JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY
Year:2012 | Volume:- | Issue:1 (59)|Papers Count:15

In this study the radio iodination process of meta-iodobenzylguanidine with 131I isotope in presence of ammonium sulphate and Cu (II) Catalyser was investigated. In order to optimize the process, the influence of different parameters on labeling yield was studied. The results of experiments showed that the use of oil bath with temperature of 160oC is necessary. After the labeling process, purification step of the final product was carried out using Dowex-1x8 resin. The mean labeling yield was 97.2%. In this method radiolabelling of MIBG with 131I (185 MBq for diagnostic dose and 3330 MBq for therapeutic dose) is quite simple and it complies with the requirements of routine production of 131I-MIBG radiopharmaceutical for diagnostic and therapeutic purposes. This paper is a narration of industrial scale production of 131I_MIBG radiopharmaceutical.

Finite element and Monte Carlo are two basic and useful methods in numerous modeling and simulation codes. Charged particles transport in electric and magnetic fields based on these methods is the feasible manipulation of some software. There are, however few codes that have the ability of explaining the secondary radiation transport resulting from the movement of the charged particles in a magnetic field. FLUKA, for example, is known to be one of them. In this paper, a modeling and the simulation process using the FLUKA code for the survey of the synchrotron radiation of the electron are presented. The results found to be in agreement with those predicted by the known theoretical approach. The analysis of the synchrotron radiation of the output photon beam and the beam energy reduction are the basic results of the present work. For this investigation a specific field card MAGFLD and a USRBIN card have been applied.

Optimization of the fuel burn up is an important issue in nuclear reactor fuel management and technology. Radial enrichment distribution in the reactor core is a conventional method and axial enrichment is constant along the fuel rod. In this article, the effects of axial enrichment distribution variation on neutronic parameters of PWR core are studied. The axial length of the core is divided into ten sections, considering axial enrichment variation and leaving the existing radial enrichment distribution intact. This study shows that the radial and axial power peaking factors are decreased as compared with the typical conventional core. In addition, the first core lifetime lasts 30 days longer than normal PWR core. Moreover, at the same time boric acid density is 0.2 g/kg at the beginning of the cycle. The flux shape is also flat at the beginning of the cycle for the proposed configuration of the axially enrichment distribution.

The knowledge of concentration of elements in foodstuffs is of significant interest. Wheat is one of the most consumed food stuffs in Iran and zinc is also considered as one of the necessary and vital elements. Since the measurement of some trace elements is not practical by the conventional analytical methods, due to the lower detection limit, the neutron activation analysis (NAA) was applied to determine the zinc in wheat and wheat bran. Food sample of roughly 50 mg was irradiated for 24h. After cooling, the interval samples were counted by a gamma spectrometry system. The concentration of zinc in wheat without bran and the wheat bran were 18.444±0.656 and 19.927±0.698 ppm, respectively. The amount of zinc in wheat bran was noticeable so it showed that consuming wheat with bran is more beneficial than the wheat with no bran for the human-beings' body requirements.

The amount of cosmic rays varies widely with the altitude, latitude and longitude in each region. In this study, the radiation doses due to the cosmic rays were estimated in two steps: in the first step, the neutron and gamma components of the radiation dose were measured for a roundtrip flight on 3 flight routes (Shiraz-Asaluye, Asaluye-Rasht and Shiraz-Mashhad) using a gamma-tracer photon detector and a Thyac 190N, neutron detector. The minimum values of the measured gamma and neutron doses of 0.15 and 0.04 mSv were measured on the Asaluyeh-Shiraz route at the lowest altitude of 19000 ft, while for Rasht-Asaluyeh route at an altitude of 35000ft those values were found to be 2.52 and 1.09mSv, respectively. In the second step, a number of aircrew members were equipped with thermoluminescence dosimeters (TLD cards) for evaluating the gamma dose and polycarbonate dosimeters (SSNTD) for assessing the neutron dose for one year. The measured value of the annual effective dose received by the crew ranged between 0.5 mSv/y and 1.16 mSv/y, with an average of 0.9 mSv/y for the gamma component and between 0.37 mSv/y and 0.77 mSv/y with an average of 0.61 mSv/y for the neutron component. The results of this investigation are comparable with the investigations that have been conducted in other countries. For instance in UK, the reported annual effective dose of aircrew is about 2mSv, and in Canada, it is estimated to be between 1 to 5mSv, depending on the flight situations (such as the latitude and longitude of the cities, the flight altitude, etc).

In this study antifeedant effect of different doses of gamma radiation as a controlling safe method on flour weevil, Tribolium castaneum (Herbst) larvae and adult was studied. Doses of 100, 400, 600, 800 and 1000 Gy of gamma radiation were used and after 72 hours, nutritional indices were evaluated. The relative growth rate (RGR), relative consumption rate (RCR), efficiency of conversion of ingested food (ECI) and feeding deterrence index (FDI) as nutritional indices were evaluated. Treatments were assessed by flour wheat disc at 27±1oC and 65% humidity in a dark condition. The results showed that the relative growth rate of flour weevil larvae and adults decreased significantly (P<0.05) by gamma radiation and the severity of this reduction in larvae was higher than the adults. Although the relative growth rates decreased in adults, this rate in doses of 400, 600, 800 and 1000 Gy showed no significant difference. The relative food consumption rate also decreased with the gamma radiation and its value found to be inversely proportional to the dose radiation. Our experiments showed that the use of gamma radiation exposure to 800 Gy had no significant effect on the efficiency of conversion of ingested food of larvae and reduction was observed only when the gamma radiation was used in 1000Gy. The feeding deterrence effect of gamma radiation, especially on the larvae was high but no significant difference between doses of 100 to 800Gy was observed. The results showed that gamma radiation that induces antifeedant effect can be applied as an effective method in control of T. castaneum.

The finite element method is applied to the spatial variables of multi-group neutron transport equation in a two-dimensional cylindrical (r, z) geometry. The equation is discretized using rectangular sub regions in the (r, z) plane. The discontinuous method with the bilinear or biquadratic Lagrang’s interpolating polynomials and basis functions is used in the ANSYS program. Here, the angular fluxes are allowed to be discontinued across the sub region boundaries. Some numerical calculations have been made on a real cylindrical Aristotle reactor with different fuel concentrations on the fuel rods; the results indicate that the flux and power of the heterogeneous critical reactor increase on the edges of the core in comparison with the homogeneous one.

This paper presents the design and construction of an apparatus in an RF ion source for automatic impedance matching between variable impedance environment (plasma) and fixed impedance system (an RF power generator) in order to transfer a maximum power to the plasma. The apparatus includes a matching box, a directional coupler and a balanced antenna associated with a transmission line transformer (TLT). The constructed automatic matching system is very simple and at the same time is capable of functioning under different conditions of the gas pressure to ensure a good performance. The matching network is mainly designed in order to be used in the first electrostatic accelerator designed and constructed in NSTIR, where the RF ion source is placed in the HV terminal, where there is no access to a manual matching box during the operation. The measured output current of the ion source is about 700 mA with 200 WRF power input in the working frequency of 70MHz. The output current of the previous ion source current could not exceed 200 mA under the same condition (10-2 Torr) without employing the present matching system. The system is capable of reaching an optimum VSWR point of about 1.2 in the pressure range of 10-1 to 10-4 Torr. This can be realized in a short matching convergence time (i.e., couple of seconds).

In operation of nuclear power plants, significant amounts of radioactive wastes are produced annually so that it is necessary to determine special ways for transportation and disposal of the radioactive wastes. According to the related standards, containers for transportation of radioactive materials should be designed in such a way that the equivalent dose rates on the outer surface and at a distance of 2m from the container do not exceed 2 mSv/hr and 0.1 mSv/hr, respectively. The purpose of this research is to design a radiological shielding for containers to transport the group II radioactive wastes of Boushehr Nuclear Power Plant. The dose distribution calculations and the container design were implemented through the Monte Carlo method using MCNPS code. The code was run by the use of 8 processors in a parallel way. The total activity of one drum and inventory density were estimated to be 4.248 Bq and 2000 kgr/m3, respectively. A steel drum with a dimension of 79.5 cm in height, 28.55 cm of radius and 0.3 cm in thickness was filled with the cemented inventory. The dose distribution for the bottom rest wastes was calculated. The simulation result showed a value of IS.67 mSv/hr for the equivalent dose rate on the surface of the drum. The result was 10% higher than the FSAR prediction. In order to decrease the dose rate, 3 leaden packages with 4 drums in each were put on the trailer for the transportation. The suitable lead thickness for reducing the equivalent dose rate in order to meet the required standards for the lateral parts, floor and top were 2.2 cm, 2 cm and 1.5 cm, respectively. With this calculated thickness, the equivalent dose rates on the surface and at a distance of 2 m from the surface were 550 mSv/hr and 94 mSv/hr, respectively.

A dramatic increase in the world-wide demand for energy requires to design nuclear reactors with high efficiency. The requirement for a high efficiency reactor necessitates using high pressure and high temperature designs. Because of the high temperature operation in the new generation of nuclear power reactors, ferritic/martensitic steel is unanimously considered to be the most suitable metal for the reactor design. In this research, by melting in a induced furnace, ferritic/martensitic steel was produced and then the micro-structures of the sed were investigated by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The mechanical properties of these types of steel at different temperatures were investigated with the tensile and impact tests. The fractography investigation has also been conducted with the SEM. The results showed that in the As-cast form, the structure involves binate ferrites that after the heat treatment change to the martensitic structure. The maximum hardness was obtained in the quenched and normalized conditions. The mechanical properties in the NT form are better than the QT form. The ductility in these types of steel reduces by increasing temperature up to 400oC, and then it improves by increasing the temperature.