نشریه تابش و فناوری هسته ای
سال چهارم شماره 2 (تابستان 1396)

Humans are usually exposed to ionizing radiations. Quantity of this radiation depends on kind of rocks, soils and geographical zone. In this research investigated radioactivity and radiological parameters of igneous rocks of Alvand zone in Hamadan in 400 hectares area. Annual Gonadal Dose Equivalent (AGDE) for samples varied from 126. 11 ± 3. 45 to 1984. 25 ± 28. 43 with average 639. 90 in µSv/y that is more than world average (416. 35). Excess Lifetime Cancer Risk (ELCR) for samples calculated which are in range (1. 27-0. 07) ×10-3 with average of 0. 41× 10-3. For all samples except sample with PGG (W) code are less than maximum acceptable value. Mean of ELCR for samples is more than world average. The I7 value for studied samples in this research varied from 0. 27 to 4. 53 with mean 1. 45 which for most samples are more than unity. For safety the region, this quantity should be less than one. The results of this study show that the amount of gamma rays is not safe for population.

Pressure investigation of air reactor containment at LOCA accident and sensitivity to inside and outside temperature of the reactor containment, include significant issues in the design of safety systems. In this study, the governing equations of different phenomena inside the reactor containment after accident has been modeled using visual basic. Following the results of modeling and sensitivity of temperature and pressure inside the BNPP containment is discussed, that represents insignificant effects of air changes in inside and outside temperature reactor containment on the pressure and temperature of the mixture of air and liquid is circuits caused by the accident.

The present article is a thermal–hydraulic analysis of the nanofluid in HPLWR fuel assembly. The High-Performance Light Water Reactor (HPLWR) is the European version of the Supercritical-pressure Water Cooled Reactor (SCWR). Light water reactors at supercritical pressure, being currently under design, are the new generation of nuclear reactors. Supercritical water cooled reactors (HPLWR & SCWR) are essentially light water reactors (LWRs) operating at higher pressure and temperature. HPLWRs achieve high thermal efficiency (i.e., about 45% vs. about 35% efficiency for advanced LWRs) and are simpler plants as the need for many of the traditional LWR components.The governing equations include energy, mass and momentum equations beside thermal–hydraulic equations are solved numerically using the finite volume (upwind) method. Thermal hydraulic results using nanofluid in coolant and moderator channel are discussed and compared to pure water results. The achieved results show that the Al2O3 with volume fraction less than 0.1 percent is the optimum case.

A fundamental knowledge of fuel behavior in different situations is required for safe and economic assessment nuclear power generation. Analysis of nuclear fuel pellet rim region is most importance, due to excessive fission gases release, reduce conductivity and high burnup in this region compared to inside regions the pellet. Due to the importance of a fuel rod behavior modelling in high burnup, in this study, the radial distribution of fission products, burnup and actinides atom density and their variations by increasing burnup and other factors such as temperature, enrichment and power density are studied in a fuel pellet of a VVER-1000 reactor in an operational cycle using the MCNPX 2.7 Monte Carlo code. To calculate the radial distribution of temperature and analyze the impact on burnup, the program was written in FORTRAN, which uses heat transfer relationship to investigate the behavior of fuel. The results, has been shown ability to do radius calculations with the model presented in MCNPX2.7 and mentioned program.

With industrialization of countries and increasing concentrations of various pollutants in the environment, developing new technologies especially nuclear technology such as ionizing radiation has been proposed for removing of environmental pollutants. In development of new methods have both conditions economically feasible and environmentally friendly. From the ionizing radiation, gamma and electron beam radiations may be used to removing contaminants and refinement of water, sewage effluent and sludge. The use of electron beam radiation for treatment and disinfection of water or effluent on industrial scale is preferred to gamma radiation due to its advantages such as generating high levels of free radicals in time, lack of replacement costs and reducing annual activity radioisotope’s gamma source, no radioactive source, comfortable control in emergencies, repairs, maintenance and switching on and off immediately. Most laboratory studies of ionizing radiation, are done by using gamma radiation especially cobalt-60 source due to ease of using gamma ray Application of ionizing radiation on industrial scale has been growing in recent years in the world. With the construction and operation of the treatment plants in Iran, the production capacity of wastewater and sewage sludge and the necessity of their safe using as fertilizer or water resources have been increased in agricultural crops. On the other hand, by implementing Joint Comprehensive Plan of Action (JCPOA) with the leading countries in laying the groundwork is inevitable to carry out research, design and construction of irradiation systems for disinfection of wastewater and sewage sludge on industrial scale.

Neutrons have many applications in various fields, such as industry and medicine. In nuclear facilities, and especially in electricity production, we are faced with such radiation. Because of this, determination of neutron dose is critical for the health of workers and patients exposed to this beam. The neutron radioisotope sources produce gamma rays in addition to the neutron, and the neutron fields around these sources are mixed-field neutron-gamma fields. Different methods of dosimetry of the neutron field include the method of gold foil activation and the method of using a thermoluminescence dosimeter pair. One of the effective ways of neutron dosimetry is the use of the TLD-600/700 thermoluminescence dosimeter pair. The TLD-600 is sensitive to thermal neutrons due to the richness of 6Li (which has a high thermal neutron absorption cross section) but the TLD-700 does not have thermal neutron sensitivity in low fluxes. In this paper, to measure the neutron dose from the Ra-Be neutron source in the core laboratory of the Faculty of Science of the University of Guilan, six TLD-600/700 dosimeters were used in three intervals of 7, 14 and 20 cm from the source. Finally, by calculating the neutron dose through the source flux and estimating the calibration coefficient, the dose rate measured by the TLDs was determined and compared with the calculated dose rate.