Abstract
Hydrogen absorption-desorption property of U-Th-Zr was investigated
in order to develop a new fuel material
based on hydrided uranium-metal alloy.
It was found that the U-Th-Zr alloy at varied atomic compositional ratio
absorbed hydrogen at high capacity compared to that of the U-Zr fuel
widely used in TRIGA reactors.
Hydrogen absorption desorption of the alloy after several cycles
have been demonstrated without any disintegration of the alloy into powder.
Absorption rate was relatively fast,
an indication of the stability of the hydrogenated specimen.
Microstructural and X-ray diffraction examinations of the alloys
exhibited that before hydrogenation it consisted of α-Th and
δ-UZr2 with Th in it on hydrogenation.
Th and Zr react with hydrogen to form stable ThZr2H7+x
(or ThZr2H7-x) and ZrH2 compounds.
The U-metal decomposed from the stable δ-UZr2
is distributed finely and homogeneously among the
ThZr2H7+x (ThZr2H7-x) and
ZrH2.
Thermal properties of the hydrogenated U-Th-Zr alloys have been proven
to be better than that of U-Zr-H alloy.
Post-irradiation experiments revealed that under high neutron fluence,
at temperature of about 973 K, the alloys were relatively stable.
It has been proven from the microstructural examination
that almost no hydrogen desorbed from the alloy.