Document Type : Research Paper
Authors
- Reza Bagheri 1
- Abolfazl souri 2
- Nader Sheikh Moghaddasi 2
- Mohammad Hossein Salamatbakhsh 2
- Iraj Moradi Gharatloo 2
- Michael Yeganeh 2
- Seyed Pezhman Shirmardi 2
1 Radiation Application Research School, Nuclear Science and Technology Research Institute, AEOI. Tehran, Iran.
2 Radiation Applications Research School, Nuclear Science and Technology Research Institute, AEOI, Tehran, Iran
Abstract
In this research using the MCNPX code, calculations were done for nuclear designing of portable two-chamber gamma irradiator facility for irradiation of grains and legumes according to international standards. Calculations were made in two parts of dose uniformity ratio and mass flow rate of the irradiated product, as well as gamma-ray shielding using 100 kCi Cobalt-60 line sources, model GIK-A6m of Mayak Co., Russia. The dose uniformity ratios of internal and external irradiation chambers were found to be about 1.77 and 2.18, respectively. Also, the mass flow rate of an irradiated typical grain with bulk density of 800 kg m-3 was calculated to be about 3.2 ton h-1. A typical grain will receive a dose between 300-656 Gy, which is less than the maximum recommended limit of absorbed dose for grains and legumes (1 kGy) in purpose of shelf-life extension and insect disinfestation by the IAEA. According to ANSI/HPS N43.7, the leakage dose rate at a distance of 5 cm far from the surface of the irradiator in the irradiate mode and for restricted areas, was calculated to be less than 200 µSv/h (maximum permissible radiation level). The results showed that the lead shield of irradiator facility with maximum thickness of 29 cm, easily blocks the emitted gamma rays and working with such a facility would not pose any radiation risk to the employees. Finally, the energy efficiency of the facility was estimated to be about 25% with an increase of about 10.5% due to the addition of external chamber.
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