Determination Of 238U Research Articles

Assessment of NORMs (238U, 232Th, 40K) and radiation hazard indices in Beldih apatite mine region of Purulia district, West Bengal, India.

The radiation arising from naturally occurring radioactive materials (NORMs) is the foremost contributor to the collective dose received by the global population. The present study aims to measure the natural background radiation level and the associated gamma radiation dose in air in the Beldih apatite mine region of Purulia district, India. This study is primarily focused on the determination of 238U, 232Th and 40K activities in the sub-surface soil of the study area. The measurements were carried out using a High Purity Germanium (HPGe) detector-based gamma-ray spectrometer with a relative efficiency of 80%. To achieve uniformity in exposure estimations, radium equivalent activity has been calculated. Additionally, the internal hazard index, external hazard index, radioactivity level index and gamma dose rates have been evaluated to estimate the radiation hazard levels in the study area. The comparison of obtained concentrations and hazard indices with global data (UNSCEAR. (2008). Sources, effects and risks of ionizing radiation. United nations scientific committee on the effects of atomic radiation (report to the general assembly, with Annexes).) suggests that this region lies in a relatively high background radiation zone.

Determination of 238U and 40K Radionuclide Concentrations in Some Granite Rocks by Gamma Spectroscopy and Energy Dispersive X-ray Analysis.

Uranium-238 (238U) and potassium-40 (40K) are important naturally occurring radionuclides. Gamma spectroscopy is a direct, non-destructive method used to determine radionuclide concentrations, but it suffers from the interference of gamma lines. 40K gamma spectroscopy is affected by background interference, which leads to a reduction in the minimum detectable activity. The energy dispersive X-ray analytical technique is quick, with fewer interference problems or background effects. However, it is an indirect method for calculating and deducing the concentrations of isotopes. The aim of the present study was to compare and evaluate both techniques so that they can be utilized efficiently. The results of 238U and 40K were measured by well-calibrated gamma spectroscopy and energy dispersive X-ray techniques. the results indicated that Halayeb White granite is the most environmentally safe compared to the other two types because it contains a very low concentration of uranium 238 and potassium 40.

Physico-chemical conditions controlling the radionuclides mobilisation in various granitic environments

ABSTRACT Nine samples were chemically characterized and radiometrically analyzed for determination of 234U, 238U, 235U, 230Th, 232Th, 226Ra and 40K by γ-ray spectrometer Hyper Purity Germanium (HPGe detector). 238U activity concentrations reach up to 79.78 Bq Kg-1in the altered granites, 1714.11 and 2223.48 Bq Kg-1in the episyenite and pegmatite. Average 234U activity concentrations in the altered granite is 59.26 Bq Kg-1, between 175.88-543.47 Bq Kg-1and 48.19-1102.88 Bq Kg-1in the episyenite and pegmatite, respectively. 232Th activity concentrations vary between 14.16-1024.8 Bq Kg-1in the episyenite, 11.46-240.27 in the pegmatite and reach up to 201.45 Bq Kg-1in the altered granites. 40K activity concentrations range between 4.42-9.15, 2.76-7.34 and 2.68-9.94 Bq Kg-1in the altered granite, episyenite and pegmatite, respectively. 235U activity concentration ranges between 3.74–2.56, 12.45-78.86 and 0.58-102.34 Bq Kg-1 in the altered granite, episyenite and pegmatite, respectively. The studied altered granite, episyenite and pegmatite samples have relatively higher values than recorded in the international standards with the exception of potassium which has lesser amounts. It is demonstrated that pH changes, oxidation-reduction conditions, mineralogical constituents, in addition to alteration processes in these variable granitic environments were the main factors controlling uranium mobilization according to valid processes. The difference in alteration processes and La/Y ratio clarified the presence of more than one event of uranium accumulation and/or leaching in these rocks as confirmed by the presence of uranium accumulation and uranium vacant occurrences. Also, the isotopic ratios of uranium as 238U/235U,234U/235U, 234U/ 238U, 226Ra/ 238U,226Ra/ 230Th, 210Pb/ 226Ra, 230Th/ 238U, 230Th/ 234U with major, trace and rare earth elements were also affected by physico-chemical conditions changes. The present study shows that the samples of episyenite and pegmatite have been affected by leaching-accumulation events in the period from (1 × 105 to ˃2 × 105years).

Development of separation procedures for determination of uranium and thorium in the 82Se source of the SuperNEMO experiment: first steps

Two methods have been tested for separation of uranium and thorium from selenium using UTEVA and anion exchange resins. The average yield for separation of uranium, thorium and selenium was determined to be for the UTEVA method 91 ± 9%, 79 ± 8% and 96 ± 8%, respectively, and 96 ± 10%, 88 ± 9% and 94 ± 8%, respectively, in the case of the anion exchange resin. The methods will be used in consequent development of analytical procedures for determination of 238U and 232Th content with mass spectrometric techniques in 82Se source materials of the SuperNEMO experiment.

Application of delayed neutron counting at CIAE

Delayed neutron counting (DNC) was applied in quantitative determination of 235U/238U, quantitative determination of 235U and 239Pu in 235U–239Pu co-existing samples at China Institute of Atomic Energy (CIAE). In this work, natural uranium, enriched uranium and their mixtures were used in the determinations of 235U/238U ratios. The results indicated that delayed neuron counting combined with neutron activation analysis(NAA) and k0-NAA for the measurement of gamma rays emitted by 239U decay is suitable for fast determination 235U/238U ratio. In addition, the contents of 235U and 239Pu in 235U–239Pu co-existing samples can also be determined respectively.

Application of neural network method to detect type of uranium contamination by estimation of activity ratio in environmental alpha spectra

The discrimination of the composition of environmental and non-environmental materials by the estimation of the 234U/238U activity ratio in alpha-particle spectrometry is important in many applications. If the interfering elements are not completely separated from the uranium, they can interfere with the determination of 234U. Thickness as a result of the existence of iron in the source preparation phase and their alpha lines can broaden the alpha line of 234U in alpha spectra. Therefore, the asymmetric broadening of the alpha line of 234U and overlapping of peaks make the analysis of the alpha particle spectra and the interpretation of the results difficult. Applying Artificial Neural Network (ANN) to a spectrometry system is a good idea because it eliminates limitations of classical approaches by extracting the desired information from the input data. In this work, the average of a partial uranium raw spectrum, were considered. Each point that its slope was of the order of 0–1% per 10 channels, was used as input to the multi-layer feed forward error-back propagation network. The network was trained by an alpha spectrum library which has been developed in the present work. The training data in this study was actual spectral data with any reasonable thickness and interfering elements. According to the results, the method applied to estimate the activity ratio in this work, can examine the alpha spectrum for peaks which would not be expected for a source of given element and provide the clues about composition of uranium contamination in the environmental samples in a fast screening and classifying procedures.

Determination of 238U, 232Th and 40K activity concentrations in riverbank soil along the Chao Phraya river basin in Thailand

The activity concentrations of 238U, 232Th and 40K in riverbank soil along the Chao Phraya river basin was determined through gamma-ray spectrometry measurements made using a hyper-pure germanium detector in a low background configuration. The ranges of activity concentrations of 238U, 232Th and 40K were found to be 13.9 ↔ 76.8, 12.9 ↔ 142.9 and 178.4 ↔ 810.7 Bq kg−1, respectively. The anthropogenic radionuclide, 137Cs, was not observed in statistically significant amounts above the background level in the current study. The absorbed gamma dose rate in air at 1 m above the ground surface, the outdoor annual effective dose equivalent, the values of the radium equivalent activity and the external hazard index associated with all the soil samples in the present work were evaluated. The results indicate that the radiation hazard from primordial radionuclides in all soil samples from the area studied in this current work is not significant.

Test spectra experimental construction for evaluating gamma-spectrometry computer codes for the 235U determination

The determination of 235U in environmental samples from its 185.72 keV photons may require the deconvolution of the multiplet photopeak at ~186 keV, due to the co-existence of the 186.25 keV photons of 226Ra in the spectrum. Successful deconvolution depends on many parameters, such as the detector characteristics, the activity concentration of the 235U and 226Ra in the sample, the background continuum in the 186 keV energy region and the gamma-spectrometry computer code used. In this work two sets of experimental test spectra were constructed for examining the deconvolution of the multiplet photopeak performed by different codes. For the construction of the test spectra, a high-resolution low energy germanium detector was used. The first series consists of 140 spectra and simulates environmental samples containing various activity concentration levels of 235U and 226Ra. The second series consists of 280 spectra and has been derived by adding 137Cs, corresponding to various activity concentration levels, to specific first series test spectra. As the 137Cs backscatter edge is detected in the energy region of the multiplet photopeak at ~186 keV, this second series of test spectra tests the analysis of the multiplet photopeak in high background continuum conditions. The analysis of the test spectra is performed by two different g-spectrometry analysis codes: (a) spectrum unix analysis code, a computer code developed in-house and (b) analysis of germanium detector spectra, a program freely available from the IAEA. The results obtained by the two programs are compared in terms of photopeak detection and photopeak area determination.

Use of chromatographic pre-concentration for routine uranium bioassay analysis by ICP-MS

Routine monitoring of urine is an effective way to detect occupational intake of radioactive material. Historically, determinations of uranium isotopic ratios have been performed by radiochemical separation followed by alpha spectrometry. With recent advancements in technology, inductively coupled plasma-mass spectrometry (ICP-MS) has become widely available for the determination of trace metals as well as radioactive nuclides with long half-lives, such as 238U in urine. Furthermore, ICP-MS measurements of 238U do not require radiochemical separation since the number of atoms in the sample is determined instead of the number of alpha particles emitted. However, this method does not provide good sensitivity for the determination of 235U due to its shorter half-life. An improved procedure using pre-concentration of uranium and determination by ICP-MS decreases the detection limit by a factor of ten or greater with only slight increase in total analysis time. The method also has the capability of accurately determining the isotopic ratio of the sample, which is very important in cases where enriched or depleted uranium is involved.

Non-destructive assay technique for the determination of 238U/232Th ratio in the mixed oxides of uranium and thorium using prompt gamma-ray neutron activation

A non-destructive assay technique based on prompt gamma-ray neutron activation analysis for the determination of 238U to 232Th ratio in the mixed oxide fuel materials has been established. The method uses closely spaced high energy gamma-rays in the region of 4000 keV to 4150 keV enabling it to be applied for samples of any geometry and thickness without having any correction for gamma-ray attenuations and detection efficiencies.

Procedure for Simultaneous Determination of Uranium and Transuranium Elements in Groundwater and Liquid Radioactive Wastes from the Shelter

An ion-exchange procedure for simultaneous determination of 234U, 235U, 236U, 238U, 238Pu, 239 + 240Pu, 241Am, and 244Cm in groundwater and liquid radioactive wastes is described. The concentration and separation of U and Pu are performed on AV-17 anion exchanger in the chloride form from 9 M HCl. Am and Cm are separated from rare-earth elements by step-by-step elution from KU-2 cation-exchange resin in the NH 4 + form with α-hydroxyisobutyric acid (pH 4.75). Finally, U, Pu, Am, and Cm are determined α-spectrometrically.

DETERMINATION OF URANIUM BY MEANS OF ICP-QMS

The use of depleted uranium (DU, 238U) as ammunition is currently a major topic for discussion. DU is the main by-product from the processing of nuclear fuel (235U). It is considered to be less radioactive than natural uranium, but despite this, there is still a serious hazard due to the alpha-radiation that is emitted. U like other heavy metals is a threat to both health and the environment because of its pronounced toxicity. Significant amounts of uranium have been released in the last decade with armor piercing ammunition that was manufactured from DU, not only during major conflicts but also on numerous military shooting ranges all over the world. The paper describes methods for the extraction of plant available DU from soils, digestion processes for plant material and the determination of 238U by Inductively Coupled Plasma-Quadrupole Mass Spectrometry (ICP-QMS) in soils, plants and waters.

Determination of 235U and 238U in urine samples using sector field inductively coupled plasma mass spectrometry

The high sensitivity of SF-ICP-MS (sector field inductively coupled plasma mass spectrometry) using a torch with the “guard-electrode” (capacitive decoupled plasma) allows the determination of 238U (isotope abundance 99.2%) and 235U (0.8%) and their isotope ratio in human urine samples down to the physiological level of <10 ng/l total uranium. For sample preparation UV photolysis was used. Some quality criteria like for the detection limit, the reproducibility, recovery and the isotope ratio are given. The method can be applied in occupational as well as in environmental medicine because of its outstanding detection power.

Determination of uranium-235, uranium-238 and thorium-232 in urine by magnetic sector inductively coupled plasma mass spectrometry

Inductively coupled plasma mass spectrometry (ICP-MS) is a very useful method for the determination of long-lived isotopes of uranium, thorium and other elements. This study investigates parameters for measurement of isotopes of these elements in human urine using a magnetic sector ICP-MS method and a previously established quadrupole ICP-MS method. The investigation was performed by means of comparison of data from the determination of 238U, 235U and 232Th in urine-based quality control materials, as well as specimens from an investigation of occupational exposure to smoke and particulates from a population of firefighters. In addition to difference in instrumentation, additional isotopes were quantitated, and sample size was decreased to 100 µL for the magnetic sector method from 500 µL for the quadrupole method. Though non-instrumental bias in samples >500 ng L−1238U due to differences in the serial dilution technique (Digiflex diluter for quadrupole, Eppendorf pipettor for the magnetic sector method) was noted, results of comparison of the analyses of samples by magnetic sector ICP-MS compare very favorably with those from quadrupole ICP-MS (rsquared = 0.991 inclusive, 0.987 excluding serially diluted samples), with a near unity slope (0.934 inclusive, 1.06 excluding serially diluted samples) and near-zero intercept (0.0105 inclusive, 0.001 excluding serially diluted samples). Addition of calibration with 235U (0.72% in NIST U standard) allowed the characterization of QCs and measurement of this isotope using the magnetic sector method with a multi-run (n = 28) urine LOD of 0.06 ng L−1. Other magnetic sector urinary isotopic multi-run LODs were in the below 3 ng L−1 range for a 100 µL sample versus 4 ng L−1 for a 500 μL sample with the quadrupole (n = 43).

Determination of235U abundance in uranium by neutron activation on the basis of the molybdenum fission interference

The purpose of the present paper is to suggest a method for determining the235U abundance in uranium samples (compounds, metallic alloys or other uranium materials, where this element may be natural or not) through a particular application of neutron activation analysis, based on the fission interference by molybdenum. The method lies on an a priori calibration with natural uranium, thus it does not require235U certified standards.

Uranium contents in raw waters from Biscay (Spain)

The determination of 234U, 238U and 235U in raw waters (surface waters) from four treatment plants located in northern Spain has given mean values of 2.52 mBq/l for 234U, 1.77 mBq/l for 238U and 0.11 mBq/l for 235U. The activity concentration is higher in summer than in winter. The knowledge of the uranium contents in waters in the previous and later instants of its treatment allows the determination of the removal percentage of uranium, whose mean value is 61.3%.

Determination of U and Th in soil and plants obtained from a high natural radiation area in China using ICP-MS and γ-counting

This study was carried out for the determination of 238U and 232Th concentrations in soil and various foods obtained in high natural radiation areas in China for estimating the internal radiation doses caused by these radionuclides. Knowledge of the daily dietary intakes of the nuclides through foods is essential to evaluate the internal radiation dose. Several analytical methods were evaluated for their applicability and quality assurance. The accuracy and precision of ICP-MS is considerably better for determining trace elements like U and Th in fine powder samples. The estimated annual effective dose is 0.302 μ Sv/y for 238U and 1.86 μ Sv/y for 232Th in the high natural radiation area, and 0.0101 μ Sv/y for 238U and 0.177 μ Sv/y for 232Th in the control area.

Radioecological measurements in the algae from İskenderun Bay

Gamma spectrometric techniques have been used for the determination of 238U, 232Th, 40K, 134Cs and 137Cs levels in algae. Brown, red, green algae were taken from 12 algae species collected from 6 different parts of İskenderun Bay on May — July 1991. The purposes of this paper is to follow up the earlier study and present results for the distribution of radionuclides in algae species of the İskenderun Bay. 238U is in the range 0.82 ± 0.24–3.35 ± 0.57 ppm, 1.47±0.12–8.85 ± 1.35 ppm for 232Th, 550 ± 20–1690 ± 40 Bq/kg for 40K, 137Cs activity result varies between 0.5 ± 0.3–1.7 ± 0.6 Bq/kg.

96/03493 Low energy scintillation spectrometry for direct determination of 238U and 210Pb in coal and ash samples

96/03493 Low energy scintillation spectrometry for direct determination of 238U and 210Pb in coal and ash samples

Determination of uranium and thorium isotopes in mineral spring waters

Concentrations levels of uranium and thorium isotopes have been analyzed in the m mineral spring waters of a high background region of Brazil: Pocos de Caldas and Aguas da Prata. The procedure was based on the determination of238U,234U,232Th,230Th and228Th by α-spectrometry after separation and purification of the isotopes of interest by using anion-exchange chromatography and preparation of the samples for α-measurements by electrodeposition. The concentration varied from <1.1 to 28.4 mBq.l−1 and from <1.6 to 141 mBq.l−1 for238U and234U, respectively. Thorium isotope measurements varied from <0.2 to 1.8 mBq.l−1 from <0.3 to 4.9 mBq.l−1 and from <0.8 to 19.9 mBq.l−1 for232Th,230Th and228Th, respectively. Calculations of thorium and uranium isotopic activity ratios were carried out giving values ranging from 1.9 to 7.2, from 1.2 to 3.0 and from 7.7 to 15.3 for234U/238U,230Th/232Th and228Th/232Th, respectively. The effective doses due to the intake of238U and234U present in these waters are expected to reach values up to 1.4×10−3 mSv y−1 and 8.0×10−3 mSv y−1, respectively.