JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY
Year:2015 | Volume:- | Issue:72|Papers Count:12

In this study, due to radionuclidic uptake evaluation by rice variety (Hashemi & Khazar types) in Gilan province-Siyahkal city and annual effective dose determination for the use of these two types of rice, 16 rice genotype samples and 16 samples from the related paddy soils were collected. After the sample preparation, the type of radionuclides and their specific activities were determined for each sample by the method of gamma spectrometry. Finally, the transfer factor and annual effective dose, due to the use of these two types of rice, were calculated via the related formulas. The soil of the area contained actinium-228 (228Ac), bismuth-214 (214Bi), cesium-137 (137Cs), lead-214 (214Pb), thallium-208 (208Tl), and potassium-40 (40K) with the average activities of 49.96, 47.73, 23.09, 50.63, 18.00 and 711.30 Bq/kg, respectively. The rice seeds contained only 40K as a natural radioactive element with the average specific activities of 128.23 and 138.28 Bq/kg for Hashemi and Khazar types, respectively. The average transfer factor of 40K from soil to rice was 0.19 for the Hashemi type and 0.21 for Khazar type. This factor for the both types of rice was approximately the same. Also, the annual effective dose for consuming these two types of rice was 0.031 and 0.034 mSv/year for Hashemi and Khazar types, respectively. The annual effective dose is much lower than the standard permissible limit (1 mSv/year). Therefore, from this point of view, the use of these two types of rice will not threaten the health of the consumers.

This article aims at investigating the genetic diversity arising from two physical mutagens (gamma ray, electron beam) with different doses (50-400 Gy) and two different levels of humidity (6.5% and 12.5%) in the (Triticum aestivum L.) plant in Tabasi cultivar, using RAPD markers. The maximum and minimum average rates of heterozygosity were obtained in the second and the fifth populations (0.155 and 0.042), respectively. Based on the obtained results, the highest genetic distance or the lowest genetic similarity was observed between M1TE population (the first generation mutant lines mutated by electron) and M2TE population (the second generation mutant lines mutated by electron). The lowest genetic distance or the highest genetic similarity was found between M2TG (the second generation mutant lines of mutated by gamma ray) and M2TE (the second generation mutant lines mutated by electron) populations. Five mutant lines and Tabasi species witnesses were investigated based on common genetic values using UPGMA cluster analysis. Cutting the obtained dendrogram from the similar point (0.89), two groups were achieved. Based on the obtained results the inter-population diversity was more significant than the intra-population diversity.

The biosorption process of thorium in a batch system by modified brown algae Sargassum glaucescens is discussed in this paper. For this purpose, the results of biosorption on raw algae and modified by glutaraldehyde and diethylenetriamine (DETA) were compared. Also, other variables that are necessary for adsorption process design such as optimum pH, time effect, biosorption isotherm, adsorbent dosage, number of biosorbent recovery stages for reuse were investigated. It was deduced that 10% of glutaraldehyde solution is the best. The experimental results indicated that the maximum sorption was observed at pH 3.5. The uptake was rapid and the biosorption process reached equilibrium within 6h of contact time at the optimum pH. The kinetics data were fitted well to Lagergren’s pseudo-second-order rate equation. Modeling of equilibrium sorption data with the Langmuir and Freundlich models (two-parameter models), and Redlich-Peterson three-parameter model indicated that the Redlich-Peterson model gave a better fitting to the experimental observations. The maximum thorium sorption was 151.52 mg Th/g adsorbent obtained from the Langmuir isotherm. The algae recovery by using 1 M HCl solution for biosorbent reuse showed that the biosorbent capacity decreases from 89.15 mg Th/g adsorbent at the first stage of recovery to 70.02 mg Th/g adsorbent at its fifth stage.

In this work, a useful equipment for recording and analysing of random processes was developed based on field programmable gate array (FPGA). The system covers a range of different applications in the nuclear fields of study. The system is potentially applicable for zero power reactor noise analysis, time coincidence of stochastic events, dead time estimation, and probability distribution function of random processes. The designed and constructed system was tested and validated by generated pseudorandom processes. Some of the basic analysing methods of random processes were checked and verified experimentally. As the performance of the system depends on the hardware, the designed architecture is implemented on a typical system. The best performance is reported in the text.

In this study, gamma irradiation as a method for fungal decontamination of a historical oil painting was evaluated. For this purpose, an oil painting belonging to the Ghajar period with Ghahvekhanei style was selected. Sampling of suspected and discolored points on the surface and backside of the artwork was done and the total counts of fungi were detected. The dose of gamma ray for decontamination of painting was calculated. To study the radiation effects on the color materials used in the painting, small samples were taken from its two main colors. The chemical structure and color measurement of the samples were monitored by FTIR and colorimeter before and after the irradiation. No infrared spectral changes were observed after the irradiation. Furthermore, it was found that gamma irradiation did not induce any significant color alterations. These results showed that irradiation with tested dose (5 kGy) did not damage the oil painting and therefore the radiation method could be recommended for disinfection of this kind of artwork.

Prostate specific antigen (PSA), a serine protease, is a highly reliable biochemical marker used for detection and management of prostate cancer. PSA in serum samples is measured by an immunoanalytical technique such as immunoradiometric assays (IRMA). In this study the preparation method and the effective factors on the efficiency and the stability of the labeled anti-PSA monoclonal antibody with I-125 as a tracer in the immunoradiometric kit (IRMA) were investigated. To perform an IRMA assay, at first, the labeled anti-PSA monoclonal antibody was formed using oxidizing agents, namely Chloramine-T and Iodogen, then the product was separated and purified by Sephadex G-25 column. After the determination of radiochemical purity, I-125 labeled antibody was used in the in-house PSA IRMA kit. The effects of the proportion antibody/I-125(17.6-53 mg/mCi), Chloramine-T/antibody (0.75 & 1.5 mg/μg) and the labeling time (15-60 s) on the efficiency and stability of the labeled antibody were studied. According to the calibration curve and concentration of control samples, Chloramine-T radioiodination procedure was optimized (Chloramine-T/antibody: 1.5 mg/mg & labeling time: 50s). The variety of the proportion antibody/I-125 was ineffective in radioiodination efficiency. The Chloramine-T radiolabeled antibody was found to be stable for 30 days when stored at 4oC. Also radioiodination using Iodogen was studied at different Iodogen concentrations (0.1&0.2 mg/ml) and Dichlromethane volumes (0,200&400 ml). According to the obtained results, the appropriate amount of Iodogen and Dichlromethane were obtained to be 0.1mg/ml and 200μl. But Iodogen radiolabeled antibody showed poor immunoradioactivity and stability after two weeks. The results show that the Chlroamine-T procedure is more suitable than the Iodogen method, so the Chloramine-T radiolabeled antibody could be used as a tracer in IRMA system for quality control of in-house PSA kit. By studying the results of t-Test analysis, the decision criteria (sig 2-tailed= 0.993) and confidence interval (95%), it can be seen that the values are well correlated.

In this paper, the process of crystal selection, samples preparation and method of shottkey and ohmic contacts creation for CdZnTe or CZT detector, to be used as a portable device operating at room temperature, have been reported. First, the ratio of CZT element and crystal dimensions was determined via MCNP4C code and its effect on the electrical and detection behavior was investigated. After the crystal preparation, its surface was activated by chemical method. On one side, Au with a thickness of 100nm was coated as a schottkey contact and on the other side, in was coated as an ohmic contact with physical vapor deposition. The electrical characters of the sensor such as current-voltage, current-capacitance and current-temperature were measured. The sensor was connected to a pre-amp, pulse shaping, amplifier and MCA. The detector was tested by point sources of Cs-137 and Th-232, and was calibrated by standard uranium samples. The results showed that the FWHM of 662 keV is 3.8 keV and the error for the enrichment determination was less than 3%.

In this paper, the effect of ArF excimer laser (193 nm) irradiation on CR-39 polymers was investigated. The polymers were divided into three sets. The first set of polymers was irradiated with ArF laser below the ablation threshold fluence and the second set was irradiated above the ablation threshold fluence with different number of pulses. The third set of polymers was irradiated with ArF laser (below the ablation threshold fluence) and then was exposed to alpha particles emitted from 241Am. After that, the samples were chemically etched in a 6.25 N NaOH solution. The morphology of the samples was investigated by a scanning electron microscope (SEM) and the registered tracks of alpha particles were investigated using an optical microscope. The results showed that worm-like structures and several cones were formed on the polymer surfaces due to laser irradiation and also the tracks diameter was decreased. So, the surface of the polymer was hardened due to irradiation.

In this research, the PR-IR50 polywell device is introduced and its physical processes are simulated using the OOPIC code. The results of the simulation showed that the device reveals special characteristic features for energy particle trapping, and the nuclear fusion is feasible by it. In addition, the nuclear fusion rate, with and without reflective plates, has been studied. The results proved that this rate, in the presence of the plates, is almost doubled compared with the case when the plates are absent. This increase is due to the reflection of electrons on the inner section of the device, reduction of particle loss, and the increase in density of ions and electrons in the center of the device. The derived results corresponding to this research may be useful for optimization of polywell devices.

In this research work, target performance under different spike pulse(s) time behavior is studied. It is shown that by applying two equal spike pulses with appropirate time delay, leads to enhancement of the target gain and reduction of the total ignitor energy. The lower spike energy is required for the lower total driver energy to be used for commercial energy production. Two trapezoidal pulses with 50 picoseconds rise time, different power levels, pulse duration, launching and delay time have been applied on a HiPER baseline target. A one- dimentional simulation by MULTI code has shown that the figure of merit for a double shock ignition scheme varies in a range of 1.1<FM<1.7. The FM>1 demonstrates that for the same compression energy the splitting of the ignitor pulse into two equal lower energy pulses has more benefit compared with the conventional method of shock ignition.

In this work, Lithium-Aluminum-Silicate (LAS) scintillator glass as a host for Tb activator, was prepared in order to reach the visible emission by UV, Gamma, X-Ray and charged particles excitation. The glass was made from 31 wt% LaF3, 12.3 wt% Li2O, 8.7 wt% Al2O3, 48 wt% SiO2. The forming methods were melting and casting. The Photo Luminescence spectra (PL) of the samples at 259 and 325nm wavelenghts were obtained. The absorption spectrum of the Tb bearing system showed peaks at 325, 436, 460, 490, 545, 414nm, corresponding to Tb energy levels, but in the case of Gd bearing system, because of the optical effects of light-activated factors such as the stacking fault in the glass, the energy transfers below 300nm were weakened. The energy transfer from Gd to Tb was not observed. Compared to the glass system, the PL emission of the glass ceramic increased significantly (80%). The samples’ PL response to beta, X-rays, and neutron, were also evaluated. It was shown that both glass and glass-ceramic have acceptable responses to X-rays and beta radiation. The glass-ceramic sensitivity was higher than that of sheer glass; also it was shown that the noutron response of the samples was negligible, presumably because of the lack of reached Li in our glass used.

In this study, the effects of process parameters including weld current and electrode force on the microstructure of resistance spot welding on Zr-1%Nb alloy sheets of 0.3mm thickness were investigated. In the microhardness investigation of the weld nugget cross section, the Vickers hardness measurement was performed in the direction of the weld nugget diameter on a base metal, HAZ, and weld nugget for the welded specimens with different parameters. Applying more electrode force in the same welding time yielded the grain growth which was found to be an important observation in this study. In the metallographic images, it was observed that the grains were deformed to be longer in the heat flow direction when more electrode force was applied. The hardness measurement of the weld zones and base metal showed that, the weld nugget had a maximum amount of hardness where it decreased in HAZ and subsequently in the base metal. This difference is due to transformation of the a+b and b phases. Transformation from b to a phase, which was carried out by a massive diffusion process and formation of the Widmanstatten a structure was achieved by slow cooling. The mentioned structure was found to be harder and stronger than the equiaxed a microstructure of the weld metal.