Post-Leaching Studies of Defect Rodlets

2003 ◽  
Author(s):  
D. H. Wegen ◽  
D. Papaioannou ◽  
J.-P. Glatz ◽  
P. D. W. Bottomly ◽  
M. Amme ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Optical Microscopy ◽  
Fission Products ◽  
Intergranular Attack ◽  
Mox Fuel ◽  
Metallographic Observation ◽  
History Of ◽  
Release Data

UO2 and MOX fuel rodlets are examined by optical microscopy after 5 years leaching in water to correlate the irradiation history of the fuels and of the fuel behaviour and with the release data for fission products and actinides. Metallographic observation revealed a strong intergranular attack of the MOX fuel in contrast to UO2. The latter effect could be responsible for the particularly high releases from the MOX fuel (upto 12% of the Cs inventory), compared to the UO2 fuel (only 0.6% of the Cs inventory). The large inventory of volatile fission products at grain boundaries can be explained by the high linear power rating (350 W/cm) with extremely high central temperatures in the MOX fuel during the irradiation.

Fission Products Release from Irradiated FBR MOX Fuel during Transient Conditions.

2003 ◽  
Vol 40 (2) ◽  
pp. 104-113 ◽  
Author(s):  
Isamu SATO ◽  
Toshio NAKAGIRI ◽  
Takashi HIROSAWA ◽  
Sinya MIYAHARA ◽  
Takashi NAMEKAWA
Keyword(s):  
Fission Products ◽  
Transient Conditions ◽  
Mox Fuel

scholarly journals Contribution to the study of fission products release from nuclear fuels in severe accident conditions: effect of the pO2 on Cs, Mo and Ba speciation

2020 ◽  
Vol 6 ◽  
pp. 2 ◽  
Author(s):  
Claire Le Gall ◽  
Fabienne Audubert ◽  
Jacques Léchelle ◽  
Yves Pontillon ◽  
Jean-Louis Hazemann
Keyword(s):  
Oxygen Potential ◽  
Fission Products ◽  
Severe Accident ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor ◽  
Mox Fuel ◽  
Chemical Behaviour ◽  
Accident Conditions ◽  
The Impact

The objective of this work is to experimentally investigate the effect of the oxygen potential on the fuel and FP chemical behaviour in conditions representative of a severe accident. More specifically, the speciation of Cs, Mo and Ba is investigated. These three highly reactive FP are among the most abundant elements produced through 235U and 239Pu thermal fission and may have a significant impact on human health and environmental contamination in case of a light water reactor severe accident. This work has set out to contribute to the following three fields: providing experimental data on Pressurized Water Reactor (PWR) MOX fuel behaviour submitted to severe accident conditions and related FP speciation; going further in the understanding of FP speciation mechanisms at different stages of a severe accident; developing a method to study volatile FP behaviour, involving the investigation of SIMFuel samples manufactured at low temperature through SPS. In this paper, a focus is made on the impact of the oxygen potential towards the interaction between irradiated MOX fuels and the cladding, the interaction between Mo and Ba under oxidizing conditions and the assessment of the oxygen potential during sintering.

scholarly journals Texture Evolution in AA6082-T6 BFSW Welds: Optical Microscopy and EBSD Characterisation

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3215 ◽  
Author(s):  
Abbas Tamadon ◽  
Dirk J. Pons ◽  
Don Clucas ◽  
Kamil Sued
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Optical Microscopy ◽  
Electron Backscatter Diffraction ◽  
Texture Evolution ◽  
Grain Structure ◽  
Friction Stir ◽  
Fine Grain ◽  
Grain Structures ◽  
Dynamic Recrystallisation

One of the difficulties with bobbin friction stir welding (BFSW) has been the visualisation of microstructure, particularly grain boundaries, and this is especially problematic for materials with fine grain structure, such as AA6082-T6 aluminium as here. Welds of this material were examined using optical microscopy (OM) and electron backscatter diffraction (EBSD). Results show that the grain structures that form depend on a complex set of factors. The motion of the pin and shoulder features transports material around the weld, which induces shear. The shear deformation around the pin is non-uniform with a thermal and strain gradient across the weld, and hence the dynamic recrystallisation (DRX) processes are also variable, giving a range of observed polycrystalline and grain boundary structures. Partial DRX was observed at both hourglass boundaries, and full DRX at mid-stirring zone. The grain boundary mapping showed the formation of low-angle grain boundaries (LAGBs) at regions of high shear as a consequence of thermomechanical nature of the process.

Examinations of Oxidation and Sulfidation of Grain Boundaries in Alloy 600 Exposed to Simulated Pressurized Water Reactor Primary Water

2013 ◽  
Vol 19 (3) ◽  
pp. 676-687 ◽  
Author(s):  
D.K. Schreiber ◽  
M.J. Olszta ◽  
D.W. Saxey ◽  
K. Kruska ◽  
K.L. Moore ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Atom Probe Tomography ◽  
Atom Probe ◽  
Alloy 600 ◽  
Pressurized Water Reactor ◽  
Intergranular Attack ◽  
Pressurized Water ◽  
Primary Water

AbstractHigh-resolution characterizations of intergranular attack in alloy 600 (Ni-17Cr-9Fe) exposed to 325°C simulated pressurized water reactor primary water have been conducted using a combination of scanning electron microscopy, NanoSIMS, analytical transmission electron microscopy, and atom probe tomography. The intergranular attack exhibited a two-stage microstructure that consisted of continuous corrosion/oxidation to a depth of ~200 nm from the surface followed by discrete Cr-rich sulfides to a further depth of ~500 nm. The continuous oxidation region contained primarily nanocrystalline MO-structure oxide particles and ended at Ni-rich, Cr-depleted grain boundaries with spaced CrS precipitates. Three-dimensional characterization of the sulfidized region using site-specific atom probe tomography revealed extraordinary grain boundary composition changes, including total depletion of Cr across a several nm wide dealloyed zone as a result of grain boundary migration.

scholarly journals Thermochemical effect of fission products on sodium – MOX fuel reaction: The case of niobium

2018 ◽  
Vol 500 ◽  
pp. 361-365
Author(s):  
Dan T. Costin ◽  
Lionel Desgranges ◽  
Victor Cabello-Ortiga ◽  
Marcus Hedberg ◽  
Jenny Halleröd ◽  
...  
Keyword(s):  
Fission Products ◽  
Mox Fuel ◽  
Thermochemical Effect

scholarly journals Characterization of solid fission products in 13.7% FIMA MOX fuel using electron microscopy techniques

2019 ◽  
Vol 524 ◽  
pp. 67-79 ◽  
Author(s):  
Riley J. Parrish ◽  
Karen E. Wright ◽  
Alexander J. Winston ◽  
Casey McKinney ◽  
Jason M. Harp ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Fission Products ◽  
Mox Fuel ◽  
Microscopy Techniques

Effect of Americium and Simulated Fission Products Addition on Oxygen Potential of Uranium-Plutonium Mixed Oxide Fuels

2009 ◽  
Vol 1215 ◽  
Author(s):  
Kosuke Tanaka ◽  
Masahiko Osaka ◽  
Ken Kurosaki ◽  
Hiroaki Muta ◽  
Masayoshi Uno ◽  
...  
Keyword(s):  
Thermogravimetric Analysis ◽  
Fission Product ◽  
Mixed Oxide ◽  
Oxygen Potential ◽  
Fission Products ◽  
Mox Fuel ◽  
Uranium Plutonium

AbstractThe oxygen potentials at 1273 K of mixed oxide (MOX) fuels with Am and 26 kinds of fission product elements (FPs), simulating low-decontaminated MOX fuel and high burn-up of up to 250 GWd/t, have been measured by using thermogravimetric analysis (TGA). The oxygen potentials for simulated low-decontaminated MOX fuels were higher than the fuels without FPs and increased with increasing simulated burn-up.

Investigation on the Influence of Precipitated Phase on Corrosion Resistance of the Ni-Based Alloys

2012 ◽  
Vol 184-185 ◽  
pp. 1038-1043
Author(s):  
Xue Hui Zhao ◽  
Zhen Quan Bai ◽  
Yao Rong Feng ◽  
An Qing Fu
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Corrosion Resistance ◽  
Electron Microscope ◽  
Grain Boundaries ◽  
Aging Treatment ◽  
Treatment Temperature ◽  
Different Temperatures ◽  
Metallographic Observation ◽  
Precipitated Phases

The influence of precipitated phases in Ni-based alloys during solid solution aging treatment on the performance of Ni-based alloys was investigated by means of metallographic observation, scanning electron microscope (SEM), and transmission electron microscope (TEM). The variation of microstructure and resultant phases as a result of solid solution aging treatment at different temperatures was discussed. The results show that the heat treatment temperature has significant influences on the type as well as quantity of precipitation phases. Lots of phases precipitated at grain boundaries, the distribution of precipitated phases are characterized by mesh-like structure. The corrosion tests results indicate that there is a potential difference between grains and grain boundaries due to the precipitation of chrome carbide at grain boundaries, resulting in pitting corrosion occurred preferentially at grain boundaries, consequently, the corrosion resistance of Ni-based alloys is reduced. In order to enhance the corrosion resistance of Ni-based alloys, it is expected to control the carbon content in a lower range and proper heat treatment process to avoid large amount precipitation of chrome carbide.

scholarly journals Defect segregation facilitates oxygen transport at fluorite UO 2 grain boundaries

2019 ◽  
Vol 377 (2152) ◽  
pp. 20190026 ◽  
Author(s):  
A. R. Symington ◽  
M. Molinari ◽  
N. A. Brincat ◽  
N. R. Williams ◽  
S. C. Parker
Keyword(s):  
Grain Boundaries ◽  
Oxygen Transport ◽  
Fission Products ◽  
Strong Interactions ◽  
Low Carbon ◽  
Energy Materials ◽  
Energy Applications ◽  
Oxygen Defects ◽  
Important Challenge ◽  
Dynamics Simulations

An important challenge for modelling transport in materials for energy applications is that in most applications they are polycrystalline, and hence it is critical to understand the properties in the presence of grain boundaries. Moreover, most grain boundaries are not pristine stoichiometric interfaces and hence dopants are likely to play a significant role. In this paper, we describe our recent work on using atomistic molecular dynamics simulations to model the effect of doped grain boundaries on oxygen transport of fluorite structured UO 2 . UO 2 , much like other fluorite grain boundaries, are found to be sinks for oxygen vacancy segregation relative to the grain interior, thus facilitating oxygen transport. Fission products further enhance diffusivity via strong interactions between the impurities and oxygen defects. Doping produces a striking structural alteration in the Σ 5 class of grain boundaries that enhances oxygen diffusivity even further. This article is part of a discussion meeting issue ‘Energy materials for a low carbon future’.

Improvement of polycrystalline Y–Ba–Cu–O by the addition of silver

1988 ◽  
Vol 3 (4) ◽  
pp. 605-609 ◽  
Author(s):  
G. G. Peterson ◽  
B. R. Weinberger ◽  
L. Lynds ◽  
H. A. Krasinski
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Optical Microscopy ◽  
Photoelectron Spectroscopy ◽  
Hydrocarbon Contamination ◽  
Boundary Effects ◽  
Metallic Silver ◽  
X Ray ◽  
Grain Boundary Effects ◽  
Lower Porosity

X-ray photoelectron spectroscopy, scanning Auger, and optical microscopy studies of polycrystalline superconducting pellets of Y–Ba–Cu–O/Ag are presented. Silver-laced samples have a lower porosity and a drastically reduced hydrocarbon contamination. Results indicate no detectable substitution of A g into the Y–Ba–Cu–O but a collection of metallic silver in voids and possibly along grain boundaries Intergranular silver could mitigate adverse grain boundary effects in polycrystalline Y–Ba–Cu–O.

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