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Journal ArticleDOI

Nuclear Reactor Fuel Elements, Metallurgy and Fabrication

01 Apr 1963-Nuclear Science and Engineering (American Nuclear Society)-Vol. 15, Iss: 4, pp 478-479
About: This article is published in Nuclear Science and Engineering.The article was published on 1963-04-01. It has received 15 citations till now. The article focuses on the topics: Nuclear reactor.
Citations
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Dissertation
01 Jan 2014
TL;DR: In this paper, the single and two-phase heat transfer in high aspect ratio mini-channels has not been well-characterized, especially in regard to the onset of nucleate boiling.
Abstract: Heat transfer in high aspect ratio mini-channels has important applications for materials test reactors using plate-type fuel. These fuel plates typically possess coolant channels with hydraulic diameters on the order of 4 mm or less. The single and two-phase heat transfer in such channels has not been well-characterized, especially in regard to the onset of nucleate boiling. While surface effects are known to dramatically influence the incipience of boiling, they have not been widely considered under forced convection. Since the limiting safety system setting for the MITR is the onset of nucleate boiling, there is considerable interest in better characterizing the phenomenon in such channels. This study presents a first-of-a-kind, two-phase flow facility designed to measure the singlephase heat transfer coefficient and onset of nucleate boiling in a high aspect ratio mini-channel over a wide range of flow conditions while also permitting high speed visualization of the entire surface. The single-phase heat transfer coefficient is measured for mass fluxes ranging from 750 kg/m2-sec up to 6000 kg/m2-sec and for subcoolings ranging from 20 °C to 70 °C. The onset of nucleate boiling superheat and heat flux are measured for mass fluxes ranging from 750 kg/m2sec to 3000 kg/m2-sec and for subcoolings ranging from 10 °C to 45 °C. Measurements are supported with high speed videography to visualize bubble incipience when conditions permit. The influence of surface wettability on the incipience point is also investigated by performing tests on a surface oxidized at high temperature in air. Using a boundary layer analysis along with experimental data obtained in the study, a semianalytical correlation is developed to predict the single-phase heat transfer coefficient in high aspect ratio rectangular channels. The correlation accounts for effects from secondary flows and heating asymmetry, and is suitable for both the transition and fully turbulent flow regimes. The new correlation predicts the Nusselt number with a mean absolute error of 4.9% in the range of 2.2

17 citations


Cites background or methods from "Nuclear Reactor Fuel Elements, Meta..."

  • ...Nickel plating has been used successfully for aluminum-clad U-Mo alloy fuel in the past [36], and is the recommended diffusion barrier to prevent aluminum-uranium interdiffusion [41], though zirconium foil has also been used successfully....

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  • ...The issue is much less significant when using U-Al alloy fuel because diffusion is possible only in the aluminum primary solid solution [41]....

    [...]

ReportDOI
01 Apr 1978
TL;DR: In this article, a microfilm copy of the original dissertation is used to reproduce the markings or patterns which may appear on this reproduction. But, the quality of the reproduction is heavily dependent upon the original submitted.
Abstract: Precipitation kinetics of a continuous precipitator, with application to the precipitation of ammonium polyuranate" (1978). Retrospective Theses and Dissertations. Paper 6459. INFORMATION TO USERS This material was produced from a microfilm copy of the original document. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the original submitted. The following explanation of techniques is provided to help you understand markings or patterns which may appear on this reproduction. 1.The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)". if it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting thru an image and duplicating adjacent pages to insure you complete continuity. 2. When an image on the film is obliterated with a large round black mark, it is an indication that the photographer suspected that the copy may have moved during exposure and thus cause a blurred image. You will find a good image of the page in the adjacent frame. 3. When a map, drawing or chart, etc., was part of the material being photographed the photographer followed a definite method in "sectioning" the material. It is customary to begin photoing at the upper left hand corner of a large sheet and to continue photoing from left to right in equal sections with a small overlap. If necessary, sectioning is continued again — beginning below the first row and continuing on until complete. 4. The majority of users indicate that the textual content is of greatest value, however, a somewhat higher quality reproduction could be made from "photographs" if essential to the understanding of the dissertation. Silver prints of "photographs" may be ordered at additional charge by writing the Order Department, giving the catalog number, title, author and specific pages you wish reproduced. 1978 Signature was redacted for privacy.

16 citations

Posted Content
TL;DR: In this article, the authors developed a practical and general modeling approach for thermal conductivity of metals and metal alloys that integrates ab initio and semi-empirical physics-based models to maximize the strengths of both techniques.
Abstract: In this work we developed a practical and general modeling approach for thermal conductivity of metals and metal alloys that integrates ab initio and semiempirical physics-based models to maximize the strengths of both techniques. The approach supports creation of highly accurate, mechanistic, and extensible thermal conductivity modeling of alloys. The model was demonstrated on {\alpha}-U and U-rich U-Zr and U-Mo alloys, which are potential fuels for advanced nuclear reactors. The safe use of U-based fuels requires quantitative understanding of thermal transport characteristics of the fuel. The model incorporated both phonon and electron contributions, displayed good agreement with experimental data over a wide temperature range, and provided insight into the different physical factors that govern the thermal conductivity under different temperatures. This model is general enough to incorporate more complex effects like additional alloying species, defects, transmutation products, and noble gas bubbles to predict the behavior of complex metallic alloys like U-alloy fuel systems under burnup.

12 citations

References
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DissertationDOI
11 Nov 2011
TL;DR: In this article, a fabrication procedure was applied to U3Si2 production at 4.8 gU/cm, with enriched uranium, in the new Brazilian Multipurpose Reactor RMB at IPEN-CNEN/SP.
Abstract: IPEN-CNEN/SP developed the technology to produce the dispersion type fuel elements for research reactors and made it available for routine production. Today, the fuel produced in IPEN-CNEN/SP is limited to the uranium concentration of 3.0 gU/cm for U3Si2-Al dispersion-based and 2.3 gU/cm for U3O8-Al dispersion. The increase of uranium concentration in fuel plates enables the reactivity of the reactor core reactivity to be higher and extends the fuel life. Concerning technology, it is possible to increase the uranium concentration in the fuel meat up to the limit of 4.8 gU/cm in U3Si2-Al dispersion and 3.2 gU/cm U3O8Al dispersion. These dispersions are well qualified worldwide. This work aims to develop the manufacturing process of both fuel meats with high uranium concentrations, by redefining the manufacturing procedures currently adopted in the Nuclear Fuel Center of IPEN-CNEN/SP. Based on the results, it was concluded that to achieve the desired concentration, it is necessary to make some changes in the established procedures, such as in the particle size of the fuel powder and in the feeding process inside the matrix, before briquette pressing. These studies have also shown that the fuel plates, with a high concentration of U3Si2-Al, met the used specifications. On the other hand, the appearance of the microstructure obtained from U3O8-Al dispersion fuel plates with 3.2 gU/cm showed to be unsatisfactory, due to the considerably significant porosity observed. The developed fabrication procedure was applied to U3Si2 production at 4.8 gU/cm, with enriched uranium. The produced plates were used to assemble the fuel element IEA-228, which was irradiated in order to check its performance in the IEA-R1 reactor at IPEN-CNEN/SP. These new fuels have potential to be used in the new Brazilian Multipurpose Reactor RMB.

7 citations

Dissertation
01 Jan 2012
TL;DR: The University of Missouri--Columbia, viewed on October 31, 2012 as mentioned in this paper, viewed on the same day as this article. But the content of the article is different from ours.
Abstract: Title from PDF of title page (University of Missouri--Columbia, viewed on October 31, 2012).

6 citations

Journal ArticleDOI
16 Jun 2020
TL;DR: In this paper, the structural properties of orthorhombic, monoclinic, and body-centered tetragonal (bct) phases of U-Mo alloys were studied using molecular dynamics simulations.
Abstract: Using molecular dynamics simulations, we studied the structural properties of orthorhombic, monoclinic, and body-centered tetragonal (bct) phases of U–Mo alloys. A sequence of shear transformations between metastable phases takes place upon doping of uranium with molybdenum from pure α -U: orthorhombic α ′ → monoclinic α ″ → bct γ 0 → body-centered cubic (bcc) with doubled lattice constant γ s → bcc γ . The effects of alloy content on the structure of these phases have been investigated. It has been shown that increase in molybdenum concentration leads to an increase in the monoclinic angle and is more similar to the γ 0 -phase. In turn, tetragonal distortion of the γ 0 -phase lattice with displacement of a central atom in the basic cell along the direction makes it more like the α ″ -phase. Both of these effects reduce the necessary shift in atomic positions for the α ″ → γ 0 -phase transition.

4 citations

DissertationDOI
04 Dec 2013
TL;DR: In this article, the authors developed a new computational method for measuring thickness of core and cladding of fuel plates, which are able to perform such measurements in less time and with more meaningful statistical data when compared with the current method of measurement.
Abstract: One of the most important components of a nuclear reactor is the Nuclear Fuel. Currently, the most advanced commercial fuel, whose applicability in Brazilian reactors has been developed by IPEN since 1985, is the silicide U3Si2. This is formed by fuel plates with nuclei dispersion (where the fissile material (U3Si2) is homogeneously dispersed in a matrix of aluminum) coated aluminum. This fuel is produced in Brazil with developed technology, the result of the efforts made by the group of manufacturing nuclear fuel (CCN Center of Nuclear Fuel) of IPEN. Considering the necessity of increasing the power of the IEAR1 and Brazilian Multipurpose Reactor Building (RMB), for the production of radioisotopes mainly for the area of medicine there will be significant increase in the production of nuclear fuel at IPEN. Given this situation, if necessary, make the development of more modern and automated classification techniques. Aiming at this goal, this work developed a new computational method for measuring thickness of core and cladding of fuel plates, which are able to perform such measurements in less time and with more meaningful statistical data when compared with the current method of measurement.

4 citations

Journal ArticleDOI
Masrukan1
TL;DR: In this article, U-Zr alloy ingot was made by melting U and Zr metal in the electric arc furnace that is equipped with a water cooler and in an atmosphere of argon gas.
Abstract: Manufacturing and characterization of U-Zr alloys for PWR fuel types have been conducted. At first U-Zr alloy ingot was made by melting U and Zr metal in the electric arc furnace that is equipped with a water cooler and in an atmosphere of argon gas. Ingot manufacturing of U-Zr alloy was done at Zr concentration 35%, 45%, 55% and 65% weight respectively. U-Zr ingot result was cut for testing, such as: density, hardness, microstructure and phases. Density testing was done by using Autopicnometer, hardness by using microhardness, microstructure by using optical microscope, and phase by XRD. The density test results showed that the increase of Zr will decrease the density, while the hardness tends to increase. At Zr concentration amount 35 % (U-35Zr) the U-35Zr density is 11.2409 g/cc and at concentration amount of 65% (U-65Zr) the U-65 Zr density to be 8.4673 g/cc, while the hardness at 35% of Zr (U-35Zr) the hardness is 374 HV and will be 400 HV at concentration of Zr amount 65%. The microstructure observation result showed that increasing of Zr will increase the amount of grain and δ1 phases, while the result of phases testing showed that the U-Zr alloy tested had been dominated by the δ1 phases. From this experiment can be concluded that adding of Zr will influence the physical properties, mechanical, and microstructure formed. Keywords: Manufacturing, characterization, U-Zr , fuel, PWR.

3 citations