Effects of the interruption of the irradiation process on PMMA Harwell Industry Dosimetry Systems

Nowadays, the use of dyed-polymethylmethacrylate dosimetry systems in measurements at industrial irradiations has been broadly, despite the use of alanine dosimeters. Accurate dosimetry measurements are essential for the sterilization applications of medical products as well as the preservation of food by ionizing radiation. Regulations in many countries require in-plant dosimetry to ensure that the specified radiation dose has been delivered to the product. Harwell commercial dosimeters commonly are built to work with measurements between 1 kGy to 50 kGy, this means that a same dosimeter could be used until reach these values. Radiation processing demands partial measurements of the absorbed dose to guarantee the final desired applied absorbed dose depending to the dose rate. In this sense, the total absorbed dose corresponds to the cumulative partial values. In this study, several dosimeters were irradiated at the Multipurpose Gamma Irradiation Facility at IPEN - CNEN/SP to evaluate the response to the interruption of the irradiation process in the total cumulative absorbed dose values considering statistical changes and some processing parameters. When studied the Harwell dyed-polymethylmethacrylate dosimeters Red 4034 and Amber 3042, applying processing interruptions, results shown a coefficient of variation under 7% for industrial irradiation conditions to the total cumulative absorbed dose. (author)