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    Wyświetlanie 1-10 z 10
    Tytuł:
    Nuclear fissile fuels worldwide reserves
    Autorzy:
    Chmielewski, A. G.
    Powiązania:
    https://bibliotekanauki.pl/articles/147011.pdf
    Data publikacji:
    2008
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    nuclear fuel
    uranium
    thorium
    Opis:
    The paper reports on the present evaluation of uranium reserves and discusses different possibilities of the efficiency of fissile fuel use including the possibility of fuel reprocessing, MOX fuel application and breeder reactors deployment. The possibility of thorium applications and uranium extraction from law grade ores and other material streams (phosphoric acid, copper leaching solution) are discussed as well.
    Źródło:
    Nukleonika; 2008, 53, suppl. 2; 11-14
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical modelling of modular high-temperature gas-cooled reactors with thorium fuel
    Autorzy:
    Oettingen, Mikołaj
    Cetnar, Jerzy
    Powiązania:
    https://bibliotekanauki.pl/articles/2055669.pdf
    Data publikacji:
    2021
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    HTR
    homogenization
    thorium
    Monte Carlo
    Opis:
    The volumetric homogenization method for the simplified modelling of modular high-temperature gas-cooled reactor core with thorium-uranium fuel is presented in the paper. The method significantly reduces the complexity of the 3D numerical model. Hence, the computation time associated with the time-consuming Monte Carlo modelling of neutron transport is considerably reduced. Example results comprise the time evolutions of the effective neutron multiplication factor and fissionable isotopes (233U, 235U, 239Pu, 241Pu) for a few configurations of the initial reactor core.
    Źródło:
    Nukleonika; 2021, 66, 4; 133--138
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Monte Carlo modelling of Th-Pb fuel assembly with californium neutron source
    Autorzy:
    Oettingen, M.
    Stanisz, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/147828.pdf
    Data publikacji:
    2018
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    californium
    lead
    Monte Carlo
    MCB
    thorium
    Opis:
    This paper describes the methodology developed for the numerical reconstruction and modelling of the thorium-lead (Th-Pb) assembly available at the Department of Nuclear Energy, Faculty of Energy and Fuels, AGH University, Krakow, Poland. This numerical study is the first step towards integral irradiation experiments in the Th-Pb environment. The continuous-energy Monte Carlo burnup (MCB) code available on supercomputer Prometheus of ACK Cyfronet AGH was applied for numerical modelling. The assembly consists of a hexagonal array of ThO2 fuel rods and metallic Pb rods. The design allows for different arrangements of the rods for various types of irradiations and experimental measurements. The intensity of the fresh neutron source intended for integral experiments is about 108 n/s, which corresponds to the mass of about 43 μg 252Cf. The source was modelled in the form of Cf2O3-Pd cermet wire embedded in two stainless steel capsules.
    Źródło:
    Nukleonika; 2018, 63, 3; 87-91
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Preliminary results of spatial distribution of uranium and thorium in soil profi les near a uranium industrial site, Guangdong province, China
    Autorzy:
    Wang, J.
    Liu, J.
    Chen, Y.
    Song, G.
    Chen, D.
    Xiao, T.
    Li, H.
    Wang, C.
    Jiang, F.
    Powiązania:
    https://bibliotekanauki.pl/articles/146530.pdf
    Data publikacji:
    2016
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    spatial distribution
    thorium
    uranium
    U/Th ratio
    Opis:
    Four soil profiles were collected from locations with different distances (5, 50, 250 and 1000 m) from a uranium mill tailings dam, Guangdong province, China, to investigate the pollution status of the soil in mining/ milling-related areas based on the contents of uranium (U) and thorium (Th), thus to understand the impacts of uranium industrial activities to the surroundings. The U and Th concentrations were determined by inductively coupled plasma mass spectrometry (ICP-MS) after conventional HF-HNO3-HClO4 digestion procedures. The results indicate that the soils within 50 m from uranium tailing were severely contaminated; those in 250 and 1000 m soil samples were observed to be with local background level even though these in 250 m had slightly higher U/Th ratios. Uranium concentrations varied from 5.50 ± 0.27 to 160.55 ± 8.03 mg/kg, with maximum values recorded in an intermediate layer of the 5-m distance soil profile. In comparison, the concentration of Th ranged from 6.02 ± 0.30 to 84.71 ± 4.24 mg/kg, with maximum values observed in the top layer of the 1000-m distance soil profile. The U/Th ratio varied from 0.15 to 11.99 compared with 0.20, 0.22 and 0.26 of the average for Guangdong province, national China and the world, respectively. The mean U/Th of four soil profiles showed a reduction with distance from the uranium mill tailing dam, suggesting the relatively large magnitude of uranium elevation in soils within limited distances.
    Źródło:
    Nukleonika; 2016, 61, 3; 367-371
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Thoron emanation and exhalation of Slovenian soils determined by a PIC detector-equipped radon monitor
    Autorzy:
    Jónás, J.
    Sas, Z.
    Vaupotic, J.
    Kocsis, E.
    Somlai, J.
    Kovács, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/146850.pdf
    Data publikacji:
    2016
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    emanation
    exhalation
    gamma spectrometry
    PIC detector
    soil
    thorium
    thoron
    Opis:
    The health risk from thoron (Rn-220) is usually ignored owing to its short half-life (55.6 s), but the generated thoron decay products can cause a significant dose contribution. In this study, altogether 51 Slovenian soil samples were investigated using an accumulation chamber technique to obtain information about thoron exhalation features. The obtained (massic) thoron exhalation results varied between 6.9 and 149 mBq•kg–1•s–1 (average: 55.2 mBq•kg –1•s–1). The Th-232 content was determined using HPGe gamma spectrometry. The Th-232 activity concentration ranged between 9.3 and 161.7 Bq•kg–1 (average: 64.6 Bq•kg –1). The thoron emanation features were also calculated from the obtained results (2.9 to 21.2% with an average of 8.6%). The thoron exhalation and emanation properties were compared with the radon exhalation and emanation features determined in a previous study. It was found that there was no correlation between the radon and thoron emanation features, according to the obtained data. This can be explained by the different Ra-224 and Ra-226 distributions in the soil grains. As a result, the thoron emanation factor cannot be predicted from radon emanation and vice versa.
    Źródło:
    Nukleonika; 2016, 61, 3; 379-384
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Accumulation properties of Norway spruce (Picea abies) for different radionuclides
    Autorzy:
    Tomankiewicz, E.
    Mietelski, J.
    Gaca, P.
    Błażej, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/148612.pdf
    Data publikacji:
    2006
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    137Cs
    50Sr
    thorium
    spruce tree
    Tatra Mts.
    aggregation coefficients
    Opis:
    The paper presents results for the 137Cs, 90Sr, 40K activity concentrations and 228Th/232Th, 230Th/232Th activity ratios in several samples needles from two Norway spruce (Picea abies) trees and two soil samples collected in the Tatra Mountains (Poland) area. Activities for artificial 137Cs and 90Sr show moderate values. Statistically different values were found between the mean concentration of 90Sr and 137Cs in current (C) and two years old (C+2) needles of the first tree, whereas for potassium no significant difference was observed. For the second, fallen tree, no significant difference between the mean activity concentration in needles for C+1 and C+2 was found for each radionuclide, but much lower levels of 137Cs contamination were observed. Observed values of the aggregation coefficients for 137Cs and 90Sr are presented.
    Źródło:
    Nukleonika; 2006, 51,suppl.2; 59-67
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Thorium nuclear fuel - thoron aspect
    Autorzy:
    Zagórski, Z. P.
    Głuszewski, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/148763.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    CR-39
    nuclear fuel
    radon-220
    radon-222
    thorium fuel
    thoron
    Opis:
    The communication reports a serious complication connected with preparation, storage and transportation of fuel for thorium and uranium/thorium nuclear reactors. Whereas uranium fuel of any degree of enrichment is free from radium, which produces radon-222, thorium itself produces thoron (radon-220). Measurement of thoron by a routine ionization-chamber device around a small sample of 2 g thorium dioxide shows already the health endangerment situation. The presence of thoron is also confirmed by a typical solid state dosemeter (polymer CR-39), exposed to the air around ThO2 and etched afterwards with warm NaOH solution. The unavoidable presence of thoron can cause increase of price of production of nuclear fuel, demanding special approach to the method of manufacture.
    Źródło:
    Nukleonika; 2010, 55, 3; 407-408
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Local structure and cohesive properties of mixed thorium and uranium dioxides calculated by "ab initio" method
    Autorzy:
    Dąbrowski, L.
    Szuta, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/147874.pdf
    Data publikacji:
    2012
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    uranium
    thorium dioxide
    DFT+U
    LDA
    GGA
    local structure
    cohesive properties
    bulk modulus
    Opis:
    Density functional theory (DFT) results of calculations of the mixed thorium and uranium dioxide Th1-xUxO2 for the following mole ratio x = 0, 0.25, 0.75 and 1 are presented and discussed. "Ab initio" calculations were performed using the Wien2k program package. To compute the unit cell parameters the 12 atom super-cell were chosen. The lattice parameters were calculated through minimization of the total energy by the change of lattice parameters and atom displacement within the unit cell. Calculations were performed for five different exchange energy approximations EXC with and without corrective orbital potential U, and obtained lattice constants are presented graphically and compared with experimental data. It is established that the initially assumed oxygen location within the unit cell plus or minus 0.25 of the mixed compounds are not their equilibrium positions. The oxygen atoms within the unit cell undergo dislocation in the (111) direction. So, the distances oxygen-uranium are smaller than the distances oxygen-thorium. The change of local structure is presented graphically and appropriate parameters values are given in Table. The bulk modulus and the cohesive properties are also counted and shown graphically.
    Źródło:
    Nukleonika; 2012, 57, 1; 101-107
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Diffusion of helium in the perfect uranium and thorium dioxide single crystals
    Autorzy:
    Dąbrowski, L.
    Szuta, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/147700.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    uranium
    thorium dioxide
    diffusion
    tunneling
    DFT+U
    generalized gradient approximation (GGA)
    potential barrier
    incorporated helium
    Opis:
    We present quantum-mechanical evaluation of helium diffusion coefficient in the crystalline UO2 and ThO2. Parameters assignment of Schrödinger’s equation were done using the crystal field potentials which were obtained applying the density functional theory (DFT). “Ab initio” calculations were performed using the Wien2k program package. To compute the unit cell parameters the 13 atom super-cell was chosen. Applying two-site model we evaluated the time for an over-barrier jump and diffusion of interstitial He. The obtained values for diffusion coefficient are compared with the experimentally obtained values and with the theoretical values of other authors. In addition, it is simultaneously shown that helium diffusion in these materials is a quantum diffusion.
    Źródło:
    Nukleonika; 2013, 58, 2; 295-300
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Radiological characterization of the phosphate deposit in Al-Jalamid phosphate mining area, Saudi Arabia
    Autorzy:
    Alhawsawi, Abdulsalam M.
    Shababa, E. I.
    Qutub, Maher M. T.
    Banoqitah, Essam M.
    Kinsara, A. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1841647.pdf
    Data publikacji:
    2021
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    Al-Jalamid site
    uranium
    thorium
    phosphate rocks
    phosphate deposits
    natural radioactivity
    environmental radioactivity
    pollution
    groundwater
    Opis:
    It is a known fact that phosphate rocks have high levels of natural radioactivity due to the presence of large concentrations of radionuclides. This work aims to estimate radiation exposure and dose levels at Al-Jalamid site in northern Saudi Arabia. Al-Jalamid area is one of the largest reserves of phosphate worldwide. Ma’aden, a Saudi Government public company, owns the mine and is responsible for all mining activities. Phosphate and soil samples collected from Al-Jalamid phosphate mining area have been analysed for their uranium and thorium content by an α-spectrometer using radiochemical techniques. The quantity of radon gas was measured both in groundwater and in the atmosphere (indoor and outdoor) at the site using a portable radiation survey instrument. Groundwater samples collected from wells surrounding the mining area were analysed using a liquid scintillation counter in addition to an α-spectrometer. Finally, it is found that phosphate rock concentrate products cannot be utilized economically based on the standards set by the International Atomic Energy Agency (IAEA), since the average activity concentration does not reach the limit set by IAEA and hence are not commercially feasible.
    Źródło:
    Nukleonika; 2021, 66, 1; 35-44
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-10 z 10

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