Thermal Aspects of Uranium Carbide and Uranium Dicarbide Fuels in Supercritical Water-Cooled Nuclear Reactors

Grande, Lisa; Villamere, Bryan; Allison, Leyland; Mikhael, Sally; Rodriguez-Prado, Adrianexy; Pioro, Igor

doi:10.1115/1.4001299

Cited by 16 publications

(5 citation statements)

References 7 publications

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“…7 , where an increment of thermal conductivity ranging from 20 to 40% was observed for UC x -graphene with respect to UC x -graphite throughout the observed temperature region (fill data points). Due to the presence of significant porosity, the absolute values of thermal conductivity of both samples resemble those of 95% dense UO 2 24 more than UC 2 14 . For comparison, a projection of thermal conductivity to fully dense UC x -graphite and UC x -graphene samples was calculated using the Maxwell formula 25 and is reported (open symbols).…”

Section: Resultsmentioning

confidence: 97%

“…The atmosphere used for the carbothermal reduction (Ar or high vacuum) determines the reaction, due to diffusion of CO by-product, whereas in vacuum the extent of interface between reactants is the controlling step 20 , 21 . In previous experiments related to composites derived from carbothermal reduction of lanthanum oxide conducted in vacuum, the use of graphene as carbon precursor led to a high degree of sintering, remarkably higher density and low porosity with respect to graphite based composites 14 . In the present case, where the reaction is diffusion controlled, the trend in density and total porosity is opposite, although the difference in porosity between graphite and graphene derived composites is not so remarkable.…”

Section: Resultsmentioning

confidence: 99%

“…The thermal conductivity of UC 2 and UC increases with increasing temperature and ranges from 10–11 (W/mK) at room temperature to 20–21 (W/mK) at 2573 K, for UC 2 and reaches even higher thermal conductivity values for UC 14 . Other refractory carbides considered for ISOL facilities include TiC [11] produced as nanostructured target in order to enhance its release efficiency, and lanthanum carbide 15 for which a slip casting process was developed to obtain refractory carbide-carbon composites.…”

Section: Introductionmentioning

confidence: 99%

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Morphological and functional effects of graphene on the synthesis of uranium carbide for isotopes production targets

Biasetto

Corradetti

Carturan

et al. 2018

Sci Rep

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The development of tailored targets for the production of radioactive isotopes represents an active field in nuclear research. Radioactive beams find applications in nuclear medicine, in astrophysics, matter physics and materials science. In this work, we study the use of graphene both as carbon source for UO2 carbothermal reduction to produce UCx targets, and also as functional properties booster. At fixed composition, the UCx target grain size, porosity and thermal conductivity represent the three main points that affect the target production efficiency. UCx was synthesized using both graphite and graphene as the source of carbon and the target properties in terms of composition, grain size, porosity, thermal diffusivity and thermal conductivity were studied. The main output of this work is related to the remarkable enhancement achieved in thermal conductivity, which can profitably improve thermal dissipation during operational stages of UCx targets.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Morphological and functional effects of graphene on the synthesis of uranium carbide for isotopes production targets

Biasetto

Corradetti

Carturan

et al. 2018

Sci Rep

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“…The carbides of uranium have received much attention in recent years as potential fuel sources for Generation IV nuclear reactors. While at least six different Generation IV reactor concepts are currently being explored, the consensus is that new nuclear fuels must be developed for these advanced systems to maintain reasonable operating temperatures . Two such possibilities are uranium carbide (UC) and uranium dicarbide (UC 2 ), which have much higher thermal conductivities than conventional nuclear fuels such as UO 2 , mixed-metal oxides, and ThO 2 .…”

Section: Introductionmentioning

confidence: 99%

Preparation of Epitaxial Uranium Dicarbide Thin Films by Polymer-Assisted Deposition

et al. 2013

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High quality epitaxial thin films of cubic UC 2 were synthesized using a solution based technique. The films were characterized using XRD, UPS, Raman, and resistivity. The substrate lattice is yttrium stabilized zirconia and serves to stabilize the high temperature cubic phaseof UC 2 (>1765°C) at room temperature. The resistivity and UPS data indicate that UC 2 has relatively low electrical conductivity consistent with HSE hybrid DFT calculations showing a narrow band gap. In situ XRD measurements show that the UC 2 films oxidize to U 3 O 8 above 200°C. KEYWORDS: actinide carbide, epitaxial thin film, nuclear energy ■ INTRODUCTIONThe carbides of uranium have received much attention in recent years as potential fuel sources for Generation IV nuclear reactors. While at least six different Generation IV reactor concepts are currently being explored, the consensus is that new nuclear fuels must be developed for these advanced systems to maintain reasonable operating temperatures. 1 Two such possibilities are uranium carbide (UC) and uranium dicarbide (UC 2 ), which have much higher thermal conductivities than conventional nuclear fuels such as UO 2 , mixed-metal oxides, and ThO 2 . This would have the effect of lowering fuel centerline temperatures, which would increase operational safety, fuel lifetime, and efficiency. In addition to their potential as nuclear fuels, uranium carbide has been used for many years as a target material in the production of neutron-rich isotopes. 2 In order to gain a more in-depth understanding of the properties of uranium carbide materials, we have synthesized and characterized epitaxial thin films of UC 2 . These thin films are of high purity and are nearly single crystal in quality and thus facilitate high quality measurements to validate computational models. Herein, we report the synthesis and characterization of these thin films including valence band photoemission, Raman spectroscopy, electrical conductivity, and in situ XRD studies of oxidation.Uranium carbides have been known for quite some time, with U 2 C 3 and UC 2 first mentioned over a century ago. 3 These bulk materials were originally prepared by treating U 3 O 8 with graphite in an electric arc furnace. 3a,c,4 While carbothermic methods are still used to prepare uranium carbides, 5 other strategies such as the reaction of uranium metal with methane have been used to prepare UC at much lower temperature. 3b In spite of the wealth of knowledge on these materials, little is known about uranium carbide thin films. In 2004, researchers used sputter codeposition to generate films that were found to have compositions UC 1.2 and UC 1.6 . X-ray diffraction studies revealed the presence of polycrystalline UC and UC 2 in these films; however, the diffraction peaks were broadened possibly due to stress, inhomogeneities, or the presence of amorphous material. 6 Herein, we report the first preparation of singlecrystal quality UC 2 by polymer-assisted deposition (PAD). In this process, metal polymer solutions are used as film precursor...

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“…The aim of this study is to investigate the interactions between carbon and technetium atoms in the solid products obtained by thermal decomposition of a number of organic pertechnetates and to establish the possibility of synthesizing nanodispersed Tc–C composites. The Tc–C system is important for understanding the behavior of uranium fission product technetium-99 in nuclear fuels based on uranium carbide (UC), , uranium nitride (UN), , or uranium carbonitrides (UCN), which were designed for fourth-generation nuclear reactors. Produced through uranium fission in this type of reactor, the Tc–C composites should be considered both from the point of view of their behavior during formation in the reactor and from the point of view of their further dissolution in the course of reprocessing of spent nuclear fuel (SNF).…”

Section: Introductionmentioning

confidence: 99%

Route to Stabilization of Nanotechnetium in an Amorphous Carbon Matrix: Preparative Methods, XAFS Evidence, and Electrochemical Studies

Kuznetsov,

German,

Nagovitsyna

et al. 2023

Inorg. Chem.

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Technetium–carbon nanophases are obtained by thermal decomposition of pertechnetates with large organic cations under an argon atmosphere. Parallel carbonization of organic cations (hexamethyleneiminium and triphenylguanidinium), which occurs during the thermal decomposition of their pertechnetates, leads to the formation of X-ray amorphous solid products. An X-ray absorption fine structure study revealed that they have a crystal structure containing technetium–carbon bonds with a length of 1.76 Å. After subsequent annealing treatment at 1073–1673 K, the synthesized technetium–carbon phase has a cubic lattice with an a of 4.01 ± 0.03 Å. The products of thermal decomposition of the same perrhenates are also X-ray amorphous; however, unlike that of pertechnetates, the distance between rhenium and carbon atoms in them is significantly greater (2.14 Å). After subsequent annealing, they have a hexagonal lattice. The electrochemical properties of technetium–carbon nanophases prepared by thermal decomposition of pertechnetates with large organic cations are different from the properties of those prepared with metallic technetium. The oxidation of technetium carbide to its oxides at the electrode surface observed in the first anodic scan of cyclic voltammograms can be used for the deposition of noble metal nanoclusters under open-circuit conditions to prepare composite catalysts for the hydrogen evolution reaction. Nanotechnetium in the amorphous carbon matrix can also be a prospective material for reactor transmutation of technetium to stable isotopically pure ruthenium-100.

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Thermal Aspects of Uranium Carbide and Uranium Dicarbide Fuels in Supercritical Water-Cooled Nuclear Reactors

Cited by 16 publications

References 7 publications

Morphological and functional effects of graphene on the synthesis of uranium carbide for isotopes production targets

Morphological and functional effects of graphene on the synthesis of uranium carbide for isotopes production targets

Preparation of Epitaxial Uranium Dicarbide Thin Films by Polymer-Assisted Deposition

Route to Stabilization of Nanotechnetium in an Amorphous Carbon Matrix: Preparative Methods, XAFS Evidence, and Electrochemical Studies

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