INTRODUCTION AND OBJECTIVES:

The self-contained dry-storage gamma 60Co irradiator, Gammacell-220, was manufactured by MSD Nordion. It arrived at our Institution (CNEA) in 1965 with around 13000 Ci and a dose rate of 10 kGy/h. The 60Co sources are shielded and double encapsulated in stainless steel tubes fixed in the bottom of the irradiator.

The chamber irradiation is a cylinder of 20 cm of high and 15 cm of diameter.

The irradiator can be used in many radiation processing applications, like dosimetry system calibration, research on biological and microbiological samples, irradiation of seeds, soil and botanical samples, etc.

The main purpose of this work is plotted the isodose curves of the irradiator after reloading with 7500 Ci of 60Co sources by Dioxitek Company in year 2022.

PROCEDURE:

For the isodose curves 5 plates of PMMA containing 25 alanine dosimeters pellets in each were irradiated. The alanine dosimeters were distributed one in the center and 8 dosimeters in three different radios and irradiated one hour at 5 kGy/h.

The dose were measured in an ESR e-scan, manufactured by Bruker.

Isodose curves (Fig. A) were plotted with Surfer 13 program.

Fig. A  Isodose curves                               

CONCLUSION:

The isodose curves showed that the source activity distribution during the recharge was very homogenous.

The dose uniformity radio (UR) is the same as the original given by MDS Nordion, which value is 1.50.

REFERENCES:

-ISO-ASTM-51607: 2013- Alanine-EPR dosimetry system.

-ISO-ASTM-52116: 2013- Dosimetry dry storage gamma facility.