RRFM 2009 Transactions - European Nuclear Society

In this experiment this pressure-sintering was chosen for a consolidated sample to be able to examine
the dispersion homogeneity of the mixed powder. In an actual practice, the mixed powder in this jig will
be pressure-compacted. And then the compacts will be heated and extruded from the fuel meat rods.
Previously 5 extruding works were done in order to meet the dispersion homogeneity for the fuel
requirements. If the method and experimental result is applied to the use of a large U-Mo particle
powder for a rod type of fuel, only one extrusion work would be possible in the fabricating fuel process.
Table 1. Measured Densities of cut pieces for pressure sintered sample.
Part 1 2 3 4 5 6 7 8 9
Density
g/cc
6.99 6.42 6.55 6.49 6.69 6.42 6.59 6.57 6.56
Variation
(%)
+6.0 -2.5 -0.6 -1.5 +1.6 -2.5 +0.04 -0.3 -0.4
Deviation
g/cc
+0.40 -0.17 -0.04 -0.1 +0.1 -0.17 0 -0.02 -0.03
Average
g/cc
6.59
Standard
Deviation
g/cc
0.16
4. Conclusion
In order to simplify the process for an acceptable homogeneous large U-Mo particle dispersion, fuel
meat rod several methods have been applied. Among them a regular arrangement of U-Mo large
particles by placing the particles into the openings of a sieve screening net was investigated to meet
on acceptable dispersion homogeneity. The variations of the 9 measured values were less than 6 %.
The limit of the U-235 homogeneity for the fuel meat rod of HANARO fuel was +/- 8.5 %. In this
experiment a pressure-sintering was done for 4 hours at 480 °C with about 440 kg/cm 2 . The average
value of the measured densities for the sintered sample was 6.59 g/cc, which corresponds to 94.3% of
the theoretical density. This would be appropriate for forming a fuel meat. In an actual practice the
mixed powder in this jig will be pressure-compacted. And then the compacts will be heated and
extruded from the fuel meat rods. When the mixed powder is extruded, it is expected that the
homogeneity of the extruded fuel meat rod would be improved. If the method and experimental results
are applied to the use of a large U-Mo particle powder for a rod type fuel, the extrusion work would be
reduced from 5 times to only one time. The developed system is very simple. It is considered that this
new dispersion fuel meat fabrication method by placing the particles into the openings of a sieve
screening net would be effective in obtaining a good dispersion from the viewpoint of a fabrication
economy.
5. Reference
1. Y.S. Lee, et. al., RRFM 2005
2. J.M. Park, et. al., RRFM 2008
3. C.K. Kim. et. al., RERTR 1998
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