Feasibility of using ¹³⁷Cs in gamma irradiators for food processing

A study was carried out on using ¹³⁷Cs as source for panoramic gamma irradiators. At present all gamma irradiators of Category II and IV (Radiation Processing Plants) in India are using ⁶⁰Co as the radiation source. If ⁶⁰Co is to be replaced by ¹³⁷Cs, to maintain the same throughput from a radiation processing plant, the activity requirement is 4 times that of ⁶⁰Co because of the characteristics of ⁶⁰Co and ¹³⁷Cs. Such large activity can be accommodated in two ways. 1). By using ¹³⁷Cs pencils of very high specific activity, maintaining the no. of pencils. 2). By using more no. of ¹³⁷Cs pencils with low specific activity. Feasibility of utilization of available ¹³⁷Cs in the Department of Atomic Energy (DAE), India without many changes in the existing irradiator designs is also considered in this study. For this, designs of two existing radiation processing plants are taken 1) for medium/ high dose products and 2) for low dose products. The dimensions of the ¹³⁷Cs pencils are optimized and the effective activity per pencil was evaluated considering self absorption losses. Throughput of the plants is estimated for ¹³⁷Cs pencils and a comparison is done with ⁶⁰Co source pencils. This paper discusses the details of the study. (author)