mohammadhossein choopan dastjerdi

The body absorbs trace elements from food, which can have positive and negative effects depending on their type and amount. The study aimed to determine the amount of trace elements found in different varieties of Iranian rice and imported varieties. The concentration of trace elements in rice samples was measured by neutron activation analysis and inductively coupled plasma (ICP-AES). Elements concentrations (mg.kg-1) were determined for aluminum (2.92-9.16), arsenic (0.064-0.156), bromine (0.24-5.20), calcium (102-981), chlorine (132-323 ), chromium (ND -20.4), lead (ND-0.232), cadmium (0.010-0.115), scandium (0.001-0.007), magnesium (262-519), manganese (2.97-18.50), sodium (3.99-14.30), mercury (ND- 0.002), zinc (2.62-23.60). This study found that Indian rice contains higher levels of bromine, calcium, and sodium, while Pakistani rice contains higher amounts of aluminum, chlorine, lead, and mercury. Shirodi rice is known to have higher levels of arsenic and magnesium, Tarem Hashemi rice has been found to contain higher amounts of chromium, manganese, and zinc, and cadmium is found in Sadri rice. However, the amount of toxic elements in all types of rice does not pose a significant threat to human health.

New nitrile butadiene rubber (NBR) materials are being considered to use for neutron shielding especially for the positions which needs a flexible neutron shield. Such light, low-cost, and suitable material could be used for sealing of the gaps or even for shielding of low radiation environments. In the present work, experimental investigation of NBR shielding performance of neutrons and gamma rays was proposed using the beam line of the Isfahan Miniature Neutron Source Reactor . MCNPX code was used to simulate the 30 kW research reactor beam line. Six NBR sheet with 2 cm thickness were used at the outlet of the beam line respectively to measure its neutron shielding as well as gamma shielding power on thickness. The experiment situations were modeled using the computational code. The obtained results showed the flexible and cheap material could be used as a good neutron shield while it acts as a very weak shield for gamma rays too. Also there is good conformity between simulation and experimental data with maximum 37% relative discrepancy.

In the present work performance of film badge as an alternative personal dosimeter for thermal neutrons is investigated. To do this, a cadmium-lead (Cd-Pb) filter with the same thickness as the tin-lead (Sn-Pb) filter is attached to the AERE/RPS badge. Since thermal neutrons are mixed with gamma rays, the dosimeter is irradiated by the 60Co gamma rays standard field of Karaj Secondary Standard Dosimetry Lab as well as the mixed neutron-gamma field of the radiography beamline of Isfahan Miniature Neutron Source Reactor. In the both fields, ten personal dose-equivalent values between 0.1 to 10 mSv are chosen. For any dose, three film badges are used and the net optical density is determined as the average of their optical densities. Finally, the calibration curves of the film badge are plotted to determine the dose-equivalent values. Obtained results reveal that film badge simultaneously determines the thermal neutrons and gamma rays dose fractions. Also, the thermal neutron doses are at most 50% different from the nominal values considered.

Technetium is one of the most important radioisotopes recognized in medicine which is obtained through ‎the decay of molybdenum 99.The half-life of this radioisotope is 6 hours and it is capable of 140 kev gamma ray emission. Due to its short half-life, this radioisotope must be produced at the site of consumption, so that the shortest possible time interval between production and consumption can be achieved. The aim of the present study was the neutronic ‎evaluation of the amount ‎of 99Mo-99TC production through nuclear fission in the Tehran research reactor. The primary core ‎of the reactor with the code MCNP X 2.6 was simulated and neutron flux was assessed in 6 locations. ‎Then, the fuel plate was placed at the site with the highest neutron flux. In different phases, changes ‎were made in the enrichment of fuel. Moreover, the amount of molybdenum produced in each phase was ‎calculated. Based on the results, the amount of‎ molybdenum produced, and thus,‎ the amount of ‎technetium were the highest in the 20% enriched fuel.