Geological Feature Modeling and Reserve Estimation of Uranium Deposits Based on Multiple Interpolation Methods

Uranium resource distribution and accurate reserve evaluation are important references for mineral investment and production. Eight kinds of interpolation methods in the Groundwater Modeling System (GMS), including ordinary kriging (OK), are used in this study to predict the spatial distribution of reserve-related parameters, such as uranium grade, ore thickness and uranium content per square meter. The present study draws the following conclusions: (1) Cross-validation found that the uranium grade value using the spherical method is the closest to the actual value. The spherical method has the best interpolation effect. (2) The relative error, which is +3.62%, between the uranium reserves that is calculated by the spherical interpolation method and that by the traditional calculation value is the smallest. (3) The setting of the number of interpolation grids is related to the actual number of boreholes. The ratio between the two will affect the accuracy of reserve estimation, and different interpolation methods have different degrees of influence on reserve estimation. This method is applicable to all in-situ leaching sandstone uranium mines. Further study needs to be carried out toward heterogeneity of three-dimensional space, which will make the estimation more accurate.

Determination of Uranium Concentration in Blood Samples for Patients with Kidney Failure in Salah din Governorate

Analysis of human biological samples, such as blood, is generally used to verify human exposure to uranium. The uranium content in the blood of patients with kidney disease in Salah al-din governorate was determined using the Fission Track Analysis (FTA) of the detector CR39. Uranium concentrations of blood samples taken from kidney failure patients ranged between 1.636 ppb to7.477 ppb, with a mean value of 5.496 ppb. And the health group values ranged between 0.301 ppb to 2.332 ppb with a mean value 1.089 ppb.

Effect of the burnable absorber arrangement on the VVER-1200 fuel assembly neutronic performance

Optimizing the use of fuel in a power reactor is a task of current concern. However, little attention has been given to investigating the dependences among the enrichment used, the content of gadolinium oxide in fuel elements, and the life time in combination with assessing the efficiency of using Gd fuel elements with different Gd2O3 contents. The paper considers fuel assembly (FA) versions for VVER-1200 reactors having different enrichments for fuel elements, including those with Gd, and different contents of gadolinium oxide in fuel. A comparative analysis is presented for assemblies with homogeneous Gd2O3 arrangements in each fuel element and with profiled Gd2O3 arrangements. In the latter case, profiling depends on the neutron flux density in the layer which includes Gd fuel elements. This suggests that the arrangement of gadolinium oxide proportionally to the neutron flux density will improve the FA neutronic performance. The results were obtained using SERPENT (a continuous-energy multi-purpose three-dimensional Monte Carlo particle transport code). The assemblies with the used parameters for a 12-month fuel cycle have shown the method under consideration to be inefficient for a period of over 300 eff. days. With increased enrichment and content of gadolinium oxide, the use of profiled versions has turned out to be more rational for longer periods (up to 900 eff. days). Therefore, this phenomenon is relevant for the reactor life, whereas it proves to be insignificant for the fuel life. A complex relationship is noted between the gadolinium and uranium content in an assembly and the effective multiplication factor for the profiled and standard assemblies. This relationship requires further detailed consideration.

Physical-chemical characterization of uranium containing sediments

The presented paper is intended to study the chemical behaviour of combined geogenicanthropogenic uranium content in specific stream sediments. The sampling points have been chosen with respect to the natural conditions in the locality of groundwater outflow from a former uranium mine adit in Považský Inovec mountain range, near Kálnica village. Besides the total uranium determination and physical-chemical characterization of the relevant water- and sediment samples we carried out modified Tessier type sequential fractionation extractions of natural- and artificially contaminated sediment samples after time dependent agitation in air and in the atmosphere of argon. The obtained results have been compared with those fulfilled with montmorillonite K-10. The total uranium concentrations of the relevant groundwater samples as well as of stream sediments have been determined by ICP-MS using HP 4500. The determinations of uranium in extracts have been accomplished according STN757614, utilizing arsenazo III as a selective complex forming reagent for spectrophotometric determination of uranyl-ions at 650 nm. The total uranium concentration of the groundwater outflow and in the sediment taken in its immediate vicinity has been 31.75±0.35 μg dm-3 and 38.0±2.7 μg g-1 respectively. Unlike montmorillonit K-10, in which the carbonate-bound fraction of uranium after 1 week aeration and agitation in argon atmosphere represents 22.8% and 18.6% respectively, uranium in investigated sediments has been present predominantly in carbonate-bound fraction-reaching under similar conditions 38.6% and 26.6%, respectively.

Distribution and modes of occurrence of uranium in coals of Eastern Yunnan, China

Uranium is an environmentally hazardous element, and is commonly present at trace levels (2.4 μg/g for world coals) in coal deposits. However, selected coal deposits could be highly enriched in uranium. In this study, 15 coal samples were collected from Eastern Yunnan coal deposits, China, aiming to characterize the distribution and the occurrence of uranium in those coals. In studied samples, uranium content varied from 0.36 to 8.28 μg/g, with an average value of 3.76 μg/g. Generally, uranium content in coals from northern coal mines (3.02 ± 2.44 μg/g, n = 5) were lower than it in southern coal mines (4.13 ± 2.30 μg/g, n = 10). Uranium in coal samples showed no obvious correlation with total sulfur, whereas was positively correlated with ash yield. The results of sequential chemical extraction procedure confirm that organic-bound is the dominant occurrence of uranium. The slight enrichment of uranium in studied coals was probably attributed to sedimentation processes, hydrological conditions and tectonic structure of the coal deposits.

The Study of Uranium Accumulation in Marine Bottom Sediments: Effect of Redox Conditions at the Time of Sedimentation

To evaluate the effect of redox conditions at the sedimentation stage on uranium content and U/TOC ratio in marine source rocks, we analyzed the accumulation of uranium in modern marine bottom sediments formed in different redox conditions. The behavior of uranium from bottom sediments formed in oxidizing and sub-oxidizing settings has been studied on the sediments of the Upper Pleistocene–Holocene age accumulated in the coastal area of the White Sea (Kandalaksha Gulf). We studied the content of uranium, Eh, pH, TOC, C, H, N, and S element and isotope compositions and other parameters in two sampled columns of bottom sediments at a depth of 0–2.5 m. The composition of sediments was typical for the shelf zone where marine genesis mixes with the continental run-off. The upper layer of sediments (0–50 cm) were characterized by oxidizing conditions (Eh ~ 400 mV); with the increase in depth, redox conditions changed from oxidizing to reducing (0 ÷ 200 mV). The uranium concentration in the upper layer was 1–1.5 ppm, U/TOC ratio varied in the range of 0.8–1.1 ppmU/%TOC. The uranium content and U/TOC ratio increased up to the values of 2.6 ppm and 1.4 ppmU/%TOC at a depth of 0.5−2.5 m, respectively, but the general content of uranium in the studied environment was close to the values characterizing continental run-off. The results obtained for the White Sea sediments were compared with the sediment of the Black Sea, formed in the anoxic conditions of hydrogen sulfide contamination. In these conditions, the uranium content varied from 10 to 20 ppm. The obtained data were interpreted using thermodynamic modeling of the uranium forms in the seawater at different pH and Eh. This study demonstrated that the change of redox conditions from oxidizing to reducing leads to increased uranium content due to a decrease in uranium’s solubility in water. These results show that oxidation–reduction potential could be one of the most important factors controlling uranium content in black shales formed in the marine environment.