Band 103, Heft 7

Studies have been carried out on removal of americium from the effluent generated during anion exchange purification of plutonium. Americium 241, generated by the beta decay of Plutonium-241, is the major source of α activity in this highly acidic effluent and its removal would render the waste easily disposable. A simple and effective co-precipitation method, using thorium oxalate has been investigated for the treatment of this alpha active aqueous waste. Experiments have been carried out to identify optimum conditions to obtain high percentage co-precipitation with minimum amount of co-precipitant. Efforts were carried out to correlate the optimum conditions of co-precipitation of americium obtained in these experiments with solubility of thorium oxalate and americium oxalate calculated from solubility products of these compounds, stability constants of thorium and americium oxalate complexes taken from literature. The saturation capacity of thorium oxalate for Am(III) was also calculated by analyzing the K d value data using Langmuir adsorption equation. The strong tendency of americium to get co-precipitated and the high capacity exhibited by thorium oxalate for the uptake of americium indicate feasibility of using this method for the treatment of anion exchange effluent.

Uranyl tris-(carbohydrazide) nitrate [UO 2 ((N 2 H 3 ) 2 CO) 3 ](NO 3 ) 2 was prepared by the reaction of water solution of dioxouranium(VI) nitrate UO 2 (NO 3 ) 2 (H 2 O) 6 with ethanol solution of carbohydrazide (N 2 H 3 ) 2 CO in a molar ratio of 1 to 3 in an neutral medium. The substance was characterized by elemental, thermal analysis and IR and 15 N MAS CP NMR spectroscopy. Ab initio crystal structure determination was carried out using X-ray powder diffraction techniques. The compound crystallizes in monoclinic lattice with unit cell parameters: a  = 15.193(1) Å, b  = 12.005(1) Å, c  = 10.842(1) Å, β  = 109.15(1) ○ , V  = 1868.11 Å 3 , Z  = 4, SG = Cc. The type of carbohydrazide coordination was additionally confirmed by 15 N MAS CP NMR and IR spectroscopy. In the complex ion [UO 2 ((N 2 H 3 ) 2 CO) 3 ] 2+ three carbohydrazide ligands coordinate to UO 2 2+ through oxygen and nitrogen forming three five-membered chelate rings. The carbohydrazide rings are tuned to the equatorial plane of complex. The crystal structure consists of zig-zag chains of [UO 2 ((N 2 H 3 ) 2 CO) 3 ] 2+ cations stretched along c -axis. The cations in the chain are linked by the hydrogen bonds between the cations themselves. The anions are located in the pores between chains and participate in hydrogen bonding between adjacent chains and additionally link the chain sections. The length of the chain section is 5.768 Å and the angle between sections is 140 ○ . The substance [UO 2 ((N 2 H 3 ) 2 CO) 3 ](NO 3 ) 2 is thermally stable up to 215 ℃ and then decomposes with an explosion.

Nuclear forensic analysis was conducted on two uranium samples confiscated during a police investigation in Victoria, Australia. The first sample, designated NSR-F-270409-1, was a depleted uranium powder of moderate purity (∼ 1000 μg/g total elemental impurities). The chemical form of the uranium was a compound similar to K 2 (UO 2 ) 3 O 4  · 4H 2 O. While aliquoting NSR-F-270409-1 for analysis, the body and head of a Tineid moth was discovered in the sample. The second sample, designated NSR-F-270409-2, was also a depleted uranium powder. It was of reasonably high purity (∼ 380 μg/g total elemental impurities). The chemical form of the uranium was primarily UO 3  · 2H 2 O, with minor phases of U 3 O 8 and UO 2 . While aliquoting NSR-F-270409-2 for analysis, a metal staple of unknown origin was discovered in the sample. The presence of 236 U and 232 U in both samples indicates that the uranium feed stocks for these samples experienced a neutron flux at some point in their history. The reactor burn-up calculated from the isotopic composition of the uranium is consistent with that of spent fuel from natural uranium (NU) fueled Pu production. These nuclear forensic conclusions allow us to categorically exclude Australia as the origin of the material and greatly reduce the number of candidate sources.

There is a lack of data on the diffusion of long-lived radionuclides in soils, especially of those originated from the leaching of radioactive waste in waste disposal facilities. Here, the simultaneous diffusion of two radioselenium species, which were postulated to be radioselenite and radioselenate, was examined for the first time in four soils at laboratory level by applying the planar-source method. The Gaussian-shaped experimental diffusion profile was deconvoluted into two Gaussian functions, and then the apparent diffusion coefficients ( D a ) were quantified for each species. Radioselenate D a values ranged from 1.4E-11 to 1.5 · 10 – 10  m 2  s – 1 , while those of radioselenite were two orders of magnitude lower (from 5.2E-13 to 2.7 · 10 – 12  m 2  s – 1 ) for all samples and conditions tested. The radioselenite distribution coefficient values derived from D a correlated to soil properties, such as pH and Al/Fe mineral content, and thus were consistent with the factors controlling the sorption of selenium species in soils.

Solid-liquid extraction of the group 4 elements Zr and Hf, which are homologues of Rf ( Z  = 104), and Th, a pseudo homologue, by triisooctylamine (TIOA) from HCl solutions was performed by batch method. After examining the time required to reach extraction equilibrium for these elements in various concentrations of TIOA and HCl, we investigated in detail variations in the distribution coefficients ( K d ) with TIOA and HCl concentrations. The K d values of Zr and Hf increased with increasing the HCl and TIOA concentrations, suggesting an increase in the abundance of the anionic chloride complexes of Zr and Hf. On the other hand, the K d values of Th were low in all the HCl concentrations studied, implying that Th does not form anionic species dominantly. We developed a new automated batch-type solid-liquid extraction apparatus for repetitive experiments on transactinide elements. Using this apparatus, we performed solid-liquid extraction employing the radioactive nuclides 89m Zr and 175 Hf produced by nuclear reactions and transported continuously from the nuclear reaction chamber by the He/KCl gas-jet system. It was found that the distribution behaviors in 7–11 M HCl are almost constant in the time range 10–120 s, and the K d values are consistent with those obtained in the above manual experiment. This result suggests that the chemical reactions in the extraction process reach equilibrium within 10 s for Zr and Hf under the present experimental conditions. It took about 35 s for the extraction using the apparatus. These results indicate the applicability of the present extraction using the developed apparatus to 261 Rf ( T 1/2  = 68 s) experiments.

The broad-spectrum antibiotic agents have been demonstrated as promising diagnostic tools for early detection of infectious lesions. We set out ofloxacin (Oflo), a second-generation fluoroquinolone, for the radioiodination process. In particular, this was carried out with 125 I via an electrophilic substitution reaction. The radiochemical yield was influenced by different factors; drug concentration, different oxidizing agents, e.g. chloramine-T, iodogen and n-bromosuccinimide, pH of medium, reaction time, temperature and different organic media. These parameters were studied to optimize the best conditions for labeling with ofloxacin. We found that radiolabeling in ethanol medium showed a 70% radiochemical yield of 125 I-ofloxacin. The radioiodination was determined by means of TLC and HPLC. The cold labeled Oflo ( 127 I-Oflo) was prepared and controlled by HPLC. The cold labeled Oflo was also confirmed by NMR and MS techniques. Furthermore, biodistribution studies for labeled 125 I-Oflo were examined in two independent groups (3 mice in each one); control and E. Coli -injected (inflamed). The radiotracer showed a good localization in muscle of thigh for inflamed group as compared to control. In conclusion, ofloxacine might be a promising target as an anti-inflammatory imaging agent.

Nickel based alloys play important role in nuclear, mechanical and chemical industry. Two semi-absolute standardless methods, k 0 -instrumental neutron activation analysis ( k 0 -INAA) and fundamental parameter X-ray fluorescence spectrometry (FP-XRF) were used for the characterization of certified nickel based alloys. The optimized experimental conditions for NAA provided results for 18 and XRF for 15 elements. Both techniques were unable to quantify some important alloy making elements. However, both reported results of other elements as information values. The techniques were analyzed for their sensitivity and accuracy. Sensitivity was evaluated by the number of elements determined by each technique. Accuracy was ascertained by using the linear regression analysis and the average root mean squared error.