JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY
Year:2003 | Volume:- | Issue:29|Papers Count:10

Column leaching is one of the experimental methods which is used for identifying the specifications of uranium ores. From the efficiency point of view, the process has some complications and usually it is applied in parallel with the conventional leaching process in order to facilitate of finding an appropriate design and operational method, to be applicable in a large practical scale. In this research work, at the first stage, the existed free chlorine in the samples was washed out using seawater. Then, in a process of acid leaching with seawater and sulfuric acid by the use of the column leaching was applied. The results show that the maximum of 85% of uranium from the ore of Anomali #1 is extracted. The extra residual of the used acid dose not react with the uranium and therefore it will increase the free acidity of the leach liquor. In Anomali #6, the extraction efficiency of uranium is 75%, while in Anomali #8, using 30 periods of leaching, the efficiency is 81%. However, the maximum efficiency achievement has to be avoided by the non-economical circumstances. Based on some comparisons, it is shown that the presence of chlorine in ore will affect the efficiency. The capability of "seawater" in uranium extraction from salted arches shaped, compared with the "normal or sweat water" has some advantages. These include: reduction of the operational period, less acid consumption, and reduction in the ore leaching costs. Thus, the heap leaching industry is believed to be a valuable and economical method for uranium extraction, where the needs for utilizing the complicated technical facilities can be reduced. The present work is the first research project on the uranium extraction and concentration in solution containing chlorine. Our experimental results can provide a valuable pattern for the heap leaching of uranium ores design from salted arches shaped in the region Bandar Abbas.

An oscillator-amplifire system consists of a corona-preionized N2-laser operating at intermediate up to atmospheric gas pressure, and a long channel N2 laser operating at low gas pressure was built and studied. When a special design of a low impedance spark gap in a flat-plate Blumlein circuit was utilized, the laser was able to operate at pulse repetition rate of 150 Hz. At this operational condition the average output power of the system was 30 mW which corresponds to 400 kW peak power with the FWHM pulse width of 5 ns. The experimental results showed that long channel N2-lasers will improve the laser output beam, but due to the self-absorption the small signal gain and the laser saturation energy density will be reduced. The technique can be applied to couple and synchronize other self-terminating laser systems, where the use of optical resonators are impractical.

Intravascular radiation therapy for prevention of restenosis is a new emerging technology, which is tested, nowadays, in clinical trials. Several methods of radiation and a variety of isotopes have been tested in different animal models in order to prove the concept and to find a friendly user system for this application. One of the possible intravascular irradiation techniques is to use catheter-based system. The 32P-radiation source made in this study was 0.5mm in diameter and 27mm in length. We first encapsulated 32P by a plastic tube and then encapsulated in a specially manufactured NiTi wire with a diameter of 0.65mm and a length of 2.5m. This solid and flexible wire with the 32P source located in the tip of the wire can be easily inserted in to a coronary vessel. We tested the quality assurance program according to classification of quality assurance of radiation sources, Atomic Energy Regulatory Board (A.E.R.B) at this case.

Reference x-radiations are of practical importance at the standard dosimetry laboratories. The specifications and the operational conditions required to produce reference x-radiations are described in the relevant standards, provided by the International Standards Organization (ISO) and the International Atomic Energy Agency (IAEA). In the present work, an x-ray generator, Philips RT250, has been used to produce medium energy reference filtered x-radiations. Attempts have been made to make the characteristics of the produced x-rays as close as possible to those of the standard beams.

In this paper a simple method for synthesis of sulfo benzyl silica is presented. At the first statge of the applied method, silicagel is dehydrated at 400oC, then the dehydrated silicagel is treated with benzyl magnesium chloride to produce benzyl silica. Finally, benzyl silica is treated with chloro sulfonic acid to produce sulfo benzyl silica. The application of the prepared sulfo benzyl silica as a heterogeneous acidic catalyst in the synthesis and hydrolyis of ethyl acetate has been investigated.

Red meat has a lot of microbial flora from different sources. Prevention of outbreak of food born diseases that are caused by pathogenic agents and prevention of microbial spoilage of meat that makes many losses to the human health and economic of society are very important. Also, different methods for decreasing the microbial flora under a standard allowance for increasing the shelf life and decontamination of microbial pathogens have been proposed. In this research, irradiation technique was used for these purposes. After drawing dose/survival curves for all kinds of meats microbial contamination, an optimum dose of 3 kGy for decreasing the contamination and specially for decontamination of salmonella was obtained. When meat is irradiated by 3 kGy gamma rays, it can be kept in a 4-7oC refrigerator for 2 week without appearing any spoilage nor color changes or odor. Also, some of biochemical factors were analyzed and amounts of 16 amino acids were measured in the irradiated and controlled samples and no difference was observed between the samples.

Uranium is present in the environment as a result of leaching from natural deposits, release in mill tailings, emissions from the nuclear industry, the combustion of coal and other fuels, and the use of phosphate fertilizers that contain uranium. Thus, it is found in drinking water. In this research, A Laser Fluorimetry Method with a minimum detection limit 0.05 µg/l is applied with a laser fluorimeter of type Scintrex® UA-3. A total number of sixteen drinking water samples from different areas of Shiraz were collected. The average results of the total uranium concentration in Shiraz drinking water is equal to 2.765 µg/l. The average annual effective doses received by adults, children and infants from 238U activity in drinking water are located in permissible level of exposure.

Effort has been made to specify surface ozone production in photochemical reaction due to the high concentration of NOX and photon rays. The secondary reactions has been considered via optical measurements using actinometry and pyranometry which was followed for photochemical reactions at high temperature and because of air pollutants due to the traffic load and because of the inversion in certain days. The concentration of surface ozone which was measured in Tehran city center was in the range of 24 - 45 ppb in 1991 - 1992 and a higher concentration of 45 – 65 ppb was measured in 1999 – 2000. This high surface ozone concentration could cause a severe damage to biota, fauna and human health.