On Effective Thermal Conductivity and Structural Change of UO<SUB>2</SUB> Powder Compacted Fuel in Thermal Simulation Experiment
スポンサーリンク
概要
- 論文の詳細を見る
The studies described in this paper relate to the effective thermal conductivity Keff of powder compacted UO2 fuel material under simulated thermal conditions of a reactor, and to structural changes brought about by large thermal gradient at elevated temperatures. From the results obtained, it is concluded that:(1) Structural change in the material occurring under such thermal conditions greatly affects K<SUB>eef</SUB>f, which is thereby increased as a result of columnar grain growth ; (2) Columnar grains developed the path of heat flow are single crystals growing in the direction <111>; (3) K<SUB>eff</SUB> is higher when measured during cooling than during heating, and the relation between K<SUB>eff</SUB> and temperature is similar to the case of a UO<SUB>2</SUB> single crystal; (4) K<SUB>eff</SUB> measured in 90% He-10% H<SUB>2</SUB> at atmospheric pressure is much higher than in vacuum, from which it can be inferred that the gas contained in the fuel pin has marked influence on K<SUB>eff</SUB>.