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Materials Science Division |
HighlightsMicrostructural Stability of the Depleted Uranium AlloysMicrostructural Stability of the Depleted Uranium Alloys Scientific Achievement Reduced-Enrichment fuel for Research Test
Reactors (RERTR) program is to develop low enrichment fuel for nuclear
non-proliferation. Most
of these fuels
are using aluminum cladding and operated at water coolant temperature
less than
100°C. It is
realized that fuel/cladding
interaction product played a strong role on overall fuel performance. Multiple phases can form
as results of
fuel/cladding interaction. The
microstructural evolution of these phases in fuel under irradiation
with
fission products is a key to understand the mechanism controlling the
fuel
swelling which is believed to be a leading cause to fuel failure.. Three depleted uranium alloys contain a
total of five phases relevant to fuel/cladding interaction product were
irradiated using 500 KeV Kr ions at 200°C using IVEM facility at
Argonne. The Kr ion
energy was chosen to retain large
portion of the injected Kr ions in the material to examine the fission
product
damage in the phases of interest.
The
microstructural evolution was monitored as the irradiation proceeded. It provides a unique
opportunity to
investigate the microstructural evolution in the surrogated
fuel/cladding
interaction product. It
was learned from
IVEM irradiation study that although U(Al,Si)3
and (U,Mo)(Al,Si)3
have very similar crystal structure before irradiation, the
microstructural
response to Kr ion irradiation is significantly different. The former remained
crystal with well
developed loops and dislocation network at 10 dpa while the latter
turned into
amorphous at dose as low as ~1 dpa without well defined loop formation.
This result is inconsistent to the
assumption that amorphization is a set point for aggressive fuel
swelling
because the experimental results from reactor fuel tests showed
acceptable
performance for these two phases.
The
follow-on high dose Kr ion irradiation will provide more insight. Significance This work revealed that the
microstructural stability of phase formed as fuel/cladding interaction
product
can be strongly affected by the fuel composition.
From fuel performance consideration, while
stabilizing the uranium phase is important, special attention should be
given
to the stability of fuel/cladding interaction product which may have a
strong
impact on RERTR fuel performance.
This
finding is significant to understand mechanisms controlling fuel
performance
for RERTR fuel development. The
Kr ion
irradiation using IVEM facility makes it possible to investigate the
microstructural evolution of fuel/cladding interaction product under
surrogated
fission product irradiation damage.
Our
next step is to use Kr ions for high dose irradiation up to 100 dpa for
U(Al,Si)3 and (U,Mo)(Al,Si)3,
crystal vs. amorphous, to
examine the swelling behavior in these two phases.
Performers 
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