JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY
Year:2006 | Volume:- | Issue:2 (37)|Papers Count:12

As, the Russian designed VVER-1000 reactor of the Bushehr Nuclear Power Plant (BNPP) by taking into account the change from German technology to that of Russian technology, and with the design of elevation change in the cold legs has been developed; therefore safety assessment of these systems for loss of coolant accident (LOCA) in elevation change in the cold legs and comparison results for non change elevation in the cold legs for a typical reactor (normal design of nuclear reactors) is the main important factor to be considered for the safe operation. In this article, the main objective is the simulation of the loss of coolant accident scenario by the ELAP5/MOD 3.2 code in two different cases; first, the elevation change in the cold legs, and the second, non change in it. After comparing and analyzing these two code calculations the results have been generalized for a new design feature of Bushehr reactor. The design and simulation of the elevation change in the cold legs process with RELAP5/MOD3.2 code for PWR reactor is performed for the first time in the country, where it is introducing several important results in this respect.

Many results have been obtained in our previous studies on the effects of structural defects on the physical properties of crystalline materials. In this work, we are presenting our experimental results for the influence of the structural deffects on the absorption coefficient and the penertration depth of b-particles in aluminum metal. For this investigation, 3 pieces of Al foils, with different thicknesses. were prepared. Then, one group of samples were annealed to show less defects. Other Al samples were exposed to heavily defect creating work, such as: hammering, rolling, and thermal quenching treatments. Then, by the use of the conventional method, the penetration depth of b-particles of different energies from 90Sr, 36Cl, and 13Cs sources were determined. Our results show that the measured R-values for the defected samples are higher than those of the annealed ones. Also, it was found that the penertration depth for the defected samples increases as the b-particle's energy increases.

Recently, the use of filled angioplasty balloon with radioactive solution was proposed as one of the new intravascular irradiation techniques to reduce restenosis. Measurement of dose distribution beyond an angioplasty balloon filled with 186Re-perrhenatewas carried out using a radiochromic film. The measured dose rate in distance of 0.4mm from the balloon surface (with diameter 4mm and length of 40mm) was 2.07 [(cGy/min)/(mCi/ml)]. Calculation of dose was carried out for the balloons with various size, using Monte-Carlo method with MCNP4B code and the result was comparable with the experimental results. Suitable specific concentrations for delivery of doses from 12 to 20 Gy in vessel wall were obtained 250 to 400(mCi/ml) in the time of irradiation less than 4min and the fall of radial dose was obtained approximately 80 percent in radial distance of 0.5mm from the balloon surface. The internal dose was calculated by MIRD method with assuming that in the case of balloon rupture, 186Re-DTPAcontents were released into the circulation system and was about 0.0027 cGy/MBq which is comparable with the 99mTc-DTP Amodel. Therefore, using from 186Re-DTPA is suitable due to the radiation safety and the delivery of dose in order to reduce restenosis for the coronary vessels with centric cross section.

In this research FMD virus type A87/IRN was used. The virus was multiplied on a BHK2I cell line. Then, the virus titration was detected by TCID50% (Tissue Culture Infection Dose 50%) method, and it was 107.5/ml. The FMD virus was irradiated by gamma ray from 60CO source in-4 till 4oC. The gamma cell, model Issledovapel-PX-30, with the dose rate of 0.551 Gy/sec was applied. Different doses of gamma ray were applied and 6 times were repeated for each dose. Antigenicity and infectivity of the irradiated and control virus samples were studied by Complement Fixation, and Cell Culture methods, respectively. The dose/survival curve for the FMD virus was drawn, according to the curve and D10 Value factor (Dose of gamma ray that decrease one logarithmic cycle of virus population) was obtained, and the optimum dose for inactivation of FMDV type A87/IRN and the unalteration its antigenicity of 40-44kGy was obtained.

In this study 38 water and sludge samples were collected from various areas of Anzali lagoon and 100 strains were isolated when the samples were cultured in the media. Among them, only one strain showed the maximum absorption capacity (65.4 mg/g dry wt). It was tentatively called MGG-83 strain. Further investigations proved that the strain MGG-83 belonged to the genus of Bacillus. The maximum uptake of tungsten was obtained at pH 2. The tungsten taken up by the Bacillus sp. MGG-83 increased by increasing the concentration of the tungsten. At 600mg/l, the uptake was 545.6 mg/g dry wt. The uptake of tungsten within 5 min of incubation was relatively rapid and the absorption continued slowly thereafter. When sodium azide and 2,4 dinitrophenol were used, it was evident the 80% of the absorbed tungsten is independent of the metabolism and 20% depends on the metabolism. When the cells were treated by the heat, the tungsten uptake decreased to 11%. The tungsten uptake increased with increasing in biomass of dry weight of the cells (87% at 20 mg biomass; 100% at 25mg biomass). The applied temperature in the range of 20-45oC did not show any significant change in the uptake.

Genetic variation is an essential factor for the crop breeding. Induced mutations are highly effective to enhance the natural genetic resources, and have assisted in developing the improved cultivars of fruits and other crops. The recent advances in biotechnological techniques have the potential to provide efficient methods of vegetative propagation, screening techniques and genetic improvement through the mutation. On this basis, we selected tangerine (Celemantin cv) as a well-adapted, and highly consumed citrus fruit which has a disadvantage of containing too many seeds in it's flash. We applied physical mutagen (g-ray) with dose rates of (35,40 and 45 Gy) for lateral bud after shoot tip grafting (stg) and production of contaminated-free plants. The irradiated buds were grafted to sour orange as root stocks (M1V1) and chimera dissolved by further vegetative propagation. Finally, the MIV3 plants were transferred to the field and after the production of the fruits, selection has been made. The results have showed that radiation was able to produce seedless, early and late ripening and cold resistance samples. Tangerine (Clemantine Cv) has also shown that it possesses a high yield of production.

Recovery and chemical purification of Mo-98 from graphite collector which was separated by EMIS were made for the first time in Iran. In this research work, metallic Mo-98 isotope deposited on the internal surface of graphite was separated from pocket by scraping. Then, carbon was removed from the mixture of molybdenum and graphite by burning at 850oC in oxygen atmosphere in the form of CO2 and molybdenum was converted to oxide form (MoO3). Molybdenum tri-oxide was dissolved in hot and concentrated ammonia solution. In alkaline condition, the major impurity of Fe as hydroxide form was precipitated. In the next step, after acidifying the solution by sulfuric acid, a-benzoin oxime was added, and molybdenum organometalic complex was formed. The complex was filtrated, dried and ignited at 500oC in electrical furnace. Finally, 98MoO3 was obtained. The crystalline structure of MoO3 was confirmed by X-ray Diffraction (XRD) and its chemical purity of 97.44% was determined using the ICP-emission spectrometer.

In this article the noise reduction of the experimental data by the Fourier and the wavelet transforms has been investigated. Using both simulated and experimental data (from the plasma focus facility, Dena), the sensitive features of the application of the Fourier transform are visualized and discussed. Then, the main idea of the wavelet transform and the results of the noise reduction with this transform are presented. Due to this investigation, for the cases such as the current derivative of the Dena facility, where the reliability of the Fourier transform can be doubtful, the wavelet transform can be considered as a more accurate alternative approach.