[en] Nano-indentation technique was applied to evaluate copper-silver composites for high performance electrical wire. The specimen was irradiated in CT hole of HANARO. The irradiation test condition was for 36 days at 320 degree C with the maximum neutron fluence of 4.8x10²⁰ n/cm² (E>1.0 MeV). The gamma heating rate was in the range of 2.0-6.45 W/gm. Statistical parameters of the indentation are given by histograms. Analytical and experimental relation between is considered. The method is well applied to estimate mechanical property changes of irradiated materials. (authors)

[en] U-Mo fuel deformation during irradiation in U-Mo/Al dispersion plates is investigated by using the irradiation data from the RERTR-3 through -9 tests. The observation of fuel particle sintering during irradiation is also presented and its influence for fuel performance is discussed. Structural analysis was also performed to examine the relationship between the stress distribution in the plate and the location of matrix-pore formation in the plate. (author)

[en] Two U-7wt.%Mo dispersion fuel rods with different fuel particle sizes, two U- 7wt.%Mo dispersion fuel rods surface-treated with pre-oxidation and Ni coating, one U-7wt.%Mo dispersion fuel rod with a poison material of Er₂O₃, a U-9wt.%Mo dispersion fuel rod, and a U₃Si dispersion fuel rod were loaded in the KOMO-test (the 2nd irradiation test of U-Mo fuels in HANARO by KAERI). In addition, the monolithic U-Mo ring fuel was loaded to develop higher U-density fuel. The fuel assembly with the above 10 fuel rods was irradiated in HAHARO successfully from January 9, 2003 to January 27, 2004. After cooling them for about 3 months, the PIE has been performed. Most of the fuel particles were interacted with the Al matrix in the central area of the rod-type U-Mo dispersion fuels with a high linear power and a higher burnup than 60 at.%. Some large pores were observed between the particles in the central area of the fuel rods. However the swellings of the fuel meats are not large, at less than 17 %. The fuel of a larger particle-size distribution showed a better stability than the fuel of a smaller particle-size distribution. Any surface treatments were observed to have no improvement on the oxidation layer formation of the cladding surface. U₃Si dispersion fuel used as a reference showed a much lesser interaction with the matrix Al when compared with the U-Mo dispersion fuel. In an examination for the tubular monolithic U-Mo fuel abnormal phenomena such as many bubbles and a large swelling happened due to an unexpected contamination of the silicon from the quartz tube used for a mold during melting and casting process. (author)

[en] A simulated fuel specimen which was irradiated at the HANARO research reactor up to 3300 MWd/tU of a burn-up at the condition of 36 kW/m of a maximum linear power was studied by a shielded EPMA (Electron Probe Micro-Analyzer). In order to obtain an accurate analysis results, chemical and EPMA analyses were also performed on un-irradiated fresh simulated fuel, the results of which were compared with those of the irradiated simulated fuel. This study concentrated on the metallic precipitates of the irradiated simulated fuel specimen which contained lots of fission products. Among the several properties of the metallic precipitate, its size and composition were investigated. A large metallic inclusion was also observed in the irradiated simulated fuel, from which X-ray photographs were taken to analyze its properties