高強度な高温ガス炉用耐酸化燃料要素の開発

（燃料成形体の機械的強度特性評価）

抄録

Fuel compact of high-temperature gas-cooled reactor (HTGR) with inherent safety employs the fuel component which was molded from graphite. However, in HTGR, when piping is broken at the time of an accident and air enters the reactor, the fuel component may be oxidized. For this reason, development of the oxidation-resistant fuel component has been advancing at present, which is the fuel component having oxidation resistance formed by SiC. In this study, strength test was conducted on oxidation-resistant fuel components prepared under various molding parameters. As the strength test, Young's modulus was measured by ultrasonic pulse velocity test, and compressive strength was measured by a compression test. In addition, as for the conditions of the molding process, temperature and time of the hot pressing, which is one step of molding processing of the oxidation-resistant fuel components, were changed. As a result of the ultrasonic pulse velocity test, the high correlation was not observed between Young's modulus and the hot pressing conditions of the temperature and the time. On the other hand, it was found that the stress-strain curve of the oxidation-resistant fuel component was non-linear like plastic deformation in the compression test. There was no correlation between the compressive strength and the hot pressing time in the range of the hot pressing temperature of 1300~1600 oC and the time of 40~120 min, but a high negative correlation was observed within the range of the hot pressing temperatures. Therefore, it was predicted that the compressive strength was increased by decreasing the hot pressing temperature.