عنوان مقاله [English]
نویسندگان [English]چکیده [English]
SVHI-Co-60-T irradiation system has been used as a portable one with Co-60 source for onion irradiation. To optimize and for the change of the system application, sufficient knowledge of the absorbed dose of the products is necessary. In this paper, the absorbed dose in the irradiation chamber is calculated for different points using MCNP4C code and then the results are compared with the measurements by the Red, Amber and Clear dosimeters of the Radiation Application Research School, along the central line of the chamber. The values obtained from dosimeters are in good agreement with the code results. The dose distribution in the irradiation chamber has been calculated on a plane with dimensions of 60cm×30cm. The minimum and maximum dose rates and the dose rate at the center of the same dose area of the isodose curve are 0.3kGy/hr, 2.6kGy/hr and 1.25kGy/hr, respectively. Also, the dose rate measured in the central area of the chamber using Red, Amber and Clear dosimeters is 1.37kGy/hr, 1.303kGy/hr and 1.302kGy/hr, respectively. Differences between the calculated dose using MCNP4C code and the measured dose emplaying three types of dosimeters are 8.7%, 3.8% and 3.8%, respectively. After loading, the spacers have been designed in front of new sources with MCNP4C code to have suitable dose with a uniform ratio to change its application from onion to wheat irradiation and also to compare with the measurements.
1. B. Whittaker, The Influence of Dose Rate, Ambient Temperature and Time on the Radiation Response of Harwell PMMA Dosimeters, Radiation Physics and Chemistry, 60 (2001) 101-110.
2. S. O’Keeffe, C. Fitzpatrick, E. Lewis, A Review of Optical Fibre Radiation Dosimeters, Sensor Review, 28(2) (2008) 136–142.
3. OAK Ridge National Laboratory, Monte Carlo N-Particle Transport Code System, Los Alamos National Laboratory (2000).
4. J.K. Shultis, R.E. Faw, An Mcnp Primer, Dept. of Mechanical and Nuclear Engineering Kansas State University (2006).
5. International Atomic Energy Agency (IAEA), Gamma Irradiators for Radiation Processing, Vienna (2002).
6. IAEA, Dosimetry for Food Irradiation, Technical Reports Series No. 409 (2002) 40.