Trace Amounts Of Uranium Research Articles

Distribution of U and 210PO in groundwater of Kodagu district, Karnataka, India.

Trace amounts of uranium along with its decay products are found in varying levels in natural soil, rocks, water and air. They are a matter of significant concern due to their carcinogenic nature. In the present work, the distribution of U and 210Po in groundwater of Kodagu District, Karnataka, India, was studied. The concentration of total U in groundwater samples was estimated using LASER and LED fluorimeter, and the activity of 210Po in groundwater was studied using electrochemical deposition followed by alpha counting method. The concentration of U and 210Po varied from 0.4 to 8.8 μgl-1 and 0.47 to 4.35 mBql-1, respectively. The ingestion dose due to U and 210Po in groundwater varied from 0.33 to 7.17 and 0.41 to 3.81μSv y-1, respectively. The estimated U activity was found to be well below the standard safe limits of 30 μgl-1 in drinking water, as recommended by WHO and USEPA. The 210Po activity was low compared with the recommended 100 mBql-1 standard of WHO.

Radiological assessment of different monazite grades after mechanical separation from black sand

In Egyptian black sands, monazite is a precious mineral characterized by its composition, which includes crucial constituents such as thorium, trace amounts of uranium, and rare earth elements. It is essential to evaluate and quantify the extent of gamma-ray exposure resulting from the presence of primordial radionuclides. This necessity arises from human activities that extract and retrieve raw materials in uranium and thorium mining operations. The current study focuses on the radiological assessment of Monazite raw material in various grades and calculates the associated hazard indices. A hyper pure Germanium detector (HPGe) determined the particular activity. For grade, 90% Monazite samples, the average activities for 232Th, 238U, and 40K were 348,008 ± 1406, 69,299 ± 2086, and 27,510 ± 245 Bq/kg, respectively. For grade 75% Monazite samples, the average activities were 219,000 ± 901, 55,000 ± 500, and 18,300 ± 86 Bq/kg, while for grade 50% Monazite samples, it was 43,294 ± 1549, 9593 ± 629, and 4000 ± 211 Bq/kg for the same element, respectively. Also, 138La’s inherent radioactivity was taken into account. The computed effective and absorbed dosages exceed the worker’s exempt limit of 20 mSv/y. The calculated hazard parameters are higher than the maximum recommended limits. Therefore, it is imperative to employ radiation safety measures to mitigate the potential hazards of ionizing radiation.

Determination of uranium in water samples with chromogenic reagent 4-(2-thiazolylazo) resorcinol after ionic liquid based dispersive liquid liquid microextraction

A simple extraction and spectrophotometric determination of trace amount of uranium was described. The method is based on complex formation between uranium and 4-(2-thiazolylazo)resorcinol (TAR), a well known ligand, C9H7N3O2S, and preconcentration of formed complex into a room temperature ionic liquid (RTIL), 1-methyl-3-octylimidazolium hexafluorophosphate. Under optimum conditions, the method is linear in the range of 7.14–1429 µg L−1, and 3Sb/m value was calculated as 0.26 µg L−1. The method was applied to uranium spiked water samples. To the best of knowledge, the use of TAR as chromogenic agent with 1-methyl-3-octylimidazolium hexafluorophosphate as extractive medium is the first for the versatile determination of uranium. The accuracy of the method was confirmed with certified reference material (TM 28.3 fortified water).

Ultra-trace analysis of plutonium by thermal ionization mass spectrometry with a continuous heating technique without chemical separation

Thermal ionization mass spectrometry (TIMS) with a continuous heating technique is known as an effective method for measuring the isotope ratio in trace amounts of uranium. In this study, the analytical performance of thermal ionization mass spectrometry with a continuous heating technique was investigated using a standard plutonium solution (SRM 947). The influence of the heating rate of the evaporation filament on the precision and accuracy of the isotope ratios was examined using a plutonium solution sample at the fg level. Changing the heating rate of the evaporation filament on samples ranging from 0.1fg to 1000fg revealed that the influence of the heating rate on the precision and accuracy of the isotope ratios was slight around the heating rate range of 100–250mA/min. All of the isotope ratios of plutonium (SRM 947), 238Pu/239Pu, 240Pu/239Pu, 241Pu/239Pu and 242Pu/239Pu, were measured down to sample amounts of 70fg. The ratio of 240Pu/239Pu was measured down to a sample amount of 0.1fg, which corresponds to a PuO2 particle with a diameter of 0.2μm. Moreover, the signals of 239Pu could be detected with a sample amount of 0.03fg, which corresponds to the detection limit of 239Pu of 0.006fg as estimated by the 3-sigma criterion. 238Pu and 238U were clearly distinguished owing to the difference in the evaporation temperature between 238Pu and 238U. In addition, 241Pu and 241Am formed by the decay of 241Pu can be discriminated owing to the difference in the evaporation temperature. As a result, the ratios of 238Pu/239Pu and 241Pu/239Pu as well as 240Pu/239Pu and 242Pu/239Pu in plutonium samples could be measured by TIMS with a continuous heating technique and without any chemical separation processes.

Fluorimetric estimation of U(VI) in the presence of a large excess of Th(IV)

A fluorescence based method has been developed for the determination of trace amounts of uranium in thorium matrix using a mixture of phosphoric acid (H3PO4) and sulfuric acid (H2SO4), as fluorescence enhancing reagent for uranyl (UO2 2+) ion fluorescence. Synthetic samples mimicking the composition of ThO2 fuel were prepared and the concentration of U(VI) was estimated. Satisfactory results are obtained when uranium is present at a concentration of 10 ppm in solid thorium samples with good precision.

Neutron Induced Fission Track Estimation of Uranium Concentration and Its Associated Health Hazards in Drinking Water of the Faisalabad Industrial City

Drinking water plays a major role regarding quality of human life because polluted water is the main cause of many types of diseases. Besides other pollutants, high concentration of uranium above a certain level in drinking water is also hazardous. As water and food are the main sources of uranium intake, it is absolutely imperative that their level of concentrations is monitored regularly for safety of the general public. In this regard, trace amount of uranium in drinking water samples collected from different locations of Faisalabadcity has been carried out using Neutron Induced Fission Track Technique. The water samples along with the standard of known uranium concentration were poured and dried over Lexan track detectors and then irradiated with thermal neutrons in Reactor. After etching, the tracks produced in the detectors as a result of 235U (n, f) reaction were counted under an optical microscope. The uranium concentration was determined by counting and comparing the observed fission track density in the samples and the standard. The observed uranium concentration in the studied water samples varied from (1.04 ± 0.30) μg·L-1 to (21.08 ± 2. 95) μg·L-1 with an average value of (7.39 ± 1.30) μg·L-1 and is found to be within safe limits as far as uranium related health hazards are concerned.

The analysis and attribution of the time-dependent neutron background resultant from sample irradiation in a SLOWPOKE-2 reactor

The Royal Military College of Canada (RMCC) has commissioned a Delayed Neutron Counting (DNC) system for the analysis of special nuclear materials. A significant, time-dependent neutron background with an initial maximum count rate, more than 50 times that of the time-independent background, was characterised during the validation of this system. This time-dependent background was found to be dependent on the presence of the polyethylene (PE) vials used to transport the fissile samples, yet was not an activation product of vial impurities. The magnitude of the time-dependent background was found to be irradiation site specific and independent of the mass of PE. The capability of RMCC’s DNC system to analyze the neutron count rates in time intervals <1 s facilitated a more detailed data analysis than that obtained in previous DNC systems recording cumulative neutron counts. An analysis of the time-dependent background behaviour suggested that an equivalent of 120 ng of 235U contamination was present on each irradiated vial. However, Inductively Coupled Plasma—Mass Spectroscopy measurements of material leached from the outer vial surfaces after their irradiations found only trace amounts of uranium, 0.118 ± 0.048 ng of 235U derived from natural uranium. These quantities are insufficient to account for the time-independent background, and in fact could not be discriminated from the noise associated with time-independent background. It is suggested that delayed neutron emitters are deposited in the vial surface following fission recoil, leaving the main body of uranium within the irradiation site. This hypothesis is supported by the physical cleaning of the site with materials soaked in distilled water and HNO3, which lowered the background from a nominal 235U mass equivalent of 120 to 50 ng per vial.

ボロンドープダイヤモンド電極を用いたストリッピングボルタンメトリーによる微量ウランの定量

ボロンドープダイヤモンド電極を用いたストリッピングボルタンメトリーによる微量ウランの定量

The determination of uranium in food samples by Compton suppression epithermal neutron activation analysis

Eight foods common to the Nigerian diet were analyzed for trace amounts of uranium using epithermal neutron activation analysis. Food sample sizes of roughly one-half gram, irradiated for 10 min, with a 15 min decay time and counting time for 10 min yielded detection limits between 0.02 and 0.04 Bq/kg. Dried milk, chicken pasta, spaghetti and biscuits had less than detectable amounts of uranium, while sorghum, wheat and brown beans contained 0.73, 0.23 and 0.16 Bq/kg, respectively.

Measurement of uranium in small quantities in phosphates by use of γ-ray spectrometry and the 1001 keV peak of 234mPa

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.

Determination of Ultra Trace Amounts of Uranium (VI) by Adsorptive Stripping Voltammetry Using L-3-(3, 4-dihydroxy phenyl) Alanine as a Selective Complexing Agent

The spectrophotometric behavior of uranium (VI) with L-3-(3, 4-dihydroxy phenyl) alanine (LDOPA) reagent revealed that the uranium can form a ML2 complex with LDOPA in solution. Thus a highly sensitive adsorptive stripping voltammetric protocol for measuring of trace uranium, in which the preconcentration was achieved by adsorption of the uranium-LDOPA complex at hanging mercury drop electrode (HMDE), is described. Optimal conditions were found to be a 0.02 M ammonium buffer (pH 9.5) containing 2.0 × 10−5 M (LDOPA), an accumulation potential of − 0.1 V (versus Ag/AgCl) and an accumulation time of 120 sec. The peak current and concentration of uranium accorded with linear relationship in the range of 0.5–300 ng ml−1. The relative standard deviation (at 10 ng ml−1) is 3.6% and the detection limit is 0.27 ng ml−1. The interference of some common ions was studied. Applicability to different real samples is illustrated. The attractive behavior of this reagent holds great promise for routine environmental and industrial monitoring of uranium.

An attempt for determining 235U/238U ratio for a trace amount of uranium: Search for an extinct radionuclide 247Cm in the early solar system

In order to search for isotopic anomalies of U caused by the disintegration of 247Cm in meteorite samples, an analytical scheme for determining 235U/238U ratio for a small amount of uranium (less than 1 ng U) was established. The isotopic ratio of U was determined by double-focusing inductively coupled plasma mass spectrometry (DF-ICP-MS). With a great improvement of chemical procedure for purifying the uranium fraction separated from meteorite samples, a variation in 235U/238U ratios was resolved at an order of ±4‰ for 100 ppt or 200 pg U in solution. For applying the procedure in searching an evidence of 247Cm as an extinct radionuclide in the early solar system, a selective chemical dissolution of constituent minerals of meteorites using EDTA and HCl was introduced and a chemical purification scheme of uranium for ICP-MS was established.

Activation and clearance of vanadium alloys and beryllium multipliers in fusion reactors

The possibility of clearance of vanadium–chromium–titanium (V–Cr–Ti) alloys is analysed. These alloys after their service in fusion power plants, have the potential to reach clearance if they are purified from activation products. The extraction part of the technological scheme for radiochemical separation of components of irradiated V–Cr–Ti alloy and their purification from metallic activation products, developed earlier, was tested for the first time in laboratory conditions using activated alloy specimens. The replacement of the acid reextraction of V with peroxide and of acid reextraction of Cr with alkaline improved characteristics of the extraction reprocessing. Duration of the V and Cr reextraction was shortened by about an order of magnitude, the output of these alloy components was increased, V purification from rare-earth metals became two times as great, and Cr decontamination from Co increased by two orders of magnitude. Activation of Be contaminated with trace quantities of uranium is an issue: estimation of Be activation in the blanket of the Power Plant Conceptual Study (PPCS) has suggested that traces of U impurity in Be should be removed – or substantially reduced – prior to use.

U-series Dating of a Speleothem from Inazumi Cave, Oita Prefecture, Japan

Trace quantities of uranium and thorium were separated from a submerged calcite speleothem (stalactite) sample from Inazumi Cave, Oita Prefecture, using Fe (OH) 3 coprecipitation followed by anion-exchange separation with HNO3 and HCl. The isotope ratios 234U/238U and 230Th/234U were determined by isotope-dilution thermal ionisation mass spectrometry. The speleothem became submerged by accumulation of the Aso welded-tuff, Aso-4, and a resulting rise in the local water table that occurred 85, 000-89, 000 years ago. The age of the analysed portion of the sample was 170, 000 years B.P., suggesting that it was deposited before the earlier Aso-2 and-3 eruptions and has been submerged at least three times.

Studies on treatment methods of the safeguards swipe samples for uranium isotope ratio measurement

In the environmental sampling and analyses for safeguards, precise and accurate isotope ratio determination of uranium at trace levels is required for detection of undeclared nuclear activities. Currently, swipe (smear) samples are being taken by IAEA from the nuclear facilities. The amount of uranium collected on the cotton swipe is expected to be in the wide range including the order of nano-gram or less. In order to measure the isotope ratios by ICP-MS, we have studied sample preparation procedures for the trace amount of uranium. Elements causing spectroscopic and non-spectroscopic interferences in ICP-MS measurement were sufficiently removed by anion-exchange of hydrochloric acid media. The uranium contamination introduced throughout the process of sample preparation was below 10 pg uranium per sample. The applicability of the treatment process for uranium isotope measurement up to 100 pico-grams was proposed.

Extraction Preconcentration of Uranium and Thorium Traces in the Analysis of Bottom Sediments by Inductively Coupled Plasma Mass Spectrometry

A procedure was developed for determining trace amounts of uranium and thorium isotopes in bottom sediments from Lake Baikal. This procedure involves sample decomposition, the coextraction of uranium and thorium with trioctylphosphine oxide, the quantitative back extraction after diluting the extract with caprylic acid, and the ICP MS analysis of the back extract. The procedure was verified by analyzing a BIL-1 Lake Baikal bottom silt standard reference material using the developed procedure and independent methods. The detection limits of abundant uranium and thorium isotopes are restricted by blank measures and equal to 1 × 10–7 mass %. The detection limits for234U and 230Th are 4 × 10–10 and 6 × 10–10 mass %, respectively.

Preconcentration of trace amounts of uranium in water samples on octadecyl silica membrane disks modified by bis(2-ethylhexyl) hydrogen phosphate and its determination by alpha-spectrometry without electrodeposition

A simple and reliable method for the selective extraction and determination of uranium in water using octadecyl-bonded silica membrane disks modified with bis (2-ethylhexyl) hydrogen phosphate and alpha-spectrometry is described. Extraction efficiency and influence of sample matrix, optimum amount of extractant, type and minimum amount of organic eluent and flow rates were evaluated. The limit of detection of the proposed method is 40 ng per 1000 ml. The influence of potential interfering cations in water samples on the recovery of U(VI) was investigated. The method was successfully applied to the extraction and determination of uranium in natural water.

Separation of traces of thorium from large amounts of uranium, by adsorption on lanthanum–ammonium oxalate

The separation of small amounts of thorium from large amounts of uranium was achieved by chromatographic columns loaded with ammonium–lanthanum oxalate LAOX, previously prepared and characterized. Good separation yields were obtained; the recovery of the elements was often greater then 95%. 234 Th , naturally occurring in uranium samples, was used as a tracer of 232 Th in order to study the behavior of thorium. The separation and preparation of a 234 Th carrier free solution was also investigated. During thorium adsorption, trace amounts of uranium may be reduced to the +4 oxidation state. The adsorption step and the washing of the column, before thorium elution, were, therefore, run in the presence of a dilute H 2O 2 solution in order to prevent uranium reduction.

Low-level measurement of alpha-particle emitting nuclei in ceramics and lead

Nearly all natural materials contain trace quantities of uranium (U) and thorium (Th) and their daughter nuclides, many of which emit α-particles in their decay. Lead, at the end of the U-decay chain, typically contains some radioactive210Pb which is chemically inseparable from the other Pb isotopes. α-particle emission from these decays can affect sensitive electronic components, such as memory chips or processors. Measurement of α-particle emitters can be accomplished by direct detection of the α-particles (which typically provides no positive identification of the emitting isotope because of energy loss in the sample) or by low-background γ-ray spectroscopy (which does provide positive identification via characteristic γ-rays.) The latter is by far the best method for screening kg-sized samples of materials like ceramics, aluminum, iron or copper. The difference between α counting and γ-ray spectroscopy is less for measuring210Pb in Pb since the 46.5 keV characteristic γ-rays directly following the210Pb decay are strongly absorbed and both methods are limited to thin layers. This paper discusses these two cases and concludes that a large n-type germanium γ-ray spectrometer is probably the best overall system for both measurements.

Trace quantities of uranium in some Indian chewing tobaccos as determined by fission track analysis

The sandwiched pellet technique using Makrofol-E plastic track detectors has been employed to determine trace quantities of uranium in nine brands of flavored chewing tobaccos consumed by the Indian population. In this technique the nuclear reaction,235U(n,f), is used for the quantitative estimation of uranium. The maximum value of uranium (1.88 ppm) has been found in raw tobacco leaves (Surti), while the minimum (0.13 ppm) in Tulsi (Double Zero brand). Other seven brands showed intermediate values of U-contents which are also reported in this paper. These values are compared with the U-contents reported in the literature for other forms of tobaccos.