Download or read book Fission Gas Bubble Behavior in Uranium Carbide written by Christopher Matthews and published by . This book was released on 2015 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: The need for cheap reliable energy, while simultaneously avoiding uranium supply constraints makes uranium carbide (UC) fueled Gas Fast Reactors offer an attractive nuclear reactor design. In order to qualify the fuel, an enhanced understanding of the behavior of uranium carbide during operation is paramount. Due to a reduced re-solution rate, uranium carbide suffers from a buildup of very large fission gas bubbles. While these bubbles serve to reduce total fission gas release through the trapping of diffusing gas atoms, they lead to high swelling and ultimately dominate the microstructure of the fuel. The bubble size distribution is determined by the competing absorption rate and the rate of knock-out, or re-solution. As a result of the enhanced thermal dissipative properties of uranium carbide fuel, the atom-by-atom knockout process was shown to be an accurate representation of re-solution in uranium carbide. Furthermore, the Binary Collision Approximation was shown to appropriately model the re-solution event, bypassing computationally expensive Molecular Dynamics simulations. The code 3DOT was developed as an off-shoot of the code 3DTrim, both of which utilize the TRIM algorithm to calculate the kinematics of ions traveling through a material. Benefiting from modern methods and enhanced computational power, the model created in 3DOT results in a more fundamental understanding of the re-solution process in uranium carbide. A re-solution parameter that was an order of magnitude lower than previously determined was cal- culated in 3DOT. A decrease in the re-solution parameter as a function of radius occurred for low bubble radii, with a nearly constant re-solution parameter for bubble radii above 50 nm. Through comparative studies on the re-solution parameter for various values of implantation energy and atomic density in the bubble, we found that while the re-solution parameter did change slightly, the overall shape did not. A new application, BUCK, was built using the MOOSE framework to simulate the fission gas bubble concentration distribution. In order to build a bare-bones foundation, the simplistic yet historically prevalent physics that can be used to model fission gas bubble nucleation, growth, and knock-out were implemented as stepping stones until more advanced models for each physical process can be created. As the first step towards models that are based on first-principles, the new re-solution parameter was included and tested within BUCK. BUCK was tested using different parameters and behaved normally. However, from studies using representative simulation parameters, it is clear that the currently implemented theory does not adequately identify the growth mechanism that leads to larger bubbles. While this currently limits the applicability of BUCK in a full fuel pin calculation, it provides the baseline structure in which new physics can be implemented, and represents an important step towards understanding the complex behavior of fission gas bubbles.

Download or read book Irradiation Behavior of Uranium Carbide Fuels written by D. I. Sinizer and published by . This book was released on 1962 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Computer Modeling of Fission Gas Behavior in Carbide Fuels written by Prajoto and published by . This book was released on 1976 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Behavior of Fission Gas in Fuels written by and published by . This book was released on 1965 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book In pile Fission gas Release from Uranium Carbide and Uranium Nitride written by James B. Melehan and published by . This book was released on 1964 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterization of Intergranular Fission Gas Bubbles in U Mo Fuel written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report can be divided into two parts: the first part, which is composed of sections 1, 2, and 3, is devoted to report the analyses of fission gas bubbles; the second part, which is in section 4, is allocated to describe the mechanistic model development. Swelling data of irradiated U-Mo alloy typically show that the kinetics of fission gas bubbles is composed of two different rates: lower initially and higher later. The transition corresponds to a burnup of ≈0 at% U-235 (LEU) or a fission density of ≈3 x 1021 fissions/cm3. Scanning electron microscopy (SEM) shows that gas bubbles appear only on the grain boundaries in the pretransition regime. At intermediate burnup where the transition begins, gas bubbles are observed to spread into the intragranular regions. At high burnup, they are uniformly distributed throughout fuel. In highly irradiated U-Mo alloy fuel large-scale gas bubbles form on some fuel particle peripheries. In some cases, these bubbles appear to be interconnected and occupy the interface region between fuel and the aluminum matrix for dispersion fuel, and fuel and cladding for monolithic fuel, respectively. This is a potential performance limit for U-Mo alloy fuel. Microscopic characterization of the evolution of fission gas bubbles is necessary to understand the underlying phenomena of the macroscopic behavior of fission gas swelling that can lead to a counter measure to potential performance limit. The microscopic characterization data, particularly in the pre-transition regime, can also be used in developing a mechanistic model that predicts fission gas bubble behavior as a function of burnup and helps identify critical physical properties for the future tests. Analyses of grain and grain boundary morphology were performed. Optical micrographs and scanning electron micrographs of irradiated fuel from RERTR-1, 2, 3 and 5 tests were used. Micrographic comparisons between as-fabricated and as-irradiated fuel revealed that the site of first bubble appearance is the grain boundary. Analysis using a simple diffusion model showed that, although the difference in the Mo-content between the grain boundary and grain interior region decreased with burnup, a complete convergence in the Mo-content was not reached at the end of the test for all RERTR tests. A total of 13 plates from RERTR-1, 2, 3 and 5 tests with different as-fabrication conditions and irradiation conditions were included for gas bubble analyses. Among them, two plates contained powders [gamma]-annealed at ≈800 C for ≈100 hours. Most of the plates were fabricated with as-atomized powders except for two as-machined powder plates. The Mo contents were 6, 7 and 10wt%. The irradiation temperature was in the range 70-190 C and the fission rate was in the range 2.4 x 1014 - 7 x 1014 f/cm3-s. Bubble size for both of the [gamma]-annealed powder plates is smaller than the as-atomized powder plates. The bubble size for the as-atomized powder plates increases as a function of burnup and the bubble growth rate shows signs of slowing at burnups higher than ≈40 at% U-235 (LEU). The bubble-size distribution for all plates is a quasi-normal, with the average bubble size ranging 0.14-0.18 [mu]m. Although there are considerable errors, after an initial incubation period the average bubble size increases with fission density and shows saturation at high fission density. Bubble population (density) per unit grain boundary length was measured. The [gamma]-annealed powder plates have a higher bubble density per unit grain boundary length than the as-atomized powder plates. The measured bubble number densities per unit grain boundary length for as-atomized powder plates are approximately constant with respect to burnup. Bubble density per unit cross section area was calculated using the density per unit grain boundary length data. The grains were modeled as tetrakaidecahedrons. Direct measurements for some plates were also performed and compared with the calculated quantities. Bubble density per unit grain boundary surface area was calculated by using the density per unit grain boundary length data. These data were used as input for mechanistic modeling described in section 4. Volumetric bubble density was calculated by using density per unit grain boundary surface area. Based on these data, bubble volumetric fraction was calculated. Bubble volume fraction was also calculated by using the density per unit cross section area. Bubble volume fraction was also directly measured for some plates. These three results are comparable although the direct measurement data are slightly larger than the others. Bubble volume fraction increased as a function of burnup, reaching ≈2% of fuel volume at 3 x 1021 f/cm3. Fission gas bubble swelling is minor compared to that of solid fission product swelling.

Download or read book A Metallographic Study of the Swelling of Uranium and Uranium Alloys written by A. Boltax and published by . This book was released on 1960 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nuclear Safety written by and published by . This book was released on 1964 with total page 1554 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the Nonequilibrium Behavior of Fission Gas Bubbles with Emphasis on the Effects of Equation of State written by W. G. Steele and published by . This book was released on 1976 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Post Irradiation Annealing Behaviour of Fission Gas Bubbles in Various Purities of Uranium written by B. Hudson and published by . This book was released on 1968 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Behavior of fission product ruthenium in uranium carbide written by N. Oi and published by . This book was released on 1969 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effect of Crystal Structure Stability on the Mobility of Gas Bubbles in Intermetallic Uranium Compounds written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Irradiation experiments with certain low-enrichment, high-density, uranium-base intermetallic alloys that are candidate reactor fuel materials, such as U3Si and U6Fe, have revealed extraordinarily large voids at low and medium fuel burnup. This phenomenon of breakaway swelling does not occur in other fuel types, such as U3Si2 and UAl3, where a distribution of relatively small and stable fission gas bubbles forms. In situ transmission electron microscope observations of ion radiation-induced rapid swelling of intermetallic materials are consistent with growth by plastic flow. Large radiation enhancement of plastic flow in amorphous materials has been observed in several independent experiments and is thought to be a general materials phenomenon. The basis for a microscopic theory of fission gas bubble behavior in irradiated amorphous compounds has been formulated. The assumption underlying the overall theory is that the evolution of the porosity from that observed in the crystalline material to that observed in irradiated amorphous U3Si as a function of fluence is due to a softening of the irradiated amorphous material. Bubble growth in the low-viscosity material has been approximated by an effective enhanced diffusivity. Mechanisms are included for the radiation-induced softening of the amorphous material, and for a relation between gas atom mobilities and radiation-induced (defect-generated) changes in the material. Results of the analysis indicate that the observed rapid swelling in U3Si arises directly from enhanced bubble migration and coalescence due to plastic flow. 34 refs., 11 figs.

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1975-04 with total page 1082 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reactor Fuels Materials and Systems under Extreme Environments written by Wenzhong Zhou and published by Frontiers Media SA. This book was released on 2022-03-25 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book ERDA Energy Research Abstracts written by and published by . This book was released on 1977 with total page 742 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reactor Materials written by and published by . This book was released on 1969 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Proceedings of the Uranium Carbide Meeting written by and published by . This book was released on 1961 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: