted to different dilutions and sulphur content in these solutions were determined. The TXRF determined results for trace determinations of sulphur in these diluted solutions were counterchecked after addition of another uranium solution, so that sulphur is at trace level compared to uranium, separating uranium from these solution mixtures using TBP extraction and determining sulphur in aqueous phase by TXRF. For such TXRF determinations, Co was used as internal standard and W Lα was used as excitation source. The precision and accuracy of the method was assessed for trace and major element determinations and was found to be better than 8% (1σ RSD) and 15% at a concentration level of 1 μg/mL of sulphur measured in solutions whereas for Rb₂U(SO₄)₃, these values were found to be better than 4 and 13%, respectively.     

Uranium in pore water from coastal sediments determined by chemical activation analysis

Chemical neutron activation analysis was applied to determine trace uranium in estuarine pore water after a simple separation through coprecipitation with hydrated iron(III) oxide. The mean coprecipitation yield of uranium was found to be ~85% under pH ranged from 6 to 8.6. The distributions of uranium in both seawater and pore water were determined alongwith the variations of uranium content in oxidation and reduction conditions. Behaviors of uranium in pore water are also discussed.     

Separation and solvent extraction of vanadium and uranium with n-propyl 2,3,4-trihydroxybenzoate

A spectrophotometric method is described for the separation and determination of trace quantities of vanadium(IV) and (V) from uranium(VI). Vanadium is selectively separated from uranium by extraction at pH 6.5 into n-propyl 2,3,4-trihydroxybenzoate (PTB) dissolved in t-pentanol. Up to 120 microg of vanadium can be determined by measuring the absorbance of the blue complex in the organic phase at 585 nm. Uranium(VI) remains in the aqueous layer and can be determined spectrophotometrically by its reaction with PTB in aqueous acetone to produce a brown-red colour at pH 7.6-8.8. Solutions containing 25-275 microg of uranium absorb at 370-380 nm according to Beer's law. By modification, this procedure can be used for the determination of the two metals in native phosphate rocks. The effects of diverse ions on the determination of vanadium and uranium have also been examined.     

Measurement of uranium in small quantities in phosphates by use of γ-ray spectrometry and the 1001 keV peak of <Superscript>234m</Superscript>Pa

Phosphates, naturally containing trace amounts of uranium, were examined using direct γ-ray spectrometry. Both normal and Compton-suppressed counting modes were utilized. The 1001 keV photo peak of the second daughter of ²³⁸U was chosen because of its isolation from other, potentially interfering peaks. The findings suggest that with the aid of Compton suppression, it is possible to quantify low uranium levels in phosphates using samples sizes of order 10 grams within an accuracy of 5%. The uranium content was determined in several sample types and was found to range from 60±4 to 70±8 μg/g, depending on the sample composition. This investigation also considered the effects of sample size, counting time, and counting technique as sources of precision maximization. This work has shown that only a small amount of phosphate is needed to determine the constituent concentration, instead of the standard several hundred grams of material.     

Analytical application of DHOA for the determination of trace metallic constituents in U based fuel materials by ICP-AES

DHOA (Di-n-hexyl-octanamide) is one of the alternative extractants to TBP (tri-n-butyl phosphate) known for the extraction of uranium from moderate nitric acid medium without significant extraction of the fission products. Analytical application of DHOA was explored to develop a methodology for determination of trace metallic constituents in uranium based nuclear materials. This involved the separation of uranium matrix by 1.1 M DHOA-dodecane followed by the analysis of the raffinate for trace constituents by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). A systematic study showed that four contacts of 1.1 M DHOA-dodecane were required for quantitative extraction of U from 4 M HNO₃ feed for the sample size of 1 g in 10 mL. The feasibility of using DHOA for extraction of U from trace metallic constituents in U based fuel materials without losing trace quantities of analytes of interest was studied by using synthetic samples after appropriate spiking of common impurities and critical elements at their required specification limits (common elements—5 ppm, critical elements—1 ppm). A systematic study was carried out to compare the analytical performance of DHOA with TBP, which revealed that DHOA could successfully be employed for the determination of 19 trace constituents with lower estimation limits of 5 ppm for common impurities and 1 ppm for critical elements.     

Determining P,S, Br,and I content in uranium by triple quadrupole inductively coupled plasma mass spectrometry

Journal of Radioanalytical and Nuclear Chemistry - The trace impurities of a uranium ore concentrate (UOC) can be examined to determine mine source, methods of production, and quality. This study...     

Chemical and radiochemical characterization of depleted uranium in contaminated soils

The main results of chemical and radiochemical characterization and fractionation of depleted uranium in soils contaminated during the Balkan conflict in 1999 are presented in the paper. Alpha-spectrometric analysis of used depleted uranium material has shown the presence of man-made radioisotopes ²³⁶U, ²³⁷Np, and ^{239, 240}Pu traces. The fractionation in different soil types was examined by the application of a modified Tessier’s five-step sequential chemical extraction procedure, specifically selective to certain physical/chemical associations. After ion-exchange-based radiochemical separation of uranium, depleted uranium is distinguished from naturally occurring uranium in extracts on the basis of the isotopic activity ratios ²³⁴U/²³⁸U and ²³⁵U/²³⁸U and particular substrates for recently present uranium material in soils are indicated. The text was submitted by the authors in English.     

天然水源中微量铀钍含量与摄入量研究

分析了居民饮用水及其天然水源中微量铀，钍的含量，并与尿液中铀，钍含量进行了比较。结果表明，上海地区天然水源在国家规定的允许范围内，接近于尿液中铀，钍的日排出量。     

Determination of low atomic number elements at trace levels in uranium matrix using vacuum chamber total reflection X-ray fluorescence

Determinations of low atomic number elements Na, Mg and Al present at trace concentrations in uranium matrix were made by vacuum chamber total reflection X-ray fluorescence spectrometer for the first time. For this purpose, synthetic samples of uranium with known amounts of these low atomic number elements were prepared by mixing different volumes of their solutions with U solution of high purity. The concentrations of these elements in the samples were in the range of 100–300 μg/g with respect to uranium and 10–20 μg/mL in the solutions. Major matrix uranium was separated by solvent extraction with 30% solution of tri-n-butyl phosphate in dodecane. After the solvent extraction, aqueous phase containing trace elements was mixed with Sc internal standard and the samples were analyzed by vacuum chamber total reflection X-ray fluorescence spectrometer having a Cr Kα excitation source. The total reflection X-ray fluorescence results obtained, after blank corrections, indicated an average deviation of 14% from the calculated concentrations of these low atomic number elements on the basis of their preparation. However, the total reflection X-ray fluorescence determined concentration of Mg was exceptionally lower than the calculated concentration in two samples. These studies have shown that vacuum chamber total reflection X-ray fluorescence is a promising technique for the determination of low atomic number elements in uranium matrix after its separation.     

Determination of Trace Lithium in Uranium Compounds by Adsorption on Activated Alumina Using a Micro-column Method

A novel method using a micro-column packed with active alumina as solid phase was proposed for separation of trace lithium from uranium compounds prior to determination. The method is based on a preliminary chromatographic separation of the total amount of uranium. This separation involves passing the solution containing sodium carbonate through active alumina and then eluting the trace lithium retained by the solid phase with a solution of sulfuric acid. Two modes, off-line and on-line micro-column preconcentration, were performed. In conjunction with atomic absorption spectrometry, this on-line preconcentration technique allows a determination of lithium at 10(-9) level. Both off-line and on-line mode operation conditions were investigated in separation and determination of trace lithium by micro-column method (length of column bed, flow rate, etc.). The adsorption capacity of activated alumina was found to be 343 microg g(-1) for lithium. Under the optimal operation condition, the detection limit (DL) of on-line preconcentration corresponding to three times the standard deviation of the blank (S/N = 3) was found to be 1.3 ng mL(-1) and the RSD of this method is 3.32% (n = 5). The on-line calibration graph was linear over the range 20 - 200 ng mL(-1). A good preconcentration factor 820 was achieved by experiment under the on-line mode. The developed method was applied to the analysis of trace lithium in nuclear grade uranium compounds.     

CL-7301微色谱柱分离铀化合物中痕量镉的方法研究

采用CL-730l树脂微色谱柱研究了铀化合物中基体铀和痕量镉的分离条件,并用在线富集法测定了铀化合物中的痕量镉.通过试验选择0.125mol/L的HI酸介质中,镉的吸附率接近100%,而铀不被吸附,分离效率达到99.9%以上.吸附在柱上的镉用10 g/L EDTA 洗脱,原子吸收光度法测定.利用在线富集技术,镉的检出限降低至2.3μg/L.对八氧化三铀和分析纯醋酸双氧铀样品中痕量镉进行测定,方法精密度为1.5%,加标回收率为96%～98%.     

Rapid laser fluorometric method for the determination of uranium in soil, ultrabasic rock, plant ash, coal fly ash and red mud samples

A simple and rapid laser fluorometric determination of trace and ultra trace level of uranium in a wide variety of low uranium content materials like soil, basic and ultra basic rocks, plant ash, coal fly ash and red mud samples is described. Interference studies of some common major, minor and trace elements likely to be present in different, geological materials on uranium fluorescence are studied using different fluorescence enhancing reagents like sodium pyrophosphate, orthophosphoric acid, penta sodium tri-polyphosphate and sodium hexametaphosphate. The accurate determination of very low uranium content samples which are rich in iron, manganese and calcium, is possible only after the selective separation of uranium. Conditions suitable for the quantitative single step extraction of 25 ng to 20 μg uranium with tri-n-octylphosphine oxide and single step quantitative stripping with dilute neutral sodium pyrophosphate, which also acts as fluorescence enhancing reagent is studied. The aqueous strip is used for the direct laser fluorometric measurement without any further pretreatment. The procedure is applied for the determination of uranium in soil, basalt, plant ash, coal fly ash and red mud samples. The accuracy of the proposed method is checked by analyzing certain standard reference materials as well as synthetic sample with known quantity of uranium. The accuracy and reproducibility of the method are fairly good with RSD ranging from 3 to 5% depend upon the concentration of uranium.     

Determinations of uranium at trace and subtrace levels in organic substances by wet ashing-Arsenazo III method

A method was developed for the determination of trace and subtrace amounts of uranium in organic substances used during the industrial process of nuclear fuel production. The method is based on decomposing 50 g of the sample by wet ashing with 25 g conc. sulfuric acid. The residue from the ashing process was ignited at 525 °C to remove all carbonaceous materials. The residue was boiled with 10 ml of 11 nitric acid. The resulting solutions was analyzed for uranium concentration using a modification of the arsenazo III method which allows for uranium determination after separating it by TBP extraction from all the interfering elements. The proposed method proved to be sensitive (detection limit: 15 ppb). The relative standard deviation of the method for a sample containing 200 ppb uranium is 5%. The dynamic range of the method is wide, since the method is applicable. for trace and subtrace levels of uranium in organic substances.     

Simultaneous determination of uranium and plutonium at trace levels in process streams using Arsenazo III by derivative spectrophotometry

A derivative spectrophotometric method has been developed for the simultaneous determination of uranium and plutonium at trace levels in various process streams in 3M HNO₃ medium using Arsenazo III. The method was developed with the objective of measuring both uranium and plutonium in the same aliquot in fairly high burn-up fuels. The first derivative absorbances of the uranium and plutonium Arsenazo III complexes at 632 nm and 606.5 nm, respectively, were used for their quantification. Mixed aliquots of uranium (20–28 μg/ml) and plutonium (0.5–1.5 μg/ml) with U/Pu ratio varying from 25 to 40 were analysed using this technique. A relative error of about 5% was obtained for uranium and plutonium. The method is simple, fast and does not require separation of uranium and plutonium. The effect of presence of many fission products, corrosion products and complexing anions on determination of uranium and plutonium was also studied.     

Chemical separation and electrothermal atomic-absorption spectrophotometric determination of Cd, Co, Cu and Ni in high-purity uranium

Summary An electrothermal atomic-absorption spectrophotometric method has been developed for the estimation of trace concentrations of Cd, Co, Cu and Ni in high-purity uranium after their chemical separation. The trace constituents from 100 mg of uranium sample in 3 M nitric acid solution were separated using 0.2 M di-n-octyl sulphoxide in xylene. The concentration of the analytes in the aqueous phase was determined by graphite furnace AAS. The detection limits were 0.001, 0.01, 0.025 and 0.05 ng for Cd, Co, Cu and Ni, respectively. The precision of the determinations was 7–14%. The effect on absorbances of the analytes due to the presence of Al, Ca, Fe, Mg, Pb, W and uranium was examined.

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Chemische Abtrennung und elektrothermische AAS-Bestimmung von Cd, Co, Cu und Ni in hochreinem Uran

Zusammenfassung Die Spuren werden aus einer 100 mg Uranprobe in 3 M salpetersaurer Lösung durch Extraktion des U mit Hilfe von 0.2 M Di-n-octylsulfoxid im Xylol abgetrennt und werden anschließend in der wäßrigen Phase durch Graphitofen-AAS bestimmt. Die Nachweisgrenzen betragen 0,001 ng (Cd), 0,01 ng (Co), 0,025 ng (Cu) und 0,05 ng (Ni). Die Reproduzierbarkeit beträgt 7–14%. Der Einfluß von Al, Ca, Fe, Mg, Pb, W sowie Resturan auf die Absorption der analysierten Elemente wurde untersucht.

     

An extractive pellet fluorimetric determination of trace uranium in thorium rich samples

An extractive pellet fluorimetry determination of trace uranium in thorium rich samples has been developed. This is based upon a solvent extraction system which completely separates both the elements uranium and thorium from each other. Thorium as a neutral complex with 2,3-dihydroxynaphthalene at pH 4–6 is extracted into ethylacetate and then uranium-2,3-dihydroxynaphthalene anionic complex is extracted into another batch of ethylacetate at pH 11–12 under the influence of a counter cation, cetyltrimethylammonium ion. This method has been applied for the determination of trace uranium in synthetic nuclear grade thorium oxide and thorium rich mineralized rock with high degree of accuracy and precision.