Various methods of preparing standards for activation analysis have been reported in the literature. This paper describes
the feasibility of preparing ion exchange resin based standards containing predetermined levels of ions. Using a solution
of known initial concentration of the ion, and given the value of its distribution coefficient, it is possible to predict
the resin concentration that will be obtained. Resins containing ppm levels of copper and manganese have been prepared and
their stabilities evaluated over a period of time. The feasibility of preparing a multielement standard has been studied with
five rare earth elements (La, Ce, Sm, Eu and Dy).
The species of radioiodine in the primary coolant water of the heavy water moderated, heavy water cooled 100 MW research reactor have been identified. It was observed that IO
was the major species in the reactor coolant during reactor operation and I– was the major species during shutdown. Organic and elemental forms amount only to less than 2% of total radioiodine. A simple method was developed for the estimation of gross iodine activity in reactor coolant water. The method involves the separation of all inorganic forms of iodine into a photographic film consisting of a thin layer of silver halide. The iodine in the film was estimated by gross counting of the film in a Geiger-Müller counter. Gross iodine activity in the reactor coolant samples estimated by the present method were in agreement with that obtained by direct -spectrometry with a Ge detector. It is concluded that the method can be used for the routine estimation of radioiodine in reactor coolant water.133I/131I and135I/131I ratios in the film were estimated and found to be useful in identifying split rod conditions in the reactor.
129I content of batches of Na131I vials, used for nuclear medicine procedures, was estimated by neutron activation analysis. The average value of the129I/131I activity ratio /corresponding to zero decay time of the latter/ was /4.98±2.8/x10–9. It is concluded that the contribution of129I from medical applications of131I in India is insignificant in relation to that from nuclear fuel cycle activities.
Authors:R. Venkataramani, S. Mehta, M. Iyer, V. Natarajan, and M. Sastry
Accidental exposure dose assessment by electron spin resonance (ESR) technique from the free radicals generated in a cotton handkerchief has been attempted in this investigation. The cotton handkerchief, a common material carried by individuals, was taken as the medium for free radical estimation. About 55 mg of the irradiated piece of cloth was loaded into a quartz tube and the dose dependence of the ESR signal at g=2.0026 was measured at room temperature, using a Bruker ESP-300 ESR spectrometer in X-band (9.74 GHz). The intensity of this signal was found to be proportional to the dose in the range of 1–1000 Gy. The stability of the free radicals with time of storage was followed. Dependence of dose rate as well as the presence of water on the yield of free radicals were also investigated.
Authors:P. Ravi, M. Iyer, S. Sahasrabudhe, M. Subramanian, and S. Somasundaram
Methods have been developed for the routine analysis of129I in effluents of fuel reprocessing plants using 29.4 keV xenon X-rays. Direct counting methods have been standardized in liquid medium as well as in ion-exchange resin medium. A low energy photon spectrometry Ge detector system and a well-type NaI/Tl/ detector are used for direct counting. Attenuation of xenon X-rays in liquid medium as well as in ion-exchange resin medium have been studied. Sample size is optimized by studying the self attenuation of xenon X-rays in the sample. Activity as low as 1 Bq could be detected with an accuracy of 11% and 30% using LEPS and NaI/Tl/counting systems, respectively.
Authors:S. Godbole, P. Iyer, M. Jayanth Kumar, and M. Sastry
Double sulfates of thallium and lanthanides form an interesting series of compounds with first fractional crystallization leading to the formation of tetrahydrated double sulfates. The radiation induced defects including changes in the oxidation states were studied by carrying out EPR investigations of -irradiated Tl (I) Ln (III) (SO4)2.4H2O (Ln=Sm, Eu and Nd) compounds. The important finding of these investigations is the formation of a radiation-induced paramagnetic center Tl2+ simultaneously with that of Eu2+, revealing their intrinsic association. Similar formation of Tl2+ was not observed in other rare earth salts, implying that the stability of the half-filled electronic configuration of Eu2+ may be responsible for the stabilization of Tl2+. Their relaxation back to Eu3+ and Tl+ simultaneously at 255 K gives further confirmation of their association and suggests that the matrix intrinsically does not favor the stabilization of Eu2+ as reported in a number of other matrices. The hyperfine coupling constant for Tl2+ was calculated using the Breit-Rabi equation and was found to be 80 GHz.
Authors:M. Reddy, A. Damodaran, J. Mathur, M. Murali, and R. Iyer
Mixed-ligand chelate extraction of trivalent lanthanides such as La, Eu and Lu and a trivalent actinide, Am into xylene with mixtures of 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP) and dihexyl-N,N-diethylcarbamoylmethylphosphonate (CMP) has been studied by tracertechniques. These trivalent metal ions are found to be extracted from 0.01 mol/dm3 chloroacetate buffer solutions as M(PMBP)3·HPMBP type self adducts with HPMBP alone and in the presence of CMP as M(PMBP)3·CMP (where M=La, Eu, Lu and Am) into the organic phase. The equilibrium constants of the above species are deduced by non-linear regression analysis. The synergistic constants of trivalent lanthanides do not increase monotonically with atomic number but have a maximum at Eu and that of Am was found to lie between that of La and Eu.
Authors:M. Reddy, G. Preetha, C. Meena, T. Rao, C. Iyer, and A. Damodaran
The extraction of Zn(II) and Cd(II) from thiocyanate solutions with bis-2-ethylhexyl sulphoxide (B2EHSO) in benzene as an extractant has been studied by tracer techniques. For comparison, extraction has also been carried out with tributylphosphate (TBP). The extraction data have been analysed by both graphical and theoretical methods by taking into account complexation of the metal in the aqueous phase by inorganic ligands and plausible complexes extracted into the organic phase. The results demonstrate that Zn(II) is extracted as Zn(SCN)2·2B2EHSO and Zn(SCN)2·2TBP. In the case of Cd(II), the extracted species are Cd(SCN)2·4B2EHSO/4TBP. The synergistic extraction of Zn(II) and Cd(II) with mixtures of 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP) and B2EHSO or TBP or trioctylphosphine oxide (TOPO) from acetate buffer solutions has also been investigated. Zn(II) is extracted as Zn(PMBP)2·B2EHSO/TBP/TOPO. On the other hand, Cd(II) is found to be not extracted with these mixed-ligand systems under the experimental conditions. These results also demonstrate the mutual separation of Zn(II) and Cd(II) using the synergistic extraction with HPMBP in the presence of various neutral oxodonors.
Authors:V. Gopalakrishnan, P. Dhami, A. Ramanujam, M. Krishna, M. Murali, J. Mathur, R. Iyer, A. Bauri, and A. Banerji
Bench-Scale studies on the partitioning and recovery of minoractinides from the actual and synthetic sulphate-bearing high level waste (SBHLW) solutions have been carried out by giving two contacts with 30% TBP to deplete uranium content followed by four contacts with 0.2M CMPO+1.2M TBP in dodecane. The acidity of the SBHLW solutions was about 0.3M. In the case of actual SBHLW, the final raffinate contained about 0.4% -activity originally present in the HLW, whereas with synthetic SBHLW the -activity was reduced to the background level.144Ce is extracted almost quantitative in the CMPO phase,106Ru about 12% and137Cs is practically not extracted at all. The extraction chromatographic column studies with synthetic SBHLW (aftertwo TBP contacts) has shown that large volume of waste solutions could be passed through the column without break-through of actinide metal ions. Using 0.04M HNO3>99% Am(III) and rare earths could be eluted/stripped. Similarly >99% Pu(IV) and U(VI) could be eluted.stripped using 0.01M oxalic acid and 0.25M sodium carbonate, respectively. In the presence of 0.16M SO
(in the SBHLW) the complex ions AmSO
, UO2SO4, PuSO
and Pu(SO4)2 were formed in the aqueous phase but the species extracted into the organic phase (CMPO+TBP) were only the nitrato complexes Am(NO3)3·3CMPO, UO2(NO3)2·2CMPO and Pu(NO3)4·2CMPO. A scheme for the recovery of minor actinides from SBHLW solution with two contacts of 30% TBP followed by either solvent extraction or extraction chromatographic techniques has been proposed.
Authors:J. Mathur, M. Murali, M. Balarama Krishna, R. Iyer, R. Chitnis, P. Wattal, A. Bauri, and A. Banerji
The partitioning and recovery of237Np from three types of simulated high level waste solutions originating from PUREX processing of spent nuclear fuels such as sulfate bearing high level waste (SB-HLW), HLW from a pressurised heavy water reactor (PHWR-HLW) and from a fast breeder reactor (FBR-HLW) have been carried out using a mixture of 0.2M CMPO and 1.2M TBP in dodecane. Quantitative extraction of neptunium was possible by either oxidizing it to the hexavalent state keeping K2Cr2O7 at 0.01M concentration or by reducing it to tetravalent state keeping Fe2+ at 0.02M concentration. Stripping of neptunium was carried out using different reagents, such as dilute nitric acid, oxalic acid and sodium carbonate. Almost quantitative recovery of neptunium has been achieved during these studies.