Artículos de revistas: "Uranium cycle"

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Costa Peluzo, Bárbara Maria Teixeira y Elfi Kraka. "Uranium: The Nuclear Fuel Cycle and Beyond". International Journal of Molecular Sciences 23, n.º 9 (22 de abril de 2022): 4655. http://dx.doi.org/10.3390/ijms23094655.

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This review summarizes the recent developments regarding the use of uranium as nuclear fuel, including recycling and health aspects, elucidated from a chemical point of view, i.e., emphasizing the rich uranium coordination chemistry, which has also raised interest in using uranium compounds in synthesis and catalysis. A number of novel uranium coordination features are addressed, such the emerging number of U(II) complexes and uranium nitride complexes as a promising class of materials for more efficient and safer nuclear fuels. The current discussion about uranium triple bonds is addressed by quantum chemical investigations using local vibrational mode force constants as quantitative bond strength descriptors based on vibrational spectroscopy. The local mode analysis of selected uranium nitrides, N≡U≡N, U≡N, N≡U=NH and N≡U=O, could confirm and quantify, for the first time, that these molecules exhibit a UN triple bond as hypothesized in the literature. We hope that this review will inspire the community interested in uranium chemistry and will serve as an incubator for fruitful collaborations between theory and experimentation in exploring the wealth of uranium chemistry.

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Andersen, Morten B., Tim Elliott, Heye Freymuth, Kenneth W. W. Sims, Yaoling Niu y Katherine A. Kelley. "The terrestrial uranium isotope cycle". Nature 517, n.º 7534 (enero de 2015): 356–59. http://dx.doi.org/10.1038/nature14062.

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Korobeinikov, Valery V., Valery V. Kolesov y Aleksandr V. Mikhalev. "Comparison of the minor actinide transmutation efficiency in models of a fast neutron uranium-thorium fueled reactor". Nuclear Energy and Technology 8, n.º 1 (18 de marzo de 2022): 49–53. http://dx.doi.org/10.3897/nucet.8.82757.

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In terms of nuclear raw materials, the issue of involving thorium in the fuel cycle is hardly very relevant. However, in view of the large-scale nuclear power development, the use of thorium seems to be quite natural and reasonable. The substitution of traditional uranium-plutonium fuel for uranium-thorium fuel in fast neutron reactors will significantly reduce the production of minor actinides, which will make it attractive for the transmutation of long-lived radioactive isotopes of americium, curium and neptunium that have already been and are still being accumulated. Due to the absence of uranium-233 in nature, the use of thorium in the nuclear power industry requires a closed fuel cycle. At the initial stage of developing the uranium-thorium cycle, it is proposed to use uranium-235 instead of uranium-233 as nuclear fuel. Studies have been carried out on the transmutation of minor actinides in a fast neutron reactor in which the uranium-thorium cycle is implemented. Several options for the structure of the core of such a reactor have been considered. It has been shown that heterogeneous placement of americium leads to higher rates of its transmutation than homogeneous placement does.

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Yang, Kun. "Study of Uranium and Thorium Fuels in Breed-and-Burn Mode". Frontiers in Science and Engineering 3, n.º 10 (23 de octubre de 2023): 14–22. http://dx.doi.org/10.54691/fse.v3i10.5663.

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The formation of fissile nuclei through breeding conversion is a hot topic in academic research, as it provides a continuous source of nuclear fuel for nuclear reactors. Fast neutron reactors, which have been extensively studied, use natural uranium or low-enriched uranium as the nuclear fuel, achieving burning after uranium-plutonium conversion. Thorium, as another potential fissile fuel, can theoretically be converted into nuclear reactor fuel through the thorium-uranium cycle. In this study, the physical evolution process of nuclear fuel in a specific core parameter is simulated using the Monte Carlo program, and the performance differences of the thorium-uranium cycle and uranium-plutonium cycle in achieving in situ breeding-burning (Breed-and-Burn, B&B) mode are analyzed using neutron balance analysis method. The optimal ratio conditions for achieving self-sustained B&B burning in a thorium-uranium fuel mixed core are investigated. The study shows that for traditional solid-state nuclear reactor cores with a lower fuel proportion, thorium-breeding fuel has poor neutron economy compared to uranium-based breeding fuel, making it more difficult to achieve the B&B mode.

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Kovalev, Nikita V., Boris Ya Zilberman, Nikolay D. Goletsky y Andrey B. Sinyukhin. "A new approach to the recycling of spent nuclear fuel in thermal reactors within the REMIX concept". Nuclear Energy and Technology 6, n.º 2 (19 de junio de 2020): 93–98. http://dx.doi.org/10.3897/nucet.6.54624.

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A review of simulated nuclear fuel cycles with mixed uranium-plutonium fuel (REMIX) was carried out. The concept of REMIX fuel is one of the options for closing the nuclear fuel cycle (NFC), which makes it possible to recycle uranium and plutonium in VVER-1000/1200 thermal reactors at a 100% core loading. The authors propose a new approach to the recycling of spent nuclear fuel (SNF) in thermal reactors. The approach implies a simplified fabrication of mixed fuel when plutonium is used in high concentration together with enriched natural uranium, while reprocessed uranium is supposed to be enriched and used separately. The share of standard enriched natural uranium fuel in this nuclear fuel cycle is more than 50%, the share of mixed natU+Pu fuel is 25%, the rest is fuel obtained from enriched reprocessed uranium. It is emphasized that the new approach has the maximum economic prospect and makes it possible to organize the fabrication of this fuel and nuclear material cross-cycling at the facilities available in the Russian Federation in the short term. This NFC option eliminates the accumulation of SNF in the form of spent fuel assemblies (SFA). SNF is always reprocessed with the aim of further using the primary reprocessed uranium and plutonium. Non-recyclable in thermal reactors, burnt, reprocessed uranium, the energy potential of which is comparable to natural uranium, as well as secondary plutonium intended for further use in fast reactors, are sent as reprocessing by-products to the storage area.

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Moiseenko, V. y S. Chernitskiy. "Nuclear Fuel Cycle with Minimized Waste". Nuclear and Radiation Safety, n.º 1(81) (12 de marzo de 2019): 30–35. http://dx.doi.org/10.32918/nrs.2019.1(81).05.

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A uranium-based nuclear fuel and fuel cycle are proposed for energy production. The fuel composition is chosen so that during reactor operation the amount of each transuranic component remains unchanged since the production rate and nuclear reaction rate are balanced. In such a ‘balanced’ fuel only uranium-238 content has a tendency to decrease and, to be kept constant, must be sustained by continuous supply. The major fissionable component of the fuel is plutonium is chosen. This makes it possible to abandon the use of uranium-235, whose reserves are quickly exhausted. The spent nuclear fuel of such a reactor should be reprocessed and used again after separation of fission products and adding depleted uranium. This feature simplifies maintaining the closed nuclear fuel cycle and provides its periodicity. In the fuel balance calculations, nine isotopes of uranium, neptunium, plutonium and americium are used. This number of elements is not complete, but is quite sufficient for calculations which are used for conceptual analysis. For more detailed consideration, this set may be substantially expanded. The variation of the fuel composition depending on the reactor size is not too big. The model accounts for fission, neutron capture and decays. Using MCNPX numerical Monte-Carlo code, the neutron calculations are performed for the reactor of industrial nuclear power plant size with MOX fuel and for a small reactor with metallic fuel. The calculation results indicate that it is possible to achieve criticality of the reactor in both cases and that production and consuming rates are balanced for the transuranic fuel components. In this way, it can be assumed that transuranic elements will constantly return to such a reactor, and only fission products will be sent to storage. This will significantly reduce the radioactivity of spent nuclear fuel. It is important that the storage time for the fission products is much less than for the spent nuclear fuel, just about 300 years.

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Asiah A, Nur, Merry Yanti, Zaki Su’ud, Menik A. y H. Sekimoto. "Preliminary design study of Long-life Gas Cooled Fast Reactor With Modified CANDLE Burnup Scheme". Indonesian Journal of Physics 20, n.º 4 (3 de noviembre de 2016): 85–88. http://dx.doi.org/10.5614/itb.ijp.2009.20.4.3.

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In this paper, preliminary design study of Gas Cooled Fas Reactors with Natural Uranium as Fuel Cycle Input has been performed. Gas Cooled Fast Reactor is slightly modified by employing modified CANDLE burnup scheme so that it can use Natural Uranium as fuel cycle input. The natural uranium is initially put in region 1, after one cycle of 10 years of burn-up it is shifted to region 2 and the region 1 is filled by fresh natural uranium fuel. This concept is basically applied to all regions. In this case the system has been applied to many power level which results relatively flexible discharge burn-up level up from about 20%HM to 30 %HM.

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Lapin, A., A. Bobryashov, V. Blandinsky y E. Bobrov. "ASSESSMENT OF THE SYSTEM CHARACTERISTICS OF A REACTOR WITH SUPERCRITICAL COOLANT PARAMETERS FOR VARIOUS FUEL CYCLES". PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. SERIES: NUCLEAR AND REACTOR CONSTANTS 2020, n.º 3 (26 de septiembre de 2020): 51–62. http://dx.doi.org/10.55176/2414-1038-2020-3-51-62.

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Nowadays nuclear energy operates in an open fuel cycle. One of the most important directions in the development of nuclear energy is the closure of the nuclear fuel cycle. The solution to this problem is possible with the use of fast neutron reactors. To achieve this goal, the possibility of using a reactor with a fast-resonance neutron spectrum cooled by supercritical water (SCWR) was considered. The SCWR reactor can be effectively used in a closed nuclear fuel cycle, since it makes it possible to use spent fuel and dump uranium with a small amount of plutonium added. The layout options of the core with a change in the size of the core and reproduction zones are considered. The possibility of placing reproduction zones from various materials inside the active zone was evaluated. Based on the studies, an acceptable version of the core is selected in terms of system characteristics. For the considered arrangement of the reactor core, the possibility of shorting the uranium-plutonium and uranium-thorium fuel cycles has been investigated. The system characteristics of the reactor installation were studied for the following fuel load options: 1. Loading MOX fuel into the core, depleted uranium in the lateral zone of reproduction. 2. Loading of uranium-thorium fuel into the core and side screens. The results of the assessments of the system characteristics of the reactor are considered in the article.

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Chen, Aimei, Xiaobei Zheng, Chunxia Liu, Yuxia Liu y Lan Zhang. "Uranium thermochemical cycle: hydrogen production demonstration". Energy Sources, Part A: Recovery, Utilization, and Environmental Effects 40, n.º 21 (1 de agosto de 2018): 2542–49. http://dx.doi.org/10.1080/15567036.2018.1504141.

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Wei, Chunlin, Xiuan Shi, Yongwei Yang y Zhiwei Zhou. "ICONE19-43519 Preliminary Research on Thorium-Uranium Fuel Cycle Characteristic in PWR". Proceedings of the International Conference on Nuclear Engineering (ICONE) 2011.19 (2011): _ICONE1943. http://dx.doi.org/10.1299/jsmeicone.2011.19._icone1943_209.

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Kazazyan, V. T., A. P. Malykhin, E. F. Vaitsetskaya, N. M. Dneprovskaya, I. E. Rubin y N. A. Tetereva. "Preliminary analysis of the possibility of using REMIX fuel in VVER-1200 reactors of the Belarusian NPP". Proceedings of the National Academy of Sciences of Belarus, Physical-Technical Series 67, n.º 1 (7 de abril de 2022): 57–64. http://dx.doi.org/10.29235/1561-8358-2022-67-1-57-64.

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The transition from conventional uranium to regenerated fuel, which uses reprocessed spent fuel and enriched natural uranium, improves fuel efficiency and reduces the amount of spent nuclear fuel (SNF). Based on the analysis of published materials concerning mainly the fuel cycles of the VVER-1000 reactor, it was concluded that the most suitable in the conditions of the Republic of Belarus is the use of REMIX fuel. To confirm this conclusion in relation to the VVER-1200 reactors of the Belarusian NPP, computational studies were carried out within the framework of the State program “Scienceintensive technologies and equipment” for 2021–2025, subprogram 3 “Scientific support for the effective and safe operation of the Belarusian nuclear power plant and promising directions for the development of nuclear energy”. The characteristics of a 12-month fuel cycle with multiple recycling (reuse of fuel) according to the REMIX technology with 19.75 % enrichment of added uranium and maintaining the design capacity and duration of the campaign have been obtained. The share of SNF that is not returned to the reactor is 12.8 % (for a cycle with uranium fuel – 100 %); the fraction of waste intended for disposal or long-term storage, respectively, decreases by 8 times, and the specific consumption of natural uranium is reduced from 202 g/(MW·day) for uranium fuel to 159 g/(MW·day) for REMIX fuel. The results obtained can be taken into account when developing a fuel use strategy at the Belarusian NPP.

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Bachmann, Amanda M., Roberto Fairhurst-Agosta, Zoë Richter, Nathan Ryan y Madicken Munk. "Enrichment dynamics for advanced reactor HALEU support". EPJ Nuclear Sciences & Technologies 7 (2021): 22. http://dx.doi.org/10.1051/epjn/2021021.

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Transitioning to High Assay Low Enriched Uranium-fueled reactors will alter the material requirements of the current nuclear fuel cycle, in terms of the mass of enriched uranium and Separative Work Unit capacity. This work simulates multiple fuel cycle scenarios using Cyclus to compare how the type of the advanced reactor deployed and the energy growth demand affect the material requirements of the transition to High Assay Low Enriched Uranium-fueled reactors. Fuel cycle scenarios considered include the current fleet of Light Water Reactors in the U.S. as well as a no-growth and a 1% growth transition to either the Ultra Safe Nuclear Corporation Micro Modular Reactor or the X-energy Xe-100 reactor from the current fleet of U.S. Light Water Reactors. This work explored parameters of interest including the number of advanced reactors deployed, the mass of enriched uranium sent to the reactors, and the Separative Work Unit capacity required to enrich natural uranium for the reactors. Deploying Micro Modular Reactors requires a higher average mass and Separative Work Unit capacity than deploying Xe-100 reactors, and a lower enriched uranium mass and a higher Separative Work Unity capacity than required to fuel Light Water Reactors before the transition. Fueling Xe-100 reactors requires less enriched uranium and Separative Work Unit capacity than fueling Light Water Reactors before the transition.

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Adeniyi, Abiodun, Bojan Petrović, Bo Feng y Take K. Kim. "Impact of Limited Reprocessing Capacity on Nuclear Material Utilization in Advanced Fuel Cycles". Journal of Energy - Energija 62, n.º 1-4 (18 de julio de 2022): 209–20. http://dx.doi.org/10.37798/2013621-4231.

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A nuclear energy scenario study was performed using VISION 3.4; to analyze three different fuel cycles: once through (open) cycle (OTC), full recycle with a transition through a modified open cycle (MOC), and direct introduction of full recycle without transition (FuRe) in terms of their impact on uranium resource utilization on both the front- and back-end of these fuel cycles, Both the MOC and FuRe show significant improvement (reduction) in the amount of uranium ore required to generate the same amount of energy for a 150-year period when compared to the OTC. The same conclusion also holds for the amount of used nuclear fuel (UNF) in storage (wet, dry and monitored retrievable (MRS)) in the back-end of the fuel cycle. Findings suggest that under the analyzed deployment scenarios, amount of separation capacity deployed have impact on resource utilization. There is no clear advantage of either MOC or FuRe over one another in the front end of the fuel cycle as far as material utilization under both separation capacities analyzed. However, due to its potential for earlier deployment, MOC offers better UNF management in the back end at 2 kT/yr separation capacity: the amount of UNF for storage is smaller compared to OTC and FuRe, this advantage is not evident when the capacity was doubled. In terms of transuranic (TRU) consumption, FuRe is the better choice compared to MOC, under the lower separation capacity scenario, however at doubled capacity, both cycles consumed about the same amount of TRU. It can be concluded that the choice of either MOC or FuRe depends on the fuel cycle objectives, however both are better compared to OTC, in terms of uranium resources utilization.

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Orlov, Mikhail A. "Economic advantages of starting up of inherently safe fast reactors with a closed fuel cycle on fortificated uranium". Nuclear Energy and Technology 9, n.º 3 (20 de octubre de 2023): 149–56. http://dx.doi.org/10.3897/nucet.9.111914.

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The publication substantiates the economic advantages of using in the starting loads of inherently safe fast reactors with a closed fuel cycle of enriched uranium instead of uranium-plutonium regenerate obtained by reprocessing of thermal reactors spent nuclear fuel (SNF). The justifications are given taking into account both the preliminary technical and economic assessments carried out by the basic enterprises of TVEL JSC and SHK JSC, and the neutron-physical and system-economic studies performed at the Private Institution of the ITCP Proryv (Breakthrough). It is shown that the starting-up of a fast reactor on enriched uranium instead of uranium-plutonium fuel, taking into account the costs of preliminary reprocessing of thermal reactors spent fuel, allows achieving a significant economic gain at the stage of construction and commissioning of nuclear power plants. It is also shown that even at moderately high values of the discount coefficient, the uranium start of a fast reactor with a closed fuel cycle is economically preferable in comparison with the option of starting on uranium-plutonium fuel from the positions of the break-even tariff.

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Chen, Aimei, Chunxia Liu, Yuxia Liu y Lan Zhang. "Uranium thermochemical cycle used for hydrogen production". Nuclear Engineering and Technology 51, n.º 1 (febrero de 2019): 214–20. http://dx.doi.org/10.1016/j.net.2018.08.018.

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David, Sylvain, Elisabeth Huffer y Hervé Nifenecker. "Revisiting the thorium-uranium nuclear fuel cycle". Europhysics News 38, n.º 2 (marzo de 2007): 24–27. http://dx.doi.org/10.1051/epn:2007007.

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McDeavitt, Sean M. "Uranium processing for the nuclear fuel cycle". JOM 52, n.º 9 (septiembre de 2000): 11. http://dx.doi.org/10.1007/s11837-000-0180-3.

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Andrianov, Andrei A., Olga N. Andrianova, Ilya S. Kuptsov, Leonid I. Svetlichny y Tatyana V. Utianskaya. "A scenario study on the transition to a closed nuclear fuel cycle using the nuclear energy system modelling application package (NESAPP)". EPJ Nuclear Sciences & Technologies 8 (2022): 2. http://dx.doi.org/10.1051/epjn/2021029.

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The paper presents the results of a case study on evaluating performance and sustainability metrics for Russian nuclear energy deployment scenarios with thermal and sodium-cooled fast reactors in a closed nuclear fuel cycle. Ten possible scenarios are considered which differ in the shares of thermal and sodium-cooled fast reactors, including options involving the use of mixed uranium-plutonium oxide fuel in thermal reactors. The evolution of the following performance and sustainability metrics is estimated for the period from 2020 to 2100 based on the considered assumptions: annual and cumulative uranium consumption, needs for uranium enrichment capacities, fuel fabrication and reprocessing capacities, spent fuel stocks, radioactive wastes, amounts of plutonium in the nuclear fuel cycle, amounts of accumulated depleted uranium, and the levelised electricity generation cost. The results show that the sustainability of the Russian nuclear energy system can be significantly enhanced through the intensive deployment of sodium-cooled fast reactors and the transition to a closed nuclear fuel cycle. The authors have highlighted some issues for further considerations, which will lead to more rigorous conclusions regarding the preferred options for the development of the national nuclear energy system.

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Boguslavsky, Anatoly, Olga Shvartseva, Nadezhda Popova y Alexey Safonov. "Biogeochemical In Situ Barriers in the Aquifers near Uranium Sludge Storages". Water 15, n.º 17 (22 de agosto de 2023): 3020. http://dx.doi.org/10.3390/w15173020.

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The long-term operation of uranium sludge storages causes serious problems: it contaminates the neighboring aquifers with dangerous substances (uranium, nitrate, ammonium, and sulfate). To purify the aquifers can be costly and time-consuming; therefore, it is important to use the potential of in situ conditions, e.g., the aboriginal microflora and its ability to biologically remediate water reservoirs. In this work, we study the geological, geochemical, and microbiological characteristics of groundwater contaminated by uranium sludge storages resulting from the production cycles of four Russian chemical plants. All of the sites under consideration were extremely contaminated with nitrate (up to 15 g/L); in each case, we used denitrifying bacteria as a dominant group of microorganisms for purification. Our laboratory studies showed that microbial stimulation of water samples by milk whey promotes O2 and nitrate removal; this, in turn, started the cycle of anaerobic processes of authigenic precipitation caused by the reduction of iron and sulfate in the system. Thus, a mineral geochemical barrier preventing uranium immobilization formed. As a result, the uranium of the liquid phase decreased about 92–98% after 3–6 months (decomposition time depends on the nitrate concentration in the groundwater probe). The resulting amorphous biogenic phases contain sulfur, iron, phosphorus, and uranium.

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Mintz Testa, Bridget. "Thunder on the Horizon". Mechanical Engineering 139, n.º 02 (1 de febrero de 2017): 38–43. http://dx.doi.org/10.1115/1.2017-feb-2.

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This article discusses the advantageous usage of thorium-based breeder reactors in the nuclear industry. Since thorium is more abundant than uranium and can be turned into fuel without the enrichment process needed to concentrate U-235, experts believe that the thorium fuel cycle could be more sustainable than the uranium cycle. The addition of thorium to the fluid salt helps reduce uranium consumption. ThorCon, a Florida-based nuclear power startup, has developed the ThorCon reactor that will be breeding some of its own fuel by irradiating thorium. Thorium is about three times more abundant than uranium, and all of it can be used to create a fuel source for nuclear reactors. Thor Energy is developing two different families of thorium-based fuels with both U-235 and Pu-239 as the fissile driver material. The interest in thorium suggests that it is going to take an unconventional approach to lead to the much-anticipated Nuclear Renaissance.

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Zhivin, Sergey, Irina Guseva Canu, Estelle Davesne, Eric Blanchardon, Jérôme-Philippe Garsi, Eric Samson, Christine Niogret, Lydia B. Zablotska y Dominique Laurier. "Circulatory disease in French nuclear fuel cycle workers chronically exposed to uranium: a nested case–control study". Occupational and Environmental Medicine 75, n.º 4 (31 de octubre de 2017): 270–76. http://dx.doi.org/10.1136/oemed-2017-104575.

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ObjectivesThere is growing evidence of an association between low-dose external γ-radiation and circulatory system diseases (CSDs), yet sparse data exist about an association with chronic internal uranium exposure and the role of non-radiation risk factors. We conducted a nested case–control study of French AREVA NC Pierrelatte nuclear workers employed between 1960 and 2005 to estimate CSD risks adjusting for major CSD risk factors (smoking, blood pressure, body mass index, total cholesterol and glycaemia) and external γ-radiation dose.MethodsThe study included 102 cases of death from CSD and 416 controls individually matched on age, gender, birth cohort and socio-professional status. Information on CSD risk factors was collected from occupational medical records. Organ-specific absorbed doses were estimated using biomonitoring data, taking into account exposure regime and uranium physicochemical properties. External γ-radiation was measured by individual dosimeter badges. Analysis was conducted with conditional logistic regression.ResultsWorkers were exposed to very low radiation doses (mean γ-radiation dose 2 and lung uranium dose 1 mGy). A positive but imprecise association was observed (excess OR per mGy 0.2, 95% CI 0.004 to 0.5). Results obtained after adjustment suggest that uranium exposure might be an independent CSD risk factor.ConclusionsOur results suggest that a positive association might exist between internal uranium exposure and CSD mortality, not confounded by CSD risk factors. Future work should focus on numerous uncertainties associated with internal uranium dose estimation and on understanding biological pathway of CSD after protracted low-dose internal radiation exposure.

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Raaj Saasthaa Arumuga Kumar, Eeshu, Piotr Darnowski, Mihir Kiritbhai Pancholi y Aleksandra Dzido. "Thorium application in the medium-sized sodium-cooled fast reactor". E3S Web of Conferences 137 (2019): 01030. http://dx.doi.org/10.1051/e3sconf/201913701030.

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The report presents an analysis of the medium-sized Sodium-Cooled Fast Reactor (SFR) core with Thorium-based Mixed-Oxide fuel. The introduction of Transuranics (TRU) to the fuel was to allow long-lived nuclear waste incineration. The studied core is based on the modified Advanced Burner Reactor (ABR) 1000MWth core design, which was analysed in the OECD/NEA “Benchmark for Neutronic Analysis of Sodium-Cooled Fast Reactor Cores with Various Fuel Types and Core Sizes”. The full-core simulations with SERPENT 2.1.31 Monte Carlo computer code and ENDF library were performed, including static criticality and fuel burnup calculations for five fuel cycles. The core inventories at the Beginning of Cycle (BOC) and End of Cycle (EOC) were studied, and the impact of thorium fuel was assessed. The proposed core design is a burner reactor which uses thorium fuel. The excess core reactivity stays positive for long time despite large net consumption of transuranic elements as new fissile Uranium 233 is constantly breed from Thorium 232. Breeding of uranium allows longer fuel cycles.

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Ashley, Stephen F., Richard A. Fenner, William J. Nuttall y Geoffrey T. Parks. "Open cycle thorium–uranium-fuelled nuclear energy systems". Proceedings of the Institution of Civil Engineers - Energy 166, n.º 2 (mayo de 2013): 74–81. http://dx.doi.org/10.1680/ener.13.00003.

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Farjana, Shahjadi Hisan, Nazmul Huda, M. A. Parvez Mahmud y Candace Lang. "Comparative life-cycle assessment of uranium extraction processes". Journal of Cleaner Production 202 (noviembre de 2018): 666–83. http://dx.doi.org/10.1016/j.jclepro.2018.08.105.

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Dekusar, V. y O. Gurskaya. "ON THE ISSUE OF PLUTONIUM COST IN A TWO-COMPONENT NUCLEAR POWER SYSTEM". PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. SERIES: NUCLEAR AND REACTOR CONSTANTS 2021, n.º 2 (26 de junio de 2021): 25–33. http://dx.doi.org/10.55176/2414-1038-2021-2-25-33.

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A possible approach to accounting for the specific present value of plutonium produced in fast reactors of a two-component nuclear power system (NPS) with thermal and fast reactors is described. The approach is based on taking into account the additional income that can be obtained by selling at the market price the natural uranium released when thermal reactors are replaced with fast reactors with MOX-fuel based on plutonium produced in NPS. At the same time, along with the sale of natural uranium, the sale at market value of other products made on its basis, for example, enriched uranium or fuel assemblies for a thermal reactors, can be considered. Relations between the main fuel characteristics of the considered nuclear reactors and the economic parameters characterizing the efficiency of nuclear reactors and the fuel cycle of a NPS are obtained. Using the methodology described in this paper, a computational study of the specific present value of plutonium in a two-product nuclear power model with commercial sodium high-power fast reactor and VVER-1200 reactors was carried out. The calculation results in all considered cases indicate very significant present value of plutonium. Comparison of the obtained cost of plutonium, which is ultimately based on the energy equivalent of plutonium and uranium, and the cost of plutonium, determined on the basis of the costs of the back-end of the fuel cycle (plutonium extraction from SNF), show the economic efficiency of closing the fuel cycle even at existing uranium prices.

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Kuzin, R., S. N. Brykin y T. Tairov. "SOURCES OF RADIOACTIVE WASTE IN LEACH PLANTS PROCESSING URANIUM ORES". Fine Chemical Technologies 11, n.º 5 (28 de octubre de 2016): 21–25. http://dx.doi.org/10.32362/2410-6593-2016-11-5-21-25.

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A distinctive feature of enterprises for extracting and processing uranium ore is the inevitable pollution by solid, liquid and gaseous waste. The amount of radioactive waste (RW) is most significant in the nuclear fuel cycle. In spite of its relatively low activity it is the major contributor to the formation of radiation hazards to the people and environment. The radioactivity of uranium ores and of their processing waste is due to natural radionuclides of uranium (238U and 235U) and thorium (232Th) radioactive decay chains.

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Kutnii, D. y S. Vanzha. "Gamma-Spectrometric Determination of the Content and the Mass of Uranium Isotopes in Samples of Unknown Composition and Products of the Nuclear Fuel Cycle". Nuclear and Radiation Safety, n.º 4(72) (14 de noviembre de 2016): 52–56. http://dx.doi.org/10.32918/nrs.2016.4(72).08.

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The results of the uranium isotopes masses and content determination in depleted and low enriched uranium bearing samples using gamma-spectrometric data and iterative method were presented in the paper. Powders of UO2 and U3O8, compact products on their basis, metal uranium and scrap with an enrichment by the isotope 235U from 0,3 to 19,9 % were used as test samples. The sample mass ranged from tens of grams to several kilograms. Gamma-spectrometric data were processed using commercial software packages by Canberra Company: Genie 2000, MGAU, ISOCS and GeometryComposer. The proposed method provides a satisfactory correlation between the experimental and calculated data and allows estimating the quantitative characteristics (enrichment, mass of isotopes, uranium content in the matrix) of uranium bearing samples with different physical shape and chemical composition.

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Al-Zahrani, Yahya A., Khurram Mehboob, Tariq F. Alshahrani, Fouad A. Abolaban y Hannan Younis. "Analysis of SMART reactor core with uranium mononitride for prolonged fuel cycle using OpenMC". Kerntechnik 87, n.º 1 (1 de febrero de 2022): 82–90. http://dx.doi.org/10.1515/kern-2021-1000.

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Abstract The neutronics performance and safety characteristics of Uranium mononitride (UN) fuel for System-Integrated Modular Advanced Reactor (SMART) has been investigated to discern the potential for non-proliferation, waste, and accident tolerance benefits of UN fuel. The neutronic evaluation of UN fuel for SMART reactor has been carried out under normal operation using OpenMC and compared with Uranium dioxide (UO2) in terms of fuel cycle length, reactivity coefficients, Fuel depletion (burnup), thermal flux, and fission product activity. The power peaking factor (PPF) has been compared at the beginning of the fuel cycle (BOC), mid of the fuel cycle (MOC), and at the end of the fuel cycle (EOC). Results indicate that the UN fuel can be operated beyond the designed fuel cycle length of the SMART reactor, which induces the positive reactivity at the end of the fuel cycle of about 4625 pcm. However, the UO2 showed negative reactivity after three years. The total fission product activity at the end of the fuel cycle (3.5 years) for UO2 and UN has been founded 1.003 × 1020 Bq and 1.023 × 1020 Bq, respectively.

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Sánchez Sánchez, Esther M., SANTIAGO LOPEZ GARCIA y JOSEBA DE LA TORRE CAMPOS. "ENUSA AND ORIGINS OF NUCLEAR FUEL MANUFACTURING IN SPAIN". DYNA 98, n.º 6 (1 de noviembre de 2023): 550–54. http://dx.doi.org/10.6036/10843.

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The purpose of this article is to explore the origins of industrial nuclear fuel fabrication in Spain. Founded in 1972 for centrally managing the nuclear fuel cycle, the Empresa Nacional del Uranio SA (ENUSA) agreed with the American multinationals Westinghouse and General Electric the assignment of licenses and technical assistance for manufacturing fuel assemblies for light water reactors (in its two variants, PWR and BWR). This is the only phase of the uranium cycle which ENUSA keeps today (Juzbado plant, Salamanca). In spite of the current energy crisis and the uncertainty of the nuclear option, the company has celebrated its 50th anniversary in a moment of success, as a result of its important export and technological activity in the nuclear, logistic and environmental fields.

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Maher, Chris J., Christine Bouyer, Tamara L. Griffiths, Solène Legand, Gilles Leturcq, Manuel Miguirditchian y Mark Sarsfield. "Impact of uranium carbide organics treated by prolonged boiling and electrochemical oxidation upon uranium and plutonium solvent extraction". Radiochimica Acta 106, n.º 2 (26 de enero de 2018): 95–106. http://dx.doi.org/10.1515/ract-2017-2799.

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AbstractThe dissolution of uranium or uranium-plutonium carbide fuel in nitric acid leads to ~50% carbon evolved as carbon dioxide, the remainder remains in the solution as soluble organics. These dissolved organic molecules interfere with the solvent extraction of uranium and plutonium by complexing to the actinide ions and decreasing the efficiency of their extraction. Experiments reported here describe two series of experiments assessing the uranium carbide dissolution liquor treatment by prolonged boiling and electrochemical oxidation. Plutonium losses to aqueous and solvent raffinates are observed for untreated liquors, highlighting that mineralisation of dissolved organics is necessary to reduce the complexing effects of organic acids to an extent that permit efficient operation of a solvent extraction process both in the first solvent use (considered here) and for maintaining solvent quality during industrial solvent reuse in the highly active cycle. Solution carbon analysis and 30% TBP solvent extraction batch tests of uranium and plutonium originating from dissolved uranium carbide liquors untreated and after treatment are compared. These experiments demonstrate the reprocessing of uranium carbides by direct dissolution coupled to a mineralisation process, can achieve near quantitative uranium and high plutonium recoveries (99.9%).

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Mäkinen, Jarno, Laura Wendling, Tiina Lavonen y Päivi Kinnunen. "Sequential Bioleaching of Phosphorus and Uranium". Minerals 9, n.º 6 (28 de mayo de 2019): 331. http://dx.doi.org/10.3390/min9060331.

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Phosphorus and uranium are both vital elements for society. In recent decades, fears have arisen about the future availability of low-cost phosphorus and uranium. This has resulted in pressure to de-centralize production of both elements by utilizing lower-grade or complex deposits. The research presented here focused on phosphorus-containing apatite ores with uranium impurities; in order to separate uranium by selective and sequential bioleaching before phosphorus leaching. This would create an alternative process route for solvent-extraction, used to remove/recover uranium from the phosphorus acid product of apatite H2SO4 wet process. In this work, it was seen that the used fluorapatite ore required 24 h leaching at pH 1 by H2SO4 to result in 100% leaching yield for phosphorus. As this ore did not contain much uranium, an artificial fluorapatite-uranium ore was prepared by mixing standard uranium ore and fluorapatite. The research with this ore showed that 89% of uranium dissolved in 3 days at pH > 2 and leaching was improved by applying Fe3+ oxidant. In these conditions only 4% of phosphorus was leached. By prolonged (28 days) leaching 95% uranium yield was reached. According to the experiments, the iron in the uranium leach solution would be mainly Fe3+, which allows the use of H2O2 for uranium recovery and then direct use of spent leachate for another uranium leaching cycle. After the dissolution of uranium, 90% of phosphorus was dissolved by decreasing the pH to 1.3. This was done by bioleaching, by utilizing biogenic sulfur oxidation to sulfuric acid.

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32

Su’ud, Zaki, Feriska H. Irka, Taufiq Imam, H. Sekimoto y P. Sidik. "Desain Study of Pb-Bi Cooled Fast Reactors with Natural Uranium as Fuel Cycle Input Using Special Shuffling Strategy in Radial Direction". Advanced Materials Research 772 (septiembre de 2013): 530–35. http://dx.doi.org/10.4028/www.scientific.net/amr.772.530.

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Design study of Pb-Bi cooled fast reactors with natural uranium as fuel cycle input using special radial shuffling strategy has been performed. The reactors utilizes UN-PUN as fuel, Eutectic Pb-Bi as coolant, and can be operated without refueling for 10 years in each batch. Reactor design optimization is performed to utilize natural uranium as fuel cycle input. This reactor subdivided into 6 regions with equal volume in radial directions. The natural uranium is initially put in region 1, and after one cycle of 10 years of burn-up it is shifted to region 2 and the region 1 is filled by fresh natural uranium fuel. This concept is basically applied to all regions. The calculation has been done by using SRAC-Citation system code and JENDL-3.2 library. The effective multiplication factor change increases monotonously during 10 years reactor operation time. There is significant power distribution change in the central part of the core during the BOC and the EOC. It is larger than that in the case of modified CANDLE case which use axial direction burning region move. The burnup level of fuel is slowly grows during the first 15 years but then grow fastly in the rest of burnup history. This pattern is a little bit different from the case of modified CANDLE burnup scheme in Axial direction in which the slow growing burnup period is relatively longer almost half of the burnup history.

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33

Ariani, Menik, Z. Su'ud, Fiber Monado, A. Waris, Khairurrijal, I. Arif, A. Ferhat y H. Sekimoto. "Optimization of Small Long Life Gas Cooled Fast Reactors with Natural Uranium as Fuel Cycle Input". Applied Mechanics and Materials 260-261 (diciembre de 2012): 307–11. http://dx.doi.org/10.4028/www.scientific.net/amm.260-261.307.

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In this study gas cooled reactor system are combined with modified CANDLE burn-up scheme to create small long life fast reactors with natural circulation as fuel cycle input. Such system can utilize natural Uranium resources efficiently without the necessity of enrichment plant or reprocessing plant. Therefore using this type of nuclear power plants optimum nuclear energy utilization including in developing countries can be easily conducted without the problem of nuclear proliferation. In this paper, optimization of Small and Medium Long-life Gas Cooled Fast Reactors with Natural Uranium as Fuel Cycle Input has been performed. The optimization processes include adjustment of fuel region movement scheme, volume fraction adjustment, core dimension, etc. Due to the limitation of thermal hydraulic aspects, the average power density of the proposed design is selected about 75 W/cc. With such condition we investigated small and medium sized cores from 300 MWt to 600 MWt with all being operated for 10 years without refueling and fuel shuffling and just need natural Uranium as fuel cycle input. The average discharge burn-up is about in the range of 23-30% HM.

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34

Hong, Yue, Lan Lan Jiang, Dong Xiao Niu, Fu Yan Liu, Xiao Yu Wang y Ling Nan Wu. "The Study of Typical PWR Nuclear Fuel Cycle". Applied Mechanics and Materials 644-650 (septiembre de 2014): 5174–78. http://dx.doi.org/10.4028/www.scientific.net/amm.644-650.5174.

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This paper analyzed two different types of nuclear fuel cycle which refferred to one-through fuel cycle and close fuel cycle (uranium-plutonium fuel cycle). Based on specific economic elements related to each cycle process, this paper built a model to evaluate PWR nuclear fuel cycle’s economy. Then, for given data of PWR, empirical analysis and sensitivity analysis were carried out. The result showed the superiority of the close fuel cycle compared to the one-through cycle.

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35

Mancheva, Zlatina y Ivaylo Naydenov. "Material Balance of Fuel Cycles for Plutonium Recycling in Pressurised Water Reactors". E3S Web of Conferences 207 (2020): 01023. http://dx.doi.org/10.1051/e3sconf/202020701023.

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An inevitable effect of uranium fuel operation is the production of plutonium. Its increasing inventory requires adoption of plutonium management strategy. The option that can provide inventory minimization and utilization of plutonium’s energy content is its usage as nuclear fuel. Since the most common power reactors are the pressurized water reactors, the current paper examines the material balance of several fuel cycles for single and multiple plutonium recycle in a reference PWR. Once-through fuel cycle’s balance has been used as a benchmark. Plutonium production and consumption rates, uranium and separative work requirements have been evaluated for four fuel cycle variations. The results affirm the overall long-term feasibility of multiple plutonium recycle in PWRs in terms of increased plutonium consumption.

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36

Suud, Zaki y H. Sekimoto. "Conceptual Design Study of Small 400 MWt Pb-Bi Cooled Modified Candle Burn-Up Based Long Life Fast Reactors". Advanced Materials Research 983 (junio de 2014): 353–56. http://dx.doi.org/10.4028/www.scientific.net/amr.983.353.

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In this paper conceptual design study of modified CANDLE burn-up scheme based 400 MWt small long life Pb-Bi Cooled Fast Reactors with natural Uranium as Fuel Cycle Input has been performed. In this study the reactor cores are subdivided into 10 parts with equal volume in the axial directions. The natural uranium is initially put in region 1, after one cycle of 10 years of burn-up it is shifted to region 2 and the region 1 is filled by fresh natural uranium fuel. This concept is basically applied to all regions, i.e. shifted the core of I’th region into I+1 region after the end of 10 years burn-up cycle. For small reactor core, it is important to apply high breeding material, so that high volume fraction of 60% fuel volume fraction nitride fuel is applied. The effective multiplication factor initially at 1.005 but then continuously increases during 10 years of burn-up. The peak power density initially about 307 W/cc but then continuously decreases to 268 at the end of 10 years burn-up cycle. Infinite multiplication factor pattern change, conversion ratio pattern change, and Pu-239 accumulation pattern change shows strong acceleration of plutonium production in the first region which is located near the 10th region. Maximum discharged burn-up is 31.2% HM.

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37

Boguslavsky, Anatoly, Olga Gaskova y Olga Naymushina. "Assessment of geochemical barriers at preservation of low-level radioactive waste storages". E3S Web of Conferences 80 (2019): 03011. http://dx.doi.org/10.1051/e3sconf/20198003011.

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The work considers geochemical aspects of the natural and man-made system for storing radioactive waste (RW) from one of the Siberian enterprises of the fuel and nuclear cycle. Careful geochemical testing of key sites of the system allows us to identify geochemical barriers that prevent the spread of uranium outside the sludge storage. In addition, experiments were conducted on the leaching of the sludge material in the laboratory using modern methods for determining the composition of solutions and solid phases, as well as experiments on uranium sorption on the main types of subsoil. Experimental and thermodynamic modeling of uranium deposition processes confirms that the system studied satisfactorily copes with the absorption of uranium taken out of the sludge storage due to dilution and sorption on rocks and bottom sediments. Particularly favorable are bottom sediments rich in organic matter, which bind uranium to organic-mineral complexes.

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38

Su'ud, Zaki, Rijal Kurniadi, Rida SNM y Zuhair Zuhair. "Feasibility Design Study of Long Life BWR with Natural Uranium/Thorium as Fuel Cycle Input". Indonesian Journal of Physics 20, n.º 1 (3 de noviembre de 2016): 13–16. http://dx.doi.org/10.5614/itb.ijp.2009.20.1.4.

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Feasibility design study of Long Life BWR with natural uranium/thorium as fuel cycle input has been performed. The reactor core is divided into 6 equal regions in radial direction. The fresh fuel is first loaded into the most outer region then shifted to the center of the core, and from there shifted to the nearby region in the outward direction. Nitride fuel is employed in the core to get better criticality and conversion/breeding ratio. The results show that uranium fuel combined with low moderating ratio environment is superior to make the system critical.

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39

Parinov, Oleg V., Mariya P. Semenova, Natalya K. Shandala, Antonina M. Lyaginskaya, Evgeny G. Metlyaev, Vladimir V. Kuptsov y Iliya I. Bogdanov. "Current concepts of the radio-biological effects of plutonium and uranium (Based on ICRP Publication 150)". Hygiene and sanitation 102, n.º 2 (25 de marzo de 2023): 175–80. http://dx.doi.org/10.47470/0016-9900-2023-102-2-175-180.

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Introduction. The article discusses the health risks associated with exposure to plutonium and uranium, given in ICRP Publication 150 and relevant in the context of the development of technologies, the production of new types of nuclear fuel. Cancer risk from plutonium exposure. Exposure to plutonium occurs predominantly in industrial settings. After inhalation and deposition in the respiratory tract, plutonium is eliminated by particle transport to the digestive tract and lymph nodes, and by absorption into the blood. The main risk associated with exposure to plutonium is lung cancer. Comparing the lifetime excess risk of mortality from lung cancer due to external gamma radiation (based on a lifetime survey of Japanese residents who survived the atomic bombing) and internal exposure to plutonium alpha particles (based on a study of Mayak employees), for the same absorbed dose to the lungs, the risk associated with exposure to plutonium alpha particles was found to be greater than the risk associated with external gamma exposure by about 15–16 and 19–22 times. Cancer risk from exposure to uranium. At present, there is very little evidence to suggest a relationship between internal dose due to uranium exposure and cancer risk. ICRP Publication 150 provides a critical review of the UNSCEAR Report 2016 (2017) and discusses recent epidemiological studies. There are different health hazards at different stages of the nuclear fuel cycle, given the different forms of uranium present at each stage. Estimating doses from exposure to uranium for workers in the nuclear fuel cycle is difficult due to the relatively rapid elimination of uranium from the bloodstream, variability in exposure to uranium compounds, and differences in the methods used to control internal exposure. Based on published research data, it is not possible to quantify the risk of cancer from uranium by doses to individual organs/tissues. Conclusion. Research was carried out as a part of the study of the properties of new types of nuclear fuel should take into account the comprehensive data presented in ICRP Publication 150.

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Kazansky, Yury A., Nikita O. Kushnir y Ekaterina S. Khnykina. "Multiple usage of thorium-based fuel in a VVER-1000 reactor". Nuclear Energy and Technology 9, n.º 2 (20 de junio de 2023): 93–98. http://dx.doi.org/10.3897/nucet.9.101762.

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This paper considers the use of unconventional fuel in nuclear power reactors, using the example of a VVER-type unit, in order to find out the possibility of saving natural fissile uranium nuclei. Saving fissile uranium is one of the important tasks, the solution of which will give time for the development of a two-component nuclear power industry that will have no problems with fuel resources. However, at present, the reserves of cheap uranium can provide the existing level of global nuclear energy for only 80–100 years. The main components of this proposed fuel are 232Th and fissile isotopes of uranium: 235U (loaded) and 233U (produced from thorium). All the uranium isotopes and added 235U nuclei at the beginning of the campaign account for about 6% of the number of thorium nuclei and uranium isotopes. The abbreviated name of this fuel is TORUR-5. To keep fissionable nuclei in the fuel cycle after the spent fuel is unloaded, it is envisaged that all the heavy nuclei will be returned back to the reactor after they have been cleaned from fission fragments, i.e., the fuel cycle will be closed. At the same time, the principle of annual movement of fuel assemblies (as they burn up) is the same as in the existing VVER-1000 reactors. Using the Serpent software, a reactor model was built, the composition and dimensions of which were close to the parameters of the VVER-1000 serial unit. The main results of calculations were the quantitative compositions of isotopes annually loaded into the reactor as well as the amounts of 235U and thorium added also annually. The analysis of the obtained results allowed us to make the following conclusions. The annual reloading of 235U during the computation period is required almost at a constant level and, in comparison with uranium fuel, is about half as much. This is feasible for the following reasons. Part of the fissions of 235U is replaced by the fission of 233U produced from 232Th. In addition, fissionable nuclei are kept in the closed Th-U fuel cycle. This is the first “advantage” of the proposed fuel. TORUR-5 requires uranium enriched to at least 90%, the cost of which is several times higher than that of 3–5% enriched uranium. But since much less highly enriched uranium is required, the cost of fuel for a TORUR-5-fueled VVER-1000 reactor is significantly lower. This is the second “advantage” of the proposed fuel. The negative characteristic of TORUR-5, which requires further investigation, is that, after the initial loading, several uranium isotopes appear in the returned fuel, the total radioactivity of which, according to estimates, exceeds the radioactivity of traditional 3–5% enriched uranium fuel by several thousand times. At the same time, the radioactivity of discharged spent conventional fuel exceeds the radioactivity of fresh fuel by millions of times, and this problem has been solved at NPPs both organizationally and technically. Therefore, it will be necessary to develop a technology for loading TORUR-5, taking into account the estimated radioactivity.

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41

Gusev, V. E. "On the problems of reusing reprocessed uranium by enrichment in schemes based on ordinary cascades". Journal of Physics: Conference Series 2147, n.º 1 (1 de enero de 2022): 012004. http://dx.doi.org/10.1088/1742-6596/2147/1/012004.

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Abstract The problem of spent nuclear fuel attracts considerable attention while its quantity is accumulating worldwide. The problem of long-term supply of the fresh fuel also remains important. One of the strategies to solve both problems is reusing the spent nuclear material. The uranium, in this way, could be recycled multiple times in light-water reactors. In order to recycle the uranium, it is extracted from the irradiated fuel during the reprocessing and then enriched in 235U, taking into account the limitations on reactor-born isotopes 232,236U in the final product. The only way to do this is enrichment in cascades of gas centrifuges. However, not every cascade scheme is able to re-enrich the uranium for multiple recycles, utilizing the whole amount of uranium extracted from the irradiated fuel each time. This study shows that configurations based on ordinary three-flow cascades could not be used for this purpose. In particular, we have shown that starting from the second uranium fuel cycle, such schemes are no longer able to reclaim the necessary proportion of the reprocessed uranium.

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42

Cumo, Maurizio. "La situazione dell'energia nucleare nel mondo: un quadro di sintesi". ECONOMICS AND POLICY OF ENERGY AND THE ENVIRONMENT, n.º 2 (mayo de 2009): 19–36. http://dx.doi.org/10.3280/efe2008-002003.

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- This article gives an overview of the situation of nuclear power in the world and analyzes the problems of this source of energy from different points of view: the generation costs, fuel cycle, particularly with regard to the resources of uranium and radioactive waste, and the programs of technological development of new reactors.Key words: Nuclear energy, generation costs, uranium resources, radioactive waste, new reactor technology.JEL classifications: L94 Q40 Q31

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43

Muhammad, Atta, Masood Iqbal y Tayyab Mahmood. "A study on improving the performance of a research reactor's equilibrium core". Nuclear Technology and Radiation Protection 28, n.º 4 (2013): 362–69. http://dx.doi.org/10.2298/ntrp1304362m.

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Utilizing low enriched uranium silicide fuel (U3Si2-Al) of existing uranium density (3.285 g/cm3), different core configurations have been studied in search of an equilibrium core with an improved performance for the Pakistan Research Reactor-1. Furthermore, we have extended our analysis to the performance of higher density silicide fuels with a uranium density of 4.0 and 4.8 U g/cm3. The criterion used in selecting the best performing core was that of ?unit flux time cycle length per 235U mass per cycle?. In order to analyze core performance by improving neutron moderation, utilizing higher-density fuel, the effect of the coolant channel width was also studied by reducing the number of plates in the standard/control fuel element. Calculations employing computer codes WIMSD/4 and CITATION were performed. A ten energy group structure for fission neutrons was used for the generation of microscopic cross-sections through WIMSD/4. To search the equilibrium core, two-dimensional core modelling was performed in CITATION. Performance indicators have shown that the higher-density uranium silicide-fuelled core (U density 4.8 g/cm3) without any changes in standard/control fuel elements, comprising of 15 standard and 4 control fuel elements, is the best performing of all analyzed cores.

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44

Altay, Melike Benan, Ceyda Kalıpçıoğlu y Zöhre Kurt. "Comparative Life Cycle Assessment of Uranium Recovery from Brine". Resources, Conservation and Recycling 181 (junio de 2022): 106237. http://dx.doi.org/10.1016/j.resconrec.2022.106237.

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45

Suglobov, D. N., R. M. Yakovlev y B. F. Myasoedov. "Thorium-uranium fuel cycle for heat and power engineering". Radiochemistry 49, n.º 5 (octubre de 2007): 441–48. http://dx.doi.org/10.1134/s1066362207050013.

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46

Neff, Thomas L. "Integrating uranium from weapons into the civil fuel cycle". Science & Global Security 3, n.º 3-4 (marzo de 1993): 215–22. http://dx.doi.org/10.1080/08929889308426384.

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47

Wojtaszek, Daniel Tadeusz y Sourena Golesorkhi. "FUEL CYCLE IMPLICATIONS OF DEPLOYING HTGRS IN HYBRID ENERGY SYSTEMS AS RESERVE POWER GENERATION IN ONTARIO". CNL Nuclear Review 10, n.º 1 (1 de enero de 2021): 30–38. http://dx.doi.org/10.12943/cnr.2020.00002.

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Nuclear power plants could potentially be deployed in a type of nuclear hybrid energy system (NHES) in which their power is used primarily to drive an industrial process but can be diverted to meet demands for electricity when needed. The purpose of this study is to analyze the effects of deploying NHESs as reserve power for the transmission grid in Ontario on the overall Canadian fuel cycle. In this scenario, the fuel cycle demands of 2 high-temperature gas-cooled reactor (HTGR) concepts are analyzed with respect to costs, resource consumption, and enrichment requirements. One HTGR concept is a 30 MW-thermal (MWth) reactor that is based on the UBattery concept, and the other is the Xe-100, which is a 200 MWth reactor. Calculations indicate that such a deployment of HTGRs would have a substantial effect on the fuel cycle in Canada. In particular, NU and enrichment demands would be greatly affected. Beginning this HTGR deployment in the year 2030 would more than double the annual NU demands in Canada, and deplete the uranium resources with extraction costs of <$80/kgU by the year 2142. The uranium enrichment demands of this fleet would be >35% of the US capacity for uranium enrichment.

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48

Carvalho, Fernando P. "Environmental Remediation and the Legacy of Uranium Mining Waste in Portugal and Europe. Lessons to Retain". Advanced Materials Research 107 (abril de 2010): 157–61. http://dx.doi.org/10.4028/www.scientific.net/amr.107.157.

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Radioactive ore mining for the production of radium and uranium in Portugal did span over most of the 20th century and ceased in 2001. It was performed mostly before the development of environmental legislation and radiation protection standards. Environmental remediation of the mining and milling sites is currently underway. Rehabilitated and non-rehabilitated sites require also radioactivity monitoring whose costs are covered by the State. The likely re start of uranium mining, in Portugal as well as elsewhere in Europe, reminds that uranium mining shall be managed under the mine “life cycle approach” in order to include decommissioning and environmental rehabilitation costs in the ore pricing.

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49

Clarkson, Matthew O., Claudine H. Stirling, Hugh C. Jenkyns, Alexander J. Dickson, Don Porcelli, Christopher M. Moy, Philip A. E. Pogge von Strandmann, Ilsa R. Cooke y Timothy M. Lenton. "Uranium isotope evidence for two episodes of deoxygenation during Oceanic Anoxic Event 2". Proceedings of the National Academy of Sciences 115, n.º 12 (5 de marzo de 2018): 2918–23. http://dx.doi.org/10.1073/pnas.1715278115.

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Oceanic Anoxic Event 2 (OAE 2), occurring ∼94 million years ago, was one of the most extreme carbon cycle and climatic perturbations of the Phanerozoic Eon. It was typified by a rapid rise in atmospheric CO2, global warming, and marine anoxia, leading to the widespread devastation of marine ecosystems. However, the precise timing and extent to which oceanic anoxic conditions expanded during OAE 2 remains unresolved. We present a record of global ocean redox changes during OAE 2 using a combined geochemical and carbon cycle modeling approach. We utilize a continuous, high-resolution record of uranium isotopes in pelagic and platform carbonate sediments to quantify the global extent of seafloor anoxia during OAE 2. This dataset is then compared with a dynamic model of the coupled global carbon, phosphorus, and uranium cycles to test hypotheses for OAE 2 initiation. This unique approach highlights an intra-OAE complexity that has previously been underconstrained, characterized by two expansions of anoxia separated by an episode of globally significant reoxygenation coincident with the “Plenus Cold Event.” Each anoxic expansion event was likely driven by rapid atmospheric CO2injections from multiphase Large Igneous Province activity.

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50

Gudavalli, Ravi, Yelena Katsenovich, Dawn Wellman, Leonel Lagos y Berrin Tansel. "Quantification of kinetic rate law parameters of uranium release from sodium autunite as a function of aqueous bicarbonate concentrations". Environmental Chemistry 10, n.º 6 (2013): 475. http://dx.doi.org/10.1071/en13117.

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Environmental context Uranium is a key contaminant of concern because of its high persistence in the environment and toxicity to organisms. The bicarbonate ion is an important complexing agent for uranyl ions and one of the main variables affecting its dissolution. Results from this investigation provide rate law parameters for the dissolution kinetics of synthetic sodium autunite that can influence uranium mobility in the subsurface. Abstract Hydrogen carbonate (also known as bicarbonate) is one of the most significant components within the uranium geochemical cycle. In aqueous solutions, bicarbonate forms strong complexes with uranium. As such, aqueous bicarbonate may significantly increase the rate of uranium release from uranium minerals. Quantifying the relationship of aqueous bicarbonate solutions to the rate of uranium release during dissolution is critical to understanding the long-term fate of uranium within the environment. Single-pass flow-through experiments were conducted to estimate the rate of uranium release from Na meta-autunite as a function of bicarbonate solutions (0.0005–0.003M) over the pH range of 6–11 and temperatures of 5–60°C. Consistent with the results of previous investigations, the rate of uranium release from sodium autunite exhibited minimal dependency on temperature, but was strongly dependent on pH and increasing concentrations of bicarbonate solutions. Most notably at pH 7, the rate of uranium release exhibited a 370-fold increase relative to the rate of uranium release in the absence of bicarbonate. However, the effect of increasing concentrations of bicarbonate solutions on the release of uranium was significantly less under higher pH conditions. It is postulated that at high pH values, surface sites are saturated with carbonate, thus the addition of more bicarbonate would have less effect on uranium release. Results indicate that the activation energies were unaffected by temperature and bicarbonate concentration variations, but were strongly dependent on pH conditions. As the pH increased from 6 to 11, the activation energy values were observed to decrease from 29.94 to 13.07kJmol–1. The calculated activation energies suggest a surface controlled dissolution mechanism.

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