Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 61 for “"UO2"”.
-
Microstructural investigations of ion (Kr) irradiated UO2
A single crystal thin film of UO2 on a YSZ substrate was irradiated with 1MeV Kr ions at doses ranging from 1x1014 ions/cm2 to 1x1016 ions/cm2 and temperatures ranging from room temperature to 1000°C. These irradiations were conducted ex situ with one in situ irradiation at 800°C. Post irradiation …
-
Electrical properties and defect structure of UO2-CeO2 solid solutions
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1984.
-
Interaction of aqueous U(VI) with goethite, montmorillonite, and UO2(s)
… was observed between aqueous U(VI) and the UO2(s) even after 47 days of reaction. However, occurrence of isotope exchange between aqueous U(VI) and the U(VI) adsorbed onto montmorillonite was observed within timescales of 5 minutes. X-ray photoelectron spectroscopy provided evidence for the …
-
Radiation enhanced diffusion of neodymium in single crystal thin film UO2
… diffusion (RED) of a Nd buried tracer layer in UO2 thin films was measured with Secondary Ion Mass Spectrometry (SIMS). Samples were irradiated with 1.8 MeV Kr+ over a temperature range from 400 to 800 C. RED in UO2 was found to be in the recombination limited regime. Dose rate dependence …
-
Thermal conductivity of UO2 and U3O8 epitaxial layers damaged by ion irradiation
… main focus lies on 360 – 500 nm single crystal UO2 and U3O8 thin films grown on YSZ substrates. The U3O8 samples are formed by heating the UO2 in air for 2.5 hours at 600°C and slow cooling. From a comparison between data measured by an optical pump-probe technique – time-domain …
-
The Deposition Characteristics of Zrc On Uo2 Kernels Produced For Advanced Triso Fuels In Gen-Iv Reactors
<p>Very high temperature reactors (VHTR) are capable of achieving temperatures up to 1000°C, allowing for increased plant efficiency, as well as the ability for using the process heat for hydrogen production and other commercial uses. However, the limits of operation of VHTRs are currently …
-
Determination of UO2 thin films mechanical properties under heavy ion irradiation using nanoindentation and finite element modeling
The mechanical response of UO2 to irradiation is becoming increasingly important due to the shift to higher burn-up rates in the next generation of reactors. In the current study, thin films of UO2 were deposited on YSZ substrates using reactive-gas magnetron sputtering. Nanoindentation was used to …
-
The effect of radiation damage by fission fragments on the structural stability and dissolution of the UO2 fuel matrix
… bulk undoped and doped ‘SIMFUEL’ disks of UO2, undoped bulk CeO2 and thin films of UO2 and CeO2 with high energy Xe and U ions. The UO2 thin films, with thicknesses in the range of 90 – 150 nm, were deposited onto (001), (110) and (111) orientations of single crystal LSAT …
-
Micro-heterogeneous thorium based fuel concepts for pressurized water reactions
… consisting of a homogeneously fueled ThO2-UO2 lattice of conventional design. It is found that homogeneously mixed ThO2-UO2 fuel in general has better physics behavior than all-UO2 fuel, e.g. more negative MTC and less reactivity swing. The H/HM ratio can be optimized to extend the burnup …
-
X-ray photoelectron spectroscopy (XPS) study of single crystal UO2 and U3O8 on r-plane sapphire and yttrium stabilized zirconium (YSZ) substrates
… X-ray Diffraction. The analysis of thin films of UO2 and U3O8 is a relatively new field with minimal data on thin films. There is however some work on bulk UO2 and U3O8. We will be able to compare our data to the data from bulk UO2 and U3O8 and predict the results from basic XPS and XRD theory. …
-
Μελέτη διαμοριακών αλληλεπιδράσεων στην κρυσταλλική δομή οργανικών ενώσεων και μεταλλικών συμπλόκων με τη μέθοδο Hirshfeld
… του ουρανυλίου: περιλαμβάνονται οι ενώσεις: [UO2(NO3)2(Mebta)2] (5), [UO2(NO3)2(6MebtaH)2] (6), [UO2(NO3)2(diMebtaH)2] (7), [UO2(NO3)2(diMebtaH)2]·(diMebtaH)·MeCN (8), [UO2(mepao)2(MeOH)2]{[UO2(NO3)(mepao)(MeOH)2]}2 (9), [UO2(mepao)2(MeOH)2] (10), [(UO2)2(O2)(O2CMe)2(mepaoH)2] (11), …
-
Fertile free fuels for plutonium and minor actinides burning in LWRs
… burned, and they are all superior to the mixed UO2-PuO2 (MOX) fuel. From this point of view, there is no good reason to favor one inert matrix over another. The burning rates in terms of kg/(GWe-Year) of different inert matrix fuels are quite stable with regard to changing the moderation level …
-
Coating Parameters of Zirconium Carbide On Advanced Triso Fuels
… metallic fission products created in irradiated UO2. Most research devoted to TRISO fuel particles has focused on the characteristics and retention ability of silicon carbide as the main barrier against metallic fission products. This work investigates the deposition parameters necessary to …
-
Radiation-enhanced diffusion of oxygen-18 in uranium dioxide thin films
… of a buried 18O tracer layer in thin film UO2 was measured using Secondary-Ion Mass Spectroscopy (SIMS). Thin films were grown using a dedicated magnetron sputtering chamber. Samples were irradiated with 1.8 MeV Kr+ over a temperature range from 295 K to 623 K. Measurements have been made …
-
Design and development of an automated pellet inspection system for nuclear fuel pellets
… non-destructive inspection of uranium dioxide (UO2) fuel pellets at production speeds of two pellets per second is presented. The system tests the surface of each cylindrical ceramic pellet using three different methods: laser 2D profile, laser surface roughness, and machine vision camera. The …
-
Modeling of Thermal Transport Properties in Metallic and Oxide Fuels
… fuel performance property not only for current UO2 oxide fuel based light water reactors but also important for next-generation fast reactors that use U-Zr based metallic fuels. In this work, the thermal transport properties of both UO2 based oxide fuels and U-Zr based metallic fuels have been …
-
Molecular dynamic simulation of xenon bubble re-solution in uranium dioxide
… mechanisms of fission gas bubble re-solution in UO2 by molecular dynamics (MD) simulations: homogeneous re-solution and heterogeneous re-solution. For the homogeneous mechanism, a hybrid approach is employed whereby Monte Carlo (MC) simulations are used to obtain the full recoil energy spectrum …
-
Thermal aspects of high efficiency channel with conventional and alternative fuels in SuperCritical water-cooled reactor (SCWR) applications
… respectively. These studies correspond to UO2 enclosed in a 43-element fuel bundle at an average thermal power per channel of 8.5 MWth. Additionally, these high operating conditions in the range of 350 - 625°C lead to high heat losses from the coolant to the moderator, which in turn reduces …
-
The Design of Reactor Cores for Civil Nuclear Marine Propulsion
… a long life core, the micro-heterogeneous ThO2-UO2 duplex fuel is well-positioned to be utilized in our proposed civil marine core. Unfortunately, A limited number of studies of duplex fuel are available in the public domain, but its use has never been examined in the context of a SBF …
-
Molecular Dynamics Studies of Grain Boundary Mobilities in Metallic and Oxide Fuels
… the most common fuel is uranium dioxide (UO2), an oxide ceramic. There is also ongoing research examining uranium-based based metallic fuels, such as uranium-molybdenum (U-Mo) fuels with low uranium (U) enrichment for research reactors as part of a broader effort to combat nuclear …
Page 1 of 4