| Abstract |
| It was studied to elucidate the high-temperature oxidation behaviors of Zirealoy-4 and A claddings in LOCA temperature ranges (700∼1200℃), using a TGA(Themogravimetric analysis) method. As the temperature increased, the weight gain of two claddings increased according to the parabolic rate law. But the discontinuity of K_(p) in Zircaloy-4 was attributed to the microstructural changes of oxide at the temperatures of 1000∼1050℃, where the oxide structures were transformed from monoclinic-ZrO_(2) to tetragonal-ZrO_(2). These results were matched to the surface color of tested specimens and the calculated parabolic rate constants. And the discontinuity temperature of K_(p) in A cladding appeared at 1100℃ higher than that in Zircaloy-4. It was thought that discrepancy of oxidation kinetics in A cladding were resulted from the stability of tetragonal-ZrO_(2) phase in A cladding due to Nb addition. Since the parabolic rate constants of A cladding were similar to that of Zircaloy-4, A cladding would maintain the mechanical integrity under the LOCA conditions. (Received May 28, 2003) |
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| Key Words |
| Zr, Fuel cladding, Steam oxidation, LOCA, Oxidation kinetics |
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