JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY
Year:2010 | Volume:- | Issue:2 (51)|Papers Count:16

Uranium is an ubiquitous constituent of natural environment with an average concentration of 4mg/kg in earth crust. However, in local areas it may exceed the normal concentration due to human activities resulting in radionuclide contamination in groundwater and surface soil. The effect of six levels of uranium concentration (0, 50, 100, 250, 500 and 1000mg kg-1) on soil phosphatase activities and microbial populations were studied in a completely randomized design as a factorial experiment with three replications. The results showed a significant decrease in phosphatase activity. The result of the experiment suggests that soil microbial populations (bacteria, funji and actinomysetes) decrease by increasing the uranium levels in the soil. Therefore, assessment of soil enzymatic activities and microbial populations can be helpful as a useful index for a better management of uranium and radioactive contaminated soils.

This paper examines heavy metals removal from synthetics wastes by the use of natural and sulfuric acid-activated bentonite so that a cheap adsorbent can be attained for removing these metals from the wastes. Bentonite is a 2:1 layer aluminnisilicate whose dominant mineral is montmorillonite which is a nano-structure and nanoporous material. Montmorillonite affects all the properties of bentonite. In the next step, the effect of acid activation on the adsorption of both of lead (Pb) and thallium (Tl) is studied. In this research, after the mineralogical and chemical composition analyses by X-ray diffraction and fluorescence (XRD and XRF) methods, granulometric analysis is carried out on five samples namely, S2-RAW, S3-RAW, ES3-RAW, G1-RAW and GH1-RAW to remove the heavy metals such as Cr, Co, Cu, Fe, Pb, Tl, Ni, and Zn accompanying atomic absorption spectroscopy (AAS). Then, the effect of four factors including concentration, liquid to solid ratio (L/S), time, and activation temperature in acid activation process were studied. This process is done by a mineral acid, sulfuric acid, to promote the adsorbability of lead and thallium in both natural and activated types of ES3-RAW and GH1-RAW. In all case, due to the presence of dominant mineral of nano-montmorillonite and its unique structure, montmorillonite has a higher adsorbability in comparison with that of the other clay minerals.

Radiation shielding lead glasses can be used in any facility, which requires protection from radiation, for example medical centers, industrial and nuclear sites. Usually, for improvement of optical properties and homogeneity control of these glasses, homogenization process in different ways is applied. One of the important methods, which also industrially is practical for other glass systems, named fritting, is the process of melting and quenching of molten materials to form small glass particles. In the current work, the effect of homogenization on the thermal and physical properties of lead glasses is investigated. In this way, a composition of lead glass was selected. Then fritting procedure applied six times for this composition and the effect of fritting on thermal, physical, properties and homogeneity of glass were discussed. Finally, microstructural analyses of glass specimens were carried out. Results showed that the increase of the fritting period has an unwanted influence on different properties of the glass samples and this process can be used in joint with considering the other effective parameters.

During 1384-1385, the plants showing root and crown rot were collected from 48 bean fields in the Khuzestan and Markazi provinces. Twenty isolates were identified as Fusarium solani based on morphological characteristics. The pathogenicity tests confirmed four isolates as Fusarium solani f.sp. phaseoli. By using specific primers for this specific form, three isolates showed concordant results with pathogenicity tests. As a result three isolates morphologically and molecularly identified as F.solani f.sp. phaseoli. In order to induce mutation, conidia scraped from F.solani f.sp. phaseoli cultures, were counted, diluted and then plated on water agar. The plates containing conidia were irradiated in a 60Co-gamma cell (with activity of 2500 curi and 0.38 gray per second dose rates) in doses 0, 60, 90, 120, 150, 180 Gy. After 18 hours, the percentage germination of spores were scored. The comparison of percentage germination and vegetative growth in different dose rates showed that spore mutagenesis can be expected in 120-180 Gy.

In this work, neutron production of SBUPF1 (a 2.5 kJ Mather type plasma focus device) at various pressures of deuterium and two different anode lengths (12 cm, 18 cm) were studied. Three silver activation counters were used at three different angels (0o, 45o and 90o) in order to determine the angular distribution of neutrons. The neutron and hard x-ray pulses were registered by a f5”x5” plastic scintillator. These pulses were further used to determine the average energy of the detected neutrons. Experiments showed that for the 18cm anode at the optimum gas pressure, the neutron generation has decreased while the neutron yield at this pressure has increased. Under these conditions, the optimum pressure is 6 mbar, the neutron yield at the optimum pressure is about 6.4x107 per pulse and the average energy of neutrons is 2.24 MeV.

[61Cu]Bleomycin ([61Cu] BLM) was prepared using [61Cu] CuCl2 produced via natZn (p, x)61Cu (180mA proton irradiation, 22MeV, 3.2h), purified by ion chromatography method. [61Cu]BLM was prepared at optimized conditions (room temperature, 45 min, 0.1 mg bleomycin for 2-10mCi 61CuCl2) with radiochemical purity over 98% determined by HPLC and RTLC. [61Cu]BLM was administered into the normal and tumor bearing rodents up to 210 minutes followed by biodistribution and co-incidence imaging studies. A significant tumor/non tumor accumulation was observed either by animal sacrification or imaging method. [61Cu]BLM can be a potential PET radiotracer for tumor imaging.

According to Atomic Energy Organization of Iran (AEOI) Uranium exploration program in Central Iran, Esfordi 1:100,000 sheet which is located in Yazd province, between Bafq & Behabad cities was prospected. The analysis result of the stream sediment samples which were collected by the Geography Society of Iran (GSI) have been used for radioactive resources of this area. Due to lacking of uranium, thorium and Rare Earth Elements (REE) analysis data, the uranium tracers have been used. The data processing, i.e. normalization, univariate and multivariate analysis were studied and ultimately, anomalies maps were prepared. Three uranium potential areas were introduced. These areas include marl and conglomerate sequence in North-west of region, south of Zarigan granite and sandstone sequence with aplites between Esfordi mine and Kooshk mine. Thus, Esfordi sheet is important as a sediment hosted uranium deposit.

In this study, the acrylonitrile (AN)-divinylbenzene (DVB)-methylacrylate (MA) resin was synthesized via suspension polymerization in the presence of toluene as a diluent, and benzoylperoxide (BPO) as an initiator. The effect of MA, toluene and alkaline treatment on the exchange capacity of the resin were investigated. The results showed that the anion exchange capacity decreases with an increase of the amount of MA, while alkaline treatment has no significant effect. Also, the cation exchange capacity increases with an increase in the amount of hydrophilic agent and reaches a maximum. The sorption equilibrium was achieved relatively fast within 40 minutes. The adsorption of uranium was directly depends on the pH value. Finally, the alkaline treatment enhances the potential for the much faster adsorption and the chelating resin provides a more favourable pore structure for the rapid diffusion of the ions.

In this work, the production of 186Re by 185Re (n, γ) 186Re reaction in the Tehran Research Reactor (T.R.R) is investigated. The activity of 186Re was measured after a cooling time of 4 days, using a liquid beta scintillation system and a dose calibrator. Also, activity of the samples was calculated using fluxes determined by Monte Carlo simulation of the reactor core. The calculated and measured values for the activity of irradiated samples are comparable in the range of±18% and the irradiation correction factors are 1.135 and 0.820 for natural rhenium (thermal neutron flux of 6.5x1013 cm-2 s-1)and rhenium samples with high the isotope abundance of 185Re (thermal neutron flux of 1.18x1013 cm-2 s-1), respectively. The results have shown that 186Re samples (in the form of perrhenate) can be achieved with 96.5% radiochemical purity and 99% radionuclidic purity. The productswith the high specific activity of about 300mCi/mg for therapeutical aplications can be achieved in T.R.R. using rhenium sample target with a high abundance from rhenium-185 target; and for the medium with the mean specific activity, natural rhenium can be used.

Gaseous pollutants purification and filtration system of Uranium Conversion Facility includes four Foam Scrubbers and four groups of 24 frame filters to remove dangerous gases and particles from polluted air. In this paper, the purification processes of the dangerous gases in foam towers and removal of the particles in filters are presented. The gas pollution of this facility includes dangerous chemical and radioactive compounds; as a result the high efficiency can be one of the main properties of this purification system. For achieving this goal, theoretical and experimental studies are made to select filter frame media. Our theoretical studies show that the characteristics of the best filter media are: upper thickness, high porosity and formed by fine fibers. The experimental studies to select suitable media concerning efficiency, pressure drop, chemical and mechanical resistance are done in 30 filter media. The efficiency of chosen media is determined of about 99.7% by the experiment. In addition, a semi industrial sample of foam scrubber system was designed and built. The absorption efficiency of the system for acidic gas, the same as in UCF, was measured to be about 97%. Considering these results and prevailing the standards used in UCF and also the level of air pollution in workshops, the air pollution level in the stack outlet must not surpass the authorized amount.