IGCAR : Annual Report - Indira Gandhi Centre for Atomic Research

IGC
Annual Report 2007
Fig.1 Variation of D Pu(IV) with nitric
acid concentration.
after washing the column, it
was eluted with 0.5 M nitric
acid. It is seen from Fig.2 that
for 4% PVP resin, about 99.8%
of the loaded plutonium could
be eluted within 3 bed volumes,
whereas for 8% PVP about 93%
of plutonium could be eluted.
The 12% resin shows a poor
and incomplete elution pattern;
only 86% of plutonium could
be eluted within 5 bed volumes.
Under similar conditions Dowex
1X4 also exhibits poor and
incomplete elution pattern.
Even after 6 bed volumes only
about 66% of the loaded Pu
could be eluted.
Fig.2 Elution profile of PVP resins
and Dowex 1X4.
Radiation degradation
The resins were irradiated in a
Co-60 gamma chamber in
presence of 8 M nitric acid,
after which the resins were
analysed for capacity, moisture
content and Pu distribution
ratios. All the resins were
irradiated up to 200 MRad of
total absorbed dose. As
expected, for all the resins the
D Pu(IV) decreased with the
increase in dose. The value of
D Pu(IV)
of 200 MRad irradiated
8% PVP resin was nearly
identical to that of 100 MRad
irradiated Dowex 1X4. At 200
MRad of total cumulative dose,
PVP resin shows little damage
in the form of dimples over
bead surface (Fig.3) but it takes
up plutonium over a range of
nitric acid concentration,
whereas Dowex 1X4 was
completely degraded. As the
total absorbed dose increases,
the strong-base capacity of the
resin decreases, indicating the
deterioration of functional
group (i.e. methyl group) upon
irradiation. The deterioration of
the polymer matrix upon
irradiation is also manifested in
the increase in moisture content
of the irradiated resin and
increase in volume of resin.
Palladium recovery
Palladium is a precious metal
with good catalytic, corrosion
and oxidation resistant
properties, which have resulted
in its widespread use in
different industries. The natural
abundance of palladium is very
low and thus, there is an
incentive in recovering
palladium from the high level
Fig.3 SEM images of unirradiated and
200 MRad irradiated 8% PVP resin.
waste generated in Fast Reactor
Fuel Reprocessing. At IGCAR,
we have developed a method
for the recovery of palladium
from nitric acid medium. We
have used 8% PVP resin for the
recovery of palladium from 2 M
and 4 M nitric acid medium. In
a small column of 7.2 ml about
1000 ml of solution containing
210 ppm of palladium was
passed and it was observed that
even the last 200 ml of effluent
contains less than 2 ppm of
palladium. Similar results were
obtained when 400 ml of
solution containing 800 ppm of
palladium was passed.
Palladium was eluted with 0.5M
thiourea in 0.1M HNO3 and
95% of loaded palladium was
eluted in four-bed volume of
column. When the solution
containing palladium,
ruthenium and rhodium were
passed through the column
only palladium was loaded.
The above studies indicate
that 4-vinylpyridine resins can
be used for recovery and
purification of plutonium as
well as for the recovery of
palladium from radioactive
waste solutions.
84 FUEL CYCLE