Thulium Oxide Fuel Characterization Study: Part 2, Environmental Behavior and Mechanical, Thermal and Chemical Stability Enhancement

摘要

A study was performed of the correlation between fuel form stability and exposure environment of (temperature and atmosphere). 100% Tm sub 2 O sub 3 , 80% Tm sub 2 O sub 3 /20% Yb sub 2 O sub 3 and 100% Yb sub 2 O sub 3 wafers were subjected to air, dynamic vacuum and static vacuum at temperatures to 2000 deg C for times to 100 hours. Results showed the Tm sub 2 O sub 3 /Yb sub 2 O sub 3 cubic structure to be unaffected by elemental levels of iron, aluminum, magnesium and silicon and unaffected by the environmental conditions imposed on the wafers. A second task emphasized the optimization of the thermal, mechanical and chemical stability of Tm sub 2 O sub 3 fuel forms. Enhancement was sought through process variable optimization and the addition of metal oxides to Tm sub 2 O sub 3 . CaO, TiO sub 2 and Al sub 2 O sub 3 were added to form a grain boundary precipitate to control fines generation. The presence of 1% additive was inadequate to depress the melting point of Tm sub 2 O sub 3 or to change the cubic crystalline structure of Tm sub 2 O sub 3 /Yb sub 2 O sub 3 . Tm sub 2 O sub 3 /Yb sub 2 O sub 3 wafers containing CaO developed a grain boundary phase that improved the resistance to fines generation. The presence of Yb sub 2 O sub 3 did not appear to measurably influence behavior.