Fuel Pin Behavior During UO sub 2 Pellet Melting

摘要

Fuel pin behavior with heat rating up to UO sub 2 melting was investigated by means of power cycling capsule of JMTR (Japan Materials Testing Reactor). The fuel pin was subjected to power irradiation examination for metallographic study. Results are: (1) UO sub 2 pellet melting occurred at 630 W/cm and the molten UO sub 2 spread cylindrically in one-third the bulk of specimen. (2) A typical cross sectional ceramography revealed that grain boundaries were not observed at the central part and non-equiaxial and equiaxial grains were observed at middle and outer parts. (3) Pores were mostly on the grain boundaries, few in the grains. (4) Cracks in the pellet were transgranular. (Atomindex citation 09:411740)