In-Pile and out-of-Pile Corrosion Behavior of Thoria-Urania Pellets (LWBR (Light Water Breeder Reactor) Development Program)

摘要

The out-of-pile corrosion behavior of ThO sub 2 and ThO sub 2 -UO sub 2 fuel pellets was studied in high temperature, flowing, oxygenated water. Weight changes of the specimens were determined periodically during the corrosions exposures, some of which were as long as 265 days; in addition, ceramographic examinations were carried out on selected specimens. Both ThO sub 2 and homogeneous ThO sub 2 -UO sub 2 (2 to 30 wt % UO sub 2 ) fuel showed excellent corrosion resistance, the former intrinsically because it cannot be oxidized and the latter because oxidation creates a mechanically stable surface phase. These out-of-pile results predicted favorable corrosion stability in defected irradiated fuel elements. The maintenance of ThO sub 2 and ThO sub 2 -UO sub 2 fuel integrity in defected fuel rods was confirmed by an irradiation test program. Both the in-pile and out-of-pile test results support the conclusion that LWBR-type fuel rods containing ThO sub 2 and ThO sub 2 -UO sub 2 pellets can successfully operate in the defect condition with limited radioactivity release to the coolant. (ERA citation 12:015857)