Resumen
Mixed oxides of uranium and plutonium (MOX) are currently considered as a reference fuel for the new generation of fast breeder reactors such as ASTRID. The key factor determining the performance and safety of a fuel such as MOX is its operational limits in the application environment which are closely related to the material?s structure and thermodynamic stability. They are in turn closely related to the ambient (zero pressure) melting point (????)
(
T
m
)
; thus, ????
T
m
is an important engineering parameter. Furthermore, PuO2
2
and UO2
2
are two endpoints of the phase diagram of MOX; therefore, their ambient ????
T
m
s are fundamental reference points. However, the current knowledge of the ????
T
m
of MOX is limited and controversial as several studies available in the literature do not converge on the unique behavior of ????
T
m
as a function of ??.
x
.
Specifically, some studies produced ????
T
m
as a monotonically decreasing function of x such that, with ????
T
m
of UO2
2
(??=0)
(
x
=
0
)
of 3150 K, ????
T
m
of PuO2
2
(??=1)
(
x
=
1
)
is ~2650 K, while other studies resulted in ????
T
m
having a local minimum at 0.5