Band 110, Heft 12

The neutron capture cross section for the 164 Dy(n,γ) 165 Dy reaction at 0.0372 eV energy was measured using the horizontal channel (Neutron Diffraction Facility) of Es-Salam nuclear research reactor in Birine-Algeria. The Neutron Activation Analysis (NAA) technique using 197 Au(n,γ) 198 Au as reference reaction was adopted. The γ ray spectra for the Dy 2 O 3 target powder and two thin gold foil were detected for the Germanium Hyper Pure coupled in the Genie 2000 data acquisition software. A resulting σ -value (2198.5 ± 94) b was measured for the thermal neutron cross section after correcting the thermal neutron self-shielding and γ attenuation effects. The measured value was then compared to the evaluated cross sections reported in two different libraries of neutron databases ENDF/B-VIII.0 and JEFF-3.3. The measured data at 0.0372 eV has been extrapolated to the energy of 0.0253 eV assuming 1/ ν dependence in the thermal energy region and the result was compared with the fully measured values reported in the literature.

The solution, containing 2 M NaOH and 4.8 mM Pu(VI) mainly in ionic-dispersed phase, becomes dark blue during 2–3 min under ozonation. The absorption spectrum of the solution in the visible range coincides with the well-known absorption spectrum of Pu(VII). The addition in Pu(VII) solution of the aliquot of Pu(VI) solution reduces the absorbance of the solution at any wave length in proportion to dilution. Consequently there is no the influence of Pu(VI) on the absorption spectrum of Pu(VII). Thus, it is become obvious no Pu(VIII) formed in the course of ozonolysis of Pu(VII) alkaline solution. Additionally, crystalline Pu(VII) and Np(VII) compounds were synthesized, their electron absorption spectra were measured and compared with the ones of alkaline solutions. A similar structure of the spectra also indicates a heptavalent oxidation state of neptunium and plutonium in the synthesized crystalline compounds. Thus, the experimental results of this work, along with an analysis of the experimental results of other authors, presented in this work, make it possible to definitely conclude that at present time the highest of the known oxidation states of plutonium oxidation in aqueous solutions is the heptavalent state and all statements about the production of octavalent plutonium in aqueous solutions should be considered as unreasonable.

Even though, pyroprocessing is considered as a suitable technique for metal fuel processing, attempts are being made in our laboratory to develop a solvent extraction based process as an interim method. Since, the metallic fuels contain considerable amount of Pu(IV) and Zr(IV), the use of conventional extractant tri- n -butyl phosphate (TBP) for reprocessing may pose problems due to third phase formation. In the exploration for the identification of an alternate extractant in the organophosphate family, tris(2-methylbutyl) phosphate (T2MBP), a branched isomer of tri- n -amyl phosphate (TAP) was found to be a potential extractant for nuclear fuel reprocessing. In this context, batch wise extraction and stripping studies with a feed solution containing U(VI) and 6 wt% Zr(IV) were carried out with unirradiated and irradiated 1.1 M solution of T2MBP in n -dodecane ( n -DD) and the results were compared with corresponding solutions of TBP and TAP in n -DD. Among all these systems under identical conditions, third phase formation was observed only in the case of irradiated TBP system which makes U–Zr fuel reprocessing difficult using TBP as the extractant. Furthermore, studies have also been carried out with U–Pu–Zr feed solution to understand the extraction and stripping behaviour of these extractants. The stage wise and cumulative percentage of extraction and stripping for each metal ion of these systems were evaluated. Overall, these batch studies indicated that, T2MBP system has comparable extraction and stripping behaviour with U–Zr and U–Pu–Zr feed solutions and T2MBP exhibits better separation factor than TBP.

Due to continuous self-sealing and good mechanical properties, the Tamusu clay rock of Inner Mongolia has been identified as the pre-selected site for high-level radioactive waste geological disposal site in China. The study of chemical behaviors related to Tamusu clay rock, such as nuclide migration, will be an important content of the performance assessment and safety assessment of the disposal repository in the future. The diffusion behavior of HTO and Se(IV)/Se(VI) with different compacted column lengths in Tamusu clay rock is discussed by the through-diffusion method. The diffusion coefficient, rock capacity factor, effective porosity, and other diffusion parameters closely related to nuclide migration are calculated, and the mechanism of nuclide diffusion is preliminarily discussed. The results show that D a (6.23 × 10 −11 ∼17.96 × 10 −11  m 2  s −1 ), D e (1.62 × 10 −11 ∼4.67 × 10 −11  m 2  s −1 ) for HTO increase with the increase of the compacted column length, and it is proposed that the diffusion process of HTO is affected by the change of geometrical factor and path tortuosity. D a (7.29 × 10 −13 ∼1.74 × 10 −13  m 2  s −1 ), D e (5.15 × 10 −12 ∼2.15 × 10 −12  m 2  s −1 ) for Se(IV), D a (3.11 × 10 −12 ∼1.09 × 10 −12  m 2  s −1 ), D e (2.53 × 10 −12 ∼1.09 × 10 −12  m 2  s −1 ) for Se(VI), which decrease with the increase of the compacted column length, it is mainly due to the existence of anion repulsion effect.

One of the innovative methods in cancer treatment with fewer side effects is the use of active principles produced by animals and microorganisms to generate new drugs with diagnosis and treatment capability for cancer. Androctonus crassicauda scorpion venom has high potential as an anti-tumor agent and has the ability to interfere with human physiology but is still unknown. Therefore, labeling venom with radionuclides is very important to study the biological distribution of toxins for diagnostic and therapeutic purposes of various diseases, especially cancer. In this research, the toxic fraction of this venom was labeled with 99m Tc. The radiochemical purity of the labeled toxic fraction was obtained by using chromatographic systems. Animal biodistribution studies were performed after injecting the labeled compound into normal rats and 4T1 breast cancer-bearing mice. The radiochemical purity of 90% was obtained for labeled compound. Biological distribution studies showed relatively rapid clearance of the labeled compound from the blood circulation system. The accumulation of the labeled compound in the liver and kidney was the highest among the organs, which could indicate the possibility of toxin excretion metabolism from liver and the kidneys. The accumulation rate of the labeled compound after 15 min was 7% in the breast cancer mass, and the ratio of the distribution of the labeled compound in the breast cancer mass to the blood was 155% at 15 min post injection. The study results indicated that scorpion venom labeling with 99m Tc could be a useful tool for the biodistribution and kinetic studies of the venoms for clinical use. On the other hand, based on the results of the biological distribution of the labeled compound in tumor-bearing mice, the 99m Tc-venom complex can be used as an imaging agent to diagnose breast cancer. Moreover at the same time, with some measures, it can be used as a therapeutic agent for breast cancer with more consideration. We hope that the results of this study will be a step in the future for the clinical diagnostic and therapeutic purposes of cancer using natural products.

A batch equilibrium method was utilized to evaluate the retention of Fe(III) and Pb(II) onto stannic oxide (SnO 2 ) nanomaterial. SnO 2 was prepared by a simple precipitation method and characterized by different analytical apparatuses like FT-IR, SEM, TEM, and XRD. Scherrer’s formula and Williamson-Hall (WH) analysis were utilized to detect the crystallite size and lattice strain. The XRD and TEM data revealed that SnO 2 has a nanoscale and crystalline nature. The retention study for Fe(III) and Pb(II) includes the influence of shaking time, batch factor, pH, initial concentrations, capacity, and applications. The data reveal that the maximum uptake of SnO 2 was achieved at pH 2.5 and 3.7 for Fe(III) and Pb(II), respectively. SnO 2 has a fast kinetic (60 min) and the reaction kinetic data obey the pseudo–second-order model. The capacity has values of 50.4 and 48.8 mg/g for Fe(III) and Pb(II), respectively. The real sample applications proved that SnO 2 is an excellent sorbent for the capture of Pb(II) and Fe(III) from industrial wastewater and low-grade monazite (LGM) respectively, in addition to the capture of 59 Fe radionuclide from low-level radioactive waste (LLRW).