CHARACTERIZATION STUDIES ON NUCLEAR FUEL POWDERS AND PELLETS AT CNAEM
A. YAYLI, F. CAN, B. KOPUZ, M. T. AYBERS
Division of Material Technologies, Cekmece Nuclear Research and Training Center Yarımburgaz Mah. Nükleer Araştırma Merkez Yolu K. Çekmece- 34303 İstanbul/TURKEY
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Powder metallurgy procedures :
Powder metallurgy procedures :
The focus of most industrial activity today is on
The focus of most industrial activity today is on
improving the performance
improving the performance
of existing nuclear power reactors and their fuel.
of existing nuclear power reactors and their fuel.
Powder production
Powder production
Powder treatment (pre-compacting, binder and lubricant adding etc.)
Powder treatment (pre-compacting, binder and lubricant adding etc.)
Compacting
Compacting
Sintering
Sintering
Small changes in parameters such as humidity, binder concentration and
Small changes in parameters such as humidity, binder concentration and
particle size distribution can effect the powder rheology and result in
particle size distribution can effect the powder rheology and result in
changes in flow rate.
changes in flow rate.
Variations of flow are likely to affect the density and dimensions of pellets
Variations of flow are likely to affect the density and dimensions of pellets
and the homogeneity of actinide oxide distribution in the pellets.
and the homogeneity of actinide oxide distribution in the pellets.
In powder metallurgy processes, the physical properties of powders effect
In powder metallurgy processes, the physical properties of powders effect
the qualitative and quantitative properties of the end products.
the qualitative and quantitative properties of the end products.
All uraniaAll urania,, thoria thoria and (U,Th)Oand (U,Th)O2 2 powder and pellet studies carried out at powder and pellet studies carried out at
CNAEM by powder metallurgical route.
Powder Synthesis
Powder Synthesis
powders and pellets are prepared with different technological regimes, on the
powders and pellets are prepared with different technological regimes, on the
properties of the finished items are investigated at CNAEM.
properties of the finished items are investigated at CNAEM.
UO2 Powder synthesis:
UO2 Powder synthesis:
-ADU process
-ADU process
-AUC Process
-AUC Process
ThO2 Powder synthesis:
ThO2 Powder synthesis:
Oxalate Precipitation ( with different conditions)
Oxalate Precipitation ( with different conditions)
(U,Th)O2 Powder Synthesis
(U,Th)O2 Powder Synthesis
Mechanical blending
Mechanical blending
Co-precipitation
UO2 Powder Synthesis
UO2 Powder Synthesis
The most popular routes in UO2 production
The most popular routes in UO2 production
are :
are :
ADU processes.
ADU processes.
AUC processes.
AUC processes.
However UO2 powders produced via ADU,
However UO2 powders produced via ADU,
which is the process most often used,
which is the process most often used,
require prepressing, crushing, grinding and
require prepressing, crushing, grinding and
screening steps to produce increased bulk
screening steps to produce increased bulk
density and partly free flow able powder
density and partly free flow able powder
and pressing requires addition of a binder
and pressing requires addition of a binder
and lubricants.
UO2 ex- ADU and ex-AUC
UO2 ex- ADU and ex-AUC
Powder and pellet investigations
Powder and pellet investigations
powders : powders :
x-ray phase analysis,
x-ray phase analysis,
specific surface area,
specific surface area,
Particle size distribution
Particle size distribution
bulk and tap density,
bulk and tap density,
Optical and
Optical and scanning electron microscopy investigations scanning electron microscopy investigations Chemical composition
Chemical composition
Pellets : Pellets :
x-ray phase analysis,
x-ray phase analysis,
determination of density, determination of density, study of microstructure, study of microstructure, chemical composition, chemical composition, visual inspection; visual inspection;
linear dimensions (pellet diameter and length),
linear dimensions (pellet diameter and length),
geometric density,
geometric density,
squareness, dish and chamfer dimensions,
squareness, dish and chamfer dimensions,
surface roughness,
surface roughness,
homogeneity, and grain size )
Th-Oxalate Powders SEM Studies
Th-Oxalate Powders SEM Studies
ThO
XRD Studies on Th-Oxalate and THO
Surface Area measurments of thoria
Surface Area measurments of thoria
powders
powders
Thermal Decomposition of ADU and AUC
Thermal Decomposition of ADU and AUC
Particle Size Distribution of Th-Oxzalate and ThO
SEM Studies on sintered (U,Th)O
SEM Studies on sintered (U,Th)O
22pellets
pellets
• Micrographs of sinterd at 1700 o C for 6 hours under H2 atmosphere (U,Th)O2 pellets • a) 10% , b) 20%, c) 30% and d) 40% UO2 and remains ThO2
