•Layered chalcogenide with CdI2 crystal structure prepared by hydrothermal route.•Exploration of the possibilities for radionuclides’ uptake using layered chalcogenide.•Proposing ‘topotactic ionic ...substitution’ as major uptake mechanism.
Ensuring environmental protection in and around nuclear facilities is a matter of deep concern. Toward this, layered chalcogenide with CdI2 crystal structure has been prepared. Structural characterizations of layered chalcogenide suggest ‘topotactic ionic substitution’ as the dominant mechanism behind uptake of different cations within its lattice structure. An equilibration time of 45min and volume to mass ratio of 30:1 are found to absorb 233U, 239Pu, 106Ru, 85+89Sr, 137Cs and 241Am radionuclides to the maximum extents.
Separation of palladium from high level liquid waste (HLLW) solution originated from the reprocessing of spent fuel by PUREX process is carried out by solvent extraction and precipitation methods ...using oximes. In solvent extraction, palladium is extracted from the waste using 1.1×10
−2M α-benzoin oxime in Solvesso 100 as extractant. The loaded organic phase is scrubbed with water prior to the stripping of palladium using the strippants 0.05 M thiourea in 0.1 M HNO
3 and 4 M NH
4OH separately. The recovery of the method is found to be >99.5%. The method has been used to recover Pd in sub mg quantities from actual waste solution originated from the reprocessing of spent fuel from pressurised heavy water reactor (PHWR-HLLW). Studies are also carried out for the separation of palladium using an aqueous solution of sodium salt of dimethyl glyoxime (0.1% w/v) as precipitant. Various parameters which influence the precipitation of palladium such as concentration of the precipitant, concentration of nitric acid in the feed and the behaviour of uranium, plutonium and other fission products at the concentration level encountered in the waste are studied in detail. Under the optimized precipitation conditions separation of Pd is carried out from a synthetic PHWR-HLLW and the recovery is found to be >99.9%. The palladium product obtained from both the methods show high decontamination factors with respect to other fission products and constituents of the waste. Based on these results a scheme has been proposed for the recovery of palladium from HLLW.
This paper describes our studies on the partitioning of actinides from high level liquid waste of PUREX origin employing
a supported liquid membrane technique. The process uses a solution of DHDECMPO ...in
-dodecane as a carrier with poly tetra
fluoro ethylene support and a mixture of citric acid, formic acid and hydrazine hydrate as a receiving phase. Transport studies
are carried out for
Am under different experimental conditions to optimize the transport parameters such as feed
acidity, carrier concentration and effect of uranium, Nd(III) and salt concentration in the feed. Studies indicated good
transport of neptunium, americium and plutonium across the membrane from a nitric acid medium. Under the optimized conditions
the transport of
Am has been studied for uranium depleted synthetic PHWR-HLW and finally the technique is used
for the partitioning of alpha emitters from an actual HLW after reprocessing. A high concentration of uranium in the feed is
found to retard the transport of americium, suggesting the need of prior removal of uranium from the waste. Separation of
actinides from uranium-lean simulated as well as actual HLW has been found to be feasible using the above described technique.
The present studies deal with the application of the supported liquid membrane (SLM) technique for partitioning of actinides from high level waste of PUREX origin. The process uses a solution of ...octylphenyl-N,N'-diisobutylcarbamoylmethyl phosphine oxide (CMPO) in n-dodecane as a carrier with a polytetrafluoroethylene support and a mixture of citric acid, formic acid, and hydrazine hydrate as the receiving phase. The studies involve the investigation of such parameters as carrier concentration in SLM, acidity of the feed, and the feed composition. The studies indicated good transport of actinides like neptunium, americium, and plutonium across the membrane from nitric acid medium. A high concentration of uranium in the feed retards the transport of americium, suggesting the need for prior removal of uranium from the waste. The separation of actinides from uranium-lean simulated samples as well as actual high level waste has been found to be feasible using the above technique.
Solvent extraction studies of Y
3+
and Sr
2+
with 2-ethylhexyl 2-ethylhexyl phosphonic acid (KSM-17) and octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) are carried out from aqueous ...media containing a wide range of nitric acid and other potential reagents to arrive at the operating conditions for the selective transport of
90
Y using supported liquid membrane (SLM) containing these reagents as carriers. Since the transport data of
90
Y using single cell SLM with KSM-17 was available from our earlier experiments, single cell transport studies with CMPO carrier are only carried out to optimize the strippant phase. Transport studies with pure
90
Y is carried out using a transport cell with two SLMs one with KSM-17 and the other CMPO carriers to optimize the transport parameters. Based on these data the development of a two stage SLM system for the generation of carrier free
90
Y from
90
Sr source is described. The procedure described is amenable for automation and scale up.
A solvent extraction technique has been developed for the radiochemical separation and purification of
144
Ce from Purex high-level waste (HLW). The feed solution initially was in contact with ...granulated ammonium molybdophosphate for the selective removal of cesium to reduce the gamma dose during the subsequent process. In the next step, uranium and plutonium were removed quantitatively by using 20% 2-ethylhexyl hydrogen 2-ethylhexyl phosphonate (KSM-17) in dodecane. The trivalent cerium present in the cesium-, uranium-, and plutonium-depleted raffinate was oxidized to its tetravalent state by using K
2
Cr
2
O
7
and was extracted into KSM-17. The loaded cerium from the organic phase was stripped with 0.5 M nitric acid. Final decontamination from trace impurities such as
106
Ru and
125
Sb could be achieved by an additional cerium-extraction step with KSM-17 at pH 2, followed by its stripping with 0.5 M HNO
3
. About 10 mCi of cerium was separated from Purex HLW by using this technique. This method is amenable for automation and scale up.
A solvent extraction technique has been developed for the radiochemical separation and purification of super(144)Ce from Purex high-level waste (HLW). The feed solution initially was in contact with ...granulated ammonium molybdophosphate for the selective removal of cesium to reduce the gamma dose during the subsequent process. In the next step, uranium and plutonium were removed quantitatively by using 20% 2-ethylhexyl hydrogen 2-ethylhexyl phosphonate (KSM-17) in dodecane. The trivalent cerium present in the cesium-, uranium-, and plutonium-depleted raffinate was oxidized to its tetravalent state by using K sub(2)Cr sub(2)O sub(7) and was extracted into KSM-17. The loaded cerium from the organic phase was stripped with 0.5 M nitric acid. Final decontamination from trace impurities such as super(106)Ru and super(125)Sb could be achieved by an additional cerium-extraction step with KSM-17 at pH 2, followed by its stripping with 0.5 M HNO sub(3). About 10 mCi of cerium was separated from Purex HLW by using this technique. This method is amenable for automation and scale up.
